Gold in Paleoproterozoic (2.1 to 1.77 Ga) Continental Magmatic Arcs at the Tapajós and Juruena Mineral Provinces (Amazonian Craton, Brazil): A New Frontier for the Exploration of Epithermal–Porphyry and Related Deposits

This review paper aims to integrate geological, tectonic and metallogenetic data, including new data, and propose a regional model for the gold (and base metal) mineralization in the south Amazonian Craton to support the mineral exploration concerning magmatic–hydrothermal deposits. The Proterozoic evolution of the Amazonian Craton comprises the accretion of terrains to the Archean Carajás Mineral Province. In the Tapajós and Juruena mineral provinces, located at the south part of the Amazonian craton, a long-lived ocean–continent subduction event produced ca. 2.0 to 1.77 Ga continental magmatic arcs. Extensive lava flows, volcaniclastic, sedimentary, and plutonic rocks were originated during at least four major orogenic magmatic events (ca. 2.1, 1.9, 1.88, and 1.80 Ga) and two post- to anorogenic events (ca. 1.87 and 1.77 Ga). Gold mineralization occurs in: (i) alluvial/colluvial occurrences, (ii) orogenic carbonate–sulfide-rich quartz veins in shear zones, (iii) stockworks, veins, and dissemination in granites, (iv) contact of basic dikes, (v) well-preserved high-, intermediate- and low-sulfidation epithermal mineralization, and (vi) porphyry-like and intrusion-related gold systems associated with late- to post-orogenic epizonal granites. The estimated historical gold production, mainly in secondary deposits, is over 27 Moz at the Tapajós and 6 Moz at the Juruena provinces. A total resource of over 5 Moz Au is currently defined in several small to large primary gold deposits. Andesite to rhyolite, volcaniclastic, and clastic sedimentary rocks (1.96–1.88 Ga) host epithermal (high-, intermediate-, and low-sulfidation) Au–(Ag–Pb–Zn) mineralization, whereas Au–Cu and Cu–M–Au mineralization is hosted in sub-volcanic tonalitic to granitic plutons. Advanced argillic alteration (alunite, pyrophyllite, enargite) associated with high-sulfidation mineralization occurs in ring volcanoes around nested volcanic calderas. This zone grades outward to propylitic or chlorite alteration, often covered by silica caps with vuggy silica. Lava flows and volcaniclastic rocks within faults or associated with volcanic edifices and rhyolitic domes host low- and intermediate-sulfidation mineralization. Low-sulfidation alteration zones typically have adularia and illite or sericite. Chalcopyrite, sphalerite, galena, pyrite, digenite, and manganiferous calcite are related to intermediate-sulfidation gold mineralization. Late- to post-orogenic evolved oxidized I-type granitoids host alkalic-type epithermal and porphyry-like gold mineralization. Porphyry-style hydrothermal alteration is analogous to those of modern systems, with inner sodic and potassic (potassic feldspar ± biotite or biotite) alterations grading to propylitic, muscovite-sericite, chlorite–sericite, and chlorite alterations. Potassic alteration zones are the locus of Cu–Mo mineralization, and gold-rich zones occur in muscovite/sericite–quartz–pyrite alteration. The Paleoproterozoic epithermal and porphyry-like mineralization in these large provinces defines a new frontier for the exploration of world-class gold deposits in the worldwide Proterozoic arc-related magmatic terrains.


Introduction
The Tapajós and Juruena (or Alta Floresta) mineral provinces have been responsible for decades of significant Brazilian gold production. Gold was discovered in the Tapajós in 1958 in alluvial deposits of the Tropas river [1]. Between 1970 and1990, the Tapajós region has become the largest gold producer in Brazil, with up to around 100,000 manual miners ("garimpeiros") working in hundreds of small mines in placers, paleoplacers and colluvial deposits. With the exhaustion of many of these secondary deposits and governmental controls on environmental degradation caused by artisanal mining, the production declined, opening opportunities to the mineral exploration of primary deposits by mining companies. At the Juruena Mineral Province (JMP), the gold occurrences were discovered in 1978, initially in alluvial placers due to the construction of the BR163 federal highway [2]. Dozens of small-size (usually <5 t Au) and high-grade gold placers and granite-hosted veins and disseminations have been exploited by artisanal prospectors or mining companies, the majority of them without geological studies and previous resource measures. Conservative estimates indicate a gold production of at least 900 t in the TMP and 250 t at the JMP until today in secondary deposits and few small high-grade quartz-sulfide lode mines.
The challenging access due to the rain forest and few roads, the geological knowledge only on a regional scale, few metallogenetic studies, and the lack of a clear definition concerning the Paleoproterozoic tectonic environment and petrogenesis precluded the preposition of comprehensive metallogenetic models for gold and copper-molybdenum mineralization. For many years, the ca. 1.88 Ga felsic magmatism of the TMP was considered exclusively as related to post-orogenic to intracratonic A-type magmatism [3][4][5][6][7][8] with only a major potential to tin deposits. This interpretation excluded the possibility of subduction-related magmatic-hydrothermal ore deposits, especially the epithermal and porphyry types, despite the presence of calc-alkaline andesite, rhyodacite, dacite and rhyolite units of such age. Besides this, a large number of gold occurrences and small mines, spatially related to ca. 2.1 to 1.88 Ga volcano-plutonic rocks at the TMP, and until ca. 1.77 Ga in the JMP, led the proposition of distinct metallogenetic models for the gold mineralization in both provinces. The pioneering studies proposed ore-forming processes linked to "mesothermal and epizonal" orogenic [1,[8][9][10] and intrusion-related [1,11] deposits post-or later than the ca. 1.88 Ga A-type magmatic event [1]. With the prevalence of the orogenic gold genetic model for several years, especially at the Tapajós, major and junior mining companies focused on exploring this model during the 1980s to 2000s, but few significant gold resources were found.
Despite the remarkable improvement of the knowledge on the mineral deposits, magmatism, and tectonic evolution of the Tapajós and Juruena mineral provinces in the last decades, rare studies deal with a comprehensive integration of the available data [38][39][40][41].  [46]. Geochronological provinces based on [44]; tectonic domains by [5]. Gravimetry of Solimões and Amazonas basins, with main Bouguer anomaly defined by the blue line (variation from +60 to −70 mGal, hot to cold colors) is from [47].
The NW-SE-oriented Ventuari-Tapajós Province [43,44] is truncated by the approximately E-W-trending Phanerozoic Amazonas basin and is in contact with the Central Amazonian Province (Figure 1) to the west and the Rio Negro-Juruena Province to the south. A strong gravimetric and magnetic anomaly under the Amazonas basin [47], along its axis, was interpreted as related to ca. 570 Ma pyroxenite and Mesozoic intrusive mafic bodies [48][49][50]. Such anomaly was also previously interpreted as a suture between two amalgamated Archean terrains, named Guyana, in the north, and Guaporé (or Central Brazil), in the south [51]. The junction of the north and south blocks in a single NW-SE block was proposed by [52] based on the similarity of the rock ages and mineral occurrences. Consequently, the Ventuari-Tapajós Province is formed by the Ventuari (or Parima) Domain, at the north, and the Tapajós Domain at the south of the Amazonas basin.
The Tapajós Mineral Province (TMP), also named Tapajós Gold Province, comprises the south part of the Ventuari-Tapajós Province (1.9 to 1.8 Ga; [43,44] (Figure 1). It is located at the Tapajós Domain of the Tapajós-Parima Province (2.03 to 1.86 Ga) and in the west region of the Central Amazonian Province (1.90 to 1.86 Ga; [42]). The Juruena Mineral Province (JMP) is the north part of the Rio Negro-Juruena Province [43,44] and is located between the Tapajós-Parima (2.03-1.88 Ga) and Rondônia-Juruena (1.85 to 1.54 Ga) geochronological provinces [5,45]. Scandolara et al. (2017) [53] proposed a new tectonic model for the southern part of the Amazonian craton, in which the Juruena accretionary orogenic belt (ca. 1.81 to from the residual magnetic field, reveals the most likely direction of the mobile belt and older magmatic arcs generated in the southern part of the Amazonian Craton [54].
Additionally, aerogeophysical and gravimetric data and the modeled depth of the MOHO discontinuity reveal deep regional E-W-oriented crustal high-and low-structures under the volcanic units, besides a system of NW-SE and NE-SW-trending major brittle faults, which host A-type granite intrusions [54]. Major tectonic blocks defined by these structures appear to control post-Paleoproterozoic uplifts and the erosion of the supracrustal units, in part due to the Mesoproterozoic collision of the N-S-oriented Araguaia belt at the east border of the Amazonian Craton.

