1、Designation: D7708 11Standard 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 case of
2、 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 determinationof the reflectance measured in oil of po
3、lished surfaces ofvitrinite dispersed in sedimentary rocks. This test method canalso be used to determine the reflectance of macerals other thanvitrinite dispersed in sedimentary rocks.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in this
4、standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Ref
5、erenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD388 Classification of Coals by RankD2797 Practice for Preparing Coal Samples for Microscopi-cal Analysis by Reflected LightD2798 Test Method for Microscopical Determination of theVitrinite Reflectance of Coal3. Terminology3.1 Def
6、initionsFor definitions of terms, refer to Terminol-ogy D121.3.2 Abbreviations:3.2.1 Roranmean random reflectance measured in oil.Other organizations may use other abbreviations for meanrandom reflectance.3.3 Definitions of Terms Specific to This Standard:3.3.1 alginite, na liptinite maceral occurri
7、ng in structuredmorphologies, telalginite, and unstructured morphologies, la-malginite.3.3.2 bituminite, nan amorphous primary liptinite maceralwith low reflectance, occasionally characterized by coloredinternal reflections and weak orange-brown fluorescence, de-rived from bacterial biomass and the
8、bacterial decompositionof algal material and faunal plankton. Bituminite is equivalentto the amorphous organic matter recognized in strew slides ofconcentrated kerogen (1).33.3.2.1 DiscussionBituminite may be distinguished fromvitrinite by lower reflectance, as well as higher fluorescenceintensity i
9、f fluorescence is present in vitrinite. Bituminite haspoorly-defined wispy boundaries and may be speckled orunevenly colored whereas vitrinite has distinct boundaries andis blockier and evenly colored. The occurrence of bituminite inassociation with lamalginite and micrinite is common. Rocktype, the
10、rmal maturity, and geologic occurrence can be used tointerpret the potential presence of bituminite; for example,bituminite may be expected to occur in lacustrine or marinesettings. It is less commonly present in fluvial or similarproximal depositional environments, where vitrinite may beexpected to
11、 occur in greater abundance.3.3.3 chitinozoan, na group of flask-shaped, sometimesornamented marine microfossils of presumed metazoan originwhich are composed of pseudochitin proteinic material andwhich occur individually or in chains. Chitinozoan cell wallsare thin, opaque to translucent, and range
12、 from dark gray towhite in reflected white light similar to vitrinite. Chitinozoansare common in Ordovician to Devonian marine shales.3.3.4 conodont, nthe phosphatic, tooth-like remains ofmarine vertebrate worm-like animals present from the Cam-brian through Triassic, composed predominantly of apati
13、tewith subordinate amounts of organic matter. Conodont mor-phology is variable, but often well-defined denticles and bladesare preserved. In reflected white light examination conodontsrange from pale yellow to light brown to dark brown and toblack.3.3.5 fusinite, nan inertinite maceral distinguished
14、 princi-pally by the preservation of some feature(s) of the plant cellwall structure, high relief, and reflectance substantially higherthan first cycle vitrinite in the same sample. When less than1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct resp
15、onsibility of Subcommittee D05.28 on PetrographicAnalysis of Coal and Coke.Current edition approved April 1, 2011. Published April 2011. DOI: 10.1520/D770811.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of A
16、STMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United S
17、tates.50-m in size this maceral is assigned to inertodetrinite. Otherorganizations may define macerals using different technicalspecifications.3.3.6 graptolite, ncolonial, chitinous animal which occursas thin, elongate bodies sometimes showing complex skeletalmorphology and with reflective dark gray
18、 to white color inreflected white light similar to vitrinite (2). Graptolites occurfrom the Cambrian through Carboniferous.3.3.7 huminite, nmaceral group present in lignite andimmature sedimentary rocks with reflectances intermediate tothose of associated darker liptinites and brighter inertinites (
19、3).Huminite is equivalent to the vitrinite maceral group thatoccurs in subbituminous and higher rank coals with measuredreflectance values greater than 0.5% (4).3.3.8 inertinite, nmaceral group with macerals that ex-hibit higher reflectance than other organic components in thesame sample; for exampl
