Petrogenesis and Tectonic Implications of the Latest Cretaceous Intrusive Rocks from the Eastern Gangdese Belt, Southeast Tibet

Self Cite

This is a review of the formation and tectonic evolution of the continental Asia in Phanerozoic. The continental Asia has formed on the bases of some pre‐Cambrian cratons, such as the Siberia, India, Arabia, North China, Tarim, South China, and Indochina, through multi‐stage plate convergence and collisional collages in Phanerozoic. The north‐central Asia had experienced the expansion and subduction of the Paleo‐Asian Ocean (PAO) in the early Paleozoic and the closure of the PAO in the late Paleozoic and early Mesozoic, forming the PAO regime and Central Asian orogenic belt (CAOB). In the core of the CAOB, the Mongol‐Okhotsk Ocean (MOO) opened with limited expansion in the Early Permian and finally closed in the Late Jurassic–Early Cretaceous. The south‐central Asia had experienced mainly multi‐stage oceanic opening, subduction and collision evolution in the Tethys Ocean, forming the Tethys regime and Himalaya‐Tibetan orogenic belt. In eastern Asia, the plate subduction and continental margin orogeny on western margin of the Pacific Ocean, forms the West Pacific regime and West Pacific orogenic belt. The PAO, Tethys, and West Pacific regimes, together with Precambrian cratons among or surrounding them, made up the major tectonic and dynamic systems of the continental Asia in Phanerozoic. Major tectonic events, such as the Early Paleozoic Qilian, Uralian, and Dunhuang orogeneses, the late Paleozoic East Junggar, Tianshan and West Junggar orogeneses, the Middle to Late Permian Ailaoshan orogeny and North‐South Lhasa collision, the early Mesozoic Indochina‐South China and North‐South China collisions, the late Mesozoic Mongolia‐Okhotsk orogeny, Lhasa‐Qiangtang collision, and intra‐continental Yanshanian orogeny, and the Cenozoic Indo‐Asian, Arab‐Asian, and West Pacific margin collisions, constrained the formation and evolution of the continental Asia. The complex dynamic systems have left large number of deformation features, such as large‐scale strike‐slip faults, thrust‐fold systems and extensional detachments on the continental Asia. Based on past tectonics, a future supercontinent, the Ameurasia, is prospected for the development of the Asia in ca. 250 Myr.

Section: Post-orogenic or Back-arc Extension In The Early Cretaceousmentioning

confidence: 99%

Construction of the Continental Asia in Phanerozoic: A Review

Chen

Dong

Shi

et al. 2022

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“…range of zircon ε Hf (t) values (−22 to 0.39, concentrated between −12.85 and −5.73) of other quartz porphyry samples (Tian et al, 2019). Such large variation of ε Hf (t) values are better interpreted by the mixing of juvenile crust-derived melts and ancient crustal materials (e.g., Zhu et al, 2011;Xu et al, 2021;Chen et al, 2022). Therefore, the Bangbule quartz porphyry was derived from the partial melting of middle-upper crust and the components of juvenile mafic lower crust might have been added into the source region.…”

Section: Petrogenesis 621 Nature Of Source Regionmentioning

confidence: 99%

Geochronology, Geochemistry and Petrogenesis of the Bangbule Quartz Porphyry: Implications for Metallogenesis

