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Article

Petrological, Textural, Compositional, and Economic Potential of Carbonatites from the Peshawar Plain Alkaline Igneous Province, Northwestern Himalaya

by
Mehboob ur Rashid
1,2 and
Hafiz U. Rehman
1,*
1
Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan
2
Geoscience Advance Research Labs, Geological Survey of Pakistan, Islamabad 44000, Pakistan
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(5), 439; https://doi.org/10.3390/min15050439
Submission received: 31 March 2025 / Revised: 18 April 2025 / Accepted: 21 April 2025 / Published: 23 April 2025
(This article belongs to the Special Issue Geochemistry and Geochronology of High-Grade Metamorphic Rocks)
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Abstract

:
Carbonatites, which are rare mantle-derived igneous rocks that are mainly enriched in carbonate minerals and host relatively higher amounts of rare earth element (REE)-bearing phases, remain subjects of extensive geological research due to their enigmatic origin and potential economic importance. This study aims to describe the petrographic, mineralogical, and some rare-earth element (REE) abundances of four carbonatite bodies (known as Sillai Patti, Loe Shilman, Warsak, and Jambil) exposed in the Peshawar Plain Alkaline Igneous Province (PPAIP), northwestern Himalaya, Pakistan, to identify their economic potential. The observed petrographic, textural features, and chemical compositions of the constituent minerals of the carbonatites were utilized to elucidate the evolutionary processes through which the rocks evolved. The results indicate distinct mineralogical assemblages dominated by calcite, dolomite, apatite, pyroxene, biotite, and feldspar, with accessory opaque and REE-bearing phases, such as pyrochlore, monazite, and britholite. The apatite grains display compositional zoning reflecting their growth under magmatic conditions. The petrographic features of apatite in some carbonatite samples, exhibiting preferred orientation in a particular direction and spongy or murky textures, indicate that the studied rocks underwent post-magmatic deformation or hydrothermal alteration. Calcite and dolomite, coexisting in some carbonatite samples, exhibit significant Mg-Fe variation, which is possibly related to magmatic differentiation. The pyroxene compositions vary from a low-calcium enstatite–ferrosilite series to high-calcium diopside, suggesting variable crystallization environments among the carbonatite bodies studied. The abundance of REE-bearing phases in the studied carbonatites emphasizes their high economic potential. These findings indicate that the PPAIP carbonatites originated from mantle-derived magmas and subsequently experienced metamorphic/metasomatic overprinting during their tectonic evolution. The abundance of REE-rich phases such as apatite, pyrochlore, monazite, and britholite underscores their high economic potential.

Graphical Abstract

1. Introduction

Carbonatites are igneous rocks with abundant carbonate minerals exceeding 50%, with silica content less than 20% [1,2]. Carbonatites, which are primarily composed of calcite, dolomite, siderite, and ankerite, are classified as calcio-, magnesio-, and/or ferro-carbonatites based on their dominant composition [3,4]. Carbonatite occurrences are diverse, and can be linked to, e.g., continental rifts, hotspots, post-collisional tectonic orogeny, and oceanic islands, ranging from the Archean Eon to the Tertiary period [5,6,7,8,9,10,11]. The origin of carbonatites remains subject to debate, but it is believed that the majority of carbonatites are generated from a mantle source [12]. The processes involved in the generation of carbonatites include liquid immiscibility, fractional crystallization, and precipitation from carbothermal fluids [13,14,15,16,17]. The rarity of carbonatites is apparent, with documented occurrences found in approximately 600 localities worldwide [6,18]. Intrusive carbonatites, with 527 identified locations, are commonly found as volcanic plugs, dykes, sheets, cones, pipes, and veins. Extrusive carbonatites are less common and are found in pyroclastic fall deposits, with 46 known instances [18].
Around 76% of carbonatite occurrences are closely associated with ultrabasic and alkaline silicate rocks, including olivinite, peridotite, pyroxenite, melilitolite, ijolite, and nepheline syenite [14,18]. Carbonatites and associated alkaline complexes may originate from residual melts from extensive fractionation of carbonated silicate magmas or primary melts of a CO2-bearing mantle source using the same alkaline-silicate plumbing system [19,20]. Carbonatites and alkaline intrusive complexes are primary sources of rare earth elements (REEs), including niobium, phosphate, titanium, barium, fluorine, copper, calcium, zirconium, manganese, strontium, tantalum, thorium, vanadium, and uranium, with significant deposits like Bayan Obo in China and Mountain Pass in the USA [21,22]. The rarity of carbonatites, the REEs associated with them, and their enigmatic origin have sparked global interest in studying these rocks.
In the Indian subcontinental part of Asia, carbonatite occurrences have been identified in India, Pakistan, Sri Lanka, and Afghanistan. In the Indian subcontinent, the age of carbonatite occurrences ranges from Precambrian to Pliocene [5,23]. In Pakistan, carbonatites have been reported from the Peshawar Plain Alkaline Igneous Province (PPAIP), which is part of the northwestern Himalaya (Figure 1a) [24,25,26,27,28,29,30]. The PPAIP extends from the Pakistan–Afghanistan border in the west to the Hazara–Kashmir syntaxis in the east and is bounded by the Main Mantle Thrust (MMT) in the north and the Khairabad fault in the south, covering a total area of about 200 square kilometers [25,31]. The dominant lithological units of the PPAIP are the Tarbela complex (mainly gabbros, albitites, and granites), Ambela granitic complex (alkali granites, syenites, and nepheline syenites), Shewa complex (microgranites, metagabbros, and metadolerites), Warsak complex (alkali granites, microgranites, gabbros, and dolerites), and four bodies of carbonatites, namely the Sillai Patti (SP), Loe Shilman (LS), Warsak (WC), and Jambil (JC) after the localities of occurrence (Figure 1b) [25,32,33,34,35,36]. The mentioned carbonatites in PPAIP are predominantly calcio-carbonatites types with WC leads toward the ferruginous type [37]. The age and emplacement of alkaline rocks and carbonatites in the PPAIP remain controversial among researchers, with four views about their emplacement: (i) a single episode of their magmatism during the Permo-Carboniferous time [29,38]; (ii) Silurian magmatism with emplacement of JC carbonatite followed by later metamorphism during Cenozoic Himalayan orogeny [30]; (iii) two-episode magmatism: an earlier regional-scale magmatism during the Permo-Carboniferous time and a later post-Himalayan orogeny-related event in the Paleogene [24,39]; (iv) mantle plume-derived magmatism [26,30]. Recent studies have established that the carbonatites of SP and LS are linked to the Cretaceous magmatism associated with the magmatism of the Reunion hotspot [26,40]; the alkaline magmatism and associated carbonatites of the Ambela complex are attributed to Permo-Carboniferous rifting events, while the younger ages of the Eocene to Oligocene are related to India–Asia collision and the associated metamorphism and exhumation [27,41].
The aim of this study is to characterize the petrography, mineralogical textures, and compositional variations within the carbonatite bodies of the PPAIP to elucidate their magmatic evolution and the post-magmatic alterations affecting these carbonatites. By integrating these methods, the study seeks to characterize the mineralogical composition and REE potential of the PPAIP carbonatites.