Tapajós Mineral Province (TMP)
In the TMP, to the east of the Tapajós river, the exposed crustal level is gradually shallower. Volcanic units and associated volcanic epiclastic, fluvial, and lacustrine sequences extend eastwards until the São Félix do Xingu area (Figure 2), where the Archean units of the Carajás Province outcrop [46]. showing the location of the main gold deposits and occurrences, main magmatic events and gold mineralization. Yellow-filled squares represent gold occurrences, green-filled squares the copper occurrences, short trace lines limit the Tapajós Province of [5], and the long traces limit of [43]. Light-color geologic base map by [45], detailed lithologic map of TMP of [61] and the JMP map by [58].
In the TMP, fault-controlled gold occurrences are mainly granite-hosted, with less common occurrences in volcanic/volcaniclastic rocks and few in sedimentary sequences. However, gold associated with base metal is also recognized in several volcanic and sedimentary cover areas, particularly where the erosion of the upper sedimentary units exposed the volcanic sequence. This indicates that the TMP delimitation is not defined by metallogenetic controls but by the occurrence of granite-hosted gold mineralized veins, more easily mined by artisanal prospectors.
As originally defined, we consider that the Uatumã magmatic event comprises Atype ignimbrites and rhyolites, including the Moraes Almeida Formation (ca. 1.88 Ga; [3], large NW-SE-and NE-SW-striking felsic dikes, and A-type granites, grouped as the ca. 1.87 Ga Maloquinha Intrusive Suite in the Tapajós to Xingu areas. The Maloquinha A-type granites are relatively common [5], but some intense K-metasomatized shallow-emplaced calc-alkaline rhyodacitic to granitic stocks have also been sometimes incorrectly included in this suite. Paleoproterozoic fluvial and marine units and several mafic intrusions with ages ranging from Paleoproterozoic to Neoproterozoic also occur in the TMP. As summarized by [8] in the west and south part of the TMP, supracrustal sequences and granites are less abundant, predominating diorite, tonalite, and granodiorite, usually with mafic xenoliths, dikes and intrusions of basic and intermediate rocks. Migmatites are also identified. Commonly these units were deformed by faults and underwent hydrothermal alteration. The supracrustal units undergone metamorphism under zeolite to prehnite-pumpellyite facies, rarely reaching greenschist facies conditions. The ca. 2.1 to 1.88 Ga Orogenic Volcanic Rocks in the TMP The orogenic volcanic rocks from different events compose at least three extended magmatic series in the Tapajós Domain and one younger in the Juruena Domain, with geochemical compositions and petrogenetic signatures compatible with Andean-type arcrelated granitoids and volcanic rocks. Moreover, two intraplate A-type granite events are registered, the oldest at TMP and a younger in the Juruena (Figures 1 and 2). The erosional level of the Juruena Mineral Province is relatively deeper, exposing metamorphic units at the central region of the province, with volcanic and volcaniclastic units essentially preserved at the north, south and east areas.
The original area of the ca. 2.1 to 1.88 Ga orogenic volcanic rocks, which vary from andesite basalts to rhyolites, predominating felsic rocks, associated intrusive rocks, and the A-type volcanic and intrusive units, is estimated up to 1,500,000 km 2 [60]. Due to the lack of access, weathering, sparse outcrops and similar macroscopic and petrographic aspects of volcanic and volcaniclastic deposits, the distinction of units from different events, as well the volcanic/volcaniclastic facies, is challenging. Only with intensive geochemistry and geochronology, new volcanic events, volcanic calderas, and eruptive and magmatichydrothermal centers have been identified [15,68,69].
The supracrustal sequences at the Tapajós, particularly those from the last orogenic event, reveal remarkably well-preserved volcanic textures and structures from deformation and metamorphism [70]. Large nested volcanic calderas (up to 50 km in diameter) over or close to large E-W lineaments have been identified in the Tapajós and Xingu areas [15,46,71], as well in the Juruena Domain [62,72].
Extensive eruptions controlled by large NW-SE and NE-SE brittle structures host ca. 1.87 Ga A-type magmatism [60]. However, the stratigraphy, age and distribution of the volcanic centers, and the identification of calderas from different magmatic events in the Tapajós and Juruena domains are only beginning.
In the TMP, the calc-alkaline volcanic sequences include some large ca. 1.89-1.87 Ga nested ash-flow caldera complexes [15,73]. The pre-caldera units are composed of flows and dikes of basaltic andesite and andesite, rhyodacite, dacite, rhyolite, and ignimbrites. Latite, trachyandesite, ash-and crystal tuffs, and acid to intermediate hyaloclastites are also present. The syn-caldera units consist of several large ignimbrite and ash-flow deposits with subordinated rhyolite flows. The post-caldera units include mainly rhyolites and ignimbrites, which form composite volcanoes and domes along with rings and within the calderas. Tuffs, epiclastic sandstone and lacustrine sediments compose the intracaldera deposits. Granophyric stocks and rhyolitic and rhyodacitic porphyry dikes crosscut the volcanic sequence. These volcanic units are interfingered and are partially covered by Paleoproterozoic lacustrine, fluvial and marine sedimentary sequences.
Inferred ca. 1.99 Ga volcanic calderas with similar lithological sequences are also proposed in areas at the north of the TMP, where typical low-to high-sulfidation gold mineralization is overprinted by porphyry-type Cu-Mo mineralization associated with sheeted felsic porphyry dikes [22]. Several rhyolitic domes (ca. 1.97-1.98 Ga) host low-and intermediate-sulfidation mineralization in the south portion of the TMP [26,34].

Gold Mineralization: Distribution and Genesis
Until the final of the 70's decade, gold was mined in alluvial (recent and Tertiary-Quaternary paleoplacers) and eluvial deposits at the Tapajós, with rare known occurrences of primary mineralization [84]. Due to the geological studies by the Geological Survey of Brazil in the Amazonian Craton in the 90's years, [85] identified the relationship of the magmatism with gold lode and stockwork mineralization at the Tapajós. These authors proposed its generation in an intermediate crustal level between those of epithermal and mesothermal environments, and proposed potential to porphyry-type gold occurrences. Santos et al. (2001) [1], in a review concerning of the Paleoproterozoic gold mineralization at the Tapajós and Alta Floresta domains, defined the following deposit types: (1) orogenic, metaturbidite-hosted disseminated and quartz−pyrite veinlets in ductile shears zones in the lower greenschist facies of the Jacareacanga Group; (2) orogenic, mesozonal, hosted by magmatic arc-related plutonic rocks, disseminated in mafic xenoliths and roof pendants and as pyrite−quartz−carbonate veins with up to 50 g/t Au and 1.5% Cu in ductile−brittle shear zones of the Cuiú-Cuiú and Tropas units; (3) intrusion-related or intrusion-centered (as proposed by [86]) epizonal quartz and quartz-pyrite veins and pyrite disseminations in extensional brittle faults, considered as similar to the Koreantype gold deposits; (4) intrusion-related epizonal (as defined by [87]), forming disseminated/stockwork mineralization, sharing some similarities with porphyry-type deposits (e.g., Serrinha deposit; [19,20]); and (5) paleoplacers, predominantly in Paleoproterozoic conglomerates.
According to these authors, most gold deposits were described as granite-hosted and attributed to intrusion-related processes in the TMP, with few occurrences associated with orogenic and only one as an epizonal intrusion-related mineralization. The orogenic gold mineralization timing was uncertain, but it was considered possibly similar to intrusionrelated mineralization [1]. The ca. 1.87 Ga A-type Maloquinha granites were considered the source for the mineralizing fluids or the thermal engine to hydrothermal fluid circulation, and the age of mineralization was defined as 1874 to 1860 Ma. In the JMP, the Serrinha deposit was characterized as the unique typical intrusion-centered disseminated gold deposit [20], but its relationship with the porphyry copper-gold type deposits was considered unclear. Except for this, none of the other gold occurrences in the JMP were classified as orogenic or intrusion-related by [1].
The discovery by Rio Tinto of a very-well preserved high-sulfidation mineralization [12][13][14][15][16] in remains of ring-volcanoes associated with nested ash-flow calderas in the TMP suggested a new potential for mineral exploration. As the high-sulfidation mineralization is genetically related to magmatic-hydrothermal fluids exsolved from more oxidized magmas, which are also associated with Cu−Au and Cu−Mo porphyry deposits [21,88], the mineral potential was extended to large-scale gold and base metals epithermal and porphyry-like deposits in the Tapajós and Juruena provinces.
In a summary of the geology and gold metallogenesis of the TMP, [8] reinterpreted all gold deposits and prospects as orogenic, predominantly deep-emplaced (mesozonal) deposits. These authors did not consider for this interpretation the common presence of copper sulfides (sometimes in high-grades), lack of arsenopyrite, ankerite and siderite, hydrothermal alteration types and zoning, and stable-isotope evidence of magmatic-derived components (e.g., fluids and sulfur). In the following years, junior and major mining companies adopted the orogenic gold deposit genetic model for the gold exploration, and several small deposits represented by discontinues and irregular quartz-pyrite and quartz-base metal sulfide veins were discovered. Few academic studies were developed to understand the genesis of this mineralization type, considered as orogenic and disconnected of the magmatic evolution [9,10].
More recently, academic and mine company works enabled the discovery of many epithermal (high-, intermediate-, and low-sulfidation) gold targets, some of them with Au-Ag-Pb-Zn-Cu, as well porphyry-like Cu-Au-Mo mineralization, in both provinces. Similar processes in the mineral exploration occurred in the JMP, with comparable results. The relationship among gold vein, disseminated and stockwork mineralization and magmatic events [8] highlights the importance of constraint the gold metallogenesis related to magmatic−hydrothermal systems.

