Cambrian magmatic flare-up, central Tibet: Magma mixing in proto-Tethyan arc along north Gondwanan margin

2021 ◽  
Author(s):  
Pei-yuan Hu ◽  
Qing-guo Zhai ◽  
Peter A. Cawood ◽  
Guo-chun Zhao ◽  
Jun Wang ◽  
...  
Keyword(s):  
Magma Mixing ◽  
Geochemical Data ◽  
Early Paleozoic ◽  
East African ◽  
Lhasa Terrane ◽  
The North ◽  
Magmatic Rocks ◽  
East African Orogen ◽  
Andean Type ◽  
Central Tibet

Accompanying Gondwana assembly, widespread but diachronous Ediacaran−early Paleozoic magmatism of uncertain origin occurred along the supercontinent’s proto-Tethyan margin. We report new geochemical, isotopic, and geochronological data for Cambrian magmatic rocks (ca. 500 Ma) from the Gondwana-derived North Lhasa terrane, located in the present-day central Tibetan Plateau. The magmatic rocks are composed of basalts, gabbros, quartz monzonites, granitoids (with mafic microgranular enclaves), and rhyolites. Nd-Hf isotopic and whole-rock geochemical data indicate that these rocks were probably generated by mixing of mantle-derived mafic and crust-derived felsic melts. The mantle end-member volumes of mafic, intermediate, and felsic rocks are ∼75%−100%, 50%−60%, and 0−30%, respectively. Integration of our new data with previous studies suggests that the North Lhasa terrane experienced long-term magmatism through the Ediacaran to Ordovician (ca. 572−483 Ma), with a magmatic flare-up at ca. 500 Ma. This magmatism, in combination with other Ediacaran−early Paleozoic magmatism along the proto-Tethyan margin, was related to an Andean-type arc, with the magmatic flare-up event related to detachment of the oceanic slab following collisional accretion of Asian microcontinental fragments to northern Gondwana. Diachroneity of the proto-Tethyan arc system along the northern Gondwanan margin (ca. 581−531 Ma along the Arabian margin and ca. 512−429 Ma along the Indian-Australian margin) may have been linked to orogenesis within Gondwana. The North Lhasa terrane was probably involved in both Arabian and Indian-Australian proto-Tethyan Andean-type orogens, based on its paleogeographic location at the northern end of the East African orogen.

scholarly journals Supplemental Material: Cambrian magmatic flare-up, central Tibet: Magma mixing in proto-Tethyan arc along north Gondwanan margin

2021 ◽  
Author(s):  
Pei-yuan Hu ◽  
et al.
Keyword(s):  
Tibetan Plateau ◽  
Analytical Methods ◽  
Magma Mixing ◽  
Mixing Model ◽  
Lhasa Terrane ◽  
The North ◽  
Magmatic Rocks ◽  
Central Tibetan Plateau ◽  
Central Tibet

Data, magma mixing model, and analytical methods of the Cambrian magmatic rocks from the North Lhasa terrane, central Tibetan Plateau.

scholarly journals Supplemental Material: Cambrian magmatic flare-up, central Tibet: Magma mixing in proto-Tethyan arc along north Gondwanan margin

2021 ◽  
Author(s):  
Pei-yuan Hu ◽  
et al.
Keyword(s):  
Tibetan Plateau ◽  
Analytical Methods ◽  
Magma Mixing ◽  
Mixing Model ◽  
Lhasa Terrane ◽  
The North ◽  
Magmatic Rocks ◽  
Central Tibetan Plateau ◽  
Central Tibet

Data, magma mixing model, and analytical methods of the Cambrian magmatic rocks from the North Lhasa terrane, central Tibetan Plateau.

Generation of the 105–100 Ma Dagze volcanic rocks in the north Lhasa Terrane by lower crustal melting at different temperature and depth: Implications for tectonic transition

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1257-1272 ◽  
Author(s):  
Yun-Chuan Zeng ◽  
Ji-Feng Xu ◽  
Feng Huang ◽  
Ming-Jian Li ◽  
Qin Chen
Keyword(s):  
Early Cretaceous ◽  
Lower Crust ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Lhasa Terrane ◽  
The North ◽  
Tectonic Transition ◽  
Group I ◽  
Group Ii