2. Geological Setting

The Loe Shilman carbonatite body, the largest of its kind in Pakistan, is situated ~50 km northwest of Peshawar, near the Pakistan–Afghanistan border [37,40]. It comprises a north-dipping, east–west striking, sheet-like body emplaced along a major fault zone within the Proterozoic to Devonian metasedimentary sequences of the Indian Plate [24,44]. It lies ~20 km north of the MMT, indicating a potential tectono-magmatic linkage with this regional suture [40]. The Sillai Pati carbonatite, the second largest in the region, is exposed ~20 km west of Malakand [37]. It is characterized by an NNE–SSW trending, south-dipping, sheet-like intrusion (~12 km long, 2–20 m thick), localized along a faulted contact between granite gneiss and metasedimentary units [26,29,43,45]. The Warsak carbonatite, positioned ~24 km northwest of Peshawar, is spatially associated with the Warsak alkaline granite, which intrudes greenschist facies metasedimentary rocks of Siluro-Devonian to Upper Paleozoic age [46,47]. The metasedimentary sequence comprises slates, phyllites, schists, and marbles, intruded by metagabbro, metadolerite (possibly Cretaceous), porphyritic microgranite (Upper Cretaceous–Lower Tertiary), and the alkaline granite [47]. The area is structurally defined by a north-plunging syncline bounded by faulting along its eastern margin, north of the Kabul River [46,47]. The Jambil carbonatite is located ~10 km southeast of Saidu in the Lower Swat Valley, northern Pakistan. The JC is emplaced as isolated, sill-like bodies and plugs of carbonatite and associated fenites within the Proterozoic Manglaur Formation and Swat granitic gneisses [30,37,48,49]. Intense Himalayan metamorphism has overprinted the original igneous textures, complicating petrographic discrimination from adjacent calc-silicate marbles [30]. The areal extent of the intrusions is obscured by thick surficial deposits [37,48].

3. Materials and Methods

Samples collected from the four carbonatite bodies of the PPAIP were investigated for whole-rock geochemistry (Supplementary Figure S1), followed by petrography, textural features, deformation structures, and mineral chemical compositions using polished thin sections. Petrography was conducted using an optical microscope and a Keyence digital microscope (VHX 8000, Keyence Corporation, Osaka, Japan). Chemical compositions of whole-rock powdered samples were determined using a hand-held X-ray fluorescence spectrometer (HH-XRF: S1 TITAN, Bruker Corporation, Karlsruhe, Germany) from Bruker’s company, Germany; detailed methodology is provided in [37]. Mineral chemistry was performed using the JEOL (JEOL Ltd., Tokyo, Japan) JXA-8230 electron probe microanalyzer (EPMA), equipped at the Kagoshima University’s instrumental analysis division, Japan. The analytical conditions of the EPMA included an accelerating voltage of 15 kV and a beam current of 6 nA, with an emission current of 10 µA. The analyses were conducted at a working distance of 11 mm under high-vacuum conditions. Imaging and data acquisition were carried out at a magnification of 40X, utilizing backscattered electron (BSE) and secondary electron imaging (SEI) detector modes. The detection limits vary depending on the element analyzed, matrix effects, and analytical conditions, such as counting time and beam parameters, but generally range between 0.01 and 0.1 wt.% under these settings. Apatite grains were separated from crushed samples using panning and gravity settling, mounted in epoxy resin, and polished to expose the middle portions of the grains; then, their internal structures were examined via CL imaging. CL imaging highlighted growth zoning, (re)crystallization patterns, and areas of alteration, aiding in interpreting magmatic conditions and subsequent fluid–rock interactions. EPMA analysis helped to determine the composition of key mineral phases that include apatite, calcite, pyroxene, biotite, feldspar, opaque minerals, and REE-bearing phases. These observations and analyses help to characterize elemental substitutions, compositional variations, and mineralogical classification critical for interpreting magmatic evolution, fractional crystallization, and metasomatic alterations within the studied carbonatites.

4. Results

4.1. Petrography

Detailed petrography and mineral assemblages observed in the PPAIP carbonatites are shown in Table 1.

4.1.1. Sillai Pati (SP) Carbonatites

The SP carbonatites predominantly comprise calcite (75%–80%), apatite (10%–15%), biotite (5%–10%), and aegirine–augite (3%–4%), with accessory minerals, including albite, hornblende, titanite, monazite, barite, and opaque minerals (magnetite/hematite) (Figure 2, Supplementary Figure S2). The rocks exhibit a coarse-grained, phaneritic texture characterized by intergrowths of euhedral to subhedral calcite with apatite and biotite (Figure 2a,b). Apatite crystals in SP carbonatites occur as subrounded as well as prismatic and contain calcitic inclusions that indicate their igneous growth during carbonatite formation, whereas subrounded shapes and abundant fractures in some grains suggest post-magmatic deformation or metamorphism (Figure 2c). The effect of deformation is further corroborated by a preferred arrangement of apatite grains in a particular orientation (Figure 2e,f). Calcite frequently fills fractures within apatite, reflecting secondary mineral precipitation. Albite occurs as distinct subhedral to euhedral grains embedded within calcite, occasionally hosting calcite inclusions (Figure 2b). Biotite displays elongate crystals with distinct cleavage, crystallizing synchronously or slightly later than apatite and albite (Figure 2b,c). Iron oxide (magnetite/hematite) grains exhibit prominent concentric zoning, with the inclusion of orthoclase, reflecting changing magmatic conditions (Figure 2d).

4.1.2. Loe Shilman (LS) Carbonatites

The LS carbonatite occurs in two distinct varieties: calcitic and biotite-rich (Figure 3, Supplementary Figures S3 and S4). The calcitic variety contains primarily calcite (90%–95%), apatite (2%–5%), and biotite (1%–2%) (Figure 3a,b, Supplementary Figure S3). The texture is coarse-grained phaneritic, characterized by interlocking calcite crystals and well-rounded, euhedral apatite grains (Figure 3a). EPMA analyses reveal that the majority of the crystals are calcite; however, several grains with significant MgO contents indicate a minor occurrence of dolomite (Figure 3b). Accessory phases include orthopyroxene, monazite, pyrochlore, and zircon. Pyrochlore is embedded in the calcitic matrix, and apatite appears as clusters of subhedral to euhedral grains. The biotite-rich variety comprises calcite (60%–70%), abundant biotite (10%–15%), apatite (5%–10%), and pyroxene (augite; 5%–8%) (Figure 3c,d, Supplementary Figure S4). Accessory minerals are titanite, magnetite, pyrite, quartz, and Ca-REE silicate identified as britholite.

4.1.3. Warsak Carbonatites (WC)

The WC has two varieties, distinguished as brownish and white. The brownish type shows significant iron staining due to oxidation, which is indicative of secondary alteration (Supplementary Figure S5). Both varieties are calcite-dominated (>95%) with biotite (2%–5%), pyroxene (aegirine; 1%–2%), and accessory apatite (Figure 4a,b). These rocks exhibit coarse-grained phaneritic textures suggesting slow crystallization, with oxidation highlighting post-emplacement processes. The BSE images illustrate a dominant calcite matrix featuring extensive fracturing (Figure 4b). Small, dispersed crystals of aegirine and apatite occur within the calcitic matrix, and magnetite grains are localized along fractures and grain boundaries, suggesting late-stage magmatic or hydrothermal fluid precipitation.

