Open AccessStructural Reverse and its Significance to Oil and Gas Accumulation in Ordos Block in Neogene
Author(s) -
Zhao Hong-yan,
Chiyang Liu,
Jianqiang Wang,
Gui Xiao-jun,
Leping Yue,
Weng Wang-fei,
Miaoling Liang
Publication year - 2009
Publication title -
energy exploration and exploitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 30
eISSN - 2048-4054
pISSN - 0144-5987
DOI - 10.1260/014459809789618803
Subject(s) - geology , unconformity , structural basin , neogene , paleontology , cenozoic , cretaceous , source rock , mesozoic , paleogene , tectonics , fission track dating , red beds , magnetostratigraphy , geochemistry
Ordos Block is considered as a rather stable basin in Cenozoic by most researchers. The result of our study is different from this opinion. Before the Cenozoic, tectonic movement directions are uplifted in the eastern part and sunk in the western part of the basin. The oldest Cenozoic strata which deposit in the east part of Ordos Basin are Neogene red clays. They appear on both Pre-Tertiary and Post-Mesozoic geological maps of Ordos Basin. According to fission track dating data from various researchers, structural unconformity contacts, paleo-current directions and regional environment, the western part of Ordos Block have become structural uplift. The red clay strata have not been observed there. The eastern Ordos Block had a wide distribution of red clay which sedimented from west to east on the Lower Cretaceous, Middle Jurassic Anding Formation, Zhiluo Formation, Early-Mid Jurassic Yan'an Formation and Late Triassic Yanchang Formation, respectively. Therefore, we concluded that there existed a structural sinking event in the eastern part of the basin. The event occurred since the red clay sedimentation. In this stage, the red clay showed about 8 Ma by magnetostratigraphy dating. We name this tectonic movement direction change as structural reverse. It is supposed that the reverse time which the west basin turned from the depression since Mesozoic to thrust and uplift is also in 8Ma or so. The structural reverse times of the eastern and western basin are synchronous. It began in 8 Ma and continued after that. The structural reverse had great significance to the fluid deposits such as oil and gas in Ordos Basin.