摘要
晚石炭—早二叠世的辽东太子河盆地是一个周边为平移断层的断陷盆地。以东西向垂直运动为主体的构造活动控制了盆地的发展和演化。根据构造特征、沉积相和古地磁与华北腹地石炭一二叠系的差异,太子河地区的石炭一二叠系应是华北型石炭一二叠系的一个分支,作者称“辽东亚型”。古地理演化表现为从晚石炭世早期的扇三角3洲→峡湾海岸→碳酸盐台地的快速海进,直至早二叠世末的三角洲→冲积平原→湖泊体系的缓慢海退,堆积了近陆特征明显的、近尔西展布的各沉积相带。随时代渐新,堆积物中碎屑组分成熟度趋于增高,大地构造背景从部分卷入大陆边缘活动带过渡为大陆板块克拉通内部,均反映本区的断陷活动由次稳定向稳定型转化。铝土矿成矿物质主要来源于北部古陆结晶岩石,系红土(钙红土)—沉积成因。G层铝土矿形成于泻湖边缘环境;B臣则位于近海湖泊的滨—浅湖地带,同受控于北纬41°20′的同沉积断裂,与北东向断裂复合凹地为成矿最佳场所。
Taizi River Basin of Late Carboniferous-Early Permian in eastern Liaoning is tensional basin related with peripheral strike-slip faults. The development and evolution of the basin was controlled by graben faulting mainly in vertical movement of E-W direction. Based on the differences with that of N.China in structure features, sedimentary facies and paleomagnetic etc., Carboniferous-Permian system of Taizi River Basin is considered to be one of branch of N.China C-P system—Eastern Liaoning Subtype called by the authors. The evolution series of palaeogeography is from fast transgression of fan delta→fiord coast→carbonate platform during early Late Carboniferous to slow regression of delta→alluvial plain→lakes during Early Permian. The sedimentary face belt was accumulated in EW-trending with obvious subcontinental features from south to north. With the time going, the maturity of clastic component in accumulation increased and geotectonic background of sandstone transited from partly envolved in mobile belt of continental margin to all in hedreocraton. All these reflect the graben faulting in the basin transforms from substable type to stable one. The ore-forming material of bauxite derived from northern crystalline basement is of Jaterite (calcilaterite) -sedimentary genesis. G-layer formed in marginal envionment of lagoon; B-layer was in littoral sideshallow lake. They are all controlled by synsedimentary faults of 41°20′ north latitude, and its concaved places compounding with NE-trending faults are the optimun ore-forming places.
关键词
铝土矿
成矿
沉积相
地质条件
Graben faulting Eastern Liaoning Subtype Sedimentary facies Palaeogeography Carboniferouse-Permian Bauxite