20、e, semifusinite, fusinite, and inerto-detrinite. Inertinite macerals generally lack fluorescence andusually retain preserved plant cell wall structure (5).3.3.9 inertodetrinite, nan inertinite maceral occurring asindividual, angular, clastic fragments incorporated within thematrix of other macerals
21、(commonly vitrinite) or minerals, andin the size range from 2- to 50-m. Other organizations maydefine macerals using different technical specifications.3.3.9.1 DiscussionInertodetrinite is derived through thedisintegration of other inertinite macerals, that is, fusinite andsemifusinite, by mechanica
22、l abrasion during transport.3.3.10 kerogen, ndispersed or concentrated organic mat-ter, or both, occurring in sediments and sedimentary rocks thatis insoluble in organic solvents.3.3.11 lamalginite, nan unstructured liptinite maceralwith low reflectance distinguished primarily by the presence ofbrig
23、ht fluorescence and lamellar character.3.3.12 liptinite, nmaceral group with macerals that ex-hibit lower reflectance than other organic components in thesame sample of sedimentary rocks and coal, appearing black todark gray in reflected white light and that fluoresce under blueto ultraviolet light
24、in coals ranked medium volatile bituminousand lower. Liptinite maceral fluorescence can be used as aqualitative thermal maturity indicator as fluorescence changesfrom green to yellow to orange before becoming extinguishedat advanced maturity.3.3.12.1 DiscussionLiptinite macerals are observed onlyin
25、coals of maturity up to approximately the high volatilebituminous to medium volatile bituminous transition, and insedimentary rocks of equivalent thermal maturity. Liptinitemacerals undergo chemical changes during maturation whichrender their optical distinction from vitrinite and inertinitemacerals
26、 difficult at maturities higher than medium volatilebituminous.3.3.13 maceral, nan organic component occurring insedimentary rocks and coal that is distinguished on the basis ofits optical microscopic properties, primarily reflectance andmorphology.3.3.14 maceral classification, nthe systematic divi
27、sion ofthe organic components (macerals) in sedimentary rocks andcoal based on their appearance in the optical microscope underincident white and fluorescent light.3.3.15 micrinite, nan inertinite maceral, generally nonan-gular, exhibiting no relict plant cell wall structure, smaller than10 m and mo
28、st commonly occurring as granular particlesaround 1- to 5-m diameter. Other organizations may definemacerals using different technical specifications.3.3.15.1 DiscussionMicrinite is a secondary maceralformed from liptinite macerals during maturation.3.3.16 mineral matter, nin sedimentary rocks and c
29、oal,the non-organic fraction composed of physically discreteparticles of minerals such as clays, pyrite, quartz, carbonates,etc., and all elements other than carbon, hydrogen, oxygen,nitrogen and sulfur in the organic fraction.3.3.17 recycled vitrinite, nvitrinite that has undergone atleast one addi
30、tional cycle of burial, exhumation, and erosion incontrast to first cycle vitrinite which has undergone only oneburial cycle. The additional cycle may result in exposure tothermal maturation, chemical or thermal oxidative processes,or both, and mechanical abrasion (sometimes resulting inincreased pa
31、rticle rounding) that is not experienced by firstcycle vitrinite contained in the same sample.3.3.17.1 DiscussionRecycled vitrinite has higher reflec-tance than co-occurring first cycle vitrinite, and sometimes isless angular, due to the rounding of grain boundaries experi-enced during transportatio
32、n. Recycled vitrinite may have brightor dark halos, representing thermal oxidation and weatheringprocesses, respectively, which are not present in the co-occurring first cycle vitrinite. Recycled vitrinite has a highervariance of reflectance values, representative of the manypossible sources and pro
33、cesses occurring during transportation,and may show greater relief than first cycle vitrinite in the samesample. Recycling of vitrinite may be inferred from thegeologic context; for example, a higher proportion of recycledvitrinite may be observed in a catchment collecting sedimentsderived from a gr
34、owing orogenic belt.3.3.18 scolecodont, nthe chitinous, variably mineralizedfossil remains of the jaw elements of polychaete annelidworms, which occur as lamellar to tooth-like structures withspongy, laminated, or granular texture, and with reflective darkgray to white color similar to vitrinite. Sc
35、olecodonts occurfrom the Ordovician to recent.3.3.19 semifusinite, nan inertinite maceral with morphol-ogy like fusinite sometimes with less distinct evidence ofcellular structure, and with reflectance ranging from slightlygreater than that of the associated vitrinite to that of the leastreflective
