scholarly journals Growth of triangle zone fold-thrusts within the NW Borneo deep-water fold belt, offshore Sabah, southern South China Sea

Geosphere ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 329-356
Author(s):  
Jonny Wu ◽  
Ken McClay ◽  
Jose de Vera
Keyword(s):  
South China Sea ◽  
South China ◽  
Deep Water ◽  
Three Dimensional ◽  
Petroleum Industry ◽  
Fold Belt ◽  
Southern South China Sea ◽  
Near Surface ◽  
Growth Strata ◽  
Triangle Zone

Abstract The NW Borneo deep-water fold-and-thrust belt, offshore Sabah, southern South China Sea, contains a structurally complex region of three to four seafloor ridges outboard of the shelf-slope break. Previous studies have suggested the seafloor ridges formed either above shale diapirs produced by mass movement of overpressured shales (i.e., mobile shale) or above an imbricate fold-and-thrust array. Here, we performed tectonostratigraphic analyses on a petroleum industry three-dimensional (3-D) seismic volume that imaged the full growth stratal record. We show fold growth history, deformation styles, along-strike structural variabilities, and synkinematic sedimentation during triangle zone–style fold growth. Nine seismic horizons within growth strata were mapped and correlated to petroleum industry seismostratigraphy. Synkinematic sedimentation interactions with growing folds and near-surface strains were analyzed from seismic attribute maps. We interpret that the seafloor structures were formed by imbricate thrusts above multiple detachments. We estimate ∼8 km minimum shortening since the late Miocene ca. 10 Ma. The folds show oversteepened fold forelimbs, back-rotated backlimbs, and forward-vergent (NW to NNW) “blind” thrust ramps that terminate within the growth strata. Fold cores show evidence of internal shear. Immature folds show detachment fold geometries, whereas mature folds show forelimb break thrusts, type I triangle zones, and rotated forward-vergent roof thrusts. Thrust linkages spaced ∼10 km apart were exploited as thrust top synkinematic sedimentation pathways; the linkages also partition near-surface strains. Our comprehensive, three-dimensional documentation of triangle zone fold growth and sedimentation in a deep-water fold belt highlights internal shear, multiple detachments, and opposite thrust vergence; mobile shales are not required to explain the deformation.

Three dimensional seismic studies of deep-water hazard-related features on the northern slope of South China Sea

2016 ◽  
Vol 77 ◽  
pp. 1125-1139 ◽  
Author(s):  
Duanxin Chen ◽  
Xiujuan Wang ◽  
David Völker ◽  
Shiguo Wu ◽  
Lei Wang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Deep Water ◽  
Three Dimensional ◽  
Northern Slope ◽  
China Sea ◽  
Water Hazard

scholarly journals Circulation Driven by Multihump Turbulent Mixing Over a Seamount in the South China Sea

2022 ◽  
Vol 8 ◽  
Author(s):  
Ruijie Ye ◽  
Xiaodong Shang ◽  
Wei Zhao ◽  
Chun Zhou ◽  
Qingxuan Yang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Deep Water ◽  
Turbulent Mixing ◽  
Three Dimensional ◽  
The South China Sea ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
China Sea ◽  
Meridional Overturning

Turbulent mixing above rough topography is crucial for the vertical motions of deep water and the closure of the meridional overturning circulation. Related to prominent topographic features, turbulent mixing not only exhibits a bottom-intensified vertical structure but also displays substantial lateral variation. How turbulent mixing varies in the upslope direction and its impact on the upwelling of deep water over sloping topography remains poorly understood. In this study, the notable multihump structure of the bottom-intensified turbulent diffusivity in the upslope direction of a seamount in the South China Sea (SCS) is revealed by full-depth fine-resolution microstructure and hydrographic profiles. Numerical experiments indicate that multihump bottom-intensified turbulent mixing around a seamount could lead to multiple cells of locally strengthened circulations consisting of upwelling (downwelling) motions in (above) the bottom boundary layer (BBL) that are induced by bottom convergence (divergence) of the turbulent buoyancy flux. Accompanied by cyclonic (anticyclonic) flow, a three-dimensional spiral circulation manifests around the seamount topography. These findings regarding the turbulent mixing and three-dimensional circulation around a deep seamount provide support for the further interpretation of the abyssal meridional overturning circulation.

scholarly journals Evaluation of HRCLDAS and ERA5 Datasets for Near-Surface Wind over Hainan Island and South China Sea

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 766
Author(s):  
Yi Jiang ◽  
Shuai Han ◽  
Chunxiang Shi ◽  
Tao Gao ◽  
Honghui Zhen ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Surface Wind ◽  
Hainan Island ◽  
The South China Sea ◽  
Wind Data ◽  
The South ◽  
Near Surface ◽  
China Sea

Near-surface wind data are particularly important for Hainan Island and the South China Sea, and there is a wide range of wind data sources. A detailed understanding of the reliability of these datasets can help us to carry out related research. In this study, the hourly near-surface wind data from the High-Resolution China Meteorological Administration (CMA) Land Data Assimilation System (HRCLDAS) and the fifth-generation ECMWF atmospheric reanalysis data (ERA5) were evaluated by comparison with the ground automatic meteorological observation data for Hainan Island and the South China Sea. The results are as follows: (1) the HRCLDAS and ERA5 near-surface wind data trend was basically the same as the observation data trend, but there was a smaller bias, smaller root-mean-square errors, and higher correlation coefficients between the near-surface wind data from HRCLDAS and the observations; (2) the quality of HRCLDAS and ERA5 near-surface wind data was better over the islands of the South China Sea than over Hainan Island land. However, over the coastal areas of Hainan Island and island stations near Sansha, the quality of the HRCLDAS near-surface wind data was better than that of ERA5; (3) the quality of HRCLDAS near-surface wind data was better than that of ERA5 over different types of landforms. The deviation of ERA5 and HRCLDAS wind speed was the largest along the coast, and the quality of the ERA5 wind direction data was poorest over the mountains, whereas that of HRCLDAS was poorest over hilly areas; (4) the accuracy of HRCLDAS at all wind levels was higher than that of ERA5. ERA5 significantly overestimated low-grade winds and underestimated high-grade winds. The accuracy of HRCLDAS wind ratings over the islands of the South China Sea was significantly higher than that over Hainan Island land, especially for the higher wind ratings; and (5) in the typhoon process, the simulation of wind by HRCLDAS was closer to the observations, and its simulation of higher wind speeds was more accurate than the ERA5 simulations.

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