Application And Research Of Gravity Focusing Inversion In The Changbai Mountain

Gravity prospecting method is a very important branch of applied geophysics, theprinciple is: the presence of the Earth’s gravitational field, and there are many factorsthat influence the distribution of the gravitational field. Gravity field exploration methods ultimately achieve the purpose of prospecting and exploration Crustal structure orstructures by detecting the gravity field caused by anomalies under the ground, analyzing the differences in the density and giving a reasonable geological interpretation. Butin nature, the real situation is often complicated. Physical parameters of different geological body are not uniform, the shape of different geological body is irregular, so often there will be some situations that effect the gravity exploration data processing and interpretation. for example: multiple geological mutual interspersed overlap, etc., Resulting in two important problems exist in the data processing and interpretation of gravity exploration, namely how to determine the stability and uniqueness results of the inversion of gravity exploration methods. Traditional gravity exploration inversion method is essentially based on the principle of maximum smoothness criteria and final receive a stable solution. This gravity exploration inversion method which based on themaximum smoothness criteria can eventually provide just a real smooth solution of geological structures to us, rather than focusing imaging.Zhdanov proposed a new inversion method in1999, he combined punish function with stabilizer of minimal conjugate gradient functional to introduce a new stable functional. This inversion method is focusing inversion. The principle of focusing inversion is: through multiple iterations of abnormal source, we can make the inversion of the image gradually focus, so as to better reflect the geometry and the physical parameters of the underground anomalies. But the focusing inversion method is less used ingravity exploration. In this article, first, we established several theoretical models withrepresentative, and apply the plane focusing inversion method to the model experiments. After the experimental results have been very good, we try to apply it to deal with the measured gravity data, and were compared with the traditional inversion methods.In this article, study method contents and results of focusing inversion as follows:1、The principle of gravity focusing inversion and its advantages and disadvantages:Focusing inversion method is a new inversion method by iteration of the abnormal source tomake the image gradually focus, so as to better reflect the geometry and physical parametersof the underground anomalies. The principle is combined punish function with stabilizer ofminimal conjugate gradient functional to introduce a new stable functional, which is a kind of extension of minimum volume method. As to the underground anomalies, this inversionmethod can perform appropriate physical results regardless of abnormal volume. So that it canprovide clearer boundaries when inversing underground anomalies; The drawback is thatsometimes excessive accumulation of underground anomalies may cause false anomalies.2、 Theoretical model experiments of gravity focusing inversion: Based on thedetermined principle of the method, we do three representative model experiments: modelexperiments of a single rectangular block anomalies body, combination model experiments oftilt and vertical anomalies body and combination model experiments of two upright abnormalbody respectively.Through several experiments and discussions of the theoretical model, focusing gravityinversion method proved to be theoretically feasible. It provides a basis for the gravityinversion method applied to the measured data next. And we found the limitations of themethod in the model experiment, which provides the author a direction for the future researchof the method.3、Tentatively apply the focusing gravity inversion method to field data processing andinterpretation of the measured data in Changbai Mountain region. Since logging work in thearea has not been carried out at the time of completion of this article, so that we can not verifythe accuracy of the applications results of gravity focusing inversion in the work area. Socompared with the more mature inversion method at the stage-Euler de convolution inversionmethods, to discuss the feasibility of the practical application.