【摘要】 本文采集了3种典型的富锰沉积物样品,即岩石漆、树枝晶与土壤铁锰胶膜,并制作了相应的纵切片。运用光学显微镜、原位微区拉曼光谱仪、扫描电镜、EDX能谱仪分别对其形貌学与矿物学特征进行了研究。结果表明岩石漆呈黑色致密层状、葡萄状,主要由水钠锰矿、赤铁矿、针铁矿、粘土矿物等组成,是一种高度混杂的沉积物。宏观上岩石漆与基岩有截然的接触面,发育有微层理结构,在微观上的表现即锰含量的周期性波动。树枝晶呈黑色分枝状,主要由锰钡矿组成,极端富锰而贫硅铝,与基质呈交织结构。土壤铁锰胶膜呈黑色粘稠层状,由水钠锰矿、赤铁矿、针铁矿、钛铁矿、粘土矿物等组成,可细分为外层黑褐色的富锰条带和内层黄棕色的富铁条带。这3种富锰沉积物的形貌学和元素分布特征与各自的成因机制密切相关。更多还原

【Abstract】 Three typical manganese coatings, i. e., rock varnish, dendrite and soil iron-manganese cutan, were collected and corresponding thin sections were made for laboratory research. The authors utilized optical microscope, micro-Raman spectrometer, scanning electron microscope and energy dispersive X-ray detector to systematically study the micro morphological features, mineral assemblage and elements distribution of these three manganese coatings. The results suggest that rock varnish is dark layered or botryoid deposit which consists of birnessite, hematite, goethite, clay minerals, etc., indicating a highly-mixed coating. The boundary between rock varnish and substrate, and also the microlaminations which arise from the manganese content fluctuation within the sample profile, are obvious on closer inspection. Dendrite is black branch-like coating and mainly composed of hollanditegroup minerals. Unlike rock varnish, dendrite, enriched in manganese and devoid of silicon and aluminum, shows pilotaxitic texture with its substrate. Soil iron-manganese cutan, a kind of black soft deposit, comprises birnessite,hematite, goethite, ilmenite, clay minerals, etc., and can be further divided into an outer black manganese-rich belt and inner yellowish-brown iron-rich belt. The micro morphological features of these manganese coatings, together with elements distribution, reveal intimate relationship with their formation mechanism.更多还原