胶莱盆地在南黄海的延伸:来自OBS深地震探测的新证据

Extension of Jiaolai Basin into Qianliyan Uplift in South Yellow Sea:New Evidence from OBS Deep Seismic Detection

为了识别胶莱盆地海阳凹陷在南黄海地区的东部延伸边界,利用穿越南黄海的OBS2013-SYS深地震测线开展2D速度结构模拟,在测线NW方向位于千里岩隆起带的OBS(海底地震仪)站位均观察到了折合走时突然增加的现象。速度结构模型显示胶莱盆地东侧海阳凹陷附近海域存在明显的低速沉积层增厚现象,模型自OBS06站位向NW方向,沉积层厚度由小于1.0km显著增厚至2.5km左右,推测该处为胶莱盆地海阳凹陷的东部边界断裂。结合前人在海阳凹陷识别出的控盆断裂进行分析,厘定了海阳凹陷在海区大体的构造边界和沉积中心,认为胶莱盆地东部控盆断裂可能延伸至连云港—石岛断裂一线,与嘉山—响水—千里岩断裂构成千里岩隆起带南北边界断裂带的一部分。海阳凹陷沉降中心可能位于南黄海海区连云港—石岛断裂北侧海阳凹陷的NE方向,发育的厚层白垩系可能存在较好的油气前景。

In order to identify the eastern extension boundary of Haiyang sag to the South Yellow Sea(SYS),a deep seismic profile OBS2013-SYS was measured across the basin.2D velocity structure modeling revealed a sudden increase of the seismic travel time in the OBSs(ocean-bottom seismometer)located in the Qianliyan uplift in the NW of the OBS profile.The velocity model shows that the sediments with low seismic velocity are obviously thickened in the offshore of Haiyang sag in the east of Jiaolai basin.From the station of OBS06 to the northwest,the sedimentary thicknesses markedly increase from less than 1.0km to about 2.5km:we speculated that it is the eastern boundary fault of Haiyang sag of Jiaolai basin.Combining with the analysis of the basin-controlling faults identified in Haiyang sag,we determined the general structure boundary and sedimentary center of Haiyang sag.We suggest that the eastern basin-controlling fault of Jiaolai basin may extend to the Lianyungang-Shidao fracture zone,which forms part of the north and the south boundary fault zone of the Qianliyan uplift with the Jiashan– Xiangshui-Qianliyan fault.The subsidence center of Haiyang sag may be located in the NE direction of Haiyang sag on the north side of the Lianyungang-Shidao fault in the South Yellow Sea area,and the developed thick Cretaceous may have good oil and gas prospect.