In this paper, we present a procedure based on Parker’s three-dimensional direct gravity inversion to determine the sedimentary basement depth rapidly and objectively. In the foregoing procedure, the Bouguer gravity anomaly is continued downward near the seabed before inversion, and the mean depth of the basement is constrained by the power density spectrum of the gravity anomaly. The bulk density of sediment and basalt rocks are also constrained by the logging data obtained from Expedition 349 Scientists (Expedition 349 Scientists, in: International Ocean Discovery Program Preliminary Report, 349, (2014). doi:10.14379/iodp.pr.349.2014). The sedimentary basement depth of the Southwest Sub-basin (SWSB) of the East Vietnam Sea (South China Sea) derived from the inversion of the downward continued Bouguer anomalies has more detail and accuracy than the sediment basement depth inverted from Bouguer anomaly at the sea level. The calculated basement depth and the sedimentary thickness in the SWSB vary from 4.0 to 6.5 km and from 0.5 to 2.0 km, respectively. The crustal thickness beneath the SWSB ranges from 4.0 to 7.5 km. Our model is consistent with sedimentary basin structure where spreading ridge valley is presented as the deepest points in the sedimentary basement and the terrain along the two banks of the valley is elevated. In addition, the SWSB is divided into four structure domains that are useful for the geodynamic and tectonic implications of the SWSB and surrounding area.

中文翻译：

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3D直接重力反演东越海西南次盆地沉积基底结构

在本文中，我们提出了一种基于帕克三维直接重力反演的程序，可以快速，客观地确定沉积基底的深度。在上述过程中，布格重力反演在反转之前一直在海床附近继续向下，并且地下室的平均深度受到重力反演的功率密度谱的约束。沉积物和玄武岩的堆积密度也受到从Expedition 349科学家获得的测井数据的限制（Expedition 349科学家，在：International Ocean Discovery Program Preliminary Report，349，（2014）。doi：10.14379 / iodp.pr.349.2014） 。从向下持续的布格异常的反演得出的东越海（南海）西南子盆地（SWSB）的沉积基底深度比从海上的布格异常反演的沉积物基底深度更为详细和准确。水平。SWSB中计算得出的基底深度和沉积厚度分别为4.0至6.5 km和0.5至2.0 km。SWSB下方的地壳厚度为4.0至7.5 km。我们的模型与沉积盆地结构是一致的，在该沉积盆地结构中，在沉积基底中的最深点出现了蔓延的山谷，而沿山谷两岸的地形则升高了。此外，SWSB分为四个结构域，可用于SWSB及其周围地区的地球动力学和构造意义。