Epithermal Au Deposits
The main epithermal Au-(Ag) mineralization is recognized in volcanic-hosted gold deposits, prospects and occurrences in the TMP, such as Botica Velha (V3), Bom Jardim, Doze de Outubro, Chapéu de Sol, Coringa, Pista, Fofão, Mato Velho, Davi, Joel and São Chico (Table S1, Supplementary Materials), as well as several occurrences in the Xingu and Iriri areas. These targets have been classified as high-, intermediate-, and low-sulfidation deposits due to their distinct hydrothermal alteration types, physicochemicalparameters and ore mineralogy. The prominent examples of each deposit type are described below.

High-Sulfidation Epithermal Au-(Ag) Deposits
The Botica Velha Au-(Ag) deposit ( Figure 3A) was the first Paleoproterozoic highsulfidation epithermal deposit identified in the Amazonian Craton and Brazil. It contains 30 t of gold at a maximum of 4.5 g/t Au, besides anomalous silver and minor Cu, Zn, and Mo [14]. Schematic cross-section of the Botica Velha (V3) high-sulfidation gold-silver epithermal deposit [15] (#1 in Figure 2); (B) Schematic cross-section of the Palito gold-(copper) porphyry deposit (#5 in Figure 2). The scale of de gold-mineralized veins and associated sericitic alteration are exaggerated to represent the style of structure-controlled mineralization (this study); (C) Cross-section of the Tocantinzinho gold porphyry-like deposit [89] (#4 in Figure 2); (D) Cross-section of the São Jorge structurally-controlled granite-hosted gold deposit [90] (#7 in Figure 2).
Intermediate to felsic lava flows and volcaniclastic rocks, related to the evolution of a nested caldera complex, host the Au-Ag mineralization [12,13,15]. In the pre-caldera stage, stratovolcanoes with a basal andesite ( Figure 4A,B) sequence and associated ignimbrite and rhyolitic lava flows were formed. The sin-caldera stage encompasses a large cover of crystal-, lapilli-and ash-tuffs ( Figure 4C), ignimbrites and volcanic breccias that resulted in collapse into the magmatic chamber. A late-stage, related to intracaldera epiclastic deposits and annular, radial, or internal volcanoes, comprises lava flows, volcaniclastic rocks, and rhyolitic resurgent domes, similar to those described by [91]. The Au-Ag mineralization occurs in inverted cone-shaped hydrothermal breccias formed in an annular rhyolitic volcano of the post-caldera stage [12,13,15]. Hydrothermal alteration zones flare upwards and are spatially related to calc-alkaline rhyolitic and rhyodacitic porphyries stocks (ca. 1.87-1.89 Ga). The Au-Ag mineralization is spatially related to the advanced argillic (quartz-alunite and pyrophyllite) alteration. Ore minerals are pyrite and minor covellite, bornite, enargiteluzonite, famatinite, tiemannite, tennantite-tetrahedrite, galena, chalcopyrite, sphalerite, aguilarite, native silver, copper, and gold. Native gold occurs mainly in the pyrophylliterich matrix and as fine inclusions in covellite [13,15].
Nine 40 Ar- 39 Ar spectra for alunite yield ages between 1869 ± 2 Ma and 1846 ± 2 Ma. The high-temperature maximum age (ca. 1.87 Ga) was interpreted as the timing of the magmatic-hydrothermal alunite formation in the high-sulfidation deposit [15]. A ca. 1805 Ma plateau age may reflect post-crystallization resetting, likely related to N-S and NW-SE faults. After that, a long period of thermo-tectonic stability prevailed at the TMP, until the deposit unroofing at 51.3 ± 0.1 Ma [15].
Quantitative analyses for active and noble (He, Ar, Ne) gases in fluid inclusions and within the alunite crystal structure confirmed a remarkable Ar retention in alunite [16]. Vapor-rich fluid inclusions trapped in alunite have high CO and H 2 contents and CO 2 /CH 4 (12.8) and H 2 S/SO 2 (2.3) ratios typical for magmatic-hydrothermal fluids. The presence of a magmatic He component was possibly derived from the primitive and relatively undegassed mantle. Overall, the N 2 -Ar-He composition of the Tapajós alunite is similar to that of other high-sulfidation epithermal deposits [16,102].
In the Coringa deposit, sericite-adularia alteration zones and open-space filling ore textures are typical of low-sulfidation epithermal deposits. However, the close relationship with the oxidized calc-alkaline rhyolite-andesite volcanic association, the intermediatesulfidation state sulfides (e.g., pyrite, chalcopyrite, Fe-poor sphalerite, galena, and tennantite), the presence of intermediate argillic alteration and Mn-bearing-carbonate, and the evidence of mixing between magmatic and meteoric water could reflect its formation in more oxidized and acidic conditions [106]. Thus, Coringa was interpreted as transitional from low-to intermediate-sulfidation [26,107] or represent an intermediate-sulfidation epithermal deposit [35] with evolutionary changes in the oxidization state of the hydrothermal fluid.
A Pb-Pb model age of 1974 Ma was obtained for gold-related pyrite crystals in sulfide-quartz veins hosted in dacite from the Mato Velho prospect, 20 km north of the Coringa deposit [114], suggesting a genetic relationship between gold mineralization and the volcanic host rocks [107]. This age may imply in a previous magmatic-hydrothermal system (ca. 1.97 Ga) at the TMP concerning the ca. 1.87 Ga Botica Velha (V3) highsulfidation deposit.
The presence of platy calcite and adularia evidences the boiling process, typical of lowsulfidation epithermal gold deposits. However, the polymetallic mineralization resulted from the overlap of a porphyry Cu-Au-Mo type mineralization over low-sulfidation alteration zones, both linked to porphyry dikes coeval to the ca. 1.87 Ga Botica Velha (V3) high-sulfidation deposit [22,115].

Porphyry-Like Au-(Cu) Deposits
The shallow-emplaced granite-hosted gold and gold-(copper) deposits are similar to porphyry deposits in genesis and, in some cases, in style, in the TMP. The main of them are the Tocantinzinho and Palito (Table S1, Supplementary Materials) deposits, described below due to their distinctive features.

