作者: W. JAMES KENNEDY , ROBERT E. GARRISON
DOI: 10.1111/J.1502-3931.1975.TB00940.X
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摘要: Phosphatic nodules are abundant in the Glauconitic Marl (Cretaceous, Cenomanian) of south-east England, particularly where sequence is condensed. Some derived from underlying Upper Greensand, and phosphatic fossil fragments, moulds, calcareous concretions. Concretions particular show signs a complex history multiple phases boring, encrustation, phosphatisation, glauconitisation. Phosphate glauconite both replacements after fine-grained carbonate sediment cement. The majority phosphates whole fragmentary moulds fossils. origin theses involved: (1) infilling shells, (2) burial, (3) prefossilisation-cementation infillings. probably by high magnesian calcite, (4) dissolution aragonitic shell material, (5) disinterment exposure on sea floor, followed (6) phosphatisation. boring. enerustation various organisms, sometimes Many bear evidence several cycles cementation, exposure, mineralisation, boring enerustation. The closest Recent analogues to appear be crust forming today off coast southern California. features described processes inferred occurrences have been widespread nodular facies.