Wang

WANG³

et al. 2023

The Bangbule skarn lead‐zinc (Pb‐Zn) deposit (>1 Mt Zn + Pb) is located in the western Nyainqentanglha polymetallic metallogenetic belt, central Tibet. Lenticular orebodies are all hosted in skarn and developed in the contact zone between the quartz porphyry and carbonate strata of the mid Paleozoic Middle to Upper Chaguoluoma Formation as well as in carbonate and sandstone beds of the Upper Paleozoic Laga Formation. As a newly discovered skarn deposit, the geological background and metallogenesis of this deposit remain poorly understood. Detailed petrological, geochemical and geochronological data of the ore‐related quartz porphyry, helps constrain the mineralization age and contributes to discussion on the ore genesis of the Bangbule deposit. Both endoskarn and exoskarn are identified in the Bangbule deposit. From quartz porphyry to carbonate formation, the exoskarn is zoned from proximal garnet skarn to distal pyroxene skarn. Zircon U‐Pb dating results show that the quartz porphyry formed at 73.9 ± 0.8 Ma. Geochemical analysis results show that the quartz porphyry has high contents of SiO2 (71.40–74.94 wt%) and K2O + Na2O (3.76–8.46 wt%) with A/CNK values of 0.69 to 1.06. Besides, the quartz porphyry is enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and have low εNd(t) (from –8.25 to –8.19) and high initial (87Sr/86Sr)i values (0.713611–0.714478). Major, trace elements and whole‐rock F concentration analysis results from the endoskarn samples show higher TFe2O3, MgO, CaO, Pb + Zn, W, Sn, Mo and F etc., and lower alkalis (K2O, Na2O, Sr and Ba) than those of fresh quartz porphyry, indicating that the early ore‐forming fluids were an Ca‐Fe‐F‐enriched fluid. Massive ore in the proximal skarn might be related to the high F content in the magma, which lowered the solidus temperature of the quartz porphyry magma and caused a lower temperature of the ore‐forming fluids, as well as facilitating the precipitation of sphalerite and galena. Based on the geochemical characteristics presented in this study, we propose that the ore‐related quartz porphyry was formed by partial melting of crust materials with some juvenile crustal component input. The partial melting of the middle‐upper crust after the initial enrichment of lead and zinc elements are important for the formation of Pb‐Zn deposits. The case study of the Bangbule deposit has proven that there is still a crust‐derived magmatic source region in the western segment of the central Lhasa terrane. Therefore, there is still great potential for Pb‐Zn mineralization and Pb‐Zn exploration.

“…The Lhasa Block was separated into two units: (i) the southern unit, as represented by the Gangdese batholith, which consists of Triassic to Eocene arc-type magmatism (Zhu et al, 2009;Ji et al, 2009Ji et al, , 2012Ma et al, 2017; Wen et al, 2021;Zhou et al, 2021;Chen et al, 2022); and (ii) a northern plutonic suite, which was formed during the Cretaceous (Zhu et al, 2011). The northern plutonic suite may extend eastwards to join the Bomi-Chayu plutons (Lin et al, 2009(Lin et al, , 2019, then southwards to the Tengchong block (Lee et al, 2003;Chiu et al, 2009;Qi et al, 2015).…”

Section: Comparison With Cretaceous-cenozoic Magmatism Of the Lhasa B...mentioning

confidence: 99%

Geochemistry and Petrogenesis of Late Cretaceous–Paleocene Granites from the Tengchong Block, Western Yunnan: Implications for Angle‐switching of Subducting Slab

Chen

Zhang

et al. 2022

The Cenozoic geological hallmark of Western Yunnan is the characteristic voluminous Late Cretaceous-Eocene granites; however, their geological background and petrogenesis have not been well constrained and elucidated. In this study, we present new zircon U-Pb dating, along with geochemical and Sr-Nd-Hf isotopic data for granites from the Tengchong-Lianghe granitoid belt (as abbreviated to Tengliang belt) and West Yingjiang batholiths from the Tengchong block. The mineralogical and geochemical features of the Tengliang granites and the West Yingjiang batholiths are ascribed to aluminous S-type granites and weak peraluminous I-type, respectively. Zircon U-Pb analyses yielded consistent ages ranging from 67.5 Ma, 68.4 Ma and 66.2 Ma from the Tengliang granitoid belt and 50.4 Ma to 60.8 Ma for three samples from the west Yingjiang batholiths. The Tengliang granites were emplaced during the Late Cretaceous (68−66 Ma) and demonstrate negative ε Hf (t) values (−24 to −4) and initial 87 Sr/ 86 Sr ratios of 0.7101-0.7139 and significant negative ε Nd (t) values from −8.91 to −13.2, indicating a Proterozoic sedimentary source or enriched components. The hornblende-bearing I -type granites from West Yingjiang are characterized by lower initial 87 Sr/ 86 Sr ratios of 0.7076-0.7106, compared to Tengliang granite and negative whole-rock ε Nd (t) values from −4.0 to −11.9. The early Eocene west Yingjiang gneissic granites show wide ranges of ε Hf (t) values from +7.4 to −8.5 and T 2DM of 1.30-0.65 Ga, indicating partial melting of ancient crust with contributions of depleted mantle materials. In combination with the regional background and previous studies, we propose that such a spatio-temporal distribution of the Tengchong granitoid belt might be related to the rollback or angleswitching of the Neo-Tethyan subducting slab. This study sheds new light on the evolutionary history of the Tengchong block.