Tocantinzinho Porphyry-Style Gold Deposit
The Tocantinzinho is the largest gold deposit of the TMP ( Figure 3C), with indicated resources of 49 Mt @ 1.35g/t Au (average) or up to 65.8 t of gold [116]. The deposit is located along a major regional NW-trending brittle fault zone, which controlled the emplacement of multi-phase intrusions ( Figure 3C). Post-mineralization NE-SW-trending and E-W steeply-dipping faults intercept the mineralized granites [89].
Fluid inclusions trapped in hydrothermal quartz related to potassic and sericite alteration reveal the presence of aqueous (H 2 O-NaCl) fluids with variable salinity (0.2 to 15.9 wt.% NaCl eq.) and homogenization temperatures (100 to 433 • C; Figure 6A). The coexistence in an equilibrium of fluid inclusions that homogenize to vapor or liquid phase, at similar temperatures, was interpreted by [24] as evidence of boiling during the magmatic fluid ascent, followed by mixing between magmatic and meteoric fluids.
The Tocanzinho deposit has been considered a magmatic-hydrothermal deposit, classified as a (reduced) intrusion-related gold deposit [25], which are associated with ilmenite-bearing granitoids. However, similarities with a porphyry-style gold deposit have been recognized due to its genetic relationship with a shallow-emplaced oxidized calc-alkaline monzogranite [24,30].

Palito Gold-(Copper) Deposit
The Palito gold-(copper) deposit ( Figure 3B) represented the first operational polymetallic underground mine in the TMP, producing 3.12 t of gold from 2003 to 2008. Proven and probable reserves at Palito were estimated at 717,000 t @ 11.74 g/t of gold [104].
Despite the mineralization that invades the Palito Granite country rocks, the intensity of hydrothermal alteration, vein frequency and thickness, and ore grade decrease outwards the Palito Granite [100] ( Figure 3B). The granite has a distinctive reddish color related to potassic alteration ( Figure 4K-M) with microcline and minor hydrothermal biotite. Infiltration textures suggest open-space or miarolitic cavity filling processes during the potassic alteration. This alteration evolves outwards to fracture-controlled and pervasive propylitic alteration with chlorite, epidote, albite, carbonate (platy calcite), titanite, fluorite, and minor prehnite. Upwards, a well-developed sericitic alteration encompasses sericite, quartz and sulfides. Minor fracture-controlled argillic/advanced argillic alteration (pyrophyllite + sericite + kaolinite) occurs.
The gold-(copper) mineralization zone is controlled by vertical to sub-vertical, NW-SE and E-W-trending brittle extensional fault systems and contained in up to one-meter-thick sulfide-quartz and semi-massive sulfide veins ( Figure 4K,M), stockworks, hydrothermal breccias ( Figure 4L), and finely disseminated sulfides within the Palito Granite and at the contact with the Rio Novo Granite [100,104] ( Figure 3B). Potassic, sericite, and propylitic alteration selvages are associated with the mineralized sulfide-(quartz) veins.
The geochemical signature and evolution of the magmatic associations, types and styles of hydrothermal alteration, metal associations, and the physicochemical conditions of the mineralizing fluids of the Palito deposit were considered compatible with those of magmatic-hydrothermal porphyry-type gold systems [28,65,100].
The granitoids underwent pervasive and fissure-controlled hydrothermal chloritic, sericitic, carbonate, propylitic alteration, and silicification [10,101,108,109,121,124,125]. Replacement of igneous feldspars by hydrothermal K-feldspar, as a result of potassic alteration, was recognized in the Guarim [10] and São Jorge [124] deposits. In other deposits, strong red color in cloudy K-feldspar, similar to that typical of the potassic alteration fronts at Palito, Tocantinzinho, and Batalha [18], has been considered an original granite feature [123] or due to an iron oxide-chlorite alteration [124].
These granite-hosted deposits and targets were considered similar to orogenic gold deposits [9,109] or associated with an intrusion-related gold system [90,101,108,110].
The conglomerate layer is the primary mineralization host [127], but geological crosssections evidence the continuity of orebodies into sandstones [130]. The hydrothermal alteration, mainly incipient to pervasive silicification, hematite sericite-(muscovite + fuchsite), tourmaline, epidote, and argillic alteration, envelops the orebodies [130]. Gold, usually associated with muscovite or magnetite, occurs within detrital quartz grains and as intergranular particles in the conglomerate and sandstone matrix. Gold grains have low Ag contents (<1 to 4.7%) and lack other significant metals, suggesting a single source. Minor gold mineralization is fracture-controlled, related to secondary iron oxides. Platy gold particles have lower Ag contents (<1%), interpreted as a result of epigenetic remobilization of the matrix gold [131].
The gold deposits on the Castelo de Sonhos plateau are classified as modified paleoplacers [127]. The morphology of the gold particles is only slightly modified and reshaped, which suggests detrital provenance and a relatively proximal distance of transport. According to [131], hydrothermal fluids exsolved from the subjacent biotite granodiorite triggered gold remobilization to fractures. Also, the low-temperature hydrothermal alteration, mainly argillic to sericitic, and the orebody geometry associated with dacite porphyry dikes may suggest an epithermal style overprint.

Gold Deposits in the Juruena Mineral Province
Gold mineralization in the JMP corresponds to Cenozoic placers, eluvial deposits, and hydrothermal occurrences, concentrated over the 150 km WNW-ESE-striking Peru-Trairão belt, but known gold occurrences extend westwards (Figure 2). Placers and eluvial deposits are associated with primary gold ores hosted in faults and granite intrusions distributed in zones roughly parallel to the outcrops of the volcanic units, suggesting that the weathering and erosional front advance resulted in the gold concentration from the rhyolitic to dacitic volcanic rocks and exposed veins and stockworks in faults and granites. Some of these shallow-emplaced granite stocks and dikes could represent feeder channels for the volcanic and volcaniclastic cover.
The gold ore is mainly associated with sericitic alteration (quartz + sericite and finegrained muscovite + pyrite) ( Figure 7C) and minor with sericite-chlorite alteration. It is mainly composed of pyrite, with variable chalcopyrite and hematite amounts and subordinate barite, galena, sphalerite, monazite, thorite, molybdenite, pyrrhotite, cubanite, Bi-Te-bearing phases, and Au-Ag tellurides inclusions. Gold (Au/Ag = 2.2-25) occurs as inclusions in pyrite or as Au-Ag alloys at its edges or fractures ( Figure 7D). At the X1 prospect, gold grades vary from 0.5 to 10 g/t Au. The highest gold values occur in disseminated and massive sulfide zones and the lowest in the stockwork zones (<0.2 g/t). Particularly in high-grade gold zones, copper may reach values between 0.1 and 0.5 wt.% and Mo between 200 ppm to 0.1 wt.% [111]. Moreover, whole-rock geochemistry of the ore shoots has demonstrated positive correlations of Au, Bi and Te at Luizão and X1 [29,111].
EMPA analyses indicate homogeneity on chlorite, muscovite and sericite compositions.

Structurally-Controlled Veins
The Paraíba, Edu, Peteca, Basílio, Serrinha do Guarantã, and Aguinaldo represent the major known fault-controlled gold veins (Table S2, Supplementary Materials). At the Paraíba deposit, drill cores along the vein strike have intercepted up to 4 m intervals with grades varying from 0.2 g/t of Au up to 29 g/t of Au. The estimated ore reserves are in the order of 350,000 t @ 15,35 g/t of Au, equivalent to 5.37 t of Au [2,11,27,63,112,132].
Trace element analyses of pyrite from the Edu occurrence, using LA-ICP-MS, indicate homogeneity in As (2.3-51.1 ppm) and Bi (0.8-53 ppm) contents, heterogeneity of Cu (2.7-2031 ppm) values and low content of invisible Au (up to 2.3 ppm) and Ag (up to 17 ppm) [113]. Additionally, performed EMPA trace elements of pyrite and chalcopyrite from the Edu and Paraíba ores. Gold concentrations are similar in the Paraíba (90-1740 ppm) and Edu (90-1150 ppm), besides the high concentrations of Ni (<65-1040 ppm) and Co (590-1920 ppm) in both cases. Reference [1] obtained a Pb-Pb age of 1841 ± 22 Ma for pyrite in equilibrium with chalcopyrite and magnetite from the Paraíba deposit.
The sericitic-chloritic (sericite + quartz ± chlorite) alteration envelopes the epithermal ore veins (Figure 7I), sometimes with adularia, and overprinted the early potassic (Kfeldspar ± biotite) alteration. The propylitic alteration is distal and regional. Silicification and quartz infill are associated with veins, stockworks and breccias. Limited amounts of fine-grained alunite are related to intense silicification zones in the Francisco occurrence [76]. Pervasive argillic alteration (kaolinite + sericite + quartz) is also recognized. Furthermore, hematite veins crosscut all the previous hydrothermal alteration zones.
This type of gold mineralization occurs as massive to banded quartz veins with small geodes, breccias, and open space-filling textures, such as crustiform, zonal, colloform, cockade, vuggy, and comb ( Figure 7J), suggesting their formation at relatively shallow levels. Moreover, platy calcite and quartz occur in veins ( Figure 7K), especially in the Luiz occurrence [23,27].
Chlorite has a dominantly brunsvigitic and minor ripidolite composition. The white mica from the sericitic halo of quartz gold veins has a composition between the muscovitephengite endmembers. The chlorite geothermometer yielded temperatures from 184 • C to 411 • C [27].
Furthermore, three sericite 40 Ar- 39 Ar plateau ages from the sericite alteration of the Francisco occurrence vary from 1779 ± 6.6 Ma to 1777 ± 6.4 Ma [76], which are similar to the pyrite and molybdenite Re-Os ages constrained to granite-hosted occurrences previously described.