Abstract Successively erupted intermediate-felsic rocks with variations in their geochemical compositions indicate physical changes in lower-crust conditions, and the variations can provide important insights into the regional tectonic setting. What triggered the late Early Cretaceous tectonic transition of the central-north Lhasa Terrane remains controversial, hindering the understanding of the mechanisms behind the formation of the central Tibetan Plateau. The sodic Dagze volcanic rocks in the north Lhasa Terrane are characterized by high contents of SiO2 and Na2O, low contents of MgO, Fe2O3, and K2O, and low values of Mg#. However, the trace element compositions of the whole-rocks and their zircons allow the rocks to be divided into two groups. The Group I rocks (ca. 105 Ma) have higher contents of Sr and Ba, higher Sr/Y and La/Yb ratios, and lower contents of Y, Yb, Ti, and Zr than Group II rocks (ca. 100 Ma). Besides, the zircons from Group I rocks have higher values of Yb/Gd and U/Yb, lower values of Th/U, and lower Ti contents than the zircons from Group II rocks. However, the rocks of both groups have identical depleted whole-rock Sr-Nd and zircon Hf isotope values. The geochemical data indicate that rocks of both groups were generated by partial melting of a juvenile lower crust, but the differences in the two groups reflect a transition from deep-cold melting to relatively shallower-hotter melting in the period from ca. 105 to 100 Ma. This transition was synchronous with the rapid cooling of granitoids, topographic uplift, and the shutdown of magmatism in the central-north Lhasa Terrane, and followed by sedimentation and the resumption of magmatism in the south Lhasa Terrane. The above observations collectively indicate that the central-north Lhasa Terrane was under an extensional setting in late Early Cretaceous, and we tentatively suggest that it was in response to lithospheric drip during roll-back of the northward-subducting Neo-Tethyan oceanic plate.

Cambrian bimodal volcanism in the Lhasa Terrane, southern Tibet: Record of an early Paleozoic Andean-type magmatic arc in the Australian proto-Tethyan margin

2012 ◽  
Vol 328 ◽  
pp. 290-308 ◽  
Author(s):  
Di-Cheng Zhu ◽  
Zhi-Dan Zhao ◽  
Yaoling Niu ◽  
Yildirim Dilek ◽  
Qing Wang ◽  
...  
Keyword(s):  
Early Paleozoic ◽  
Southern Tibet ◽  
Magmatic Arc ◽  
Bimodal Volcanism ◽  
Lhasa Terrane ◽  
Andean Type

An early Paleozoic silicic large igneous province in NE Gondwana: a preliminary synthesis

2020 ◽  
Author(s):  
Wei Dan ◽  
J. Brendan Murphy ◽  
Gong-Jian Tang ◽  
Xiu-Zheng Zhang ◽  
Qiang Wang
Keyword(s):  
Tectonic Setting ◽  
Oceanic Lithosphere ◽  
Large Igneous Province ◽  
Early Paleozoic ◽  
Magmatic Rocks ◽  
Igneous Province ◽  
Granitoid Rocks ◽  
Andean Type ◽  
Almost All ◽  
The Relationship

<p>Five major oceans (Iapetus, Rheic, Proto-Tethys, Paleo-Tethys and Paleo-Asian) formed during or after assembly of the Gondwana continent. However, the relationship between them is poorly understood, largely due to the complex and disputed evolution of NE Gondwana in the early Paleozoic. Here we present a summary of early Paleozoic tectono-thermal events in the NE Gondwana and discuss their tectonic settings. Early Paleozoic magmatic rocks are widely distributed in the Himalaya, Lhasa, Southern Qiangtang, Baoshan, Sibumasu and Tengchong terranes, and their ages were loosely constrained to be ca. 530-430 Ma. However, after a critical review of these dating results, we propose the magmatic rocks were mostly formed between ca. 500-460 Ma. Although bimodal, they are dominated by granitoid rocks distributed over an area of >2500 km × 900 km. Thus, they constitute a typical silicic large igneous province. Almost all granitoid rocks were derived from partial melting of sedimentary rocks, but a few show A-type characteristics. Coeval amphibolite-facies metamorphic rocks yield ages of 490-465 Ma. A sedimentary hiatus marked by either a disconformity or angular unconformity coeval with the major magmatic flare-up period is evident in all terranes. Thus, present evidence doesn’t favor either the conventional Andean-type subduction model, in which these magmatic rocks reflect subduction of Proto-Tethys oceanic lithosphere beneath the northern Gondwanan margin, or a post-collision setting, in which extension is associated with the collapse of the Pan-African orogeny in NE Gondwana. The tectonic setting for this magmatic province is tentatively related to a plume in a far-field subduction zone.</p>

scholarly journals A Geochemical Overview of Mid-Archaean Metavolcanic Rocks from Southwest Greenland

