Discussion on the "Sedimentary Environment-Type of Coal-forming-Characteristic of Coal Quality" Rough Genetic Model I. Environment and Coal Facies

Abstract: 

Analyses of the deposit-genetic mark in typical coal-bearing members have shown that Taiyuan Formation （C₂） in the southern part of North China represents a complete tidal flat-depositional system, consisting of subtidal flat （subtidal zone）, strand flat （intertidal lone-well developed） and supratidal flat （supralittoral zone）,which belong to the typical coal-forming model of barrier-tidal flat-lagoon.Shanxi Formation （P₁¹） represents a comparatively complete delta-depositional regine,consisting of prodelta. delta front and delta plain, which belongs to the typical coal-forming model of delta. While longtan Formation （P₂） in the South of china mainly represents the coal-forming model of barrier-tidal flat-lagoon with well developed lagoon deposit. Through the researches above, three kinds （four categories） of coal factes are devided based upon reductibility, which is the integrated mark of charactering coal-forming environment （by a series of indexes）. These coal facies with their character revealed respectively are I₁-Sapropelic coals or humic-sapropelic coals of strong type-reductibility,I₂-Humic coals or humic-sapropelic coal in rich-liptinites/rich-perhydrous vitrinites of strong type-reductibility,Ⅱ-Humic coals of stronger type-reductibility and Ⅲ-Humic coals of weak type reductibility,A series of indexes above contain total sulfur,index of ash composition,total iron,Fe⁺⁺,B/ Ga,Sr/Ba,F/Cl,Palaeosalinity,isotopes of carbon,isotopes of sulfur,Eh,pH,alkane chromatography （the ratio of Aliphatic hydrocarbon to Aromatic hdrocarbon,carbon number of main peak,C₂₁^-/C₂⁺ 21 and Pr/Ph）,biomarker of alkane （Quantity of terrigenous higher plants/amount of organisms source,Quantity of lower plants source/amount of organisms source,hepanes/terrigenous terpenoids and steroids/hopanes ratio） and biomarker of Aromatic hydrocarbon （dibenzothiopene/tri-fluorene and benezonthracene/chrysene ratio）.
Authers suggest that coals of different type-reductibility be characterized respectively by constituent of plants sources,organic and inorganic mather as well as properties of chamistry-technology-generating hydro carbon.Reductibility of coal （i.e. type-coal） may be of both characterizing coal-forming environment and feature of Quality-coal.It is by reductibility that environment is connected with Quality-coal.Therefore,the genetic model of environment-type-coal-Quality-coal build-up.
Authors thinks of coal-facies as total generality of sedimentary environment in peat-forming bog and must implicate environment,type-coal and Quality-except coal rank.
Authors advocate that from the point of view in practice（prediting environment and estimating Quality coal）,coal facies are researched and therefor,the regine of "practice coal facieology" should be set up,whose aim is to push the advance of coal-geology,coal-petrology and serve energy sources industry.
The study in this regine of both theoretical and practical importance.