4.1.4. Jambil Carbonatites (JC)

The JC carbonatites are predominantly composed of calcite (85%–90%), pyroxene (diopside–hedenbergite; 5%–10%), scapolite (2%–5%), and titanite (1%–3%) (Figure 4c,d, Supplementary Figure S6). Accessory minerals include apatite, quartz, orthoclase, zircon, and opaque phases. The phaneritic texture comprises interlocking calcite crystals hosting numerous mineral inclusions, consistent with extensive metamorphic and hydrothermal alteration. The BSE imaging highlights the intergrowth of calcite with orthoclase and scapolite (Figure 4d, Supplementary Figure S6). The diopside crystals exhibit a poikiloblastic texture, enclosing distinct quartz and calcite inclusions (Figure 4d).

4.2. Whole-Rock Geochemistry

Whole-rock geochemical analyses of carbonatites from LS, JC, WC, and SP reveal significant compositional variation (Supplementary Table S1; note that the results given in Table S1 show total weight of major oxides < 100%; this is because values for the loss-on-ignition ‘LOI’ are not added; however, the studied rocks are primarily composed of CaCO3; hence, the remaining percentage is considered as volatiles or water). The calcite-rich variety of LS carbonatites (LS1-1, LS1-3) exhibits high CaO contents (61.4–64.7 wt.%) and low SiO2 (0.8–1.1 wt.%), whereas biotite-bearing samples (LS3-1, LS3-2) show markedly higher SiO2 (6.6–6.8 wt.%) and FeO (9.7–10.4 wt.%). The JC samples (JCN-2, JCN-3) are comparatively siliceous (3.6–3.7 wt.% SiO2) with moderate MgO (7.1–7.7 wt.%) and relatively low CaO (51.4–55.4 wt.%). The samples of WC show elevated FeO (8.7–9.1 wt.%) and MgO (8.2–10.2 wt.%) with modest CaO (52.6–58.2 wt.%). The samples from SP (SP-3, SP-4) are the most silica-rich (9.6–10.6 wt.% SiO2), with moderate to high FeO (8.5–9.2 wt.%) and CaO (56.6–58.2 wt.%). Trace element concentrations also vary widely. Sulfur and chlorine are enriched in LS carbonatites (S: 1781–4185 ppm, Cl: 885–1606 ppm), whereas the JC samples display extreme enrichment in Cl (4490–4587 ppm). REEs such as Ce and La are strongly enriched in LS and SP, with the highest values in SP (Ce: up to 2090 ppm; La: up to 2040 ppm). The Ba and Sr contents are generally high, especially in SP-3 and SP-4 (Ba: 1454–1535 ppm; Sr: 1390–2063 ppm). Nb (61—115 ppm, LS; 98—117 ppm, SP), Th (31—68 ppm, LS; 14—28 ppm, SP), and U (14—67 ppm, LS) show elevated levels primarily in the LS and SP samples.

4.3. Apatite Textures

Distinct textural features were observed in apatite grains from the PPAIP carbonatites (Figure 5). Apatite grains from SP carbonatite exhibit well-defined concentric zoning, characterized by alternating bright and dark luminescent bands (Figure 5a). The cores of these grains are notably CL-dark, suggesting higher trace element or REE concentrations gained during their growth from magmatic crystallization. Apatite grains from LS show well-defined oscillatory zoning with clear growth bands, where CL-bright cores contrast distinctly with CL-dark rims; however, several grains show the reverse pattern with Cl-bright cores or inner domains and CL-dark outer domains (Figure 5b). Such patterns suggest their magmatic growth with decreasing trace element concentrations possibly in the later stages of their crystallization. Apatite grains from WC carbonatite are characterized by relatively homogeneous CL responses, with subtle or narrow brighter rims and darker cores (Figure 5c). The thin rims could be due to a late metamorphic stage or overgrowth. Numerous inclusions are observed in WC apatite. Apatite grains from JC exhibit more complex internal textures, characterized by patchy and irregular appearance and mottled luminescence (Figure 5d). These textural features suggest recrystallization or hydrothermal alteration, possibly reflecting late-stage metasomatism that has disturbed the original magmatic zoning and redistributed the trace/REE element contents in the grains.

4.4. Mineral Chemistry

The EMPA analysis on constituent minerals was performed to understand the compositional variation of those minerals in the studied carbonatite bodies. The chemical compositions of the analyzed mineral phases are presented in Supplementary Tables S2–S6, while the corresponding analytical points and detailed mineralogical features of each carbonatite locality are illustrated in Supplementary Figures S2–S6. Below, we present details of the mineral chemistry for individual minerals.

4.4.1. Apatite

The chemical compositions of the apatite grains from the carbonatites are summarized in Figure 6, Supplementary Table S2. The apatite grains from SP are characterized by CaO (52.95–61.79 wt.%), P2O5 (35.52–44.22 wt.%), and F (2.68–4.29 wt.%). The apatite grains from LS show CaO from 52.86 to 56.04 wt.%, P2O5 from 41.69 to 43.11 wt.%, and F contents of 2.90 to 4.48 wt.%. The apatite minerals of WC exhibit similar chemical signatures, with CaO varying between 53.51 and 54.41 wt.%, P2O5 between 42.21 and 43.22 wt.%, and F between 3.20 and 4.04 wt.%. The apatite grains from JC show relatively higher contents of CaO (55.40–56.2 wt.%), moderate P2O5 (40.2–41.4 wt.%), and F (3.06–3.18 wt.%). The halogen analysis indicates consistently low Cl concentrations (<0.12 wt.%) across all localities. Minor oxides (Na2O, MgO, Al2O3, SiO2, K2O, TiO2, MnO, FeO) generally show trace or below-detection-limit concentrations representing limited substitution by these elements. The analyzed apatite grains from the studied carbonatites predominantly fall within the fluorapatite group.

4.4.2. Pyroxene

The compositional variation in pyroxenes from the studied carbonatites is presented in Supplementary Table S3 and illustrated in Figure 7. The pyroxenes from SP have compositions with SiO2 ranging from 53.28 to 54.86 wt.%, moderate CaO (9.69–11.02 wt.%), MgO (5.24–6.61 wt.%), and elevated FeO (16.59–19.27 wt.%). These pyroxenes primarily fall within the augite signifying hi-Ca pyroxene varieties. The pyroxenes from LS exhibit higher SiO2 contents (51.28–57.47 wt.%) and variable CaO (1.97–19.74 wt.%), with MgO ranging from 3.90 to 18.53 wt.% and FeO between 9.21 and 21.62 wt.%. These grains plot within the Ferrosilite–Augite fields, indicating compositional diversity from low- to high-Ca pyroxenes. The pyroxenes from WC have compositions characterized by moderate SiO2 (51.11–54.18 wt.%), high CaO (14.76–23.36 wt.%), MgO (8.39–12.25 wt.%), and FeO (7.56–15.88 wt.%), classifying them predominantly as an augite–diopside series (high-Ca pyroxenes). The pyroxene grains from JC are consistently high-Ca varieties, characterized by high CaO (23.31–25.35 wt.%), MgO (12.20–13.71 wt.%), FeO (6.12–13.43 wt.%), and SiO2 (52.41–53.87 wt.%); thus, they are firmly plotted within the diopside field. The ternary classification diagram (wollastonite–enstatite–ferrosilite) illustrates compositional variations clearly, distinguishing high-Ca clinopyroxenes of WC and JC from the low-Ca pyroxenes of SP and LS carbonatites.

