The geological event and the assemblage of source-reservoir-seal rock during the Sinian-Ordovician period in Kuruktag region of northeastern Tarim Basin

Kuruktag region of Tarim Basin is one of the most important strategic replacement areas of oil and gas resources, and is an effective entry point based on special structural setting for studying basin-mountain coupling and evolution of regional structures. Events deposited products from glacial event, volcanic event, storm event and turbidity event are developed widely in the Sinian-Ordovician sedimentary strata of Kuruktag region on the northeastern margin of Tarim Basin. The formation time of these events has obvious coupling relationship with tectonic evolution of Kuruktag region. The breakup of Rodinia supercontinent was a inducing factors for global glacial deposition of Neoproterozoic, which caused the formation of glacialfacies in the Kuruktag region. In addition, volcanic event in Early Cambrian was also a reflection of the breakup of Rodinia. Continuous tension caused by cracking continued until the end of Early Ordovician. However, shorter-period reversed structures occurred during the late Cambrian, which led to the shallowing of south and north facies and caused the formation of tempestuous deposits. The rapid uplift of Kuruktag Mountain under the pressing structural surroundings during the Middle-Late Ordovician caused the increase of material source, which offered advantage conditions for turbidity event. In addition, changing of regional tectonics was a decisive factor for the development of source rocks and reservoirs. Early and Middle Cambrian as well as Early Ordovician constitute a main stage for the development of source rocks under the extension condition. High-quality reservoirar of pore type comprised bonatite and clastic rocks, and the pores were intracrystalline pores, dissolved pores and cracks mainly distributed in Late Sinian, Late Cambrian and Middle-Late Ordovician strata. These source rocks and reservoirs with mudstone formed multiple source-reservoircaprock association in the vertical direction.