1、Designation: D7708 11D7708 14Standard Test Method forMicroscopical Determination of the Reflectance of VitriniteDispersed in Sedimentary Rocks1This standard is issued under the fixed designation D7708; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the microscopical determination of the reflectance measured in
3、oil of polished surfaces of vitrinitedispersed in sedimentary rocks. This test method can also be used to determine the reflectance of macerals other than vitrinitedispersed in sedimentary rocks.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are inclu
4、ded in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to
5、use.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD388 Classification of Coals by RankD2797 Practice for Preparing Coal Samples for Microscopical Analysis by Reflected LightD2798 Test Method for Microscopical Determination of the Vitrinite Reflectance of CoalE177 Practi
6、ce for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 DefinitionsFor definitions of terms, refer to Terminology D121.3.2 Abbreviations:3.2.1 Roranmean random reflectance measur
7、ed in oil. Other organizations may use other abbreviations for mean randomreflectance.3.3 Definitions of Terms Specific to This Standard:3.3.1 alginite, na liptinite maceral occurring in structured morphologies, telalginite, and unstructured morphologies,lamalginite.3.3.2 bituminite, nan amorphous p
8、rimary liptinite maceral with low reflectance, occasionally characterized by colored internalreflections and weak orange-brown fluorescence, derived from bacterial biomass and the bacterial decomposition of algal materialand faunal plankton. Bituminite is equivalent to the amorphous organic matter r
9、ecognized in strew slides of concentrated kerogen(1).33.3.2.1 DiscussionBituminite may be distinguished from vitrinite by lower reflectance, as well as higher fluorescence intensity if fluorescence is1 This test method is under the jurisdiction ofASTM Committee D05 on Coal and Coke and is the direct
10、 responsibility of Subcommittee D05.28 on PetrographicAnalysisof Coal and Coke.Current edition approved April 1, 2011May 1, 2014. Published April 2011May 2014. Originally appeared in 2011 as D7708-11. DOI: 10.1520/D770811.10.1520/D770814.2 For referencedASTM standards, visit theASTM website, www.ast
11、m.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The boldface numbers in parentheses refer to a list of references at the end of this standard.This document is not an AST
12、M standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In al
13、l cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1present in vitrinite. Bituminite has poorly-defined wispy boundaries and ma
14、y be speckled or unevenly colored whereas vitrinitehas distinct boundaries and is blockier and evenly colored. The occurrence of bituminite in association with lamalginite andmicrinite is common. Rock type, thermal maturity, and geologic occurrence can be used to interpret the potential presence ofb
15、ituminite; for example, bituminite may be expected to occur in lacustrine or marine settings. It is less commonly present in fluvialor similar proximal depositional environments, where vitrinite may be expected to occur in greater abundance.3.3.3 chitinozoan, na group of flask-shaped, sometimes orna
16、mented marine microfossils of presumed metazoan origin whichare composed of pseudochitin proteinic material and which occur individually or in chains. Chitinozoan cell walls are thin,opaque to translucent, and range from dark gray to white in reflected white light similar to vitrinite. Chitinozoans
17、are common inOrdovician to Devonian marine shales.3.3.4 conodont, nthe phosphatic, tooth-like remains of marine vertebrate worm-like animals present from the Cambrianthrough Triassic, composed predominantly of apatite with subordinate amounts of organic matter. Conodont morphology isvariable, but of
18、ten well-defined denticles and blades are preserved. In reflected white light examination conodonts range from paleyellow to light brown to dark brown and to black.3.3.5 fusinite, nan inertinite maceral distinguished principally by the preservation of some feature(s) of the plant cell wallstructure,
19、 high relief, and reflectance substantially higher than first cycle vitrinite in the same sample. When less than 50-m insize this maceral is assigned to inertodetrinite. Other organizations may define macerals using different technical specifications.3.3.6 graptolite, ncolonial, chitinous animal whi
