Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (2): 285-298.doi: 10.11743/ogg20210203

• Petroleum Geology • Previous Articles     Next Articles

Framework evolution of North Tarim Paleo-uplift from the Late Ordovician to Middle Devonian

Jiajun Chen1,2(), Dengfa He1,2, Fangyuan Sun1, Fanglei Tian1,2   

  1. 1. School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Enrichment Mechanism (Ministry of Education), China University of Geosciences (Beijing), Beijing 100083, China
  • Received:2020-05-18 Online:2021-04-28 Published:2021-04-21

Abstract:

The discovery of the Ordovician giant oil and gas fields in the North Tarim Uplift has triggered heated discussion on the Early Paleozoic tectonic framework evolution.An analysis on the early Paleozoic unconformity in terms of geography, geometry, and temporal variables will facilitate the understanding of North Tarim Paleo-uplift development.Based on quantities of drilling and seismic data, this study analyzed the Silurian unconformities at the base and on top, determined the distribution and geometry of the paleo-uplift at the end of the Late Ordovician and the end of the Middle Devonian, and discussed the evolution of tectonic stress field.Both the Silurian unconformities at the base and on top are characterized by "truncation and onlap", that is, the stratum below the unconformity was truncated while younger onlaps on the surface.The paleo-uplift struck nearly E-W at the end of the Late Ordovician, while NE-SW in the south slope region at the end of the Middle Devonian developed as three individual paleo-lower uplifts (i.e., Yingmaili Lower Uplift, Lunnan Lower Uplift, and nose-shaped Korla Salient).The tectonic framework evolution (the near NS-trending structures superimposed by NE-SW folding) indicates that the compressive stress field changed from NS striking at the end of the Late Ordovician to NW-SE striking at the end of the Middle Devonian.In all, the results serve to provide essential evidence and detailed reasoning for the Late Caledonian tectonic framework of the North Tarim Uplift.

Key words: unconformity, paleo-uplift, tectonic stress field, Middle Devonian, Late Ordovician, North Tarim Uplift, Tarim Basin

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