Petrogenesis of the early Paleozoic low-Mg and high-Mg adakitic rocks in the North Qilian orogenic belt, NW China: Implications for transition from crustal thickening to extension thinning

Yu, Shengyao; Zhang, Jianxin; Qin, Haipeng; Dong, Sun; Zhao, Xilin; Cong, Feng; Li, Yunshuai

doi:10.1016/j.jseaes.2015.04.018

Cited by 89 publications

(86 citation statements)

References 89 publications

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“…The NQOB is a typical oceanic suture zone and contains Neoproterozoic to Early Palaeozoic ophiolite sequences, high‐pressure metamorphic belts, island‐arc volcanic rocks, and granitoid plutons; Cambrian to Silurian flysch formations (515–429 Ma; Song et al, ; Yu, Zhang, Qin, Sun, et al, ); Devonian molasses; and Carboniferous to Triassic sedimentary cover sequences. The QB, located between the NQOB and NQ‐UHPMB, is characterized by widespread Precambrian basement rocks overlain by Palaeozoic sedimentary lithologies (BGMRGP, ; BGMRQP, ; Figure ).…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

“…The Qilian Orogenic Belt (QOB), located at the north‐eastern margin of the Qinghai–Tibet Plateau (Figure a), is key to understanding the tectonic evolution of the Central China Orogenic Belt. The QOB (Figure ) records a long history of continental break‐up, seafloor spreading, and final continental collision from the Neoproterozoic to the Palaeozoic (Li, Jahn, et al, ; Li, Zhao, et al, ; Song, Niu, Su, & Xia, ; Song, Niu, Su, Zhang, & Zhang, ; Song, Niu, Zhang, & Zhang, ; Tung et al, ; Wang et al, ; Xiao et al, ; Yang et al, ; Yu et al, ). Based on tectonics (Song et al, ; Song et al, ; Song et al, ), the QOB is divided into the following: (1) North Qilian Orogenic Belt (NQOB), (2) Qilian Block (QB), and (3) North Qaidam Ultrahigh‐Pressure Metamorphic Belt (NQ‐UHPMB; Figure b).…”

Section: Introductionmentioning

confidence: 99%

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Geochronology and petrogenesis of Neoproterozoic S‐type granites from the Qilian Block, north‐west China, and their geological implications

Liu

Ren

et al. 2018

Geological Journal

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Early Neoproterozoic granites rarely outcrop in the Qilian Orogenic Belt (QOB) at the north‐eastern margin of the Qinghai–Tibet Plateau; however, they are vital to understanding the Precambrian evolution of the QOB. Thus, we present an integrated study, comprising petrology, geochronology, and whole‐rock geochemistry of two Early Neoproterozoic granitic plutons (Baihuagou and Yamacha plutons) in the eastern Qilian Block (QB). The results provide three key findings. First, their magma emplacement age is ca. 900 Ma (i.e., 918 Ma for Baihuagou and 910 Ma for Yamacha), and the two plutons have similar high‐K calc‐alkaline, strongly peraluminous characteristics, with slight enrichment in light rare earth elements; weak negative Eu anomalies; enrichment in large‐ion lithophile elements (e.g., K, Th, Ba, and Rb); strong depletion in Ti; and weak depletion in Nb, Ta, and, Sr. These characteristics indicate that the granites from these plutons are S‐type granites. Second, the two‐mica granite and gneissic granite samples may have been formed by partial melting of ancient crustal material (mainly psammitic rocks), with contributions from a meta‐igneous component, under high‐temperature and low‐pressure conditions. Third, new data from this study, combined with previously reported dates, indicate a continental margin arc setting for the QB during the Early Neoproterozoic (ca. 900 Ma).

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Section: Geological Setting and Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geochronology and petrogenesis of Neoproterozoic S‐type granites from the Qilian Block, north‐west China, and their geological implications

Liu

Ren

et al. 2018

Geological Journal

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“…The Early Palaeozoic is the critical period for tectonic evolution of the Shangdan Ocean in the Qilian and Qinling orogenic belts. The Qilian Orogenic Belt has a typical subduction‐accretionary tectonic evolution (Yu et al, ). This small ocean basin started to dive to the north in Middle Ordovician and collided with orogenic movement in Late Ordovician–Early Silurian (Ding, ).…”

