The Sedimentary Characteristic Of Cenozoic In Weihe Basin And Its Relationship With Tectonics

The structural patterns, the sedimentary facies, the provenance, the sedimentary sequence, and tectonic subsidence of the Weihe basin have been discussed in this paper, according to the work done by previous researchers, a lot of information obtained from field working and in office, the coupled relationship of the basin filled and the structure. The result of the researches not only proclaims the complicate of the sedimentary facies characterize and distribution, the provenance system, and the sedimentary sequence of the basin, but also analyses the coupled relationship between the facies, the provenance, the sequence and the fault, the subsidence of the basin.The sedimentary facies belt goes forward one by one from the fault edge to the center of the basin which has the characteristic of many provenances, many centers of the sediment, fast facies change, narrow facies belt, and small and fast change water area because of the control with fault. The topographic protrusions and depressions affect the characteristic and distribution of the sedimentary facies, was divided into protrusions and depressions, the eolian deposition piled up on the protrusions. The lacustrine deposition heaved up in the depressions.The provenance systems that the sediment in sudden event has more proportion have the character of near provenance and fast deposit. The filled sediments come from three directions which are southern, northern and western, the decency sediments mainly formed by magmatic and metamorphic come from the Qinling orogenic belt, and the sediments mainly formed by sedimentary rock come from the tectonic steady area in the southern of the Huabei basin. Their characters belong to many provenance sedimentary systems.The Cenozoic Era is the major Period of the growth of the Weihe basin, this basin underwent four stages of the tectonic evolution, i.e. the first Period of the rifting stage (from the late of Middle Eocene to the Late of Eocene); the second Period of the rifting stage(from the Miocene to the late of Late Miocene); the Middle Period of the strike slip-extensional stage(from the latest of Late Miocene to the late of Early Pleistocene);the late Period of the compressional-uplifting stage(from the late period of the Early Pleistocene to the present). The sedimentary sequence of the basin has been divided to four period corresponding to them: Palaogene tectonic sequence T_S1, Neogene tectonic sequence T_S2, Late Neogene- Early Quaternary tectonic sequence T_S3, and Quaternary tectonic sequence T_S4.The sedimentary characteristic is distinctly controlled and affected by the faults. Weather the sedimentary facies or the provenance, the sequence and the component of the sediments, all demonstrate the control of the faults of the outer and inner of the basin. Its character is the sedimentary response of the structure movement in the basin. From it we can find that the relationship between the deposit and the structure is mutually related.