漠河盆地上侏罗统物源分析及其地质意义

为了探讨晚侏罗世漠河盆地的构造类型,笔者等对其物源特征进行了系统分析。通过古水流分析、母岩成分分析和源区构造背景分析认为:①晚侏罗世漠河盆地的物源来自南北两个方向;②北部物源区位于西伯利亚板块南缘,为蒙古—鄂霍茨克造山带,母岩成分主要为花岗岩、变质岩、中酸性火山岩、中基性火山岩和沉积岩;③南部物源区位于大兴安岭北部,为下伏板块基底,母岩成分主要为花岗岩、变质岩和沉积岩;④北部造山带物源区的构造背景为早中生代的活动大陆边缘。晚侏罗世漠河盆地具有典型前陆盆地的双向物源特征,一方面来自北部造山带,一方面来自盆地下伏板块基底。根据物源特征、区域大地构造背景和俄罗斯上阿穆尔盆地(黑龙江在俄罗斯称为阿穆尔河)有关资料认为晚侏罗世漠河盆地可能为漠河—上阿穆尔周缘前陆盆地的南半部分,其形成和演化受蒙古—鄂霍茨克造山带制约。

Provenance Analysis of Upper Jurassic and Its Geological Significances in Mohe Basin

In order to study the tectonic type of the Mohe Basin in Late Jurassic, this paper discusses its provenance characteristics.Based on analyses of the palaeocurrent, the composition of source rocks and tectonic setting of provenance, this paper presents the provenance characteristics of the Mohe basin in Late Jurassic.(1) the provenance of the Mohe basin in Late Jurassic was from the south and the north;(2) the northern provenance was the Mongolia-Okhotsk orogenic belt, lying on the southern margin of the Siberian plate, and the source rocks were predominantly granites, metamorphic rocks, intermediate acidity volcanic rocks, intermediate basic volcanic rocks and sedimentary rocks;(3) the southern provenance was the underlying plate(basin) basement, lying in the northern of the Da Hingan Mountains, and the source rocks were predominantly granites, metamorphic rocks and sedimentary rocks;(4) the tectonic settings of the northern provenances was the Early Mesozoic active continental margin.The Mohe basin in Late Jurassic had provenance characteristics of the classical foreland basin that has apparently double source, and one of its provenances came from the northern orogenic zones, the other one came from the underlying plate basement (basin basement).According to provenance characteristics, regional tectonic setting and some materials of the Upper Amur basin in Russian, the Mohe basin in Late Jurassic could be considered to be the southern half part of the Mohe-Upper Amur periphery foreland basin, whose formation and evolution were associated with the Mongolia-Okhotsk orogenic belt.