Analysis Of Geophysical (gravity) Response Characteristics Of Volcanic-sedimentary Boron Deposits In The Ngari Region Of Tibet

Boron ore,as an important chemical raw material mineral in military industry,chemical industry,metallurgy,agriculture and other fields,plays an important role in the development of modern industry and agriculture.With the rapid development of China's economy,the demand for boron is also increasing.However,the main base of boron minerals in Liaoji is nearly exhausted,and the production of boron in China can not meet the needs of China's development.Every year,70% of boron products in China need to spend a lot of foreign exchange to import from Turkey,Russia and the United States.It is urgent to find a new reserve base for boron resources.The predecessors have done a lot of research in the study area,such as the determination of dilute alkali elements in the formation,the metal content is obviously positive anomaly;and massive and banded borate minerals have been found in Xiongba Formation and its weathering products,with local boron content reaching the boundary grade;the boron mineralization section has been found in182-273 m drilling north of Geronalong in the study area;and the previous work shows that the study area has a boron mineralization section.It has good prospecting prospects for boron deposits.After fully collecting the geological and drilling data of the study area,I found that the main minerals of boron deposits in the study area are borax and sodium boron calcite with low density;the boron-bearing strata are Neogene Xiongba Formation with low relative density;the sedimentary conditions of volcanic-sedimentary boron deposits are relatively closed terrain such as basin;these factors will cause the change of gravity field and negative gravity anomaly anomaly.Gravity exploration in the study area provides a precondition.In order to study the geophysical response characteristics of volcanic-sedimentary boron deposits in the study area and obtain the information of distribution and scale of volcanic-sedimentary boron deposits,a 1:50000 gravity exploration was carried out in2017 to study the volcanic-sedimentary boron deposits in the study area.Through data acquisition,data processing,gravity anomaly separation(sliding average method,interpolation cut field method,wavelet transform,trend analysis,analytical continuation method),Bouguer gravity anomaly and residual gravity anomaly in the study area are obtained.Based on the analysis of Bouguer gravity cascade zone and notched boundary,six concealed faults,including four ore-controlling faults,are inferred in the study area.Through the analysis of residual gravity anomaly and notched boundary,the tectonic boundary of the basin is identified,and five basins are inferred.Through the three-dimensional inversion of gravity,the vertical information of the basin is obtained,including the basin size and the depth of the basin bottom.Through well location verification,the inferred result of the basin is in good agreement with the well data.Four favorable metallogenic belts in the study area are deduced synthetically,one of which includes the drilling and ore-finding areas,and the specific positions of four recommended wells are given.This study analyzed the geophysical response characteristics of volcanic-sedimentary boron deposits,provided geophysical basis for further exploration in the study area in the future,and provided an example for the application of geophysical methods to study volcanic-sedimentary boron deposits in the future.