The Tectonic Setting of the Volcanic-Plutonic Associations of the TMP
The tectonic evolution of the Tapajós and Juruena mineral provinces is not well understood, especially concerning the volcanic units that host epithermal gold-(polymetallic) mineralization. Their formation has been attributed both to anorogenic and continental magmatic arc settings [1,3,8,40].
The previous tectonic models for the Amazonian Craton [5,43,44,53] imply NW-SEtrending subduction zones and magmatic arcs. In the TMP, five magmatic arcs were  [42]). Also, an NW-SE continuity of the Tapajós crust into the E-W-trending Juruena Province was admitted. However, the delimitation of geochronological (or tectonic) provinces is debatable. Consequently, tectonic evolution and metallogenetic zoning relationships are not well established, hampering the proposition of comprehensive mineral exploration models.
According to [54], the TMP was generated in an~E-W-oriented long-lived oceancontinent subduction event dipping to the north, probably with one flat-subduction stage [56,59]. This resulted in the building of at least two partially overlapped E-W-oriented continental plutonic/volcanic arcs caused by arc migration due to the oceanic plate dip variation at ca. 2.01 to 1.88 Ga. Considerable uplift and erosion within these two arcs are indicated by the juxtaposition of terrains from different crustal levels and discordances, exposing a crustal level from the plutonic environment to the Paleoproterozoic surface [15]. No evidence of collisional metamorphism, accreted island arcs, oceanic terrains, nor suture zones is observed in fieldworks. Post-orogenic to A-type volcanism and shallow-emplaced intrusions occur essentially along with great NW-SE and NE-SW-trending fault zones [60]. In this context, a lateral collision of the Juruena Province to the Tapajós Province caused by a roughly E-W-oriented north dip subduction would be possible [53,58,77,78], but lack clear geological evidence yet. This alternative tectonic model is consistent with the spatial zoning of magmatichydrothermal base metal and gold mineralization developed between ca. 2.0 and 1.88 Ga in the TMP. This zoning extends from the western TMP to the São Felix do Xingu region and suggests an origin in an E-W-trending Andean-type subduction zone with initial generation of calc-alkaline magmas, evolving to high-K calc-alkaline and finalizing with intraplate crustal melts. The spatial distribution of the arc-related mineralization would have been controlled by the subduction angle, which flattened [144] as the arc migrated northward until it stabilized, leading to the production of A-type magmas in the back-arc, as described in the Trans-Mexican Volcanic Belt [145][146][147] and the Andes [148][149][150].
These volcanic associations are typical of orogenic magmatism, where magmatichydrothermal systems are usually present. The intrusive rocks can be related to variable crustal level emplacement, varying from plutonic batholith to epizonal stocks and dikes of granophyre and porphyries, indicating an almost complete erosional cross-section. Supracrustal and plutonic rocks are juxtaposed through faults and erosional surfaces. This points to intense tectonic and erosional periods in the Paleoproterozoic, which was followed by long thermo-tectonic stability at the TMP after ca. 1.85 Ga, as evidenced by the 40 Ar- 39 Ar alunite spectra and Ar retention in alunite of the Botica Velha (V3) high-sulfidation epithermal Au-Ag mineralization, until the deposit unroofing at 51.3 ± 0.1 Ma [15,16]. The late magmatism, typically fissure-controlled alkalic A-type, is similar to that of intra-and back-arc settings, produced in the final evolution stage of an orogenic belt.

The Magmatic-Hydrothermal Gold-(Polymetallic) Systems of the TMP
The correlation among the timing of arc magmatism, the Pb-Pb sulfide ages [8], and Ar-Ar data for ore-related hydrothermal minerals (Figure 8), evidences a clear association between gold mineralization and magmatic (intrusive and extrusive) events in the TMP.
The magmas associated with porphyry-like mineralization are predominantly I-type, oxidized (magnetite-bearing) high-K calc-alkaline or transitional to ilmenite-bearing granites, indicating magmas with distinct oxidation states. Usually, the hydrothermal paragene-sis of these magmatic-hydrothermal deposits reveals several pulses and variations on the oxygen fugacity and sulfur content in TMP.
More evolved, less oxidized high-K calc-alkaline granites could be represented by the Tocantinzinho gold deposit, which shares some characteristics of alkalic porphyry deposits [152] and Intrusion-Related Gold Systems (IRGS), in the conception of [153] and [154]. However, its hydrothermal alteration patterns (e.g., intense potassic, sericitic, propylitic alteration), and lack of copper association, in our conception, are likely related to the alkalic gold porphyry type deposits, as considered by [24,30].
Epithermal mineralization in the TPM includes the high-, intermediate-and lowsulfidation types [15,16,22,26,35,107] hosted in volcanic breccias, rhyolite domes, plutonic, volcaniclastic, and sedimentary rocks (Figure 9). Hydrothermal alteration zoning, stable isotope data ( Figure 5A) and noble (He, Ar, Ne) gases in fluid inclusions and alunite crystals point to notable similarities of the ca. 1.87 Ga Botica Velha (V3) Au-Ag mineralization to those of the typical high-sulfidation epithermal deposits, such as Tambo, in the El Indio-Pascua belt, Chile [15,16,102]. In the intermediate-sulfidation Au-Ag-(Cu-Pb-Zn) deposits (e.g., Coringa), as well as some low-sulfidation occurrences, the hydrothermal fluid source and mixing trend defined by H-O stable isotopes (δ 18 O H2O = +9.8 to −1.8‰; δD H2O = −92‰, at 400 to 234 • C; Reference [35] data are similar to that of the Botica Velha (V3) high-sulfidation Au-Ag mineralization ( Figure 5A). In the intermediate-sulfidation deposits, these data suggest primary neutralization [96,106] of the original acid magmatic fluid by reaction with the host rocks during the migration around the magmatic intrusion, followed by mixing with meteoric fluids. Low-sulfidation gold epithermal occurrences associated with the tardi-to post-orogenic to A-type magmatism may also be related to alkalic epithermal systems in the São Félix do Xingu area, east of the TMP [32].
The main difference between the magmatic-hydrothermal fluids related to ca. 1.97 Ga and 1.88 Ga deposits of the TMP with modern arc-related systems is the magmatic fluid evolution towards low-latitude meteoric waters ( Figure 5A). This trend is interpreted as due to intense evaporated surficial waters [155]. In the nearby São Felix do Xingu area, ca. 1.88 Ga cross-bedding calcarenites with layers of mud-cracks with marks of anhydrite/gypsum, as well several dissection structures in sedimentary rocks, is compatible with the interpreted fluid mixing and evolution.
The magmatic fluid participation and mixing processes with meteoric water characterized in the ca. 1.97 Ga and 1.88 Ga high-, intermediate-, and low-sulfidation Au-(Ag) epithermal mineralization associated with hydrothermal breccias (in volcanic crater and dikes) are also identified for thick quartz-(sulfide) veins and stockworks. These veins are hosted in tectonic and volcanic structures, crosscutting all rock types in shallow to relatively deep crustal levels. Hydrothermal breccias are common within the gold-mineralized veins. The veins present variable amounts of sulfides and are pyrite-rich to polymetallic, with associated Mn-calcite in the intermediate-sulfidation epithermal deposits. Veinlets to massive sulfide veins are frequent, including gold-rich chalcopyrite veins (up to 3.5 kg/t of Au).
Gold-mineralized quartz, quartz-sulfide or sulfide veins hosted in the deeper intrusive rocks are predominantly associated with brittle or brittle-ductile faults close to subvolcanic to plutonic intrusions (e.g., Cuiú-Cuiú gold camp; [9,108,121,122]). Fluid inclusion data indicate evolution from immiscibility of a magmatic aqueous-carbonic fluid, generating high-salinity brines (up to 30 wt.% NaCl and 410 • C) and CO 2 -only fluids, followed by mixing with meteoric fluids [121] (Figure 6A). Stable isotope data (S, O, D) is also consistent with magmatic fluid and sulfur sources [8,101,121] (Figure 5A).
These veins could be interpreted as the roots of epithermal systems (Figure 9), as described by [156] for deeper epithermal systems. Alternatively, the deeper veins could be related to fluids exsolved from high-f H2O granites emplaced in a deeper level than that typical of porphyry type deposit formation, releasing fluid along with rock discontinuities, mainly faults, as exemplified by [18,157]. This mineralization type was correlated to the Korean-type gold mineralization [1], which occurs below epithermal veins in the Korean Peninsula. However, according to [158,159], these deeper veins in Korea are genetically linked to the magmatic-hydrothermal epithermal systems, as proposed here.
The preserved erosional level, from the Paleoproterozoic surface to an intermediate crustal level, the sin-to post-depositional rift and pull-apart volcano-sedimentary basins, and the presence of some small calc-alkaline porphyry-like hydrothermal systems (e.g., Palito; [28,38,40,100]) indicate an exploratory potential for Au, Cu and Mo in the TMP. In addition, the later felsic alkalic shallow-emplaced intrusions and the common extensive propylitic, sericitic-chloritic, sericitic and potassic (biotite or biotite + microcline) sulfide-rich hydrothermal alteration with retrograde argillic, adularia, silicic, and carbonate alteration suggests a potential to alkalic gold-only or Au-Cu porphyry mineralization similar to those of the Cadia and Northparkes districts, Australia [152,160,161]. At Cadia and Northparkes, the island arc setting result in prevalent oceanic mafic-intermediate magmatism, whereas intermediate-felsic rocks formed in continental arc predominate in the TMP and JMP. Despite differences in arc-related units and ages, the macroscopic lithological aspects, geochemistry, hydrothermal alteration patterns, including the characteristic reddish potassic altered rocks, and intrusion morphology (e.g., "pencil" intrusions) are very similar between these Australian and Brazilian gold mineralization types.

