摘要
南段组的研究始于１９８３年，但南段组的沉积环境和成因至今还存在一些争论。罗君烈（１９９０）和王祖关（１９９１）提出南段组是一套滨海－浅海沉积。刘本培等（１９８９—１９９３）认为南段组为一套类复理石沉积或为一套斜坡至盆地边缘的非正常浊流沉积。作者在南段组中新发现了ｃｈｏｎｄｒｉｔｅｓｓｐ．，ｓｃａｌａｒｉｔｕｂａｓｐ．，ｐｈａｎｏｌｉｔｅｓｓｐ．等三种遗迹化石和一些浅海底栖生物化石及植物碎片，这些化石的总体面貌显示了一个陆棚沉积环境。南段组是一套厚度巨大的砂岩与泥岩的互层沉积，沉积构造主要是块状层理、小型滑动构造、小型斜层理和粒序层理及少见的浪成波痕。砂岩成分成熟度高（石英＞９０％），结构成熟度中等（杂质为０－１０％）。当胶结物为硅质时，一些砂岩成为沉积石英岩。砂岩的粒度概率累积曲线显示牵引流与重力流的过渡特征，各层位砂岩粒度的Ｃ－Ｍ图基本上显示重力流沉积特征。以上特征表明南段组是一套浪控三角洲前缘斜坡和深陆棚环境的近源片泛性（非扇模式）重力流和正常的陆棚的复合沉积。
Nanduan formation were studied in 1983,but now there is some arguements about its sedimentary environment and origin. Yunnan Regional Ggology Surveying Team considered that Nanduan formation is a set of abyss subabyss turbidit of the rift belt. Luo junlie (1990)and Wang Zuguan(1991)proposed that Nanduan formation is a set of shore shallow sea deposit. Liu Benpei(1993)thought that Nanduan formation is a set of flyschoid deposit of non normal turbidit from slope to basin margin. Author have discovered newly three trace fossils: Chondrites sp., Scalarituba sp., Phanolites sp. and some neritic benthos fossils、plant pieces in Nandun formation,they reflect a shelf scdimentary environment. Sedimentary features of Nanduan formation is vast thickness, the special sandstone/mudstone interbedding. Sedimentary structure is mainly massive bedding and rare small type slump structure,diagonal bedding、graded bedding and wave ripple. The compositional maturity of sandstone is highter (Q>90%), but texture maturity is middle (matrix 0 10%). Some sandstone with siliceous cement and poor matrix have become sedimentary quartzite. The grain size cumulative probability curves of the sandstone show translitional deposition of gravity flow and tractive current. The C M plot appears basicly gravity flow characteristic, These features appear that Nanduan formation is a set of proximal wide ranging happening (no fan model) grain flow, turbidite and normal shelf deposit in the wave control delta front slope and deep shelf environment, but not abyssal flysch formation.
出处
《西南工学院学报》
1998年第1期33-38,共6页
Journal of Southwest China Institute of Technology
关键词
南段组
沉积环境
沉积机理
Nanduan formation
Sedimentary environment
Sedimentary mechanism
