The dominating biogenic compounds are: (i) calcite as < 5 m[micro] micrite
forming the groundmass mudstone, and both micrite
of the matrix and > 5 m[micro] to 1 mm grains--skeletal particles (shells and their broken fragments) in wackestone, (ii) silica as < 5 m[micro] particles belonging to the groundmass of mudstone and wackestone matrix, (iii) organic matter (kerogen) in the mudstone and matrix of wackestone, (iv) phosphate skeletal fragments in certain interbeds of wackestone and very fine apatite in groundmass.
The presence of diverse fauna and micrite
matrix indicates subtidal marine conditions suggesting that AMB 1 facies was deposited below fair weather wave base under distal middle shelf settings.
The effect of eo or telodiagenetic processes by meteoric water in the different carbonate components commonly is reflected by increasing textural alteration of the matrix that change successively from micrite
to microsparite, to minor pseudosparite and/or to precipitation of interparticle sparite cement.
Inside, they are characterized by micrite
structure, composed of fine-grained carbonate minerals and dispersed clays with an admixture of pyrite and quartz (Rybak, 2000; Bak et al.
The western Yingshan Formation is based on the open platform of the low-energy micrite
development phase and has a lithological density.
As lower layers contain substantial micrite
and other hydrologically significant carbonate morphologies, it is possible that this system is related to a currently active, albeit distant (>1 km), local spring that may have experienced intermittent flows of varying rates and emergence locations.
These facies pass laterally northward into heavily bioturbated, pale green, argillaceous, micrite
facies that carry in situ lingulid brachiopods and mollusks; these are inferred to record shallow lagoonal settings.
By contrast, the presence of soft and small-sized nodules with loose micrite
crystals suggests limited development of pedogenic calcite (Khormeli et al.
Tubucellaria, Memberanipora and Onychocella) and abundant micrite
This recent tufa deposit expressing active precipitation of micrite
on bacteria and algal filaments, mosses and roots indicate the influence and role of organisms on tufa formation.
The target prospect is oil located in micrite
, a type of limestone within the Kimmeridge shale formation.
The lithofacies-5 is dominantly rich in micrite
with subordinate dolomite, quartz, kaolinite microbioclasts and shell fragments.