新元古代扬子—华夏陆块拼合带：来自华南重磁异常的启示

扬子和华夏两大陆块是构成华南大陆的最基本单元， 但它们的拼合带位置（尤其是西延位置）是人们长期争论的焦点。本文以国家专项“深部探测技术与实验研究”探测得到的深反射地震剖面以及华南大陆的地质资料为约束， 对重、 磁异常作地壳构造融合解译， 追踪扬子—华夏陆块拼合带。由于华南大陆广泛发育具有剩磁多期、 多类的火山—侵入岩， 本文将磁异常换算为受剩磁影响小的解析信号作构造解译， 减小剩磁造成的地质解释偏差。研究认为， 扬子与华夏两陆块的拼合带东界为鹰潭—萍乡—衡阳—贺州—北海一线， 而西界为宜昌—张家界—铜仁—都匀—百色一线， 鹰潭以东和以北的拼合带位置因为受大规模岩浆岩的干扰而不清。

The geosuture between the Yangtze and Cathaysia blocks,South China,during Neoproterozoic era revealed from gravity and magnetic data

The Yangtze and Cathaysian continents are the two basic tectonic units of the South China Continent （SCC）， but the location of their suture zone （especially the west extension location）is the focus of debate for a long time. With constraints of the newly seismic reflection profile detected by the SinoProbe—02 project and the geological data of the SCC， we performed fusion analysis of gravity and magnetic data in the SCC for understanding crustal structures of the Yangtze—Cathaysian blocks and then tracing their geosuture during Neoproterozoic era. Because multiple types of magma formed during multiple geological eras are widely distributed in the South China， presenting non—ignorable effects of remanence， our fusion analysis was performed on the Analytic Signal （AS） rather than on the original magnetic total field anomalies or the reduce to pole anomalies. Our results revealed that the eastern boundary of the geosuture is the line of Yingtan—Pingxiang—Hengyang—Hezhou—Beihai， while the western one is the line of Yichang—Zhangjiajie—Tongren—Duyun—Baise. The geosuture to the east and north of Yingtan become unclear due to the large—scale magma in the crust over there.