4.4.3. Biotite

The EPMA analysis for biotite from the SP, LS, and WC carbonatites is presented in Supplementary Table S4 and in Figure 8. Biotite from SP shows SiO2 contents ranging from 39.50 to 42.47 wt.%, with FeO (17.81–25.54 wt.%), MgO (10.85–13.64 wt.%), Al2O3 (11.93–13.54 wt.%), K2O (7.32–11.92 wt.%), and minor TiO2 (2.41–3.54 wt.%). The compositional variation indicates enrichment in Fe and moderate Mg contents, placing it predominantly within the siderophyllite–annite fields. Biotite in LS has SiO2 contents ranging from 37.18 to 43.01 wt.%, FeO (10.57–23.33 wt.%), MgO (12.07–23.26 wt.%), Al2O3 (10.45–14.50 wt.%), and K2O (10.13–11.12 wt.%), alongside lower TiO2 (0.46–2.73 wt.%). These compositions fall distinctly within the siderophyllite field, reflecting intermediate Fe-Mg-Al composition. Biotite from WC exhibits SiO2 (42.50–43.24 wt.%), FeO (14.72–17.79 wt.%), higher MgO contents (18.36–21.07 wt.%), Al2O3 (10.88–11.98 wt.%), moderate K2O (6.99–8.84 wt.%), and low TiO2 (0.83–1.01 wt.%). These compositions cluster mainly within the siderophyllite field, reflecting relatively higher Mg content. The FeAl vs. MgLi mica classification diagram of Tischendorf et al. [50] confirms these observations, placing biotite from SP towards the Fe-rich annite–siderophyllite boundary, while biotite from LS and WC plot centrally within the siderophyllite field, indicating intermediate Fe-Mg mica compositions.

4.4.4. Feldspars

Feldspars from the SP and JC carbonatites are presented in Supplementary Table S5 and Figure 9. Feldspar from SP displays higher SiO2 content ranging from 67.49 to 72.44 wt.%, Na2O varying between 5.92 and 16.05 wt.%, Al2O3 between 18.33 and 21.17 wt.%, and negligible K2O (0.14–0.32 wt.%). The CaO contents are consistently low (0.05–0.37 wt.%), with minor FeO and TiO2 (<0.33 and <0.11 wt.%, respectively). These chemical compositions plot entirely within the albite field, indicating sodium-rich plagioclase (Figure 9). In contrast, feldspar from JC carbonatite contains relatively lower SiO2 (64.51–64.63 wt.%), significantly higher K2O (14.89–15.55 wt.%), moderate Al2O3 (18.36–18.80 wt.%), and low Na2O (1.13–1.64 wt.%). CaO (0.04–0.15 wt.%), FeO, and TiO2 remain negligible. These compositions plot within the orthoclase field, clearly indicating potassium-rich alkali feldspar (Figure 9). Feldspar grains were not analyzed for the LS and WC carbonatites because feldspar was either absent or occurred only as accessory mineral phases in trace amounts that were insufficient for reliable electron probe microanalysis (EPMA).

4.4.5. Opaques

The EPMA data for opaque minerals from the SP, LS, and WC carbonatites are summarized in Supplementary Table S6. In SP, opaque minerals display high FeO contents (91.14–94.41 wt.%), indicating a dominance of magnetite and hematite. Minor elements such as SiO2 (3.93–5.73 wt.%), CaO (0.40–1.01 wt.%), and Al2O3 (up to 0.96 wt.%) reflect impurities or silicate inclusions. Opaque minerals in LS show distinct Fe–S compositions; high SO3 contents (55.61–63.68 wt.%) coupled with significant FeO (36.32–44.40 wt.%) indicate pyrite (FeS2), whereas pure FeO (around 100 wt.%) compositions suggest magnetite. The opaque phases from WC have variable FeO contents (43.89–97.35 wt.%), occasionally high SO3 (up to 55.74 wt.%), and noticeable SiO2 contents (up to 12.08 wt.%), reflecting predominantly magnetite/hematite with minor pyrite and silicate impurities.

4.4.6. Rare Earth Element-Bearing Minerals

The EPMA data (Table 2) indicate significant REE potential in the studied carbonatites; this is particularly highlighted by the elevated La2O3, CeO2, Nd2O3, and Nb2O5 concentrations. The REE-bearing phases in the calcitic variety of LS carbonatites exhibit considerable concentrations of La2O3 between 13.1 and 29.44 wt.%, CeO2 ranging from 17.76 to 41.38 wt.%, and Nb2O5 varying significantly from 76.89 to 84.83 wt.%. These high REE and Nb concentrations reinforce the potential presence of Nb and La, Ce-rich REE minerals of pyrochlore, and monazite (Figure 3a,b; Supplementary Figure S3). The minerals present in the biotitic variety of LS carbonatite show La2O3 ranging from 9.79 to 10.42 wt.% and CeO2 from 12.68 to 14.44 wt.%. This REE enrichment, coupled with the high content of CaO, Al2O3, SiO2, and P2O5, indicated the presence of La and Ce REE silicate phases, most likely britholite (Figure 3d,e; Supplementary Figure S4). In contrast, EPMA analyses of the SP carbonatite presented comparatively lower REE and Nb2O5 values (La2O3: 25.44 to 31.22 wt.%, CeO2: 32.69 to 39.21 wt.%) based on limited spot data, showing monnazite. Importantly, as previously discussed (Section 4.4.1), the dominant mineral in SP is apatite. Apatite is a recognized mineral that hosts significant concentrations of REEs, as documented in previous researches [51,52]. Other dominant REE minerals in SP carbonatite include monazite, britholite, and pyrochlore.

4.4.7. Scapolite

The EPMA results of scapolite from the JC indicate variations in its chemical composition (Table 3). The scapolite grains show CaO ranging from 10.70 to 24.75 wt.%, Na2O from 0.01 to 7.55 wt.%, Al2O3 from 22.93 to 28.56 wt.%, and SiO2 from 39.46 to 53.33 wt.%. K2O and FeO show relatively minor amounts up to 0.53 and 8.14 wt.%, respectively. The minor contents of TiO2, MnO, and P2O5 are generally below 0.5 wt.%. The halogen concentrations are marked by Cl (0.04–1.36 wt.%) and F (<0.21 wt.%), reflecting a predominantly chlorine-rich scapolite composition. Additionally, minor SO3 up to 2.2 wt.% indicates sulfate substitutions within the scapolite structure. Overall, the EPMA data suggest that scapolite is predominantly marialitic (Na-rich) to meionitic (Ca-rich) in composition, with limited potassium substitution and halogen-enriched varieties reflecting crystallization under halogen-rich conditions.

5. Discussion

Carbonatites from the PPAIP exhibit distinct chemical, mineralogical, and textural features, and they all reflect complex magmatic and post-magmatic processes. Below, we briefly describe the results and interpretations.

