北天山地区近期重力场及地壳密度变化特征研究

Study on the Characteristics of Recent Gravity Field and Crustal Density in North Tianshan Area

利用2014~2019年北天山地区流动重力资料,采用绝对重力控制进行经典平差计算,获取该地区重力场时空演化特征图像,并结合重力段差可视化方法,得到该地区重点构造部位物质迁移规律。采用紧凑反演方法进行北天山中段不同深度地壳密度模拟计算,结果表明,北天山中段地壳物质密度变化最佳深度为30~40 km,是地壳密度变化的正值区域,基本位于北天山北坡和准噶尔盆地南缘,表明该地区物质不断汇聚,或者表明地壳呈现下沉的趋势;而在北天山山体附近,物质密度变化为负值,表明山体物质处于亏损态势,或者山体受到构造应力的作用,使地壳处于不断隆升过程中。

A spatiotemporal evolution characteristic image of the gravity field in the north Tianshan area is obtained using the multi-stage mobile gravity data from 2014 to 2019 combined with the classical adjustment calculation of absolute gravity points.The material migration pattern of main structural parts in north Tianshan area is obtained using the visualization method of gravity interval difference.Finally,the density of crust at different depths in the middle part of north Tianshan mountain is simulated by using compact gravity inversion method.The results shows that the best depth of crustal material density change is 30 to 40 km.The positive crustal density change area is basically located in the north slope of north Tianshan mountain and the southern edge of Junggar basin,which indicates that the material migration in this area is relatively concentrated,or that the crust presents the tendency of subsidence.However,near the mountain body,the change of material density presents a negative value;the crust is in the process of uplifting due to the tectonic stress of the mountain.