20、ch occurs as thin, elongate bodies sometimes showing complex skeletalmorphology and with reflective dark gray to white color in reflected white light similar to vitrinite (2). Graptolites occur from theCambrian through Carboniferous.3.3.7 huminite, nmaceral group present in lignite and immature sedi
21、mentary rocks with reflectances intermediate to those ofassociated darker liptinites and brighter inertinites (3). Huminite is equivalent to the vitrinite maceral group that occurs insubbituminous and higher rank coals with measured reflectance values greater than 0.5% (4).3.3.8 inertinite, nmaceral
22、 group with macerals that exhibit higher reflectance than other organic components in the samesample; for example, semifusinite, fusinite, and inertodetrinite. Inertinite macerals generally lack fluorescence and usually retainpreserved plant cell wall structure(5).3.3.9 inertodetrinite, nan inertini
23、te maceral occurring as individual, angular, clastic fragments incorporated within the matrixof other macerals (commonly vitrinite) or minerals, and in the size range from 2- to 50-m. Other organizations may definemacerals using different technical specifications.3.3.9.1 DiscussionInertodetrinite is
24、 derived through the disintegration of other inertinite macerals, that is, fusinite and semifusinite, by mechanicalabrasion during transport.3.3.10 kerogen, ndispersed or concentrated organic matter, or both, occurring in sediments and sedimentary rocks that isinsoluble in organic solvents.3.3.11 la
25、malginite, nan unstructured liptinite maceral with low reflectance distinguished primarily by the presence of brightfluorescence and lamellar character.3.3.12 liptinite, nmaceral group with macerals that exhibit lower reflectance than other organic components in the samesample of sedimentary rocks a
26、nd coal, appearing black to dark gray in reflected white light and that fluoresce under blue toultraviolet light in coals ranked medium volatile bituminous and lower. Liptinite maceral fluorescence can be used as a qualitativethermal maturity indicator as fluorescence changes from green to yellow to
27、 orange before becoming extinguished at advancedmaturity.3.3.12.1 DiscussionLiptinite macerals are observed only in coals of maturity up to approximately the high volatile bituminous to medium volatilebituminous transition, and in sedimentary rocks of equivalent thermal maturity. Liptinite macerals
28、undergo chemical changesduring maturation which render their optical distinction from vitrinite and inertinite macerals difficult at maturities higher thanmedium volatile bituminous.3.3.13 maceral, nan organic component occurring in sedimentary rocks and coal that is distinguished on the basis of it
29、s opticalmicroscopic properties, primarily reflectance and morphology.3.3.14 maceral classification, nthe systematic division of the organic components (macerals) in sedimentary rocks and coalbased on their appearance in the optical microscope under incident white and fluorescent light.D7708 1423.3.
30、15 micrinite, nan inertinite maceral, generally nonangular, exhibiting no relict plant cell wall structure, smaller than 10m and most commonly occurring as granular particles around 1- to 5-m diameter. Other organizations may define macerals usingdifferent technical specifications.3.3.15.1 Discussio
31、nMicrinite is a secondary maceral formed from liptinite macerals during maturation.3.3.16 mineral matter, nin sedimentary rocks and coal, the non-organic fraction composed of physically discrete particles ofminerals such as clays, pyrite, quartz, carbonates, etc., and all elements other than carbon,
32、 hydrogen, oxygen, nitrogen and sulfurin the organic fraction.3.3.17 recycled vitrinite, nvitrinite that has undergone at least one additional cycle of burial, exhumation, and erosion incontrast to first cycle vitrinite which has undergone only one burial cycle. The additional cycle may result in ex
33、posure to thermalmaturation, chemical or thermal oxidative processes, or both, and mechanical abrasion (sometimes resulting in increased particlerounding) that is not experienced by first cycle vitrinite contained in the same sample.3.3.17.1 DiscussionRecycled vitrinite has higher reflectance than c
34、o-occurring first cycle vitrinite, and sometimes is less angular, due to the roundingof grain boundaries experienced during transportation. Recycled vitrinite may have bright or dark halos, representing thermaloxidation and weathering processes, respectively, which are not present in the co-occurrin
35、g first cycle vitrinite. Recycled vitrinitehas a higher variance of reflectance values, representative of the many possible sources and processes occurring duringtransportation, and may show greater relief than first cycle vitrinite in the same sample. Recycling of vitrinite may be inferred fromthe
