The Method And Application Studies Of Downward Continuation For East Tianshan Gravity Field

The spatial distribution characteristics of gravity and magnetic field are highly visible, so that they are the important basises of researching the field-source. Currently, Field's upward continuation has been in a more complete way. On the contrary, downward continuation is one of the most difficult operations in conversion and processing of potential field, because of the high frequency oscillation effect. However, more near the field source, the characteristics of the field can reflect the characteristics of the field-source more particularly. So downward continuation plays an important part in potential field processing, that can not be replaced by other processing methods. Therefore, it is extremely necessary to search for a more reasonable method to eliminate or weaken the high frequency oscillation effect, in order to realize downward continuation accurately and stably.On the basis of the previous studyies, we put forward a stable downward continuation program. The program uses methods in frequency domain as the main methods and makes full use of the advantages and complement of many processing methods to realize the gravity field downward continuation stably. We use the outstanding digital signal processing software Matlab7.0 as the main development platform, and made procedures (functions) more than 20 to realize many downward continuation methods. Through designing and making a model which models the actural gravity field, we made quantitative or comparative analysises and evaluations to the various downward continuation methods. The results show that the stable downward continuation program has higher accuracy and stability than other single method.East Tianshan Mountain is the focus of mineral exploration region currently. It still has the tremendous exploration potential. It has practical significance on the geological studies and mineral prospecting work to realize the downward continuation of East Tianshan gravity field stably. Using the stable downward continuation program, we realized the different depths downward continuation, the acquisition of deep-abnormals'information and the separation of vertical field. Different processing results can provide more gravity information to the geological studies and mineral prospecting in East Tianshan. In particular, we can obtain the detail information of each depth of the gravity field. It's fully proved that the stable downward continuation is important and necessary.