The Geological And Structural Characteristics And Origin Of The Jiaozhou Bay

As economies develop dramatically fast, more and more engineering projects are being constructed near jiaozhou bay and offshore areas. The paper is written to harmonize marine engineering activities with marine geological condition and avoid the unfavorable effects that may be brought about by these faults happening ,as well as to provide reliable fundamental data for exploitation and utilization of jiaozhou bay.The paper is supported by several geological and geophysical exploration surveys taken by FIO recent years. many means are applied to gain detailed first-hand data, including marine magnetic anomaly map,single-channel seismic profile and drilling core data, many other researchers'data are also combined in this paper. It includes the following aspects of the bay: regional geology, topography and geomorphy, seismic stratum, fault feature, bedrock and origin of the bay. The study shows that:1 ) Three regional acoustic impedance boundaries in jiaozhou bay are recognized, including R0——the seabed reflection interface, R1——the interface between Holocene and Late Pleistocene,R2——the bedrock reflection interface.2) In jiaozhou bay, three seismic stratigraphic units are classified, including U1——the Holocene marine which is mainly the blue silt and clayey soil,U2——the Late Pleistocene bedland formation which is mainly grit and clayey soil, U3——the bedrock, which is mainly Cretaceous sedimentary rock, volcanic rock,athrogenic rock and ganite.3) In jiaozhou bay, there are three group fault including NE-trending,NW-trending,EW-trending, which are inherited with the land fauts. The north part of the cangkou fault is the boundary of the Cretaceous and lao mountion ganite, and the south is between the lao mountain——xiaozhu mountain ganite.The NW-trending Dagu river-Chaoliandao fault is divided into three parts, the north part drawdowning turn northeast step-shapedly is the boundary of the gneiss and Cretaceous. The EW-trending Haoguanzhuang fault converges to the cangkou fault. In short , the NE-trending and NW-trending faults converge to the mouth of the jiaozhou bay with fan-shaped.4) The bedrock cover depth behaves three convexes and four concaves in overall tendency. Controlled by the faults, as the same as the esat and the west, it behaves the south is deeper than the the north, with the deepest point at the mouth of the jiaozhou bay.5) It can be divided into fourⅤ-level building unit: qingdao-laoshan bulge, jimo-cangkou fault zone, jiaozhou bay fault bason,xiaozhu mountain bulge.6) Jiaozhou bay is a faulted basin that controlled by the three NE-trending,NW-trending,EW-trending faults.