The passive margin of northern Gondwana during Early Paleozoic: Evidence from the central Tibet Plateau

2020 ◽  
Vol 78 ◽  
pp. 126-140 ◽  
Author(s):  
Yiming Liu ◽  
Sanzhong Li ◽  
M. Santosh ◽  
Huahua Cao ◽  
Shengyao Yu ◽  
...  
Keyword(s):  
Passive Margin ◽  
Tibet Plateau ◽  
Early Paleozoic ◽  
Central Tibet

The generation and reworking of continental crust during early Paleozoic in Gondwanan affinity terranes from the Tibet Plateau

2019 ◽  
Vol 190 ◽  
pp. 486-497 ◽  
Author(s):  
Yiming Liu ◽  
Sanzhong Li ◽  
M. Santosh ◽  
Huahua Cao ◽  
Shengyao Yu ◽  
...  
Keyword(s):  
Continental Crust ◽  
Tibet Plateau ◽  
Early Paleozoic ◽  
The Tibet Plateau

scholarly journals Early Paleozoic rifting and reactivation of a passive-margin rift: Insights from detrital zircon provenance signatures of the Potsdam Group, Ottawa graben: Comment

2019 ◽  
Vol 131 (3-4) ◽  
pp. 695-698
Author(s):  
Ed Landing ◽  
Osman Salad Hersi ◽  
Lisa Amati ◽  
Stephen R. Westrop ◽  
David A. Franzi
Keyword(s):  
Detrital Zircon ◽  
Passive Margin ◽  
Early Paleozoic

The initiation of the early Paleozoic Cordilleran miogeocline: evidence from the uppermost Proterozoic – Lower Cambrian Hamill Group of southeastern British Columbia

1988 ◽  
Vol 25 (1) ◽  
pp. 1-19 ◽  
Author(s):  
William J. Devlin ◽  
Gerard C. Bond
Keyword(s):  
British Columbia ◽  
Lower Cambrian ◽  
Direct Evidence ◽  
Thermal Anomaly ◽  
Passive Margin ◽  
Early Paleozoic ◽  
Upper Proterozoic ◽  
Windermere Supergroup ◽  
Depositional Setting ◽  
Thermal Subsidence

The uppermost Proterozoic–Lower Cambrian Hamill Group of southeastern British Columbia contains geologic evidence for a phase of extensional tectonism that led directly to the onset of thermally controlled subsidence in the Cordilleran miogeocline. Moreover, the Hamill Group contains the sedimentological record of the passage of the ancient passive margin from unstable tectonic conditions associated with rifting and (or) the earliest phases of thermal subsidence to post-rift conditions characterized by stabilization of the margin and dissipation of the thermal anomaly generated during the rift phase (the rift to post-rift transition). Widespread uplift that occurred prior to and during the deposition of the lower Hamill Group is indicated by an unconformable relation with the underlying Windermere Supergroup and by stratigraphic relations between Middle and Upper Proterozoic strata and unconformably overlying upper Lower Cambrian quartz arenites (upper Hamill Group) in the southern borderlands of the Hamill basin. In addition, the coarse grain size, the feldspar content, the depositional setting, and the inferred provenance of the lower Hamill Group are all indicative of the activation of basement sources along the margins of the Hamill basin. Geologic relations within the Hamill Group that provide direct evidence for extensional tectonism include the occurrence of thick sequences of mafic metavolcanics and rapid vertical facies changes that are suggestive of syndepositional tectonism.Evidence of extensional tectonism in the Hamill Group directly supports inferences derived from tectonic subsidence analyses that indicate the rift phase that immediately preceded early Paleozoic post-rift cooling could not have occurred more than 10–20 Ma prior to 575 ± 25 Ma. These data, together with recently reported isotopic data that suggest deposition of the Windermere Supergroup began ~730–770 Ma, indicate that the rift-like deposits of the Windermere Supergroup are too old to represent the rifting that led directly to the deposition of the Cambro-Ordovician post-rift strata. Instead, Windermere sedimentation was apparently initiated by an earlier rift event, probably of regional extent, that was part of a protracted, episodic rift history that culminated with continental breakup in the latest Proterozoic – Early Cambrian.

