本文選題：臺灣海峽西南部 + 澎湖—北港隆起��； 參考：《地球物理學(xué)進(jìn)展》2017年05期

【摘要】：臺灣海峽位于東海陸架盆地和南海東北部的邊界,其西南端構(gòu)造上屬于隆起區(qū),分隔廈澎斷陷和珠江口盆地,勘探程度較低,以往對該區(qū)地質(zhì)結(jié)構(gòu)的認(rèn)識僅來源于鄰區(qū)零星鉆井和早期的地震、重磁資料.本文對福建省地震局2015年在漳浦外海部署的一條長約69.7 km的淺層反射地震測線進(jìn)行了處理,得到了反射波組特征明顯、構(gòu)造現(xiàn)象易于識別的偏移疊加時間剖面.剖面上有一強(qiáng)反射界面可從西端的約300 ms連續(xù)追蹤到東側(cè)的約600 ms,推測為新生代沉積的底界.偏移速度分析得到的上覆地層P波速度約為2200 m/s,而從海底地震儀記錄的折射波中提取的下伏地層P波速度約為5100 m/s.為研究新生代沉積基底的巖性,我們通過融合研究區(qū)多種來源的重力數(shù)據(jù)得到較為準(zhǔn)確的剖面重力異常,依據(jù)反射地震剖面給出的界面模型進(jìn)行了重力模擬,結(jié)果顯示該強(qiáng)反射界面兩側(cè)密度差高達(dá)0.75 g/cm~3,根據(jù)這些特征結(jié)合鄰區(qū)地質(zhì)露頭和鉆井資料推測該測線海底至300~700 m深度可能為新生代低固結(jié)度的砂巖或泥巖,而其下的沉積基底極有可能為玄武巖等基性火成巖.該結(jié)果為研究臺灣海峽西南部的地質(zhì)構(gòu)造和新生代演化提供了新的地球物理學(xué)證據(jù).
[Abstract]:The Taiwan Strait is located at the boundary of the East China Sea shelf basin and the northeast part of the South China Sea. The southwestern end of the Taiwan Strait belongs to the uplift area, separating the Xiapeng fault depression from the Pearl River mouth basin. In the past, the understanding of geological structure in this area was only derived from sporadic drilling, early earthquakes and gravity and magnetic data. In this paper, a shallow reflection seismic line, about 69.7 km long, which was deployed by Fujian Seismological Bureau in the Zhangpu Sea in 2015, has been processed. The migration stacking time profile with obvious characteristics of reflection wave group and easy recognition of structural phenomena has been obtained. There is a strong reflection interface which can be continuously traced from about 300 Ms in the western end to about 600 Ms on the eastern side, which is supposed to be the bottom boundary of the Cenozoic sediments. The velocity of P wave of overlying strata is about 2200 m / s by migration velocity analysis, and the velocity of P wave of underlying strata extracted from refraction wave recorded by submarine seismograph is about 5100 m / s. In order to study the lithology of Cenozoic sedimentary basement, we obtain more accurate profile gravity anomaly by merging gravity data from various sources in the study area. Gravity simulation is carried out according to the interface model given by reflection seismic profile. The results show that the density difference between the two sides of the strong reflection interface is as high as 0.75 g / cm ~ (-3). According to these characteristics and combined with the geological outcrop and drilling data of the adjacent area, it is inferred that the depth from the bottom of the survey line to the depth of 300 ~ 700 m may be a Cenozoic sandstone or mudstone with low consolidation. The underlying sedimentary basement is probably basalt and other basic igneous rocks. The results provide new geophysical evidence for the study of geological structure and Cenozoic evolution in the southwestern Taiwan Strait.
【作者單位】： 福建省地震局廈門地震勘測研究中心;中國科學(xué)院邊緣海與大洋地質(zhì)重點(diǎn)實(shí)驗(yàn)室(南海海洋研究所);中國科學(xué)院大學(xué);
【基金】：福建省地震局青年科技基金(Y201407)資助
【分類號】：P736.2

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