Integrated analyses constraining the provenance of sandstones, mudstones, and conglomerates, a case study: the Laojunshan conglomerate, Qilian orogen, northwest China

2007 ◽  
Vol 44 (7) ◽  
pp. 961-986 ◽  
Author(s):  
Zhen Yan ◽  
Wenjiao Xiao ◽  
Zongqi Wang ◽  
Jilian Li
Keyword(s):  
Tibetan Plateau ◽  
Middle Devonian ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Geochemical Data ◽  
The North ◽  
Northern Tibetan Plateau ◽  
Wide Range ◽  
Qilian Orogen ◽  
North Qilian

The Qilian orogenic belt in the northern Tibetan plateau connects the Altaids to the north with the Tethyan orogenic system to the south and occupies a key tectonic position in the evolution and assembly of Asia. The belt contains a wide range of subduction–accretion-related petrotectonic units. The Early–Middle Devonian Laojunshan conglomerate, deposited unconformably upon Cambrian–Silurian strata along the northern margin of the North Qilian terrane, contains a record of the late Paleozoic tectonism of the Qilian orogen. Its provenance and tectonic setting are critical in understanding not only the tectonic evolution of Tibetan plateau, but Paleozoic global reconstructions as well. The composition of clastic conglomerates and heavy mineral assemblages of sandstones suggests that coeval mafic, felsic, metamorphic, and sedimentary rocks were the main sources. The geochemistry of volcanic clasts and paleocurrent and paleogeographic data suggest derivation from subduction–accretion complexes in the North Qilian terrane. The geochemistry of siltstones and mudstones indicates that the Laojunshan conglomerate was derived from an arc and accumulated in an active continental margin. Geochemical data of granitoid clasts suggest that they were derived from Ordovician–Silurian subduction-related magmatic rocks. Mafic and ultramafic clasts, chromite, and magnetite decrease upwards in the stratigraphy whereas metamorphic, sedimentary and granitoid clasts, and garnet increase. These data imply that mafic rocks were the predominant source during initial deposition. Regional studies suggest that the North China plate subducted southwards and produced subduction-related arc magmatism along the southern margin of the North Qilian terrane during the Early–Middle Devonian. Therefore, we interpret the Laojunshan conglomerate as a fore-arc basin fill.

scholarly journals Erosion, fault initiation and topographic growth of the North Qilian Shan (northern Tibetan Plateau)

Geosphere ◽  
2010 ◽  
Vol 6 (6) ◽  
pp. 937-941 ◽  
Author(s):  
Dewen Zheng ◽  
Marin K. Clark ◽  
Peizhen Zhang ◽  
Wenjun Zheng ◽  
Kenneth A. Farley
Keyword(s):  
Tibetan Plateau ◽  
The North ◽  
Northern Tibetan Plateau ◽  
North Qilian

Origin of chert in the Upper Ordovician–Lower Silurian: implications for the sedimentary environment of North Qilian Orogen

2021 ◽  
pp. 1-16
Author(s):  
Qian HOU ◽  
Chuanlong MOU ◽  
Zuozhen HAN ◽  
Xiangying GE ◽  
Qiyu WANG
Keyword(s):  
Volcanic Ash ◽  
Tectonic Setting ◽  
Sedimentary Environment ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
The North ◽  
Qilian Orogen ◽  
North Qilian ◽  
Deep Water Basin

ABSTRACT During the Upper Ordovician–Lower Silurian, chert was widely distributed in the Zhongbao Formation in the eastern part of the North Qilian Orogen. The origin and the tectonic setting of these chert were largely unknown. In order to analyse the material provenance, sedimentary environment, their formation and the tectonic setting, we present petrology and geochemical research on chert samples collected from Shihuigou Section. The evidence provided by radiolarite occurrences, Aluminium (Al)–iron (Fe)–manganese diagram and the silicon(Si)/Si + Al + Fe + calcium ratios suggesting a non-hydrothermal input and the biogenic origin chert. The geochemical features and the petrographic signatures have shown that the chert was also influenced by a terrigenous origin. It is considered that the deposition of the Late Ordovician chert is mainly affected by tectonic collision and volcanic ash events. During the Late Ordovician–Early Silurian transition, huge amounts of volcanic ash were released by massive volcanic activity that fell into the ocean, triggering the proliferation of radiolarians. Finally, in the Late Ordovician–Lower Silurian the tectonic setting of the North Qilian Orogen was not a typical deep-water basin, nor a typical continental margin, but a multi-island deep-water basin, which is closed to the mainland.