36、geologic context; for example, a higher proportion of recycled vitrinite may be observed in a catchment collecting sedimentsderived from a growing orogenic belt.3.3.18 scolecodont, nthe chitinous, variably mineralized fossil remains of the jaw elements of polychaete annelid worms,which occur as lame
37、llar to tooth-like structures with spongy, laminated, or granular texture, and with reflective dark gray to whitecolor similar to vitrinite. Scolecodonts occur from the Ordovician to recent.3.3.19 semifusinite, nan inertinite maceral with morphology like fusinite sometimes with less distinct evidenc
38、e of cellularstructure, and with reflectance ranging from slightly greater than that of the associated vitrinite to that of the least reflective fusinite.Semifusinite may show irregular mosaic texture or satin anisotropy when viewed under polarized reflected white light.3.3.19.1 DiscussionLow-reflec
39、ting semifusinite may be distinguished from vitrinite by higher reflectance and relief, and the presence of more arcuateboundaries. The most reliable distinguishing feature of low-reflecting semifusinite is the frequent presence of well-preservedcellular structure or open cell lumens, or both. Howev
40、er, it is not unusual for cell lumens to also remain open in vitrinite whendeposited in clay-rich sediments. Semifusinite usually has more distinct particle boundaries, which distinguishes it from vitrinitewhich has a more porous and textured surface. Geologic context is important; a greater proport
41、ion of semifusinite can be expectedin sediments or coals associated with more arid locations, climates, and time periods.3.3.20 solid bitumen, na secondary maceral associated with hydrocarbon generation from kerogen distinguished primarily byits conformation to pores, voids and fractures in the rock
42、 matrix, embayment by authigenic mineral grains, and the absence offeatures such as cellular structure indicating derivation from precursor plant material. Solid bitumens may show homogenous orgranular textures; irregular anisotropic mosaic textures also are common, particularly at advanced stages o
43、f thermal maturity (6).Solid bitumens may exhibit fluorescence at low thermal maturity.3.3.20.1 DiscussionFor the purpose of reflectance measurement it is important to distinguish solid bitumen from vitrinite since both macerals appeargray under reflected white light and the reflectance of both adva
44、nces with increasing maturity. Several populations of solid bitumenwith distinct reflectance ranges can be present in a single whole-rock sample. Solid bitumens are characterized by their pore-fillingor anastamosing forms. Boundaries of solid bitumen can be well-defined by textural embayment by auth
45、igenic minerals such ascalcite and dolomite that commonly form contemporaneously with solid bitumen deposition. However, vitrinite can be replacedby authigenic minerals and therefore textures indicative of embayment or mineral inclusion are not always diagnostic of solidbitumen. Solid bitumen exhibi
46、ts mosaic anisotropic domains at higher thermal maturity whereas vitrinite does not. Use ofcross-polarized light by insertion of a post-sample analyzer into the light path may help to distinguish mosaic bitumens. Solidbitumens may be deposited in voids and fractures with orientations normal to sedim
47、entary bedding. Solid bitumens may occur asD7708 143droplets and may be translucent (recognized by reflections from pyrite inclusions) and contain pyrite crystals at edges. Rock type,thermal maturity, and geologic occurrence can be used to interpret the potential presence of solid bitumens; for exam
48、ple, bitumensmay be present if the sample is or occurs in proximity to a mature hydrocarbon source rock or if the sample is from an exhumedoil reservoir. Solid bitumens can be physically associated with bituminite or other liptinite macerals from which they are derived.Some solid bitumens are solubl
49、e in organic solvents and may be distinguished from vitrinite in low maturity source rocks by lowmagnification observation of fluorescence streaming after pipetted solvation of the examination surface.3.3.21 telalginite, na liptinite maceral characterized by strong fluorescence and structured morphologies. Common botanicalvarieties include Botryococcus, a freshwater indicator, and Tasmanites, a marine indicator. Fluorescence intensity diminishes andfluorescence color shifts toward red wavelengths with increasing thermal maturity.3.3.22 thermal
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