琼东南盆地中央坳陷带拆离断层及其控盆作用

Using regional geological, newly acquired 2D and 3D seismic, drilling and well log data, especially 2D long cable seismic profiles, the structure and stratigraphy in the deep-water area of Qiongdongnan Basin are interpreted. The geometry of No.2 fault system is also re-defined, which is an important fault in the central depression belt of the deep-water area in the Qiongdongnan Basin by employing the quantitative analysis techniques of fault activity and backstripping. Furthermore, the dynamical evolution of the No.2 fault sys-tem and its controls on the central depression belt are analyzed. This study indicates that the Qiongdongnan Basin was strongly influenced by the NW-trending tensile stress field during the Late Eocene. At this time, No.2 fault system initiated and was characterized by several discontinuous fault segments, which controlled a series small NE-trending fault basins. During the Oligocene, the regional extensional stress field changed from NW-SE to SN with the oceanic spreading of South China Sea, the early small faults started to grow along their strikes, eventually connected and merged as the listric shape of the No.2 fault system as ob-served today. No.2 fault detaches along the crustal Moho surface in the deep domain of the seismic profiles as a large-scale detachment fault. A large-scale rollover anticline formed in hanging wall of the detachment fault. There are a series of small fault basins in both limbs of the rollover anticline, showing that the early small basins were involved into fold deformation of the rollover anticline. Structurally, from west to east, the central depression belt is characterized by alternatively arranged graben and half-graben. The central depression belt of the Qiongdongnan Basin lies at the extension zone of the tip of the V-shaped northwest-ern ocean sub-basin of the South China Sea, its activity period is the same as the development period of the northwestern ocean sub-basin, furthermore the emplacement and eruption of magma that originated from the mantle b     

南海北部新生代构造应力反演及其动力学背景探讨*

南海北部为我国重要的含油气区之一, 但目前南海北部盆地的演化史及其与周边构造事件的关系仍不明确。基于钻孔和地震资料, 通过数学模拟, 反演了琼东南盆地和珠江口盆地的构造应力演化特征和初始地壳厚度。结果表明, 南海北部盆地具有较薄的初始地壳厚度和岩石圈厚度。珠江口盆地存在两期应力松弛期, 而琼东南盆地在深水区和浅水区分别存在一期应力松弛期。南海北部第一期应力松弛在空间上具有连续性, 主要分布在深水区, 在时间上东早西晚; 第二期应力松弛空间上存在东西分异性。分析认为, 南海北部深水区应力松弛期由东至西的演化应为西北次海盆由东至西的剪刀式张裂所致。珠江口盆地第二期构造应力松弛与局部岩浆侵入有关, 琼东南盆地浅水区的构造应力松弛期与红河走滑断裂平静期相对应。     

南海北部新生代构造应力反演及其动力学背景探讨

南海北部为我国重要的含油气区之一,但目前南海北部盆地的演化史及其与周边构造事件的关系仍不明确。基于钻孔和地震资料,通过数学模拟,反演了琼东南盆地和珠江口盆地的构造应力演化特征和初始地壳厚度。结果表明,南海北部盆地具有较薄的初始地壳厚度和岩石圈厚度。珠江口盆地存在两期应力松弛期,而琼东南盆地在深水区和浅水区分别存在一期应力松弛期。南海北部第一期应力松弛在空间上具有连续性,主要分布在深水区,在时间上东早西晚;第二期应力松弛空间上存在东西分异性。分析认为,南海北部深水区应力松弛期由东至西的演化应为西北次海盆由东至西的剪刀式张裂所致。珠江口盆地第二期构造应力松弛与局部岩浆侵入有关,琼东南盆地浅水区的构造应力松弛期与红河走滑断裂平静期相对应。     

琼东南盆地中央峡谷沉积充填特征及油气地质意义

综合利用地震、测井、岩芯、岩屑分析化验资料及古生物资料,研究了琼东南盆地中央峡谷形态、沉积充填特征及其油气地质意义。结果表明,位于琼东南盆地中央坳陷带的中央峡谷,西起始莺歌海盆地东部陆坡,东终止南海西北次海盆,整体呈SW—NE走向,平面上呈"S"形,剖面上呈对称或不对称"V"和"U"型,峡谷长、底宽、顶宽和谷深分别约为580km、1～3km、6～15km、400～600m;峡谷以溯源堆积方式充填了相互叠置的多期砂岩和泥岩,中、下部以近基浊积岩充填为主,向上逐渐过渡为远基浊积岩和深海相泥岩;峡谷沉积体系划分为峡谷中心、边缘和漫溢3个微相;峡谷不仅是碎屑物质的通道,也是碎屑物质卸载堆积和油气运移、富集的重要场所,发育隐蔽岩性和构造-岩性复合油气藏。