scholarly journals Petrogenesis of Early Paleozoic high Sr/Y intrusive rocks from the North Qilian orogen: Implication for diachronous continental collision

Lithosphere ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 53-73 ◽  
Author(s):  
He Yang ◽  
Hongfei Zhang ◽  
Wenjiao Xiao ◽  
Biji Luo ◽  
Zhong Gao ◽  
...  
Keyword(s):  
Crustal Thickness ◽  
Crustal Thickening ◽  
Geochemical Data ◽  
Thickness Variation ◽  
Early Paleozoic ◽  
Isotopic Data ◽  
Differential Distribution ◽  
The North ◽  
Qilian Orogen ◽  
North Qilian

Abstract A combination of U-Pb zircon ages and geochemical and Sr-Nd-Hf isotopic data are presented for the Early Paleozoic granodiorites from the Haoquangou and Baimawa plutons in order to probe the crustal thickness variation of the eastern North Qilian and the diachronous evolution of the North Qilian orogen. The granodiorites formed at 436–435 Ma and have high Sr/Y ratios (63–117). Elemental and isotopic data combined with geochemical modeling and comparisons with experimental data suggest that they were produced from the melting of relatively juvenile mafic rocks in the thickened lower crust. Together with other petrological and geochemical data and the calculation of variation in crustal thickness, this indicates that the eastern North Qilian experienced clear crustal thickening and thinning from the Late Ordovician to Late Silurian. Based on available data, we suggest that diachronous collision from east to west, which probably resulted in the distinct intensity of orogenesis between eastern and western North Qilian, can well account for the differential distribution of Early Paleozoic high Sr/Y magmatism and other geological differences between the eastern and western parts of the North Qilian. Our study also implies that diachronous collision may lead to, apart from distinct metamorphic, structural and sedimentary responses, the large differences in magmatism and deep crustal processes along the orogenic strike.

Palaeoproterozoic metasedimentary rocks of the Ji'an Group and their significance for the tectonic evolution of the northern segment of the Jiao–Liao–Ji Belt, North China Craton

2017 ◽  
Vol 155 (1) ◽  
pp. 149-173 ◽  
Author(s):  
EN MENG ◽  
CHAO-YANG WANG ◽  
ZHUANG LI ◽  
YAN-GUANG LI ◽  
HONG YANG ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Granitic Rocks ◽  
Geochemical Data ◽  
Metasedimentary Rocks ◽  
The North ◽  
Northern Segment

AbstractIn this paper we present new petrological and whole-rock geochemical data for the Palaeoproterozoic metasedimentary rocks in the upper part of the Ji'an Group within the Jiao–Liao–Ji Belt, China, as well as zircon U–Pb age dates andin situLu–Hf isotope data. The new data improve our understanding of the original nature of the metasedimentary rocks, further providing insights into their tectonic setting and the evolutionary history of the northern segment of the Jiao–Liao–Ji Belt. The zircons can be divided into two groups, viz., one of magmatic origin and the other of metamorphic origin. Zircon U–Pb dating gave mean or statistical peak ages for the magmatic zircons at 2035, 2082, 2178, 2343–2421, 2451–2545, 2643–2814 and 2923–3446 Ma, and mean peak ages for the metamorphic zircons at 1855 and 1912 Ma, which indicate a maximum depositional age of 2.03 Ga and two-stage metamorphic events atc. 1.91 and 1.85 Ga for the metasedimentary rocks. Geochemical data show that (1) the protoliths of these rocks were mainly sandstones, greywackes and claystones, together with some shales; (2) the main sources of the sedimentary material were Palaeoproterozoic granites and acid volcanic rocks, with minor contributions from Archaean granitic rocks; and (3) the sediments were deposited in an active continental margin setting. Moreover, along the northeastern margin of the Eastern Block of the North China Craton there is evidence of ancient crustal materials as old as 3.76 Ga, and multiple crustal growth events at 3.23–3.05, 2.80–2.65, 2.54–2.45 and 2.28–2.08 Ga.