Relationship between Orogenic and Magmatic-Hydrothermal Gold Deposits in the TMP: A Critical Evaluation
The proposition of the orogenic model for the gold veins in the Tapajós and Juruena provinces [1,[8][9][10]101,109] has been based on: (i) control by faults and shear zones, (ii) deep crustal level of the host rocks, mainly granitoids, sometimes interpreted as submitted to amphibolite facies metamorphism, and amphibolites, perhaps considered as metavolcanic rocks; (iii) low-salinity aqueous-carbonic fluid inclusions in quartz, which define pressure (0.86 to 3.0 kb) reaching up to 7 km deep in the crust, and (iv) carbonate alteration.
The hydrothermal fluid origin commonly was attributed to deep crustal, metamorphic sources [9,10]. However, a magmatic fluid contribution is admitted [90,109], as aqueouscarbonic fluids have highly variable salinity, usually <7 wt.% NaCl eq., ranging from 1.6 to 21 wt.% NaCl eq [9,10,90,101,108,121,122] (Figure 6). Reference [99] indicated the possibility of magmatic-derived fluids in the genesis of orogenic gold deposits. However, the importance of pelitic, basaltic and oceanic sequences as the source for orogenic gold and fluids by metamorphic devolatilization is emphasized [162][163][164][165]. Similar geological units are not present in the TMP, as well as typical regional metamorphic zones or large ductile shear zones. Volcanic and other supracrustal units underwent zeolite/prehnitepumpellyite metamorphism. Brittle to brittle-ductile fault zones are discontinuous, with gold mineralization spatially related to felsic intrusions.
Intermediate-to high-saline aqueous fluid inclusions in restrict parts of less deformed quartz in structurally-controlled sulfide-quartz veins (>20 to 30 wt.% NaCl eq.; [9,109], at the Palito mine (up to 50% NaCl eq. in quartz from the potassic alteration zones; [28]) and the Tocantinzinho deposit (up to 21.4% NaCl eq.; [24]) ( Figure 6A) precludes an orogenic origin, as summarized by [99]. In addition, low-to intermediate-salinities are also typical of epithermal veins. The high CO 2 content in fluids could be related to the roots of epithermal veins or more alkaline granite magmas [166]. According to [167], salinity estimates in fossil epithermal systems are in error when based on ice melting temperature without an independent CO 2 content measurement. Misinterpretation of fluid inclusion freezing could result in large errors for the interpreted physicochemical environment. Carbonic gas is also highlighted as a common component in low-salinity fluids from fossil epithermal precious metal mineralization. In this case, deeper gold mineralized veins hosted in granites cannot be surely correlated with orogenic gold deposits based only on low-salinity and CO 2 contents.
Available O and H stable isotope data for minerals and fluid inclusion ( Figure 5A) do not indicate a typical correlation with orogenic gold deposits. Instead, fluids that crystallized alunite and associated hydrothermal minerals of the Botica Velha (V3) highsulfidation mineralization are similar to those compiled for worldwide high-sulfidation deposits, which have significant participation of magmatic-hydrothermal brines. Data from fluid inclusions interpreted as evidence of an orogenic "mesothermal to epizonal" origin [8] show good agreement with ore-forming fluids in high-sulfidation deposits, indicating a magmatic source and mixing with low-latitude meteoric water, in minor proportion, as before defined by [15]. Similar fluid source and fluid mixing processes are observed for all epithermal, porphyry-like and undifferentiated "intrusion-related or orogenic" gold mineralization in the TMP ( Figure 5A).
Gold veins hosted by deeper granites tend to exhibit a higher formation pressure (up to 7 km deep), where a porphyry system starts its evolution; [88] with a minor meteoric contribution. Veins hosted in volcanic-volcaniclastic rocks are formed in the shallow crustal environment and show a greater meteoric contribution. Magmatic source for the hydrothermal fluids in TMP has been characterized for all veins formed in the two or more mineralizing episodes, in temporal agreement with the major magmatic episodes (Figure 8), but without any correlation with metamorphic events, reinforcing this interpretation.
The structural control is clear in most gold-bearing quartz-sulfide veins, but undoubted mylonites are restricted (e.g., Ouro Roxo; [109,122]) and associated with mica-rich hydrothermal mineral assemblages, indicating synchronous or post-mineralization de-formation. In fact, at TMP, deformation overprinting is usual in quartz veins, ores and hydrothermally altered rocks, resulting in undulated extinction, fracturing and recrystallization of quartz and sulfides, and strong foliated hydrothermal mica-rich vein halo zones. The presence of NW-SE-oriented ductile shear zones in the TMP has yet to be proven, but NW-SE, NE-SW, and E-W-striking brittle faults are widespread, several of them hosting gold lodes. Hydrothermal breccias, open-fill structures, banding, druses in vugs, and late carbonate infills are frequently associated with gold mineralized veins considered as related to orogenic "mesothermal" processes [8,10,101,168]. Although hydrothermal breccia formation is possible in a relatively high-pressure environment, fluid inclusion isochores point to depths up to 7 km. In such a crustal environment, open-space filling textures and breccias are unlike [169,170]. In this case, the possibility of hydrostatic overpressure caused by the release of large fluid volumes from magma intrusions and the low permeability of country rocks may be considered [171].
The relatively deeper ore formation environment inferred for the TMP gold mineralized veins is based on fluid inclusion barometry, indicating crustal level deeper than expected to porphyry deposits (<5 km). However, [171,172] demonstrated that fluid inclusion isochores in porphyry systems with fluid immiscibility define higher pressures than those based on geological evidence.
Overpressured to pressured hydrothermal fluids occur typically at deep of 3 km (or less than 1.5 kb) due to a seal of a relatively impermeable unit (e.g., shales or diagenetically cemented sandstone) or by lateral sealed steeply dipping fault zones by several processes, including thermal expansion [173]. High CO 2 volumes in fluid inclusions in quartz from veins at the TMP could also point to a sealed and overpressured hydrothermal system up to above the lithostatic pressure, which resulted in episodic hydrothermal breccias.
Although non-lithostatic overpressure is controversial, well-documented evidence regarding crustal evolution, geothermobarometry, tectonism and metamorphism cases confirm this phenomenon. Overpressure would be provoked by non-hydrostatic thermodynamics, deviatoric stress, strength contrasts, tectonic mode switching, and autoclave processes [174]. Extreme events of uplift and erosion, pull apart sedimentary basins and large fault zones, which contributed to preserving the volcanic units and juxtapose deepand shallow-emplaced rocks, indicate a significant compressional event in the TMP. The Amazonian Craton crust is thick, with an average of 38.1 km, and relatively thicker (up to 42 km) at the south of the Amazonas basin, where the TMP is located [175]. In such conditions, flexural and horizontal stresses in the upper crust under the brittle regime, similar to those environments of gold mineralization formation, could result in hydrostatic pressure two times higher than the lithostatic pressure value [176]. Major faults controlled different magma intrusion phases and hosted gold-and base metal mineralized veins in the TMP. Water-rich magmas should be consolidated in a deeper crustal level than those typical of porphyry emplacement, releasing hydrothermal fluids through fault channels, as represented by the Batalha granite mineralization at TMP [18]. If hydrothermal minerals seal the fault, fluid overpressure could be reached, explaining the relatively high-pressure of entrapment defined by fluid inclusions studies in quartz veins with textures typical of shallow crustal levels.
Pyrite (≤3-5%) is the main gold host mineral, arsenopyrite and pyrrhotite are common, and carbonates are subordinated (≤5-15%) in orogenic gold lodes [162,177]. Gold veins in the TMP do not present arsenopyrite, pyrrhotite is scarce, and chalcopyrite, sphalerite, galena, molybdenite and sulfosalt minerals are usual. Massive sulfide veins and the correlation of gold content with copper (up >1.5%) are very common. In the Palito mine, massive chalcopyrite veins (up to 1 m-thick) could be very gold-rich. These characteristics appear to be more compatible with magmatic-hydrothermal systems rather than orogenic deposits. In addition, no siderite or ankerite is present in gold veins; instead, later calcite is the typical carbonate, and occasionally as platy calcite. Mn-calcite is frequent in polymetallic veins, commonly associated with sericite and minor adularia or alunite, as is typical of intermediate-sulfidation epithermal mineralization [106]. Finally, the hy-drothermal alteration types (potassic (K-feldspar + biotite or biotite), sericitic, propylitic, argillic, adularia-sericite, alunite-quartz), styles, and zoning are not consistent with those of orogenic gold deposits. They are similar to those observed in epithermal veins, in the root of epithermal or in porphyry systems, from shallow to deep levels [97,166,178,179].
Besides typical cataclastic textures in granites and foliation in hydrothermally altered mica-rich rocks in faults, no medium to high-grade regional metamorphism deformation affected older tonalites, granodiorites, and minor granites [1,5,8,42]. Instead, the described textures, structures and mineralogy are more likely magmatic and representative of thermal effects on contacts, roof pendant and enclaves. Typical migmatites are present, but in small volumes, inside the tonalite, granodiorite, and granite bodies, apparently representing enclaves. In this case, no source appears to be present to the metamorphic fluid generation in the TMP.
Collectively, the geological environment, structural control, geochronology, and stable isotope and fluid inclusion data suggest major importance of magmatic-hydrothermal processes in the TMP, instead of orogenic gold deposits, with good examples of wellpreserved high-, intermediate-and low-sulfidation epithermal, and porphyry-like gold mineralization associated with high-K calc-alkaline granites. However, we do not discharge the existence of orogenic gold mineralization in more eroded units, although this type of gold mineralization in the TMP needs more data to be better constrained.

