华北地块北缘中元古界几个重要不整合面的地质特征及构造意义

华北地块北缘中元古代沉积层序中出现多个沉积间断和不整合面。此次研究对其中5个不整合面进行了野外考察,分析了它们的地质特征和空间分布,认为它们与不同的地质过程有关。大红峪组底部不整合面是早期裂谷盆地演化为被动大陆边缘的记录,属于裂解不整合面性质;高于庄组底部和杨庄组底部的不整合面是海平面变化造成被动大陆边缘内部高地沉积间断和海岸超覆沉积的结果;铁岭组顶部不整合面可能与弧后环境发生挤压抬升有关;下马岭组沉积后的抬升可能是相邻大陆地块碰撞作用的产物。华北地块北缘中元古代层序中不整合面的形成与Columbia和Rodinia超大陆的形成和裂解过程密切相关。

Geological characteristics of unconformities in Mesoproterozoic successions in the northern margin of North China Block and their tectonic implications

This study attempted to acquire information of tectonic activity in Western China from the data of the land surface temperature (LST) field. Based on the established relationship between heat and strain,we have analyzed the LST distribution in Western China using the satellite data product MODIS/Terra. The result shows that there are departures of annual changes of LST in some areas,which are associated with activity of some active tectonic zones. After removal of the annual-change background values caused by climatic factors,the long-period component (LSTLOW) of the residual annual change(ΔT) of the LST can reveal better the tectonic activity,and serve as its indicator. It is found that one major earthquake can produce different effects on the LST fields of broad areas surrounding or even far away from the epicenter,characterized by rise or drop of temperature. For example,a most noticeable temperature decline associated with the Indonesia M 9 earthquake of 2004 appeared in the Bayan Har-Songpan Block of the central Tibetan Plateau. On the other hand,the LST field of one area may have different responses to different major shocks in the regions surrounding China. For instance,the East Kunlun M 8.1 event has made the LST on the Longmenshan fault zone increase,whereas the Zaisangbo M 7.9 earthquake of 2003 and the Indonesia M 9 event of 2004 caused decrease of LST on the Longmenshan. The temporal variations of LST are different in different tectonic areas,which may provide clues for the study of tectonic deformation processes. In combination of data of ground temperature at varied depths,seismicity and GPS measurements,we have checked the information of tectonic activity derived from variations of the LST field,and discussed its implications to the models of regional tectonic deformation.