5.1. Interpretations Based on Petrography Regarding Magmatic Process

Petrographically, the SP carbonatites show dominant calcite intergrown with apatite, biotite, and aegirine–augite (Figure 2), indicative of crystallization from a mantle-derived carbonatitic melt [20]. The presence of albite and zoned magnetite in SP carbonatite indicates late-stage alkali metasomatism and fluctuating magmatic redox conditions [53]. The LS carbonatites exhibiting two texturally distinct varieties—calcitic and biotite-rich (Figure 3)—indicate that the calcitic variety (containing calcite and dolomite, Figure 3b, Supplementary Figure S3) had significant ionic substitution at elevated temperatures. This compositional variability suggests progressive fractionation and differentiation of the carbonatitic magma, as reported from carbonatites in past studies [5,19]. The initial carbonatite melt was possibly calcium-rich, which could crystallize nearly pure calcite first, removing Ca from the melt. After the removal of calcite, the residual magma became relatively enriched in Mg, Fe, and other components. This could have possibly led to the later crystallization of carbonates that are Mg–Fe-rich, such as dolomite or Fe-bearing dolomite. The biotite-rich variety, exhibiting textural features and mineral paragenesis, such as britholite inclusions and calcite-filled augite crystals (Figure 3d), provides compelling evidence of first magmatic and later magmatic–hydrothermal interaction. Pyrochlore, britholite, and monazite, enriched in Nb and REE, respectively, additionally imply considerable fertility of the magma, consistent with other mantle-derived carbonatites [5,54]. The WC samples predominantly consisting of calcite, aegirine, biotite, and minor apatite, showing substantial iron staining, indicate oxidation and late-stage hydrothermal alterations (Figure 4). The samples from JC, characterized by diopside–hedenbergite pyroxenes and abundant scapolite (Figure 4d), indicate extensive hydrothermal and metasomatic overprinting, consistent with post-emplacement tectono-thermal events in the region [30,49,55]. Oscillatory zoning in apatite (SP, LS) is consistent with stable magmatic crystallization environments, whereas apatite grains of JC displaying patchy, mottled textures may reflect significant hydrothermal alteration (Figure 5). Such alteration patterns are commonly observed in apatites from hydrothermally modified carbonatites [27,56,57].

5.2. Interpretations Based on Whole-Rock Geochemistry

Whole-rock geochemistry classifies the studied rocks as typical carbonatites; however, their compositional variation indicates calcitic to ferroan members for WC, which may have been chemically modified during late-stage hydrothermal events. The REE geochemistry of the investigated minerals highlights the significant REE potential of the studied carbonatites, particularly the samples of SP samples (containing high REE contents, with Ce 2050 to 2090 ppm; La from 119 to 2090 ppm) and LS samples (exhibiting strong LREE enrichment, Ce: 1747 to 2308 ppm; La: 1078 to 1259 ppm) with notable concentrations of Nb (61—117 ppm), Th (31—68 ppm), U (14—67 ppm), Th, and U. This enrichment is consistent with the observed presence of monazite and apatite, both of which are known as REE-bearing phases. The LREE enrichment suggests that these rocks represent evolved carbonatites, potentially derived from the low-degree partial melting, or they were subjected to late-stage magmatic fluid enrichment [54].

5.3. Interpretations from Mineral Chemistry

The elemental compositions of minerals from the EPMA analysis indicate that the studied apatites are fluorapatites (Figure 6, Supplementary Table S2), reflecting F-rich magmatic conditions typical of mantle-derived carbonatites [56,58,59]. The calcite compositions varied significantly, with LS calcite exhibiting the most considerable ionic substitutions, with the presence of dolomite (Figure 3). The pyroxene compositions from the PPAIP carbonatites (Figure 7) reflect differences in magmatic evolution and fluid–rock interaction. The SP and LS carbonatites (calcitic) contain predominantly low-Ca pyroxenes, indicative of crystallization under relatively low Ca and variable Si conditions [60]. The pyroxenes of WC and LS (biotitic variety), plotting in the augite field, suggest moderate to high Ca conditions associated with later stages of magma evolution or hydrothermal alteration. The samples of JC exclusively host high-Ca pyroxenes (diopside), consistent with crystallization from Ca-rich melts, with significant post-magmatic metasomatic activity. Diopside produced by metasomatic processes is depleted in Na and Al and enriched in Ca relative to magmatic clinopyroxenes [61]. Diopside with the inclusion of quartz and calcite shows a poikiloblastic texture representing its metamorphic origin with hydrothermal overprinting. The presence of quartz as an inclusion and as a vein further confirms the secondary hydrothermal to metasomatic/metamorphic activities in JC (Figure 4c). Carbonatites are considered as Si-deficient rocks; however, the presence of quartz leads to a signature of later processes. The occurrence of quartz in carbonatites is commonly attributed to hydrothermal activity, post-magmatic silicification, or infiltration by metamorphic fluids [62,63,64]. Silicification may result from the introduction of Si-rich fluids during late-stage magmatic activity or regional metamorphism, producing quartz veining or replacement textures [65,66]. Previous studies have reported similar quartz associations in carbonatites affected by metamorphic overprinting or crustal fluid interaction, underscoring the importance of multiple fluid sources in their genesis [22,62,65,66]. The protolith age of the JC, dated at 438 Ma from titanite [30], contrasted with younger ages of 40–15 Ma based on monazite and apatite [30,49], supports a significant metamorphic overprint that is likely related to the Himalayan orogeny and Oligocene exhumation. Biotite compositions of SP, LS, and WC, ranging from siderophyllite–annite fields (Figure 8), suggest intermediate Fe-Mg conditions that are typical for carbonatites associated with mantle-derived origin [67,68]. Feldspars from SP (albite-rich) and JC (orthoclase-rich) highlight diverse magmatic evolutions and different degrees of alkali metasomatism (Figure 9). Opaque phases, dominated by magnetite and minor pyrite, highlight oxidizing conditions and late-stage hydrothermal activity. The presence of high REE-bearing phases, such as pyrochlore, britholite, and monazite, emphasizes the significant REE fertility of LS and SP apatite (Table 2). The scapolite chemistry from JC further confirms significant Cl-rich fluid activity (Table 3), which is typical in metasomatic halos around carbonatite intrusions globally [55]. Scapolite is a feldspathoid containing halogens and carbonates, formed through metasomatic alteration of plagioclase or marls in the presence of Cl–- or CO3–-rich fluids. [69]. The formation of scapolite, diopside, and K-feldspar (orthoclase) is likely a result of metamorphic/metasomatic overprint. The presence of K-feldspar (orthoclase) indicates the introduction of potassium, a common element in fenitization halos around carbonatites. Metasomatism occurs when alkalis from carbonatite magma or fluids infiltrate rocks, resulting in the formation of K-feldspar and Na-rich minerals [13,70]. The concentration and mobility of REEs in carbonatites are strongly influenced by alkali and silica activity during magmatic to post-magmatic evolution [71,72,73]. The presence of REE-bearing minerals, such as monazite, britholite, and pyrochlore—particularly in SP and LS—likely reflects this multi-stage enrichment process. The mineralogical and geochemical evidence presented indicates a mantle-derived origin for the PPAIP carbonatites, followed by significant post-emplacement tectonic deformation and hydrothermal alteration, substantially modifying their mineralogy and enhancing their potential for REE and HFSE mineralization.