Gold Metallogeny in the Juruena Mineral Province
The primary gold occurrences in the JMP exhibit a close spatial relationship with calc-alkaline and oxidized (magnetite-bearing) I-type granites, volcanic rocks, and volcanosedimentary sequences originated in continental magmatic arcs. The hydrothermal alteration, styles, and the ore paragenesis, together with fluid inclusions and isotopic data, suggest their formation in Paleoproterozoic magmatic-hydrothermal systems developed in different crustal levels and positions regarding the magmatic source. The JMP has been tectonically juxtaposed to TMP between 1.69 to 1.63 Ga through a roughly E-W-trending shear zone [53].
Moreover, the radial fine-grained muscovite in granite-hosted gold-rich ore zones and fault-hosted veins, as well as the moderate to high-temperature H 2 O-CO 2 -NaCl fluids, indicate magmatic degassing into deeper porphyry-like systems [76,180]. Nevertheless, the pressure conditions (0.7-3.6 kbar) estimated by fluid inclusions are dissimilar to those expected for arc-related magmatic-hydrothermal systems, as porphyry deposits. Such conditions might represent hydrostatic overpressure caused by large fluid volume discharged by magmas emplaced at shallower levels than 3.6 kbar, in a similar way as considered for TMP deeper gold veins. Alternatively, pressure estimates are unreliable due to the effects of heterogeneous fluid entrapment [171,172], as observed by [172] regarding the excessively high pressures calculated from fluid inclusions for most porphyry-copper deposits.
On the other hand, the sulfide-gold veins in faults and shear zones are hosted in ca. 2.7-1.98 granitic-tonalitic basement, ca. 2.0 foliated granite, 2.05-1.95 Ga granitoids, and 1.79 Ga porphyritic syenogranite. The ore zones comprise essentially disseminated to massive pyrite and chalcopyrite in banded to massive quartz ± carbonate veins housed in faults and shear zones. Such veins are capped by sericitic-quartz alteration, gradually overprinted by radial muscovite ± sericite, biotite-rich, and late carbonate alteration. These alterations are centered into potassic alteration, in a first stage as K-feldspar-rich, and then as biotite-rich [27,136], which exbibit a regional envelope of propylitic and chloritic alteration. Adularia-sericite and adularia-sericite-chlorite alteration are also present, as well as adularia veinlets. Furthermore, spaced-parallel veins with chlorite, chloriteepidote, epidote-quartz, epidote, sericite, or quartz, often with pyrite ± chalcopyrite, exhibit narrow K-feldspar halos [2,27,132,136].
The proximal sericitic, sericitic-chloritic, and carbonatic alteration stages are mainly parallel to subparallel to the foliation, syn-to post-deformation and overprinted tectonic fault reactivation. Additionally, late idiomorphic gold-free pyrite overprints the restricted sericite-quartz mylonite zones of the Edu deposit [11].
The H 2 O-CO 2 -rich fluids could be derived from metamorphic dehydration reactions, commonly responsible for fluid generation in orogenic gold deposits [99,165,181]. However, CO 2 -rich fluids can also be released by deep or alkaline granites, as pointed out by [153,182], or in epithermal systems [167]. Since no evidence for alkaline A-type magmatism has been constrained on the fault-hosted gold veins, such fluids might be sourced from deeper granodiorite-tonalite bodies. Such fluids could reflect magmatic immiscibility processes [38,112], possibly linked to the root of magmatic-hydrothermal systems. Moreover, the saline fluids (up to 27 wt.% NaCl eq.; Figure 6B), in coexistence with these aqueous-carbonic fluids, represent additional evidence to magmatic-sourced rather than metamorphic-derived fluids, as previously discussed for TMP. The unique available stable isotope data for these gold occurrences, obtained from hydrothermal calcite of the Serrinha de Guarantã deposit [63], also indicate a magmatic signature for the mineralizing fluids (δ 13 C = −2.6‰ to −2.4‰; and δ 18 O SMOW = +6.5‰ to +7.4‰).
Although an orogenic gold model has been advocated for such structurally-controlled gold veins [183], their descriptive geological features converge to a magmatic-hydrothermal genesis. Such features include: (i) low volume of metamorphic host rocks (e.g., gneisses), in contrast to the larger volume of undeformed and not metamorphosed ca. 1.97-1.95 Ga calc-alkaline, oxidized I-type granites and porphyries; (ii) absence of metamorphic paragenesis outer to the hydrothermal halos; (iii) their paragenetic hydrothermal evolution (e.g., K-feldspar, biotite, sericite, sericite-adularia, radial coarse-grained muscovite, late calcite, chlorite, and regional propylitic); (iv) the coexistence of medium-to high-saline and CO 2 -rich fluids ( Figure 6B); and (v) the carbon and oxygen isotopic signature of calcite. Since copper is not a significant metal in the Intrusion-related gold systems [153,154], such features are more consistent with the roots of magmatic-hydrothermal systems than orogenetic gold deposits. These features are similar to those here reported for the structurally-controlled gold deposits in the TMP. Therefore, it is suggested that porphyrylike gold deposits correspond to a more coherent model for them. However, these deposits and occurrences in JMP are possibly older than those reported to granite-hosted ore and polymetallic-veins occurrences at ca.  [27,38,76]. The calculated isotope fluid compositions in equilibrium with hydrothermal minerals representative of the paragenetic evolution attest to magmatic and volcanic sources with important input of meteoric water ( Figure 5B), from the potassic (δ 18 O H2O = +8.4 to +9.7‰, at 254 • C), to sericitic (δ 18 O H2O = +2.1 to +3.4‰ and δD H2O = −42 to −35‰), argillic, silicic alteration and silica infill (δ 18 O H2O = +3.9 to +4.6‰), and propylitic alteration. Open space-filling textures corroborate the fluid circulation into shallow crustal levels (ca. 0.7 kbar), whereas the predominantly heterogeneous aqueous fluid regime indicates boiling processes. Additional boiling evidence corresponds to bladed quartz, platy calcite, and rarer well-crystallized adularia in quartz and Mn-calcite quartz veins from the Pezão and Luiz occurrences, as pointed out by [27]. Local alunite is restricted to highly-silicified rocks, indicating high-oxidized mineralizing fluid stages. Collectively, such features suggest low-to intermediate-sulfidation epithermal systems, especially considering the paragenesis with pyrite, galena, sphalerite, chalcopyrite and Mn-calcite, with restricted alunite and adularia.
Collectively, the wide occurrence of undeformed tonalites, granodiorites and granites, but minor microgranites, porphyries, volcanic rocks, and fault and shear zones that affected the basement nuclei and ca. 2.05-1.96 Ga granites suggest higher erosive levels in JMP than those observed at TMP. That might have implied in exposing deeper crustal levels, up to the roots of porphyry systems, and therefore, the granite-hosted gold veins could represent distal vein generated in porphyry systems in JMP.
The 2.05-1.90 Ga magmatic events, grouped into the Peixoto de Azevedo Domain [58,77,78], have been attributed as an extension of the TMP under the Cachimbo graben toward the JMP. However, it would imply a southward continuity of the TMP, crosscutting the clear E-W tectonic trend of the Juruena Province [53,77], which hosts the most known gold deposits and occurrences in JMP. This appears to be geologically inappropriate if the Juruena province was juxtaposed to the Tapajós Province due to a later (1.69-1.63 Ga) lateral continental collision [27,53]. Alternatively, these older rocks in the JMP would be better explained as: (i) a basement core in the Juruena continental magmatic, chronocorrelate to the Cuiú-Cuiú Complex; (ii) an imbricated tectonic slab (e.g., a klippe) of the TMP into the JMP due to the collision event; or (iii) a part of the TMP moved from west to the actual position by a later dextral fault along with the contact between the provinces.
The Re-Os sulfide and 40 Ar- 39 Ar ages concerning the disseminated gold and polymetallic-veins occurrences indicate a single ca. 1.78 Ga Statherian gold event into the Juruena Province, thus, chronocorrelate to highly-evolved I-type magmas from the third magmatic event, responsible for the emplacement of fine-grained porphyritic granites, porphyries and volcanic rocks, belonging to the ca. 1.81 to 1.78 Ga Colíder Group. It points out the importance of porphyry-related magmatic-hydrothermal activity within the province, aided by regional structures for large-scale magmatic-hydrothermal circulation, as corroborated by the often presence of hydrothermally altered and sulfide-bearing porphyries in all occurrences and prospects. However, it is not discarded the possibility of gold events older than 1.78 Ga, especially if considered the ca. 1.97-1.95 Ga calc-alkaline shallow-emplaced (sub-volcanic) porphyry intrusions in the Luiz and Paraíba deposits [27], and in the fault-controlled occurrences, for which the hydrothermal activity seems to have been syn-to post deforming processes. However, additional information on petrography, geochronology and isotopic composition on hydrothermal minerals are crucial for better constraining such occurrences. The main gold mineralization in the TMP (ca. 1.88), related to calc-alkaline magmatism, and in the JMP (ca. 1.78 Ga), point to important differences between both provinces and in relation to the interpreted extension of TMP into JMP.
Additionally, the often presence of fine-grained granite, aplite and mafic to intermediate volcanic dikes over the gold-rich occurrences, affected by hydrothermal processes, can be interpreted as intermineral epizonal intrusions, such as those often observed in Andean arc-related porphyry gold systems [88,184]. At JMP, such intrusions (granite to syenite and diorite to fine-grained gabbro) vary in ages from 1.78 to 1.77 Ga and commonly have disseminated to vein-type pyrite ± chalcopyrite [27,29,79,81]. This epizonal magmatism could have supplied the mineralizing magmatic-hydrothermal system with vapor, sulfur, and heat. Furthermore, such magmatism might suggest a magmatic event occurred during a post-orogenic extension, related to high-evolved I-type magmatism from the third magmatic event that took place in the JMP [76]. The 1.78-1.77 Ga gold event in the JMP might have been triggered by the 1.8-1.77 Ga post-orogenic magmatism, possibly related to the thickening of the Juruena magmatic arc. Into this scenario, the asthenospheric upwelling may have caused a second stage of melting of a relatively Au-rich residue in the lower crust and lithospheric mantle produced after the first stage melting during the Arc-type magmatism. This process might produce high Au/Cu ratios in magmas due to the dissolution of Au-rich residue, producing postsubduction Au-rich porphyry and epithermal systems [185]. Such processes might be the geodynamic key for understanding the reasons why the JMP hosts copper-poor and goldrich hydrothermal occurrences of high-to medium-grade and low tonnage gold deposits, as pointed out by [134].

