江西信江盆地红层及其地貌发育研究

江西信江盆地丹霞地貌的成景地层为晚白垩系陆相红色碎屑岩,红层的厚度、岩石学和地球化学特征及其在盆地内出露制约着丹霞地貌的发育、景观类型及其组合以及在盆地内的分布。信江盆地边缘主要出露茅店组、河口组和莲荷组巨厚层砾岩、含砾砂岩和砂岩,以铁质胶结和少量钙质胶结为主,可溶性成分含量低,这些红层以发育高大的顶斜型峰林型、峰丛型丹霞地貌组合为特征。盆地中部的河口组上部和塘边组地层含砾砂岩和砂岩为主,以钙质胶结为主,可溶性成分含量较低,常发育低矮的圆丘状丹霞地貌组合为特征,大型岩洞是其典型的景观类型。过渡地带主要为河口组上部、塘边组和莲荷组下部的砂岩、含砾砂岩,丹霞地貌只发育于断层或河流发育地区,以顶平型丹霞地貌组合为特征。以钙泥质胶结为主,可溶性成分含量高的细碎屑岩中一般不发育丹霞地貌。

A study on the red beds and its landforms in Xinjiang Basin

The strata that formed Danxia landforms in Xinjiang basin, Jiangxi province are terrestrial red classic rocks of late Cretaceous. The development of Danxia landforms, landscape types, assemblages and their distribution in the basin are controlled by thickness, lithological and geochemical features and distribution of red beds. In the marginal parts of Xinjiang basin there are exposed very thick bedded rocks including conglomerate, pebbled sandstone and sandstone of Maodian formation, Hekou formation and Lianhe formation, the cements in the rocks are mainly ferric and calcareous, thus the contents of soluble components are low. These red beds are characterized by development of Danxia landforms with oblique-shaped peaks, upright-shaped peaks and cluster-shaped peaks. The strata of upper Hekou formation and Tangbian formation in the middle parts of basin are mainly composed of thick or very thick bedded sandstone and pebbly sandstone with large-scale cross beddings, the cements in the rocks are mainly calcareous and the contents of soluble components are very low, they are characterized by development of Danxia landscapes with low knoll-shaped landform assemblages, the typical landscape types of the basin are big stone caves along the banks. In the transitional parts of the basin, there are exposed mainly sandstone and pebbled sandstone of upper Hekou formation, Tangbian formation and lower I.ianhe formation, they formed Danxia landform assemblages of mesas, narrow valleys, stone cliffs with flat tops. The fine grained elastic rocks, in which the cements are mainly calcareous and the contents of soluble components are high, generally can not form Danxia landforms.