Post-collisional extension of the South Altun subduction-collision belt, northern Tibetan Plateau: insight from phase equilibria modeling and zircon geochronology of pelitic migmatites

2021 ◽  
pp. 105069
Author(s):  
Xia Teng ◽  
Jianxin Zhang ◽  
Thomas Müller ◽  
Xiaohong Mao ◽  
Zenglong Lu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Phase Equilibria ◽  
Zircon Geochronology ◽  
The South ◽  
Northern Tibetan Plateau

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

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.

Origin of Devonian mafic magmatism in the East Kunlun orogenic belt, northern Tibetan Plateau: implications for continental exhumation

2020 ◽  
Vol 157 (8) ◽  
pp. 1265-1280 ◽  
Author(s):  
You-Jun Tang ◽  
Bin Liu ◽  
Mei-Jun Li ◽  
Yue Wu ◽  
Jian Huang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Orogenic Belt ◽  
Primitive Mantle ◽  
Zircon Geochronology ◽  
Mafic Rocks ◽  
Northern Tibetan Plateau ◽  
East Kunlun ◽  
Group 2 ◽  
East Kunlun Orogenic Belt ◽  
Group 1

AbstractThis paper presents a comprehensive study of the zircon geochronology, geochemistry and Sr–Nd isotope geology of Devonian mafic rocks developed in the East Kunlun orogenic belt, northern Tibetan Plateau, and reveals their mantle sources, petrogenesis and geodynamic implications for continental exhumation. The zircon geochronology of typical samples indicates that these mafic rocks crystallized at 406∼408 Ma. They can be classified into two different groups based on petrographic observations and geochemical compositions. Group 1 rocks exhibit low TiO2 and FeOt contents and Nb/Y ratios and have enriched mid-ocean ridge basalt (E-MORB)-like compositions with slight negative Nb and Ta anomalies. However, Group 2 rocks have distinctly high TiO2 and FeOt contents and Nb/Y ratios, comparable to typical Fe–Ti-rich mafic rocks worldwide. All the samples exhibit weak enrichments in light rare earth elements, Nb and Ta relative to the primitive mantle. Based on geochemical and isotopic studies, Group 1 rocks are suggested to be derived from depleted asthenospheric mantle that was metasomatized by c. 3–5 % continental crustal components, while Group 2 rocks originated from partial melting of enriched lithospheric mantle. The high contents of Fe, Ti and Nb for Group 2 rocks could be attributed to a high degree of olivine crystallization under low fO2 conditions with delayed nucleation of Fe–Ti oxides. Combining those results with other geological data, we conclude that slab break-off was the key factor causing exhumation of eclogites and triggering flare-up of the Devonian magmatism, and that continental collision or continental subduction may have initiated at 431∼436 Ma.

New insights into the age and metamorphic evolution of the Irumide orogeny in Malawi

2021 ◽  
Author(s):  
Sofia C. Böhme ◽  
Steven D. Boger
Keyword(s):  
Phase Equilibria ◽  
Island Arc ◽  
Zircon Geochronology ◽  
The South ◽  
Metamorphic Evolution ◽  
Temperature Conditions ◽  
The North ◽  
Southern Margin ◽  
Mineral Assemblages

<p>Metapelitic rocks of the Irumide Domain in central Malawi contain detrital and metamorphic zircons. U-Pb zircon geochronology yielded two age populations, which have been dated at c. 1995 Ma and 1050 Ma. The ages demonstrate that the precursor sediments to these rocks were derived from erosion of the Palaeoproterozoic Ubendian Domain, which is adjacent to the north, and at a later stage were affected by the Irumide orogeny. The metapelitic rocks are characterised by garnet + sillimanite + biotite ± muscovite ± K-feldspar mineral assemblages. Phase equilibria modelling shows that they equilibrated under pressure-temperature conditions of about 7 kbar and 700–740˚C.  In combination with the metamorphic ages this is interpreted to record late Mesoproterozoic (c. 1050 Ma) accretion of a juvenile island arc, the South Irumide Domain, to the southern margin of the Tanzania-Congo Craton.</p>

Sign in / Sign up

Export Citation Format

Share Document