36、fusinite. Semifusinite may show irregular mosaictexture or satin anisotropy when viewed under polarizedreflected white light.3.3.19.1 DiscussionLow-reflecting semifusinite may bedistinguished from vitrinite by higher reflectance and relief,and the presence of more arcuate boundaries. The most reliab
37、ledistinguishing feature of low-reflecting semifusinite is thefrequent presence of well-preserved cellular structure or opencell lumens, or both. However, it is not unusual for cell lumensto also remain open in vitrinite when deposited in clay-richsediments. Semifusinite usually has more distinct pa
38、rticleboundaries, which distinguishes it from vitrinite which has amore porous and textured surface. Geologic context is impor-tant; a greater proportion of semifusinite can be expected inD7708 112sediments or coals associated with more arid locations, cli-mates, and time periods.3.3.20 solid bitume
39、n, na secondary maceral associatedwith hydrocarbon generation from kerogen distinguished pri-marily by its conformation to pores, voids and fractures in therock matrix, embayment by authigenic mineral grains, and theabsence of features such as cellular structure indicating deri-vation from precursor
40、 plant material. Solid bitumens may showhomogenous or granular textures; irregular anisotropic mosaictextures also are common, particularly at advanced stages ofthermal maturity (6). Solid bitumens may exhibit fluorescenceat low thermal maturity.3.3.20.1 DiscussionFor the purpose of reflectance mea-
41、surement it is important to distinguish solid bitumen fromvitrinite since both macerals appear gray under reflected whitelight and the reflectance of both advances with increasingmaturity. Several populations of solid bitumen with distinctreflectance ranges can be present in a single whole-rocksampl
42、e. Solid bitumens are characterized by their pore-fillingor anastamosing forms. Boundaries of solid bitumen can bewell-defined by textural embayment by authigenic mineralssuch as calcite and dolomite that commonly form contempo-raneously with solid bitumen deposition. However, vitrinitecan be replac
43、ed by authigenic minerals and therefore texturesindicative of embayment or mineral inclusion are not alwaysdiagnostic of solid bitumen. Solid bitumen exhibits mosaicanisotropic domains at higher thermal maturity whereas vitrin-ite does not. Use of cross-polarized light by insertion of apost-sample a
44、nalyzer into the light path may help to distinguishmosaic bitumens. Solid bitumens may be deposited in voidsand fractures with orientations normal to sedimentary bedding.Solid bitumens may occur as droplets and may be translucent(recognized by reflections from pyrite inclusions) and containpyrite cr
45、ystals at edges. Rock type, thermal maturity, andgeologic occurrence can be used to interpret the potentialpresence of solid bitumens; for example, bitumens may bepresent if the sample is or occurs in proximity to a maturehydrocarbon source rock or if the sample is from an exhumedoil reservoir. Soli
46、d bitumens can be physically associated withbituminite or other liptinite macerals from which they arederived. Some solid bitumens are soluble in organic solventsand may be distinguished from vitrinite in low maturity sourcerocks by low magnification observation of fluorescence stream-ing after pipe
47、tted solvation of the examination surface.3.3.21 telalginite, na liptinite maceral characterized bystrong fluorescence and structured morphologies. Commonbotanical varieties include Botryococcus, a freshwater indica-tor, and Tasmanites, a marine indicator. Fluorescence intensitydiminishes and fluore
48、scence color shifts toward red wave-lengths with increasing thermal maturity.3.3.22 thermal maturity, nthe degree of thermal alterationof the dispersed organic matter contained in sedimentary rocks,synonymous with coal rank. Thermal maturity of sedimentaryrocks commonly is defined by vitrinite refle
49、ctance, spectralfluorescence, X-ray diffraction crystallography, or by organicgeochemical parameters.3.3.23 vitrinite, nvitrinite dispersed in Upper Silurian andyounger age sedimentary rocks is the remains of coalifiedmaterial from vascular land plants. Vitrinite dispersed insedimentary rocks may be representative of a large variety ofprecursor plant materials with differing original chemistriesand structures. Vitrinite typically occurs as finely comminuteddark gray to white particles (in reflected white light) of sizesless than 100 m dispersed
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