Cenozoic tectonic jumping and implications for hydrocarbon accumulation in basins in the East Asia Continental Margin

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The East China Sea Shelf Basin (ECSSB) lies at the south‐eastern margin of the Eurasian Plate and was affected by the subduction of the Pacific Plate and the Philippine Plate. It experienced and recorded multistage tectonic inversions in the Cenozoic, especially in the Xihu Sag. In an attempt to investigate the evolution and mechanism of tectonic inversion, this paper presents numerical simulation results by the finite element method to the Xihu Sag. Combined with comprehensive structural analyses of seismic profiles, this paper determines the structural geometry of the sag for establishing a viscoelastic geologic model including six‐layer strata and nine major faults. Simulation results show that the boundary conditions of transtension and transpression control the inversion process that propagates from east to west, and the distribution of low compressive stress displays certain correlations with the distribution of oil deposits. Based on quantitative analysis of the vertical displacement field of the Xihu Sag, this paper identifies a tectonic inversion process, which indicates that the western part of the sag uplifts and the eastern part subsides during the first‐stage inversion; whereas the western part subsides and central‐eastern parts uplift during the second and third stages. The formation of the tectonic inversion is controlled by the adjustment of the stress field from dextral transtension to sinistral transpression caused by the change of subduction rates and direction of the Pacific Plate and the Philippine Sea Plate.

Section: Geological Settingmentioning

confidence: 99%

Dynamic mechanism of tectonic inversion and implications for oil–gas accumulation in the Xihu Sag, East China Sea Shelf Basin: Insights from numerical modelling

Dai

et al. 2017

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“…). The previous studies mainly focused on the Cenozoic strata (Li, Yu, et al, ; Liu, Liao, Jia, Zhou, & Yang, ; Liu, ; Liu, ) and proposed various evolutionary mechanisms of the Cenozoic basins (Suo, Li, Dai, Liu, & Zhou, ; Suo, Li, Yu, et al, ; Zheng, Zhou, Cai, Lu, & Cao, ). It is generally believed that the Mesozoic evolution of the East China Sea Continental Shelf has experienced extensional processes and voluminous magmatic events evidenced by those intrusive rocks obtained from drilling and some seismic profiles in the region (Mao, ; Sun et al, ; Zhang & Li, ; Liu, ).…”

Section: Introductionmentioning

confidence: 99%

Mesozoic magmatic activity and tectonic evolution in the southern East China Sea Continental Shelf Basin: Thermo‐mechanical modelling

Liu

Dai

et al. 2017

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Based on the seismic profiles, drilling, tomographic images and other geological data, we use the I2VIS code to program the Mesozoic finite‐difference numerical model in the southern part of the East China Sea Continental Shelf Basin (ECSCSB). We try to model the basin evolutionary process by setting up different boundaries to the 2‐D models. After analysing the simulation results of low‐speed and high‐speed stretching models, we found that under the condition of preliminary tensile value, the magma could not be generated in both rapid and slow stretching cases. This means that the regional extension of the Mesozoic ECSCSB is not the only dominant factor for basin evolution. Based on the analysis of the regional geological features and the modelling results, we suggest that the low‐velocity lithosphere mantle in the study area may be due to the melting of the mantle caused by the subduction and dehydration of the Izawa Nasaki Plate. The evolutionary process of the Mesozoic basins in the ECSCSB is closely related to regional extension and the magma upwelling caused by subduction and dehydration of the Izawa Nasaki Plate during the Mesozoic Era. The magma upwelling led to large‐scale magmatic events. It is likely to act in the Minjiang Sag, which resulted in the further rise of the Minjiang Sag and the formation of the present slope zone.

“…However, these basins had similarities and comparisons based on previous researches and studies on these basins (Ding et al, 2004;Wu et al, 2004;Li, 2008;Li et al, 2012Li et al, , 2013Suo et al, 2012Suo et al, , 2014. The ECSSB and the Cenozoic basins in the northeastern South China Sea Continental Shelf (SCSCS) are separated by the Taiwan Orogen and thus have been considered traditionally to form two individual basins.…”

Section: Introductionmentioning

confidence: 99%

Similarity and differentiation between the East China Sea Shelf Basin and Cenozoic basins in the northeast South China Sea

Zang

Guo

et al. 2016

The East China Sea Shelf Basin (ECSSB), the Pearl River Mouth Basin (PRMB) and the Taixinan Basin (TXNB) in the northern continental margin of the South China Sea (SCS) are important oil‐ and gas‐bearing basins on the Western Pacific Continental Margin. During the Paleocene to Late Miocene, their strata can be compared, and the lithofacies were continuous from the TXNB, via the Taixi Basin (TXB) to the ECSSB. The lithologies mainly consist of interbedded shale, sandstone and mudstone layers. In addition, these basins have similar tectonic and sedimentation features. The three basins had similar marine‐terrigenous facies in the Paleocene and marine–lacustrine–fluvial facies during the Eocene and Late Miocene. The basins experienced several coeval tectonic movements and episodes, and they developed a series of NE‐ and NNE‐trending faults during the Paleocene and Eocene, which controlled the structure of the basins. During the Early Oligocene and Middle Miocene, they developed a series of NW‐ and WNW‐trending strike‐slip faults, reverse folds and flower‐like strike‐slip faults. However, there were obvious differences in sedimentary and tectonic evolution since the Late Miocene. The TXNB and TXB developed marine facies after the Late Miocene, while in the Quaternary, open marine facies replaced the Pliocene terrigenous facies in the ECSSB. Since the Late Miocene, the south of the ECSSB developed into a subsidence stage, and fault activity stopped. The TXB and TXNB developed some inverse structures and then developed into a thermal subsidence episode after the Dongsha Movement. Thus, this paper proposes that the ECSSB and the Cenozoic basins in the SCS were originally a unified basin and then subsequently separated into two basins as a result of the indentation of the Philippine Sea Plate (PSP) and the arc–continent collision between the Luzon Arc and the Eurasian Plate. Copyright © 2016 John Wiley & Sons, Ltd.