贵州主要岩石类型风化土壤微量、稀土元素分布特征与生态环境关系探讨

Trace Element and Rare Earth Element Content in Main Rock-Type Weathering Soil in Guizhou Province and Eco-Environment Effect

根据贵州省地表出露岩石分布情况,将贵州分为5个区,即中部的碳酸盐岩区,东部新元古界浅变质岩区,西部威宁-赫章一带的玄武岩区,西北习水侏罗系碎屑岩区和西南部三叠系碎屑岩区。分别描述了4类岩石风化形成土壤的成土情况,认为碎屑岩和变质岩分布区成土性最好,玄武岩次之,碳酸盐岩区最差。对各岩石区形成的土壤微量、稀土元素含量分析,结果表明玄武岩风化形成的土壤元素含量最高,碎屑岩风化的土壤次之,碳酸盐岩风化形成的红粘土表层土壤元素含量低,底部粘土元素含量高,变质岩风化形成土壤元素含量最低。同时提出玄武岩风化形成的土壤有利于耐寒的马铃薯种植,碳酸盐岩风化红粘土表层欠营养元素,是喀斯特环境脆弱的主要内在原因。变质岩风化形成的土壤缺少营养元素,不适合农作物种植,但变质岩风化层的特征,其适合木本植物生长。

carbonate rock region in central Guizhou, Neoproterozoic metamorphic rock region in eastern Guizhou, WeiningHezhang basalt rock region in western Guizhou, Jurassic clastic rock region in northwest Guizhou and clastic rock region in southwest Guizhou. Laterization characteristic of 4 rock-types were studied respectively, the result shows that laterization of clastic rock region and metamorphic rock region are best, and laterization of basalt rock is well, laterization of carbonate rock region is weak. The content of trace element and rare earth element in soil of different rock laterization were studied, the result shows that basalt rock forming soil has highest content of trace element and rare earth element, clastic rock forming soil has high content of trace element and rare earth element, surface layer of carbonate rock forming soil has low content of trace element and rare earth element,but base layer soil presents highest content of trace element and rare earth element. Sometime, authors suggested that basalt rock forming soil plants potato very well. Because of carbonate rock forming surface soil is lack in nutrition element; it may be reason for karst environment weak. Metamorphic rock forming soil is lack in element, especially nutrition element. Therefore, metamorphic rock forming soil is bad for agriculture, but good for woody plant growing because of thickness weathering layer of metamorphic rock.