6. Conclusions

The carbonatites from PPAIP demonstrate diverse mineralogical assemblages reflecting complex mantle-derived magmatic processes followed by significant post-magmatic modifications. Petrographic and geochemical evidence (apatite zoning, Fe and Mg content in calcite, dolomite, and biotite, and pyroxene variations) supports a mantle-derived origin for the carbonatitic melts, characterized by progressive fractional crystallization and differentiation. In addition, extensive fracturing and mineral inclusions, along with preferred orientation of minerals in SP carbonatite, confirm a later stage of tectonic deformation. The presence of different suits of calcitic and biotitic variety in the LS carbonatite confirms the extensive fractional crystallization of carbonatitic magma. The calcite inclusions in the apatite and augite confirm that the growth of minerals occurs synchronously within carbonatitic magma. Moreover, the presence of quartz veins, scapolite, and pyroxene compositional and textural relationships indicates substantial fluid–rock interactions, affecting the JC carbonatites. The variable pyroxene compositions from low-Ca (enstatite–ferrosilite) to high-Ca (diopside–hedenbergite) confirm distinct evolutionary pathways, ranging from primary magmatic crystallization to intense metasomatic overprinting in the studied carbonatite complexes. Finally, the REE-bearing phases (pyrochlore, britholite, monazite, and apatite), identified particularly in LS and SP, highlight the fertility and metallogenic potential associated with these mantle-derived carbonatite bodies. While this study provides key mineralogical and geochemical insights, future investigations incorporating high-resolution analytical techniques, such as LA-ICP-MS, are recommended to comprehensively constrain the REE budget. Such data would enable more detailed evaluation of the distribution, partitioning, and economic potential of REE-bearing phases within the carbonatite complexes.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/min15050439/s1, Figure S1: Field photographs of carbonatite bodies from the Peshawar Plain Alkaline Igneous Province (PPAIP): (a) Sillai Patti, (b) Loe Shilman, (c) Warsak, and (d) Jambil carbonatites; Figure S2: BSE images of SP carbonatite showing textural relationships between major and accessory mineral phases; Figure S3: BSE images showing representative mineral assemblages from the LS (calcitic) carbonatite; Figure S4: BSE images of the LS biotite-rich carbonatite variety; Figure S5; BSE images of WC carbonatite showing compositional and textural differences characteristics; Figure S6: BSE images of JC carbonatite showing mineral and textural characteristics; Table S1: Whole-rock major (wt.%) and trace element (ppm) geochemistry of carbonatites from PPAIP; Table S2: Chemical composition (wt.%) of representative apatite grains from studied carbonatites; Table S3: Chemical composition (wt.%) of representative pyroxene grains from carbonatites of PPAIP; Table S4: Chemical composition (wt.%) of representative biotite grains from carbonatites of PPAIP; Table S5: Chemical composition (wt.%) of representative feldspar grains from carbonatites of PPAIP; Table S6: Chemical composition (wt.%) of representative opaque minerals from carbonatites of PPAIP.

Author Contributions

Conceptualization, M.u.R. and H.U.R.; methodology, M.u.R. and H.U.R.; software, M.u.R.; validation, M.u.R. and H.U.R.; formal analysis, M.u.R.; investigation, M.u.R.; resources, H.U.R.; data curation, M.u.R. and H.U.R.; writing—original draft preparation, M.u.R.; writing—review and editing, H.U.R.; visualization, M.u.R.; supervision, H.U.R.; project administration, H.U.R.; funding acquisition, H.U.R. All authors have read and agreed to the published version of the manuscript.

Funding

The research project was partly supported by the JSPS Kakenhi fund (#20K004135 to H.U.R.).

Data Availability Statement

All data are presented in the manuscript, with Supplementary Data attached to the manuscript.