Passive-margin magmatism caused by enhanced slab-pull forces in central Tibet

Geology ◽  
2020 ◽  
Author(s):  
Wei Dan ◽  
Qiang Wang ◽  
William M. White ◽  
Xian-Hua Li ◽  
Xiu-Zheng Zhang ◽  
...  
Keyword(s):  
Passive Margin ◽  
Lower Plate ◽  
Isotopic Signatures ◽  
Ridge Subduction ◽  
Slab Rollback ◽  
Element Enrichment ◽  
Central Tibet ◽  
Back Arc ◽  
Ocean Ridge ◽  
Qiangtang Terrane

We report on a ca. 239 Ma mafic dike swarm intruded in the Southern Qiangtang terrane, central Tibet, that was generated on the passive continental margin of a subducting lower plate. The dikes are tholeiitic basalts and exhibit light rare earth element enrichment, modest negative anomalies in Nb and Ta, and enriched isotopic signatures. The dikes are coeval with a back-arc basin formed in the upper plate as a result of the rollback of the Paleo-Tethys oceanic slab. Thus, after ocean-ridge subduction, enhanced slab-pull forces related to slab rollback on one side of the ocean induced extension and magmatism in the passive margin on the opposite side. We argue that enhanced slab-pull forces are a previously unrecognized mechanism for the generation of lower-plate passive-margin magmatism.

Volcanism on the passive margin of Laurentia: an early Paleozoic analogue of Cretaceous volcanism on the northeastern American margin: Reply

1990 ◽  
Vol 27 (11) ◽  
pp. 1552-1554 ◽  
Author(s):  
Stephen Kumarapeli ◽  
Karen St. Seymour ◽  
Hillar Pintson ◽  
Elizabeth Hasselgren
Keyword(s):  
Passive Margin ◽  
Early Paleozoic ◽  
Cretaceous Volcanism

Middle Ordovician (Darriwilian) conodonts from southern Tibet, the Indian passive margin: implications for the age and correlation of the roof of the world

2020 ◽  
pp. 1-25
Author(s):  
Svend Stouge ◽  
David A. T. Harper ◽  
Renbin Zhan ◽  
Jianbo Liu ◽  
Lars Stemmerik
Keyword(s):  
Middle Part ◽  
Passive Margin ◽  
Continental Margins ◽  
Oceanic Circulation ◽  
Mount Everest ◽  
Southern Tibet ◽  
Middle Ordovician ◽  
The North ◽  
Carbon Isotope Excursion ◽  
Central Tibet

Abstract New occurrences of middle–late Darriwilian (Middle Ordovician) conodonts are reported from the Nyalam region, southern Tibet. The conodont-yielding strata, referred to the Chiatsun Group, accumulated on the north Indian continental margin of northern Gondwana. These Middle Ordovician conodonts include the informal species Histiodella sp. A in the middle part of the Lower Formation of the Chiatsun Group succeeded by a fauna of the Pygodus serra Zone in the upper part of that formation. Pygodus anserinus is recorded from the base of the Upper Formation of the Chiatsun Group. The Nyalam succession and its conodont taxa allow for precise correlation of the strata preserved on top of Mount Qomolangma (Mount Everest), eastern Tibet and the Peri-Gondwana Lhasa (north central Tibet), South China, North China, Tarim Basin and Thailand-Malaysia (Sibumasu Terrane) terranes and/or microcontinents. The middle Darriwilian positive increase in δ13Ccarb values (carbon isotope excursion, or MDICE) is recorded from most terranes, and can be related to a late middle Darriwilian global short-term cooling and sea-level drop. The cooling event prompted temperate- to warm-water taxa to migrate towards the palaeoequator and constrained the Australasian Province to locations near and at the palaeoequator. The intensified oceanic circulation and upwelling on continental margins probably caused some characteristic taxa to become extinct. The incoming fauna was mainly of cool-water taxa. The conodont specimens from southern Tibet are black to pale grey, corresponding to conodont colour index (CAI) values of 5 to 6, which demonstrates that the host sedimentary rocks were once heated to more than 360°C.

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