Geosciences ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 266 ◽  
Author(s):  
Kristoffer Szilas
Keyword(s):  
Magma Mixing ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Present Contribution ◽  
Data Set ◽  
Basaltic Rocks ◽  
The North ◽  
Metavolcanic Rocks ◽  
Geochemical Analyses ◽  
Southwest Greenland

The present contribution reviews bulk-rock geochemical data for mid-Archaean (ca. 3075–2840 Ma) metavolcanic rocks from the North Atlantic Craton of southwest Greenland. The data set includes the most recent high quality major and trace element geochemical analyses for ten different supracrustal/greenstone belts in the region. When distilling the data set to only include the least altered metavolcanic rocks, by filtering out obviously altered samples, mafic/ultramafic cumulate rocks, late-stage intrusive sheets (dolerites) and migmatites, the remaining data (N = 427) reveal two fundamentally distinct geochemical suites. The contrasting trends that emerge from the filtered geochemical data set, which best represents the melt compositions for these mid-Archaean metavolcanic rocks are: (1) tholeiitic (mainly basaltic) versus (2) calc-alkaline (mainly andesitic). These two rock suites are effectively separated by their La/Sm ratios (below or above three, respectively). It is demonstrated by geochemical modelling that the two contrasting suites cannot be related by either fractional crystallization or crustal assimilation processes, despite occurring within the same metavolcanic sequences. The tholeiitic basaltic rocks were directly mantle-derived, whereas the petrogenesis of the calc-alkaline andesitic rocks involve a significant (>50%) felsic component. The felsic contribution in the calc-alkaline suite could either represent slab-melt metasomatism of their mantle source, mafic-felsic magma mixing, or very large degrees of partial melting of mafic lower crust. At face value, the occurrence of andesites, and the negative Nb-Ta-Ti-anomalies of both suites, is consistent with a subduction zone setting for the origin of these metavolcanic rocks. However, the latter geochemical feature is inherent to processes involving crustal partial melts, and therefore independent lines of evidence are needed to substantiate the hypothesis that plate tectonic processes were already operating by the mid-Archaean.

scholarly journals Supplemental Material: Three stages of arc migration in the Carboniferous-Triassic in northern Qiangtang, central Tibet, China: Ridge subduction and asynchronous slab rollback of the Jinsha Paleotethys

2021 ◽  
Author(s):  
Yin Liu ◽  
W.J. Xiao ◽  
et al.
Keyword(s):  
Geochemical Data ◽  
Data Set ◽  
Ridge Subduction ◽  
Data Table ◽  
Magmatic Rocks ◽  
Slab Rollback ◽  
Three Stages ◽  
Zircon Morphology ◽  
Central Tibet ◽  
Qiangtang Terrane

Sampling details (Table S1), zircon geochronological data (Table S2), geochemical data (Table S3), and a summary of zircon morphology and geochronology (Table S4) for Carboniferous-Triassic samples from the northern Qiangtang terrane. Geochemical data set of Carboniferous-Triassic magmatic rocks from the northern Qiangtang terrane (Table S5).

scholarly journals Supplemental Material: Three stages of arc migration in the Carboniferous-Triassic in northern Qiangtang, central Tibet, China: Ridge subduction and asynchronous slab rollback of the Jinsha Paleotethys

2021 ◽  
Author(s):  
Yin Liu ◽  
W.J. Xiao ◽  
et al.
Keyword(s):  
Geochemical Data ◽  
Data Set ◽  
Ridge Subduction ◽  
Data Table ◽  
Magmatic Rocks ◽  
Slab Rollback ◽  
Three Stages ◽  
Zircon Morphology ◽  
Central Tibet ◽  
Qiangtang Terrane

Sampling details (Table S1), zircon geochronological data (Table S2), geochemical data (Table S3), and a summary of zircon morphology and geochronology (Table S4) for Carboniferous-Triassic samples from the northern Qiangtang terrane. Geochemical data set of Carboniferous-Triassic magmatic rocks from the northern Qiangtang terrane (Table S5).

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