Characteristics and Environmental Interpretation of Cone-in-Cone Structure, Early Cretaceous Bayingebi Formation,Celaomiao Depression
Song Ji
Jiao Yangquan
Li Jinhua
Abstract：To better understand the sedimentary characteristics of the cone-in-cone structure in the outcrop areas,and to explore the causes of the formation and the environmental issues of the cone-in-cone structure,we employ methods such as outcrop measure,polished thin section observation,X-ray diffraction analysis,cathode-ray luminescence,electronic scanning in this study.It is discovered that cone-in-cone structure develops radially around the calcareous concretions,with conical apex point-ing straight to the concretion center;the major mineral composition of cone-in-cone structure is fibrous low magnesium calcite, with fibrous calcite crystals being cone-shaped nest,with wavy extinction which appears uniform red-brown under cathodolumi-nescence microscopy without diagenetic ribbon with trace element fractionation and precipitation.The developing scale of cone-in-cone concretions is in the control of primary sedimentary environment obviously.It is considered that the growth of cone-in-cone concretions has distinct stages;the original sedimentary environment should be shallow lake sedimentary environment with about 5-30 m depth and relatively higher energy.It is concluded that the formation of cone-in-cone structure is a result of synsedimentary biological deposition,cementation and later overburden static pressure.
Keywords：cone-in-coneBayingebi FormationCelaomiao depressionsedimentologyenvironmental geology
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：12( 851-862 )