The Exploration And Research Of The Gravity Method To Sedimentary Bauxite Prospecting

Being a very excellent metal, the demands of Aluminum in national industrydemand grows constinuously.As a consequence, bauxite exploration is becoming moreand more important. TBauxite is mainly contained in tropical and subtropical regions.Only17%of bauxite is reversed in Asia and China’s reserve is even less, which makesthe exploration of bauxite a much more urgent task for us. Ancient weathering crustsedimentary bauxite foorms the main type of bauxite in china, accounting for98.83%,and the lateritic bauxite exists only along the coast line. Therefore, in China, the bauxiteexploration mainly focuses on the ancient weathering crust sedimentary bauxite. Due tothe special properties of such type of bauxite, new theory is needed to improve theexploration methods.The study shows that ancient weathering crust sedimentary bauxite deposit in thenorthern part of China mainly locates in the sag of the touching area between Ordovicianlimestone and Carboniferous Benxi Group. If we can work out the distribution ofOrdovician limestone depression using gravity exploration, it is able to accuratelydelineate target, providing guidance to bauxite exploration.Basing on the physical basis information, we know there is a density differencebetween the sides of the above touching region, the target areas can be located by the lowbouguer gravity anomaly. However, due to the influence by the observation on undulatedsurface and by the difficulties in density selection when apply the middle layer and theterrain corrections, the bouguer gravity anomaly may appears several mirroring orpositive correlative false anomalies regarding to the topography, which gives troubles todetermine the target areas. In order to eliminate or weaken this false anomaly, weobtained a new gravity anomaly by using a potential field on curved surface processingmethod and a moving window regression analysis method, and reinterpret it. The resultsshow that the false anomalies can be well eliminated in bouguer gravity anomaly by thesetwo methods, and the undulating topography of the above touching area is correctly reflected, and the target areas is accurately determined, which helps to achieve theefficient prospecting purpose.