华北陆台北缘重磁异常的地质解释

通过对华北陆台北缘1:100万重磁异常图的地质研究和综合分析,认为华北陆台北缘由东胜、赤峰和辽东二个太古宙地块组成。在三个地块的边界地带和内部深大断裂带附近有晚太古宙绿岩带分布,表明三个地块在晚太古—早元古早期(约2500Ma)可能衔接在一起。三个地块北部都存在一边缘隆起带,但重磁异常场不连续,反映它们各自的基底演化历史的不同。根据三个地块上的重磁异常场推断的断裂带方位比较,表明各地块之间的相对运动主要沿这些深大断裂带进行。

GEOLOGICAL INTERPRETATION OF GRAVITY AND MAGNETIC ANOMALIES ON THE NORTHERN MARGIN OF THE NORTH CHINA PLATFORM

Based on geological study and integrated analysis of the 1:1,000,000 gravity and magnetic anomaly map for the northern margin of the North China platform, we hold that the northern margin of the North China platform is composed of three Archeozoic landmasses, i. e. Dongsheng, Chifeng and Liao-dong. Along the border areas of the three landmasses and near the deep fault zones within these landmasses there occur Late Archeozoic greenstone belts, suggesting that these three landmasses might have been linked with each other in Late Archeozoic-Early Proterozoic period (some 2500 Ma). Amarginal uplifted zone exists in the northern part of each landmass, but the discontinuity of the gravity and magnetic anomalous fields suggests the difference in the basement evolutionary history of these landmasses. Acomparison of orientations of fault zones inferred on the basis of gravity and magnetic anomalous fields in these three landmasses indicates that the relative movement between these landmasses must have proceeded along these deep fault zones.