Acknowledgments

The first author gratefully acknowledges the Geoscience Advance Research Laboratories, Geological Survey of Pakistan, for providing logistical support during fieldwork in the study area. Special appreciation is extended to MEXT for the financial support to the first author to pursue his PhD studies at Kagoshima University, Japan. We acknowledge the support provided by the staff of Kagoshima University’s Instrumental analytical research center.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. (a) Geological map of the Himalayan belt showing its major litho-tectonic units; the location of the study area is marked. Abbreviations and geological units are MKT = Main Karakoram Thrust, KIA = Kohistan Island Arc, MMT = Main Mantle Thrust, GCT = Great Counter Thrust, STDS = South Tibetan Detachment System, MBT = Main Boundary Thrust, MCT = Main Central Thrust, K = Kashmir Basin. The inset in left-bottom corner shows a sketch of Indian subcontinent with rectangular box marking the study area. (b) Geological map of the Peshawar Plain Alkaline Igneous Province (PPAIP) showing the dominant alkaline rock complexes and four carbonatite bodies (sources are from [24,31,42,43]).
Figure 1. (a) Geological map of the Himalayan belt showing its major litho-tectonic units; the location of the study area is marked. Abbreviations and geological units are MKT = Main Karakoram Thrust, KIA = Kohistan Island Arc, MMT = Main Mantle Thrust, GCT = Great Counter Thrust, STDS = South Tibetan Detachment System, MBT = Main Boundary Thrust, MCT = Main Central Thrust, K = Kashmir Basin. The inset in left-bottom corner shows a sketch of Indian subcontinent with rectangular box marking the study area. (b) Geological map of the Peshawar Plain Alkaline Igneous Province (PPAIP) showing the dominant alkaline rock complexes and four carbonatite bodies (sources are from [24,31,42,43]).
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Minerals 15 00439 g002
Figure 2. Petrographic characteristics of SP carbonatite: (a,b) Photomicrographs (captured under cross-polarized light) and backscattered electron (BSE) image showing intergrowth of euhedral to subhedral calcite (Cal) with apatite (Ap), elongated biotite (Bt), and albite (Ab); (c) BSE image displaying apatite with inclusions of Cal and Ab; (d) BSE image of euhedral grain of magnetite/hematite (Fe ore) exhibiting concentric zoning and inclusion of orthoclase (Or); (e) photomicrograph (taken under plane-polarized light) of an entire thin section from SP carbonatite, displaying calcite (grayish white portion), apatite, biotite, pyroxene, amphibole, alkali feldspar with dispersed accessory minerals of barite and monazite; (f) tracing of apatite grains in the thin section (thin section as shown in e) to highlight their distribution and orientation, indicating post-magmatic deformation.
Figure 2. Petrographic characteristics of SP carbonatite: (a,b) Photomicrographs (captured under cross-polarized light) and backscattered electron (BSE) image showing intergrowth of euhedral to subhedral calcite (Cal) with apatite (Ap), elongated biotite (Bt), and albite (Ab); (c) BSE image displaying apatite with inclusions of Cal and Ab; (d) BSE image of euhedral grain of magnetite/hematite (Fe ore) exhibiting concentric zoning and inclusion of orthoclase (Or); (e) photomicrograph (taken under plane-polarized light) of an entire thin section from SP carbonatite, displaying calcite (grayish white portion), apatite, biotite, pyroxene, amphibole, alkali feldspar with dispersed accessory minerals of barite and monazite; (f) tracing of apatite grains in the thin section (thin section as shown in e) to highlight their distribution and orientation, indicating post-magmatic deformation.
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Figure 3. Petrography of LS carbonatite: (a,b) Calcitic variety with dominant calcite (Cal), dolomite (Dol), apatite (Ap), biotite (Bt), monazite (Mnz), zircon (Zr), and pyrochlore (Pcl). (c,d) Biotite-rich variety showing large calcite grains intergrown with biotite (Bt), apatite (Ap), augite (Aug), quartz (Qz), and britholite (Brt). (a,c) Cross-polarized images; (b,d) BSE images. Scale bar = 100 µm.
Figure 3. Petrography of LS carbonatite: (a,b) Calcitic variety with dominant calcite (Cal), dolomite (Dol), apatite (Ap), biotite (Bt), monazite (Mnz), zircon (Zr), and pyrochlore (Pcl). (c,d) Biotite-rich variety showing large calcite grains intergrown with biotite (Bt), apatite (Ap), augite (Aug), quartz (Qz), and britholite (Brt). (a,c) Cross-polarized images; (b,d) BSE images. Scale bar = 100 µm.
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Figure 4. Petrographic characteristics of (a,b) WC and (c,d) JC carbonatites; (a,b) WC carbonatite dominated by coarse-grained calcite (Cal), apatite (Ap), biotite (Bt), and augite (Aug), with magnetite (Mag) and pyrite (Pyr) along fractures; (c,d) JC carbonatite featuring intergrowth of calcite (Cal), diopside (Di), scapolite (Scp), orthoclase (Or), titanite (Ttn), quartz (Qz), and apatite (Ap). (a,c) Cross-polarized images; (b,d) BSE images. Scale bar = 100 µm.
Figure 4. Petrographic characteristics of (a,b) WC and (c,d) JC carbonatites; (a,b) WC carbonatite dominated by coarse-grained calcite (Cal), apatite (Ap), biotite (Bt), and augite (Aug), with magnetite (Mag) and pyrite (Pyr) along fractures; (c,d) JC carbonatite featuring intergrowth of calcite (Cal), diopside (Di), scapolite (Scp), orthoclase (Or), titanite (Ttn), quartz (Qz), and apatite (Ap). (a,c) Cross-polarized images; (b,d) BSE images. Scale bar = 100 µm.
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Figure 5. Cathodoluminescence (CL) images of apatite grains from the four studied carbonatite bodies in the PPAIP: (a) Apatite grains from SP show concentric zoning with darker cores and brighter outer domains; (b) apatite grains from LS displaying prominent oscillatory as well as banded/sector zoning; (c) apatite grains from WC exhibiting homogeneous luminescence at the inner domains with subtle growth of rims; and (d) apatite grains from JC showing patchy and irregular zoning with darker, mottled cores. Scale bar = 100 µm.
Figure 5. Cathodoluminescence (CL) images of apatite grains from the four studied carbonatite bodies in the PPAIP: (a) Apatite grains from SP show concentric zoning with darker cores and brighter outer domains; (b) apatite grains from LS displaying prominent oscillatory as well as banded/sector zoning; (c) apatite grains from WC exhibiting homogeneous luminescence at the inner domains with subtle growth of rims; and (d) apatite grains from JC showing patchy and irregular zoning with darker, mottled cores. Scale bar = 100 µm.
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Figure 6. Plot of CaO versus P2O5 (wt.%) contents of apatite grains analyzed from the four studied carbonatite bodies of the PPAIP.
Figure 6. Plot of CaO versus P2O5 (wt.%) contents of apatite grains analyzed from the four studied carbonatite bodies of the PPAIP.
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Figure 7. Classification diagram (wollastonite–enstatite–ferrosilite) for pyroxene grains analyzed from the carbonatite bodies.
Figure 7. Classification diagram (wollastonite–enstatite–ferrosilite) for pyroxene grains analyzed from the carbonatite bodies.
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Minerals 15 00439 g008
