摘要
贵州紫云县猴场镇扁平村的上石炭统叶状藻礁及其周边灰岩中广泛发育大量的各类胶结物。通过对胶结物的形态、结构和阴极发光特征以及胶结物间的接触关系的研究,可以确定成岩作用的先后并识别成岩环境。浅海海底同生成岩阶段大的孔隙中形成等厚环边针状胶结物、葡萄状胶结物,小的孔隙里形成微晶胶结物。早成岩阶段形成微亮晶和斑块状亮晶方解石胶结物和放射纤维扇状胶结物,表生成岩阶段的溶蚀作用和胶结作用强烈,胶结物类型有斑块状或等粒的方解石胶结物和等厚环壁柱状胶结物,等厚环壁柱状胶结物在所有胶结物中体积是较大的。早期胶结作用使叶状藻礁灰岩孔隙度大为降低。中、晚成岩阶段,孔隙被等厚环壁刃状胶结物和晶簇或斑块状亮晶方解石所充填,有些先成的胶结物被热液改造。后生作用阶段发生的主要是构造破裂作用,其中少数裂隙被红褐色含Fe2O3微晶层和晶体粉砂及渗流豆粒充填。叶状藻礁灰岩的孔隙在晚成岩阶段前或中被胶结而之后没有创造出大且连通的孔隙,是它没能成为油气储集层的原因之一。
Diagenesis and its corresponding cements are extensively developed in the upper Carboniferous phylloid algal reef and circumjacent limestone of Bianping Village,Houchang Town,Ziyun County.These cements are prominent and representative in Houchang Town.A study of crystal shape,fabric and cathodoluminescence images of cements as well as the contacts between cements can help determine paragenetic sequences,recognize diagenetic environments,and understand the porosity evolution in the phylloid algal reef limestones.During the syndiagenetic stage,wackestone and packstone sediments generally had low porosity and permeability,pores were filled with sea-floor micrite cement,biological encrustation and sea-floor cementation sediments rich in the fragments of phylloid algal thalli had high porosity and big pores,and marine botryoidal cement and isopachous acicular cement grew in the pores.During the early diagenetic stage,cementation supplied a great amount of cements,constructed rock framework,and consequently decided the features of the limestone rock.Blocky calcite spar and calcite microspar were formed in small pores,and radiating cement fans grew in big pores.During the epidiagenetic stage,extensive dissolution and cementation occurred.Vuggy or channel porosity was created by dissolution in the recharge area,and calcite precipitation was greatly increased in downflow areas.Meteoric phreatic cements include isopachous columnar calcite and blocky or equant calcite cement.Isopachous columnar cement is volumetrically more abundant.The porosity of the reef limestone was reduced dramatically through the early-stage cementation,so the reef limestone could prevent mechanical compaction.During the middle and late diagenetic stage,nearly all porosity was occluded by cements with low rates of fluid influx and efflux,and the remaining pores were filled with isopachous bladed cement and drusy or blocky calcite spar.Some preexisting cements were altered during the middle or late diagenetic stage,the color of isopachous bladed to co
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2012年第1期50-60,共11页
Acta Petrologica et Mineralogica
基金
国家自然科学基金资助项目(40972004)
中央高校基本科研业务费专项资金资助项目(090401011)
关键词
扁平村
上石炭统
叶状藻礁灰岩
胶结物
阴极发光
Bianping Village
Upper Carboniferous
phylloid algal reef limestone
cement
cathodoluminescence image
