Large N–S convergence at the northern edge of the Tibetan plateau? New Early Cretaceous paleomagnetic data from Hexi Corridor, NW China

Diverse rock types and contrasting geochemical compositions of post-collisional mafic rocks across the Tibetan Plateau indicate that the underlying enriched lithospheric mantle is heterogeneous; however, how these enriched mantle sources were formed is still debated. The accreted terranes within the Tibetan Plateau experienced multiple stages of evolution. To track the geochemical characteristics of their associated lithospheric mantle through time, we can use mantle-derived magmas to constrain the mechanism of mantle enrichment. We report zircon U-Pb ages, major and trace element contents, and Sr-Nd isotopic compositions for Early Cretaceous and late Eocene mafic rocks in the southern Qiangtang terrane. The Early Cretaceous Baishagang basalts (107.3 Ma) are characterized by low K2O/Na2O (<1.0) ratios, arc-like trace element patterns, and uniform Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7067−0.7073, εNd(t) = −0.4 to −0.2]. We suggest that the Baishagang basalts were derived from partial melting of enriched lithospheric mantle that was metasomatized by subducted Bangong−Nujiang oceanic material. We establish the geochemistry of the pre-collisional enriched lithospheric mantle under the southern Qiangtang terrane by combining our data with those from other Early Cretaceous mafic rocks in the region. The late Eocene (ca. 35 Ma) post-collisional rocks in the southern Qiangtang terrane have low K2O/Na2O (<1.0) ratios, and their major element, trace element, and Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7042−0.7072, εNd(t) = −4.5 to +1.5] are similar to those of the Early Cretaceous mafic rocks. Based on the distribution, melting depths, and whole-rock geochemical compositions of the Early Cretaceous and late Eocene mafic rocks, we argue that the primitive late Eocene post-collisional rocks were derived from pre-collisional enriched lithospheric mantle, and the evolved samples were produced by assimilation and fractional crystallization of primary basaltic magma. Asthenosphere upwelling in response to the removal of lithospheric mantle induced the partial melting of enriched lithospheric mantle at ca. 35 Ma.

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Silurian clastic sediments in the North Qilian Shan, NW China: Chemical and isotopic constraints on their forearc provenance with implications for the Paleozoic evolution of the Tibetan Plateau

Sedimentary Geology ◽

10.1016/j.sedgeo.2010.09.001 ◽

2010 ◽

Vol 231 (3-4) ◽

pp. 98-114 ◽

Cited By ~ 43

Author(s):

Z. Yan ◽

W.J. Xiao ◽

B.F. Windley ◽

Z.Q. Wang ◽

J.L. Li

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Nw China ◽

The North ◽

Clastic Sediments ◽

North Qilian ◽

Isotopic Constraints

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Characteristics and sources of dissolved organic matter in a glacier in the northern Tibetan Plateau: differences between different snow categories

Annals of Glaciology ◽

10.1017/aog.2018.20 ◽

2018 ◽

Vol 59 (77) ◽

pp. 31-40 ◽

Cited By ~ 2

Author(s):

Lin Feng ◽

Yanqing An ◽

Jianzhong Xu ◽

Shichang Kang

Keyword(s):

Organic Matter ◽

Tibetan Plateau ◽

Dissolved Organic Matter ◽

Melting Rate ◽

Ion Cyclotron Resonance ◽

The Tibetan Plateau ◽

Mountain Glaciers ◽

Northern Tibetan Plateau ◽

Fresh Snow ◽

Northern Edge

AbstractDissolved organic matter (DOM) in mountain glaciers is an important source of carbon for downstream aquatic systems, and its impact is expected to increase due to the increased melting rate of glaciers. We present a comprehensive study of Laohugou glacier no. 12 (LHG) at the northern edge of the Tibetan Plateau to characterize the DOM composition and sources by analyzing surface fresh snow, granular ice samples, and snow pit samples which covered a whole year cycle of 2014/15. Excitation–emission matrix fluorescence spectroscopy analysis of the DOM with parallel factor analysis (EEM-PARAFAC) identified four components, including a microbially humic-like component (C1), two protein-like components (C2 and C3) and a terrestrial humic-like component (C4). The use of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) showed that DOM from all these samples was dominated by CHO and CHON molecular formulas, mainly corresponding to lipids and aliphatic/proteins compounds, reflecting the presence of significant amounts of microbially derived and/or deposited biogenic DOM. The molecular compositions of DOM showed more CHON compounds in granular ice than in fresh snow, likely suggesting newly formed DOM from microbes during snowmelting.

