A series of essentially time-equivalent shales and sandstones from the Middle Devonian Hamilton Group in New York State was traced and collected from those rocks representing the offshore marine environment through the nearshore and brackish water deposits into the nonmarine red bed facies to the E. The samples were studied by means of X-ray diffraction, X-ray fluorescence, and electron microscopy. The results of these analyses were treated statistically for reproducibility and significance of trend. The data indicate that the clay mineralogy of the shales and sandstones consists of dominant illite and subordinate chlorite. The chlorite is more susceptible to diagenetic change than is the illite. In the transition from the nonmarine to the marine environment, the evidence indicates that detrital chlorite is being supplemented by a diagenetic chlorite that seems to form more readily in the shales than in their associated sandstones. Subtle lateral variations in the clay mineralogy are discussed. Both illite and chlorite show a decrease in c-axis and an increase in a-b axis dimensions with distance from the source. Total Fe content decreases with distance.
The results of a detailed petrologic investigation of underclays of various types occurring beneath the coals in Illinois are presented. The mineral composition of the clay grade was determined by optical, X-ray, and chemical criteria, frequently following sedimentation and supercentrifuge separations into fractions sufficiently simple mineralogically so that the analytical data could be definitely interpreted. Constituents coarser than clay were identified with the petrographic microscope. Base-exchange capacity values and textural characteristics are presented and discussed. The completely noncalcareous underclays occurring most commonly beneath coal No. 2 and older coals are composed largely of kaolinite. Varying amounts of illite and quartz are also present. Occasional beds are found in these underclays which are composed almost wholly of a distinctive member of the illite clay mineral group. The calcareous underclays and those grading from noncalcareous to calcareous which occur beneath younger coals contain illite as the essential clay mineral constituent. Except for variations in the calcite and quartz content and a slight concentration of limonite in a zone several inches below the coal, there is no evidence of variation in the mineral constitution or chemical composition within beds of the latter underclays as they are traced downward from the overlying coal. The analytical data definitely indicate no appreciable vertical variation of the completely noncalcareous underclays. Underclays seemingly have been subjected little or not at all to processes similar to those forming modem soils. The significance of the petrographic data on the origin and genesis of underclays is discussed in detail.
The thesis is presented that some of the clay minerals are more at home in certain environments than in other environments. Also, structural considerations indicate that possibilities of the transformations of the clay minerals and the ease with which they may take place are not the same for all varieties of them. The transformations during diagenesis, therefore, vary with the nature of the environment and the material brought to the environment--they may be substantial or almost non-existent. It seems generally true that there may be a considerable change immediately when a sediment enters a new environment with different characteristics followed by a further very slow gradual change. Evidence favoring this concept is presented.
Research Article| November 01, 1949 CLAY MINERAL COMPOSITION OF SOME SEDIMENTS FROM THE PACIFIC OCEAN OFF THE CALIFORNIA COAST AND THE GULF OF CALIFORNIA RALPH E GRIM; RALPH E GRIM ILLINOIS STATE GEOLOGICAL SURVEY, URBANA, ILL.; U. S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIF.; U. S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIF. Search for other works by this author on: GSW Google Scholar ROBERT S DIETZ; ROBERT S DIETZ ILLINOIS STATE GEOLOGICAL SURVEY, URBANA, ILL.; U. S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIF.; U. S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIF. Search for other works by this author on: GSW Google Scholar W. F BRADLEY W. F BRADLEY ILLINOIS STATE GEOLOGICAL SURVEY, URBANA, ILL.; U. S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIF.; U. S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIF. Search for other works by this author on: GSW Google Scholar GSA Bulletin (1949) 60 (11): 1785–1808. https://doi.org/10.1130/0016-7606(1949)60[1785:CMCOSS]2.0.CO;2 Article history received: 29 Nov 1948 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation RALPH E GRIM, ROBERT S DIETZ, W. F BRADLEY; CLAY MINERAL COMPOSITION OF SOME SEDIMENTS FROM THE PACIFIC OCEAN OFF THE CALIFORNIA COAST AND THE GULF OF CALIFORNIA. GSA Bulletin 1949;; 60 (11): 1785–1808. doi: https://doi.org/10.1130/0016-7606(1949)60[1785:CMCOSS]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract This report presents the results of a study of the clay mineral composition of a series of bottom core samples collected by the staff of the Scripps Institute of Oceanography of the University of California in Pacific Ocean off the California coast and in the Gulf of California. The clay minerals were studied by X-ray diffraction, differential thermal, optical, chemical, and electron microscopic methods following particle size fractionation by sedimentation and supercentrifuge procedures.All of the samples from the Pacific Ocean and from the Gulf of California contained illite, montmorillonite, and kaolinite; generally illite was most abundant and kaolinite least abundant. A chloritic clay mineral could be identified definitely in some samples. The clay minerals were in very complex mixtures, including mixed crystallizations as well as mechanical mixtures of discrete phases. In general the crystallinity was lower, the individual size smaller, and the intergrowth more intimate than in ancient sediments which have been studied by the authors.Small amounts of quartz were associated with the clay minerals in the 1 to 0.1 and minus 0.1 micron fractions. Small amounts of another nonclay mineral crystalline phase that is probably a feldspar were also found in the finest size fractions of many samples.The analytical data suggest that kaolinite is slowly lost during diagenesis under marine conditions, perhaps being changed to an illite or chloritic clay mineral. The data also afford evidence that potash is taken up by the clay and suggest that it is taken up largely by partially degraded illite which is carried into the sea. Magnesium also appears to be taken up by the clay, perhaps by the illite.The widespread occurrence of montmorillonite indicates that this clay mineral is not lost quickly if at all during diagenesis under marine conditions. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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