Abstract: The weathered crust of bedrock, including granite, metamorphic rock, volcanic rock, and clastic rock, exhibits distinct tectonic zoning characteristics vertically. However, scholars have not reached a consensus on the division scheme of the weathered crust structures, which leads to confusion in understanding the development regularity of such type of buried hill weathered crust reservoirs. Based on field survey and existing findings, it is believed that granite, metamorphic rock, volcanic rock, and clastic rock are all aluminosilicate-rich rocks, and their weathering processes and weathered crust structural characteristics are consistent. A unified scheme for dividing weathered crust structures has been proposed based on the development process and mechanism of weathered crust, i.e., fractured bedrock zone, disintegration zone, and leaching zone. The fractured bedrock zone is mainly characterized with the development of structural fractures formed by multiple tectonic movements; the feature of the disintegration zone is that physical weathered fractures and tectonic fractures are superposed to form network fractures, and the dense fractures lead to disintegration and fragmentation of rocks, as well as enhancement of leaching efficiency; the leaching zone is mainly characterized by chemical alteration of aluminosilicate minerals. From the bottom of the leaching zone to the surface of the weathered crust, the chemical alteration of aluminosilicate minerals along various fractures is enhanced continuously, forming clay minerals and corrosion pores, and the rocks become loose and sandy. Due to the change of intensity caused by erosion, physical weathering, and chemical weathering, the weathered crust of aluminosilicate-rich rock has different models such as fractured bedrock type, disintegration type, disintegration-leaching type, and leaching type. The structures of weathered crust of various aluminosilicate-rich rocks were divided uniformly according to the weathering mechanism, which is helpful to further study and understand the development law of buried hill reservoirs of aluminosilicate-rich rocks.

Key words: buried hill, weathering, weathering crust structure, aluminosilicate mineral, reservoir

摘要： 包括花岗岩、变质岩、火山岩和碎屑岩在内的基岩风化壳在垂向上具有明显的结构分带特征。但对于这些风化壳结构的划分方案,学者们还未达成共识,导致对此类潜山风化壳储层发育规律认识混乱。基于野外实际考察和对已有研究成果进行梳理认为,花岗岩、变质岩、火山岩和碎屑岩均属于富铝硅酸盐岩,其风化过程和风化壳结构特征具有共性。基于风化壳的发育过程与机理分析,提出了统一的风化壳结构划分方案,其自下向上依次包含:含裂缝基岩带、崩解带和淋滤带。含裂缝基岩带的主要特征为发育多期构造运动形成的构造裂缝;崩解带的特征为物理风化缝与构造缝叠加形成网状裂缝,密集的裂缝导致岩石崩解破碎和淋滤作用增强;淋滤带以铝硅酸盐矿物的化学蚀变为主。从淋滤带底部到风化壳表面,铝硅酸盐矿物沿各种裂缝进行的化学蚀变不断增强,形成黏土矿物和溶蚀孔隙,岩石变得疏松和砂化。由于剥蚀作用、物理风化作用和化学风化作用强度变化,富铝硅酸盐岩风化壳具有含裂缝基岩型、崩解型、崩解-淋滤型和淋滤型等不同模式。按照风化作用机理,将各种富铝硅酸盐岩风化壳的结构进行统一划分,以期推动富铝硅酸盐岩潜山储层发育规律的研究和认识。

关键词: 潜山, 风化作用, 风化壳结构, 铝硅酸盐矿物, 储层