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Crust–mantle coupling at the northern edge of the Tibetan plateau: Evidence from focal mechanisms and observations of seismic anisotropy

Tectonophysics ◽

10.1016/j.tecto.2012.05.013 ◽

2013 ◽

Vol 584 ◽

pp. 221-229 ◽

Cited By ~ 6

Author(s):

Vadim Levin ◽

Guo-chin Dino Huang ◽

Steven Roecker

Keyword(s):

Tibetan Plateau ◽

Seismic Anisotropy ◽

Focal Mechanisms ◽

The Tibetan Plateau ◽

Northern Edge

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Devonian post-orogenic extension-related volcano-sedimentary rocks in the northern margin of the Tibetan Plateau, NW China: Implications for the Paleozoic tectonic transition in the North Qaidam Orogen

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2018.01.009 ◽

2018 ◽

Vol 156 ◽

pp. 145-166 ◽

Cited By ~ 7

Author(s):

Yu Qin ◽

Qiao Feng ◽

Gang Chen ◽

Yan Chen ◽

Kaizhen Zou ◽

...

Keyword(s):

Tibetan Plateau ◽

Sedimentary Rocks ◽

The Tibetan Plateau ◽

Nw China ◽

Northern Margin ◽

The North ◽

Tectonic Transition ◽

North Qaidam

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Superposition of Cretaceous and Cenozoic deformation in northern Tibet: A far-field response to the tectonic evolution of the Tethyan orogenic system

Geological Society of America Bulletin ◽

10.1130/b35944.1 ◽

2021 ◽

Author(s):

Ye Wang ◽

Xuanhua Chen ◽

Yaoyao Zhang ◽

Zheng Yin ◽

Andrew V. Zuza ◽

...

Keyword(s):

Tibetan Plateau ◽

Early Cretaceous ◽

Detrital Zircons ◽

The Tibetan Plateau ◽

Far Field ◽

The South ◽

Field Mapping ◽

The North ◽

Northern Tibetan Plateau ◽

Field Response

Although the Cenozoic Indo-Asian collision is largely responsible for the formation of the Tibetan plateau, the role of pre-Cenozoic structures in controlling the timing and development of Cenozoic deformation remains poorly understood. In this study we address this problem by conducting an integrated investigation in the northern foreland of the Tibetan plateau, north of the Qilian Shan-Nan Shan thrust belt, NW China. The work involves field mapping, U-Pb detrital-zircon dating of Cretaceous strata in the northern foreland of the Tibetan plateau, examination of growth-strata relationships, and construction and restoration of balanced cross sections. Our field mapping reveals multiple phases of deformation in the area since the Early Cretaceous, which was expressed by northwest-trending folding and northwest-striking thrusting that occurred in the early stages of the Early Cretaceous. The compressional event was followed immediately by extension and kinematically linked right-slip faulting in the later stage of the Early Cretaceous. The area underwent gentle northwest-trending folding since the late Miocene. We estimate the magnitude of the Early Cretaceous crustal shortening to be ∼35%, which we interpret to have resulted from a far-field response to the collision between the Lhasa and the Qiangtang terranes in the south. We suggest that the subsequent extension in the Early Cretaceous was induced by orogenic collapse. U-Pb dating of detrital zircons, sourced from Lower Cretaceous sedimentary clasts from the north and the south, implies that the current foreland region of the Tibetan plateau was a topographic depression between two highland regions in the Early Cretaceous. Our work also shows that the Miocene strata in the foreland region of the northern Tibetan plateau was dominantly sourced from the north, which implies that the rise of the Qilian Shan did not impact the sediment dispersal in the current foreland region of the Tibetan plateau where this study was conducted.

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Expanse of greater india in the cretaceous

10.5194/egusphere-egu21-636 ◽

2021 ◽

Author(s):

Jun Meng ◽

Stuart Gilder ◽

Yalin Li ◽

Chengshan Wang

Keyword(s):

Early Cretaceous ◽

Plate Boundary ◽

Vertical Axis ◽

Indian Plate ◽

Paleomagnetic Data ◽

Fundamental Parameter ◽

The Tibetan Plateau ◽

Northern Margin ◽

Indian Lithosphere ◽

Tethyan Himalaya

Knowing the original size of Greater India is a fundamental parameter to quantify the amount of continental lithosphere that was subducted to help form the Tibetan Plateau and to constrain the tectonic evolution of the India-Asia collision. Here, we report Early Cretaceous paleomagnetic data from the central and eastern Tethyan Himalaya that yield paleolatitudes consistent with previous Early Cretaceous paleogeographic reconstructions. These data suggest Greater India extended at least 2,675 &#177; 720 and 1,950 &#177; 970 km farther north from the present northern margin of India at 83.6&#176;E and 92.4&#176;E, respectively. The paleomagnetic data from Upper Cretaceous rocks of the western Tethyan Himalaya that are consistent with a model that Greater India extended ~2700 km farther north from its present northern margin at the longitude of 79.6&#176;E before collision with Asia. Our result further suggests that the Indian plate, together with Greater India, acted as a single entity since at least the Early Cretaceous. An area of lithosphere &#8805;4.7 &#215; 106 km2 was consumed through subduction, thereby placing a strict limit on the minimum amount of Indian lithosphere consumed since the breakup of Gondwanaland. The pre-collision geometry of Greater India&#8217;s leading margin helped shape the India-Asia plate boundary. The proposed configuration produced right lateral shear east of the indenter, thereby accounting for the clockwise vertical axis block rotations observed there.

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