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Line 43: − − [[file:core-description_fig1.png|thumb|left|{{figure number|1}}Idealized graphic log. Explanation for some symbols used for sedimentary structures, lithologies, fossils, and contacts are given. Grain size of sillclclastic rocks and Dunham's)<ref name=pt05r50>Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture, in Ham, W. E., ed., Classification of Carbonate Rocks: AAPG Memoir 1, p. 108–121.</ref> classification of limestones are indicated in the column on the left. All sedimentary structures are depicted graphically as accurately as possible. Porosity amounts in percent can be scaled as needed. (Modified from <ref name=pt05r32>Casey, J. M., 1980, Depositional systems and basin evolution of the Late Paleozoic Taos trough, northern New Mexico: Ph. D. Dissertation, The University of Texas at Austin, 236 p.</ref><ref name=pt05r28 />.)]] Line 54:
Line 55: − − [[file:core-description_fig2.png|thumb|{{figure number|2}}(a) Comparison chart for sorting and sorting classes. (Modified from <ref name=pt05r125>Pettijohn, F. J., Porter, P. E., Siever, R., 1987, Sand and Sandstone, 2nd. ed.: New York, Springer-Verlag, 553 p.</ref>.) (b) Comparison chart for roundness and sphericity. (Modified from <ref name=pt05r130>Powers, M. C., 1953, A new roundness scale for sedimentary particles: Journal Sedimentary Petrology, v. 23, p. 117–119.</ref>.)]] Line 68:
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→Format for core logging
==Format for core logging==
==Format for core logging==
[[file:core-description_fig1.png|thumb|{{figure number|1}}Idealized graphic log. Explanation for some symbols used for sedimentary structures, lithologies, fossils, and contacts are given. Grain size of sillclclastic rocks and Dunham's)<ref name=pt05r50>Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture, in Ham, W. E., ed., Classification of Carbonate Rocks: AAPG Memoir 1, p. 108–121.</ref> classification of limestones are indicated in the column on the left. All sedimentary structures are depicted graphically as accurately as possible. Porosity amounts in percent can be scaled as needed. (Modified from <ref name=pt05r32>Casey, J. M., 1980, Depositional systems and basin evolution of the Late Paleozoic Taos trough, northern New Mexico: Ph. D. Dissertation, The University of Texas at Austin, 236 p.</ref><ref name=pt05r28 />.)]]
A graphic log format, which visually expresses a stratigraphic succession, is strongly recommended for describing continuous cores. Such logs should reflect the following:
A graphic log format, which visually expresses a stratigraphic succession, is strongly recommended for describing continuous cores. Such logs should reflect the following:
* Fracturing
* Fracturing
* [[Porosity]]
* [[Porosity]]
Recommended formats for graphic logging are given by Bebout and Loucks<ref name=pt05r24>Bebout, D. G., Loucks, R. G., 1984, Handbook for Logging Carbonate Rocks: The University of Texas at Austin, Bureau of Economic Geology Handbook 5, 43 p.</ref> and Boyles et al.<ref name=pt05r28>Boyles, J. M., Scott, A. J., Rine, J. M., 1986, A logging form for graphic descriptions of core and outcrop: Journal of Sedimentary Petrology, v. 56, p. 567–568., 10., 1306/212F89DB-2B24-11D7-8648000102C1865D</ref> A completed graphic log is shown in [[:file:core-description_fig1.png|Figure 1]]. Grain size, sedimentary structures, and accessories are shown in the left column. Let's look at how each type of data is handled in the graphic log.
Recommended formats for graphic logging are given by Bebout and Loucks<ref name=pt05r24>Bebout, D. G., Loucks, R. G., 1984, Handbook for Logging Carbonate Rocks: The University of Texas at Austin, Bureau of Economic Geology Handbook 5, 43 p.</ref> and Boyles et al.<ref name=pt05r28>Boyles, J. M., Scott, A. J., Rine, J. M., 1986, A logging form for graphic descriptions of core and outcrop: Journal of Sedimentary Petrology, v. 56, p. 567–568., 10., 1306/212F89DB-2B24-11D7-8648000102C1865D</ref> A completed graphic log is shown in [[:file:core-description_fig1.png|Figure 1]]. Grain size, sedimentary structures, and accessories are shown in the left column. Let's look at how each type of data is handled in the graphic log.
===Accessories===
===Accessories===
Fossils, trace fossils, diagenetic and structural features, and other accessories are shown on the far right side of the left column of a graphic log. Standard symbols for these features are found in Swanson<ref name=pt05r150 /> and Bebout and Loucks.<ref name=pt05r24 />
Fossils, trace fossils, diagenetic and structural features, and other accessories are shown on the far right side of the left column of a graphic log. Standard symbols for these features are found in Swanson<ref name=pt05r150 /> and Bebout and Loucks.<ref name=pt05r24 />
===Maturity===
===Maturity===
[[file:core-description_fig2.png|thumb|{{figure number|2}}(a) Comparison chart for sorting and sorting classes. (Modified from <ref name=pt05r125>Pettijohn, F. J., Porter, P. E., Siever, R., 1987, Sand and Sandstone, 2nd. ed.: New York, Springer-Verlag, 553 p.</ref>.) (b) Comparison chart for roundness and sphericity. (Modified from <ref name=pt05r130>Powers, M. C., 1953, A new roundness scale for sedimentary particles: Journal Sedimentary Petrology, v. 23, p. 117–119.</ref>.)]]
Textural maturity of sandstone units is recorded in the next column to the right (“Textural Maturity” in [[:file:core-description_fig1.png|Figure 1]]) and is described following the method outlined by Folk.<ref name=pt05r57>Folk, R. L., 1974, Petrology of Sedimentary Rocks: Austin, TX, Hemphill Publishers, 159 p.</ref> Detrital clay (matrix) content and the sorting and roundness of grains are all considered in the determination of textural maturity. Because it is difficult to estimate the relative abundance of detrital versus authigenic clay without thin section or scanning electron microscope data, care must be taken in making estimates of detrital clay content. Image charts can be used for estimating sorting and roundness ([[:file:core-description_fig2.png|Figure 2]]).
Textural maturity of sandstone units is recorded in the next column to the right (“Textural Maturity” in [[:file:core-description_fig1.png|Figure 1]]) and is described following the method outlined by Folk.<ref name=pt05r57>Folk, R. L., 1974, Petrology of Sedimentary Rocks: Austin, TX, Hemphill Publishers, 159 p.</ref> Detrital clay (matrix) content and the sorting and roundness of grains are all considered in the determination of textural maturity. Because it is difficult to estimate the relative abundance of detrital versus authigenic clay without thin section or scanning electron microscope data, care must be taken in making estimates of detrital clay content. Image charts can be used for estimating sorting and roundness ([[:file:core-description_fig2.png|Figure 2]]).