Figure 8. Biotite classification diagram (FeAl vs. MgLi in apfu) for mica compositions from the studied carbonatite localities, following classification scheme after [50]; (MgLi = (Mg − Li); FeAl = (Fe + Mn + Ti − Al).
Figure 8. Biotite classification diagram (FeAl vs. MgLi in apfu) for mica compositions from the studied carbonatite localities, following classification scheme after [50]; (MgLi = (Mg − Li); FeAl = (Fe + Mn + Ti − Al).
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Figure 9. Feldspar compositions from SP and JC carbonatites plotted on the Or–Ab–An ternary diagram, (Or = Orthoclase, Ab = Albite, An = Anorthoclase).
Figure 9. Feldspar compositions from SP and JC carbonatites plotted on the Or–Ab–An ternary diagram, (Or = Orthoclase, Ab = Albite, An = Anorthoclase).
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Table 1. Mineral assemblage observed in the carbonatite bodies of PPAIP. Solid circles indicate major minerals, empty circles represent minor minerals, and broken circles denote accessory minerals.
Table 1. Mineral assemblage observed in the carbonatite bodies of PPAIP. Solid circles indicate major minerals, empty circles represent minor minerals, and broken circles denote accessory minerals.
Mineral PhaseSillai PattiLoe ShilmanWarsakJambil
CalciticBiotite
CalciteMinerals 15 00439 i001Minerals 15 00439 i001Minerals 15 00439 i001Minerals 15 00439 i001Minerals 15 00439 i001
ApatiteMinerals 15 00439 i001Minerals 15 00439 i001Minerals 15 00439 i001Minerals 15 00439 i001Minerals 15 00439 i002
PyroxeneMinerals 15 00439 i001Minerals 15 00439 i002Minerals 15 00439 i001Minerals 15 00439 i002Minerals 15 00439 i001
BiotiteMinerals 15 00439 i001Minerals 15 00439 i002Minerals 15 00439 i001Minerals 15 00439 i002
TitaniteMinerals 15 00439 i003 Minerals 15 00439 i003 Minerals 15 00439 i001
AmphiboleMinerals 15 00439 i003
Alkali feldsparMinerals 15 00439 i002 Minerals 15 00439 i002
OpaqueMinerals 15 00439 i001Minerals 15 00439 i003Minerals 15 00439 i002Minerals 15 00439 i001Minerals 15 00439 i002
Quartz Minerals 15 00439 i003 Minerals 15 00439 i002
Scapolite Minerals 15 00439 i001
MonaziteMinerals 15 00439 i003Minerals 15 00439 i002
Pyrochlore Minerals 15 00439 i002
Britholite Minerals 15 00439 i002
Zircon Minerals 15 00439 i003 Minerals 15 00439 i003
Table 2. Chemical composition (wt.%) of REE-bearing minerals from SP and LS carbonatites analyzed by EPMA.
Table 2. Chemical composition (wt.%) of REE-bearing minerals from SP and LS carbonatites analyzed by EPMA.
LocalitySpotCaOAl2O3SiO2P2O5TiO2FeOLa2O3CeO2Nb2O5Nd2O3TotalMinerals
Sillai Pattii44.30.080.0930.450.370.0525.4439.21b.d.lb.d.l99.99Mnz
m4b.d.lb.d.lb.d.l34.65b.d.lb.d.l26.2739.08b.d.lb.d.l100Mnz
m5b.d.lb.d.lb.d.l32.65b.d.lb.d.l31.2235.69b.d.lb.d.l99.56Mnz
n6b.d.lb.d.lb.d.l33.2b.d.lb.d.l29.3137.49b.d.lb.d.l99.99Mnz
Loe ShilmanLS—Biotite varietya510.1510.8233b.d.lb.d.l21.3310.2714.44b.d.lb.d.l100.01Brt
a69.911.9332.150.011.7219.819.8213.64b.d.lb.d.l98.98Brt
c510.5211.7733.56b.d.lb.d.l21.0610.4212.68b.d.lb.d.l100.01Brt
c611.9411.8833.68b.d.lb.d.l20.86b.d.l12.87b.d.lb.d.l91.23Brt
c711.2411.2933.17b.d.lb.d.l20.3910.8113.1b.d.lb.d.l100Brt
c810.3911.9634.07b.d.lb.d.l20.379.3413.86b.d.lb.d.l99.99Brt
d711.019.9332.78b.d.lb.d.l21.359.7914.1b.d.lb.d.l98.96Brt
LS—Calcitic Varietya114.17b.d.lb.d.lb.d.l2.44b.d.lb.d.l2.5580.84b.d.l100Pcl
a214.42b.d.lb.d.lb.d.l1.61b.d.lb.d.l2.7281.25b.d.l100Pcl
a314.78b.d.lb.d.lb.d.l3.25b.d.lb.d.lb.d.l81.97b.d.l100Pcl
a415.17b.d.lb.d.lb.d.lb.d.lb.d.lb.d.lb.d.l84.83b.d.l100Pcl
b1b.d.lb.d.lb.d.l32.69b.d.lb.d.l28.0439.27b.d.lb.d.l100Mnz
b256.16b.d.lb.d.l11.39b.d.lb.d.l13.117.76b.d.lb.d.l98.41Mnz
b3b.d.lb.d.lb.d.l32.09b.d.lb.d.l29.4838.43b.d.lb.d.l100Mnz
b4b.d.lb.d.lb.d.l32.01b.d.lb.d.l28.8539.15b.d.lb.d.l100.01Mnz
b5b.d.lb.d.lb.d.l31.95b.d.lb.d.l30.837.25b.d.lb.d.l100Mnz
b6b.d.lb.d.lb.d.l32.73b.d.lb.d.l29.4437.84b.d.lb.d.l100.01Mnz
b74.71b.d.lb.d.l30.93b.d.lb.d.l27.4636.91b.d.lb.d.l100.01Mnz
b80.86b.d.lb.d.l31.84b.d.lb.d.l28.4838.82b.d.lb.d.l100Mnz
c113.23b.d.lb.d.lb.d.l4.37b.d.lb.d.l2.7876.892.72100Pcl
c215.47b.d.lb.d.lb.d.l2.16b.d.lb.d.lb.d.l82.37b.d.l100Pcl
c317.27b.d.lb.d.lb.d.l5.07b.d.lb.d.lb.d.l77.66b.d.l100Pcl
d1b.d.lb.d.lb.d.l32.98b.d.lb.d.l28.1238.9b.d.lb.d.l100Mnz
d2b.d.lb.d.lb.d.l33.17b.d.lb.d.l25.4541.38b.d.lb.d.l100Mnz
d518.21b.d.lb.d.l26.35b.d.lb.d.l23.4132.04b.d.lb.d.l100.01Mnz
d68.270.86b.d.l27.65b.d.lb.d.l28.3534.88b.d.lb.d.l100.01Mnz
d7b.d.lb.d.lb.d.l33.33b.d.lb.d.l25.8140.87b.d.lb.d.l100.01Mnz
d8b.d.lb.d.lb.d.l31.96b.d.lb.d.l29.3838.66b.d.lb.d.l100Mnz
e6b.d.lb.d.lb.d.l33.11b.d.lb.d.l25.0341.86b.d.lb.d.l100Mnz
e7b.d.lb.d.lb.d.l33.16b.d.lb.d.l26.9239.93b.d.lb.d.l100.01Mnz
Footnote. LS—biotite variety, spot shown in Supplementary Figure S3. b, c, d; LS—calcitic variety, spot shown in Supplementary Figure S2 (for reference). Mnz = Monazite, Pcl = Pyrochlore, Brt = Britholite. The b.d.l represents values below the detection limit.
Table 3. Chemical compositions (wt.%) of scapolite from JC carbonatite analyzed by EPMA.
Table 3. Chemical compositions (wt.%) of scapolite from JC carbonatite analyzed by EPMA.
LocalitySpotCaONa2OMgOAl2O3SiO2P2O5K2OTiO2MnoFeOFClSO3Total
Jambil Carbonatitea110.997.22b.d.l23.5250.41b.d.lb.d.lb.d.lb.d.lb.d.lb.d.l1.322.0795.53
a211.057.13b.d.l22.9350.67b.d.lb.d.lb.d.lb.d.lb.d.lb.d.l1.282.1095.16
a310.707.55b.d.l23.0750.39b.d.lb.d.lb.d.lb.d.lb.d.lb.d.l1.322.0995.12
c512.147.41b.d.l24.7953.330.190.530.03b.d.l0.130.081.36b.d.l99.99
c612.696.49b.d.l24.9251.930.080.330.020.070.020.211.022.2099.98
c712.757.00b.d.l25.3353.070.100.500.050.050.02b.d.l1.13b.d.l100.00
d124.71b.d.l0.0327.3439.460.01b.d.l0.190.098.140.020.01b.d.l100.00
d224.140.030.0528.3639.710.050.040.260.027.34b.d.lb.d.lb.d.l100.00
d324.520.010.0828.5339.470.14b.d.l0.130.236.90b.d.lb.d.lb.d.l100.01
e123.920.080.0528.2439.780.140.01b.d.l0.187.54b.d.l0.04b.d.l99.98
e224.750.050.0528.5639.60b.d.lb.d.l0.22b.d.l6.74b.d.l0.04b.d.l100.01
e310.997.22b.d.l23.5250.41b.d.lb.d.lb.d.lb.d.lb.d.lb.d.l1.322.0795.53
e411.057.13b.d.l22.9350.67b.d.lb.d.lb.d.lb.d.lb.d.lb.d.l1.282.1095.16
e510.707.55b.d.l23.0750.39b.d.lb.d.lb.d.lb.d.lb.d.lb.d.l1.322.0995.12
Footnote. Scapolite spots shown in Supplementary Figure S5.
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Rashid, M.u.; Rehman, H.U. Petrological, Textural, Compositional, and Economic Potential of Carbonatites from the Peshawar Plain Alkaline Igneous Province, Northwestern Himalaya. Minerals 2025, 15, 439. https://doi.org/10.3390/min15050439

AMA Style

Rashid Mu, Rehman HU. Petrological, Textural, Compositional, and Economic Potential of Carbonatites from the Peshawar Plain Alkaline Igneous Province, Northwestern Himalaya. Minerals. 2025; 15(5):439. https://doi.org/10.3390/min15050439

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Rashid, Mehboob ur, and Hafiz U. Rehman. 2025. "Petrological, Textural, Compositional, and Economic Potential of Carbonatites from the Peshawar Plain Alkaline Igneous Province, Northwestern Himalaya" Minerals 15, no. 5: 439. https://doi.org/10.3390/min15050439

APA Style

Rashid, M. u., & Rehman, H. U. (2025). Petrological, Textural, Compositional, and Economic Potential of Carbonatites from the Peshawar Plain Alkaline Igneous Province, Northwestern Himalaya. Minerals, 15(5), 439. https://doi.org/10.3390/min15050439

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