Provenance and tectonic setting of the Early and Middle Devonian Xueshan Formation, the North Qilian Belt, China

2017 ◽  
Vol 53 (4) ◽  
pp. 1404-1422 ◽  
Author(s):  
Qian Hou ◽  
Chuanlong Mou ◽  
Qiyu Wang ◽  
Zhiyuan Tan
Keyword(s):  
Middle Devonian ◽  
Tectonic Setting ◽  
The North ◽  
North Qilian

Petrogenesis and tectonic evolution of the Palaeozoic to Mesozoic Niuxinshan granitoids in the North Qilian orogen, NW China

2021 ◽  
Author(s):  
Fan Yang ◽  
Fei Xue ◽  
M. Santosh ◽  
Zesheng Qian ◽  
Cun Zhang ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
Nw China ◽  
The North ◽  
Qilian Orogen ◽  
North Qilian

scholarly journals On the origin of mafic magmatic enclaves (MMEs) in syn-collisional granitoids: evidence from the Baojishan pluton in the North Qilian Orogen, China

2015 ◽  
Vol 109 (5) ◽  
pp. 577-596 ◽  
Author(s):  
Shuo Chen ◽  
Yaoling Niu ◽  
Wenli Sun ◽  
Yu Zhang ◽  
Jiyong Li ◽  
...  
Keyword(s):  
The North ◽  
Magmatic Enclaves ◽  
Qilian Orogen ◽  
North Qilian

Neoproterozoic Amdo and Jiayuqiao microblocks in the Tibetan Plateau: Implications for Rodinia reconstruction

2020 ◽  
Author(s):  
Yiming Liu ◽  
Yuhua Wang ◽  
Sanzhong Li ◽  
M. Santosh ◽  
Runhua Guo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
South China ◽  
Tectonic Setting ◽  
Parental Magma ◽  
Tibet Plateau ◽  
Geochemical Data ◽  
The Tibetan Plateau ◽  
South China Craton ◽  
Neoproterozoic Magmatism ◽  
T Values

The Tibetan Plateau is composed of several microblocks, the tectonic affinity and paleogeographic correlations of which remain enigmatic. We investigated the Amdo and Jiayuqiao microblocks in central Tibet Plateau with a view to understand their tectonic setting and paleogeographic position within the Neoproterozoic supercontinent Rodinia. We present zircon U-Pb and Lu-Hf isotope, and whole-rock geochemical data on Neoproterozoic granitic gneisses from these microblocks. Zircon grains from the Jiayuqiao granitic gneiss yielded an age of 857 ± 9 Ma with variable εHf(t) values (−8.9 to 4.0). The Amdo granitic gneisses yielded ages of 893 ± 5 Ma, 807 ± 5 Ma, and 767 ± 11 Ma, with εHf(t) values in the range of −4.9 to 3.5. Geochemically, the granitoids belong to high-K calc-alkaline series, with the protolith derived from partial melting of ancient crustal components. The ascending parental magma of the Amdo granitoids experienced significant mantle contamination as compared to the less contaminated magmas that generated the Jiayuqiao intrusions. In contrast to the Lhasa, Himalaya, South China, and Tarim blocks, we suggest that the Amdo and Jiayuqiao microblocks probably formed a unified block during the Neoproterozoic and were located adjacent to the southwestern part of South China craton. The Neoproterozoic magmatism was probably associated with the subduction of the peripheral ocean under the South China craton and the delamination of lithospheric mantle beneath the Jiangnan orogen.

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