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通过不整合面、断裂体系和盆地构造格局的综合分析,研究珠一坳陷早-中始新世与晚始新世—早渐新世之间的构造变革特征,探讨构造转型机制。印支半岛的旋转挤出及古南海向南俯冲,造成了区域应力场由NW向顺时针转变为近SN向拉张,导致了NE和NEE向断裂控盆向近EW和NWW向断裂控盆转变,且发育大量近EW向新生断裂。岩石圈伸展变形由均一式的宽裂谷模式向集中式的窄裂谷模式转变,且向南海北部大陆边缘迁移,造成了盆地格局由彼此孤立、分割性强的半地堑或窄地堑系趋于相互连通,盆地范围增大。在近SN向拉张作用下,珠一坳陷北缘控盆断裂作为北部的拉伸边界,为先存薄弱带,应力较集中,断裂活动强烈且明显向北扩展,沉降中心整体向北迁移。裂陷期盆地构造变革造成了文昌组与恩平组烃源岩特征的差异,导致了油气资源分布的贫富不均。
Through comprehensive analysis of unconformities, fault systems and basin tectonic settings, the tectonic transformational characteristics of early-middle Eocene and Late Eocene-Oligocene in the Zhu 1 depression are studied, and the mechanism of tectonic transformation is discussed. The rotary extrusion in the Indo-China Peninsula and the subduction of the South China Sea to the south caused the regional stress field to shift clockwise from NW to near SN, resulting in NE and NEE trending faults to near EW and NWW faults. Change, and the development of a large number of near-EW newborn fracture. The lithospheric extensional deformation transforms from a homogeneous wide-rift pattern to a centralized narrow-rift pattern and migrates to the northern continental margin of the South China Sea, resulting in the basin pattern consisting of isolated and highly segregating semi-graben or narrow-grab features Tends to communicate with each other, the basin increased. In the near SN stretching, the controlled basin fault in the northern margin of the Zhu 1 depression, as the extensional boundary in the north, is a pre-existing weak zone with more concentrated stress. The fault activity strongly and obviously expands northward, and the center of the subsidence migrates to the north . The tectonic transformation of the basin during the rifting period has caused the difference of the source rocks between the Wenchang Formation and Enping Formation, resulting in the uneven distribution of oil and gas resources.