从重磁场特征探讨南北构造带北段与地震带的统一性

THE INVESTIGATION OF THE UNITY BETWEEN THE NORTHERN PART OF THE NS-TRENDING TECTONIC ZONE AND THE SEISMIC ZONE FROM THE CHARACTERSITICS OF THE GRAVIMETRIC AND MAGNETIC FIELD

从分析地球物理场特征着手,提出将南北向重力梯级带和重磁场特征东西差异作为划分南北构造带的依据,探讨了形成南北构造带的区域与深部地质构造背景以及地震成带分布的对应关系。重力梯级带反映的南北构造带既有与中轴构造一致的继承性,又有向西拓展的新生性,并在南北统一成带的基础上叠加了分段性,形成南压北张不同背景的控震、控热机制,同时也是构成青藏高原东界和我国大陆构造域东西分界线,对应着狭义南北地震带。

Starting with an analysis of the characteristics of the geophysical field, this paper puts forward the evidence for determining the NS-trending tectonic zone on the basis of the east and west differences of NS-striking gravity gradient zone and gravity-magnetic field characteristics, and investigated the regional and deep geological-structural background for the formation of NS-trending tectonic zone as well as the corresponding relationship of the zoned distributions of the earthquakes. The NS-trending tectonic zone reflected by the grav- itational gradient zone has not only inheritance manifested by its consistency with the central axis structure but also newborn nature of westward expansion. In addition, there exists the superimposition of the segmentation on the basis of the unified NS-trending zone. It forms the earthquake-controlling and heat-controlling mechanism in different backgrounds of southward compression and northward ex- pansion. It also constitutes the east-west dividing line between the eastern boundary of the Tibetan Plateau and China＇s continental tec- tonic domain, corresponding to the narrow sense NS-striking seismic zone.