Section: Petrogenesismentioning

confidence: 99%

Early Silurian adakitic high‐Mg diorite from the Longshan area: Implication for melting of mantle lithosphere in the south‐eastern Qilian Orogenic Belt

et al. 2018

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The Longshan area is located in the junction zone between the Qinling and eastern Qilian orogenic belts. Early Palaeozoic igneous rocks in this area can provide important insights into the evolution of Shangdan Ocean. This paper reports new petrology, chronology, major and trace element geochemistry, Sr–Nd isotope, and zircon Lu–Hf isotopic compositions for the Early Silurian pyroxene diorite in the Longshan area. The pyroxene diorite has a zircon U–Pb age of 432 ± 1 Ma (MSWD = 0.25, n = 27). The pyroxene diorite intrusion displays low SiO2 (53.34 to 56.32 wt.%), high Na2O (3.11% to 3.79 wt.%) and Sr (1112 to 1234 ppm) contents, and moderate Mg# (52.70 to 55.00) values, high Sr/Y (67 to 84) ratios, depleted in Y and HREE; these features are identical with the low‐Si adakite or sanukitoids that derived from melting of metasomatized mantle wedge. The pyroxene diorite intrusion has evolved Sr–Nd isotopic compositions, (87Sr/86Sr) i = 0.705286 to 0.705310, εNd(t) = −3.4 to −3.9. Zircons from the pyroxene diorite display variable εHf(t) values of −3.6 to +0.1. These features suggest that the pyroxene diorite intrusion was derived from a hydrous melting metasomatized mantle wedge which has been modified by slab melts. The occurrence of pyroxene diorite indicates an Early Silurian active continental margin setting in the south‐eastern Qilian Orogenic Belt.

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“…710 Ma (Song, Niu, Su, & Xia, ), followed by the Middle Cambrian initiation of orogenesis in the NQOB and Early Palaeozoic subduction of the Qilian Ocean. Orogenesis continued until the closure of the Qilian Ocean at the end of the Ordovician (~445 Ma; e.g., Song et al, ; Yu et al, ; Yu, Zhang, Qin, Sun, & Zhao, ; Z. C. Zhang et al, ; J. X. Zhang, Yu, & Mattinson, ).…”

Section: Geological Settingmentioning

confidence: 99%

“…Simplified geological map of the western segment of North Qilian area, China (modified from Song et al, and Yu et al, )…”

Section: Geological Settingmentioning

confidence: 99%

Origin of the Mesoproterozoic Jingtieshan bedded barite deposit, North Qilian Mountains, NW China: Geochemical and isotope (O, S, Sr) evidence

2017

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The bedded Jingtieshan barite deposit, which occurs in the western part of North Qilian, NW China, is intimately associated with banded iron formation (BIF) and is hosted in weakly metamorphosed Mesoproterozoic clastic–carbonate rocks. Although numerous studies have focused on the BIF, the origin of the barite mineralization is poorly understood. The barite orebody occurs as a lenticular/stratiform unit overlying and locally interlayered with the BIF. In this contribution, we present a comprehensive and integrated study of the geochemistry and S–O–Sr‐isotope characteristics of the Jingtieshan barite deposit, thereby constraining its origin and the depositional conditions in the Mesoproterozoic ocean. The ore is composed of barite, minor carbonate minerals, specularite, and other minerals and is characterized by low Sr concentrations (711–1469 ppm), total rare earth element concentrations (7–28 ppm), and La/Ce values, relative enrichment in light rare earth element, positive Gd anomalies, and elevated Lan/Cen, which indicate that mineralizing fluids were derived from seawater and submarine hydrothermal solutions. Barite separates yield δ34S = 19.5–29.1‰ and δ18O = 12.7–23.6‰, which are consistent with a coeval seawater origin for SO42− modified bacterial sulfate reduction. Moreover, the 87Sr/86Sr values suggest that Sr, as well as Ba, was derived from contemporaneous seawater and hydrothermal solutions, with additional radiogenic Sr derived from late‐stage hydrothermal alteration. The redox‐sensitive trace element ratios of V/(V + Ni), V/(V + Cr), and V/Cr, combined with negative Ce anomalies (0.11–0.82), indicate that the barite formed under oxic marine conditions in a redox stratified ocean. Geological, geochemical, and isotope data support a sedimentary–exhalative origin for the Jingtieshan barite deposit, where barite was deposited under oxic conditions in a shallow marine environment when ascending Ba‐bearing submarine hydrothermal solutions encountered sulfate‐rich seawater.

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Petrogenesis of the early Paleozoic low-Mg and high-Mg adakitic rocks in the North Qilian orogenic belt, NW China: Implications for transition from crustal thickening to extension thinning

Cited by 89 publications

References 89 publications

Geochronology and petrogenesis of Neoproterozoic S‐type granites from the Qilian Block, north‐west China, and their geological implications

Geochronology and petrogenesis of Neoproterozoic S‐type granites from the Qilian Block, north‐west China, and their geological implications

Early Silurian adakitic high‐Mg diorite from the Longshan area: Implication for melting of mantle lithosphere in the south‐eastern Qilian Orogenic Belt

Origin of the Mesoproterozoic Jingtieshan bedded barite deposit, North Qilian Mountains, NW China: Geochemical and isotope (O, S, Sr) evidence

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