Search Results (4)

Multiple occurrences of adakitic rocks, with crystallization ages clustering around ~160 Ma, have been documented in the Zhuxi district, northeast Jiangxi Province, South China. This research identifies a new adakitic biotite granite porphyry within the Zhuxi W-Cu polymetallic deposit. Zircon U-Pb geochronology of this porphyry yields a crystallization age of 161.6 ± 2.1 Ma. Integrated with previously published data, the adakitic rocks in the study area—comprising diorite porphyrite, biotite quartz monzonite porphyry, and the newly identified biotite granite porphyry—are predominantly calc-alkaline and peraluminous. They exhibit enrichment in light rare-earth elements (LREEs) and depletion in heavy rare-earth elements (HREEs), with slight negative Eu anomalies. The trace element patterns are characterized by enrichment in Ba, U, K, Pb, and Sr, alongside negative Nb, Ta, P, and Ti anomalies, indicative of arc-like magmatic signatures. Comparative analysis of geological and geochemical characteristics suggests that these three rock types are not comagmatic. Petrogenesis of the Zhuxi adakitic suite is linked to a dynamic tectonic regime involving Mesozoic crustal thickening, subsequent delamination, and lithospheric extension. Asthenospheric upwelling likely triggered partial melting of the overlying metasomatized lithospheric mantle, generating primary mantle-derived magmas. Underplating and advection of heat by these magmas induced partial melting of the thickened lower crust, forming the biotite granite porphyry. Partial melting of delaminated lower crustal material, interacting with the asthenosphere or asthenosphere-derived melts, likely generated the diorite porphyrite. The biotite quartz monzonite porphyry is interpreted to have formed from mantle-derived magmas that underwent assimilation of, or mixing with, silicic crustal melts during ascent. The ~160 Ma crystallization ages of these adakitic rocks are broadly contemporaneous with W-Mo mineralization in the Taqian mining area of the Zhuxi district. Furthermore, their geochemical signatures imply a prospective metallogenic setting for Cu-Mo mineralization around this period in the Taqian area. Full article

The Taqian–Zhuxi–Fuchun metallogenic belt in northeastern Jiangxi Province contains significant ore deposits that are closely associated with the Gaohushan granites. The Gaohushan granites predominantly consist of two-mica granites and have been dated using zircon U-Pb isotopic dating to be 129.4 ± 1.9 Ma (MSWD = 3.8). These granites have high SiO₂, ranging from 73.79% to 76.04% and low CaO and MgO contents (ranging from 0.24% to 0.59% and from 0.03% to 0.1%, respectively). The Gaohushan granites also exhibit high FeO^T/MgO ratios from 9.00 to 27.55 with an average of 17.55. The total alkali contents (Na₂O + K₂O) range from 7.08% to 8.43%, and the K₂O/Na₂O ratios range from 1.07 to 2.00 with an average of 1.47. These rocks are peraluminous series with A/CNK ratios (or ASI index) ranging from 1.19 to 1.47 and an average of 1.30. The Gaohushan granites have low rare earth element (REE) contents (∑REE = 2.33~23.50) with strongly negative Eu anomalies (δEu from 0.02 to 0.32) and a distinctive differentiation between heavy rare earth elements (HREEs) and light rare earth elements (LREEs) (LREE/HREE = 1.99~7.79). The normalized distribution pattern of REE in Gaohushan granite exhibits a right-dipping feature classified A-type; these rocks range from 1.06 to 2.71. The spider diagram shows that these rocks are characterized by depletion of Ba, Th, La, Sr, Nd, and Ti and enrichment of Rb, U, Ta, Nb, and P. The Gaohushan granites are classified as A-type granite and were emplaced during an anorogenic extensional event that occurred in the late Yanshannian period, driven by mantle-derived magma underplating. It is these granites or their analogues that have the potential for hosting tungsten, tin, niobium, and tantalum deposits, making them a promising target for mineral exploration. Full article

Mesozoic granitic magmatism in Northeastern Jiangxi, China is of tectonic significance for the evolution of the South China Block. Whole-rock geochemical and zircon U–Pb geochronological and Lu–Hf isotopic data for Mesozoic Zhuxi granites in the Jingdezhen area of Northeastern Jiangxi were presented. The Zhuxi granites are composed of granodiorite, biotite granite, and two-mica granite. Zircon LA–ICP–MS U–Pb isotopic analyses indicated emplacement at 159–147 Ma. The granites are characterized by a strongly peraluminous nature with high A/CNK values (>1.1), high SiO₂ (66.09–74.46 wt.%) and K₂O (3.50–5.52 wt.%) contents, depletion in Ba, Nb, Ce, Sr, and Ti, moderately negative Eu anomalies (Eu/Eu* = 0.40–0.63), enrichment in LREE, and depletion in HREE ((La/Yb)_N > 7.43). The A/CNK > 1.1, widespread aluminum-rich minerals (e.g., muscovite and tourmaline), indicating they are S–type granites and belong to muscovite–bearing peraluminous granites (MPG). The Zhuxi granites exhibited negative εHf(t) values (−9.9 to −3.7) and the T_DM2 model ages of 1840–1442 Ma indicated derivation from ancient crustal sources. The magma is possibly caused by the subsequent process of intracontinental subduction. It is inferred that the Mesozoic magmatism in Northeastern Jiangxi was associated with oceanic–continental convergence of the Paleo–Pacific and Eurasian plates as well as the intracontinental subduction of the Yangtze and Cathaysia blocks. The Zhuxi granites highlight the primary role of oceanic–continental convergence and intracontinental subduction in early Yanshanian granitoid magmatism in South China. Full article

Whole-rock and apatite geochemical analyses and zircon U–Pb dating were carried out on the lamprophyres in the world-class Zhuxi W–Cu skarn deposit in northern Jiangxi, South China, in order to understand their origin of mantle sources and their relationship with the deposit, as well as metallogenic setting. The results show the lamprophyres were formed at ca. 157 Ma, just before the granite magmatism and mineralization of the Zhuxi deposit. These lamprophyres have from 58.98–60.76 wt% SiO₂, 2.52–4.96 wt% K₂O, 5.92–6.41 wt% Fe₂O_3t, 3.75–4.19 wt% MgO, and 3.61–5.06 wt% CaO, and enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE), and depletion of high-field-strength elements (HFSE). Apatites in the lamprophyres are enriched in LREE and LILE, Sr, S, and Cl, and have ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.7076 to 0.7078. The conclusions demonstrate that the lithospheric mantle under the Zhuxi deposit was metasomatized during Neoproterozoic subduction. Late Jurassic crustal extension caused upwelling of the asthenospheric mantle and consecutively melted the enriched lithospheric mantle and then crustal basement, corresponding to the formation of lamprophyres and mineralization-related granites in the Zhuxi deposit, respectively. Full article