Conclusions
The review, systematization and new geologic, petrological, and metallogenetic data of the TMP and JMP presented in this paper indicate Paleoproterozoic episodes of magmatichydrothermal mineralization in continental magmatic arcs as the main source for gold, despite the possibility of orogenic gold deposits and the Paleoproterozoic Castelo de Sonhos modified paleoplacer.
A summary of the gold metallogenesis in the TMP, and also in JMP, which records different ages for the magmatism and mineralization, is presented in Figure 9. Epithermal and porphyry mineralization are important sources for gold [88,184,185], but the preservation of epithermal systems, due to the near-surface formation and regional metamorphism, is not expected in old terrains, as the Paleoproterozoic TMP and JMP. The exceptional preservation of high-, intermediate-and low-sulfidation epithermal systems, the large and growing identification of a number of these hydrothermal deposits, and the extensive distribution of these occurrences in the TMP point to an unexplored potential for highgrade veins in volcanic/volcaniclastic and shallow-to deep-emplaced granites. Despite the relatively deeper erosion in part of the JMP, there is also a potential for epithermal gold deposits in volcanic/volcaniclastic sequences and associated with faults in granites.
The exposition of plutonic and volcanic units formed in at least three continental magmatic arcs in both provinces, together with porphyry-like hydrothermal systems, also point to the potential for low-grade and large volume Au-(Cu)-(Mo) deposits associated with arc-related to post-orogenic magmatism, including alkalic porphyry gold deposits. Some distinct characteristics of these porphyry-like systems, as thicker veins and less intense hydrothermal fracturing, should be better understood since this could be related to Paleoproterozoic geologic processes in the TMP and JMP.
The magmatic-hydrothermal systems involved variable oxygen fugacity of hydrothermal fluids and intrusive compositions, from diorites to alkali-feldspar granites in all magmatic arcs, but more evolved I-type and K-rich calc-alkaline rocks predominate, favoring gold deposit potential. The amount of produced gold, mineralized alluvial and eluvial/colluvial deposits and primary occurrences show a huge potential for economic magmatic-hydrothermal gold deposits in both provinces.
In addition, the relationship among more primitive magmas with high-sulfidation Au-Ag mineralization, Mo and Pb-Zn-Cu-(Ag) intermediate-sulfidation mineralization, and a large number of chalcopyrite-bearing mineral occurrences highlight the possibility of occurrence of porphyry base metal mineralization in both provinces, including Cu-Au alkalic porphyries, yet not explored, in the TMP and JMP.
Identifying the fertile magmatic suites, the delimitation of the magmatic, and a better understanding of magmatic-hydrothermal epochs will be critical in future works to support mineral exploration in both provinces.