Mineralogy and early diagenesis of deep Gulf of Mexico basin sediments.
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1986.
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| Subjects: | |
| Online Access: | Link to ProQuest copy Link to OAKTrust copy |
| Abstract: | Late Pleistocene to Middle Miocene turbidite sands (0 to 900 m depth below seafloor) from Deep Sea Drilling Project (DSDP) Leg 10 Sites 85, 90, and 91 have an average framework, grain composition of 30% quartz, 25% feldspar, and 45% rock fragments, although this composition is highly variable. Fine-grained, Pleistocene and younger Miocene sands, from Sites 85, 90, and 91, contain abundant carbonate rock fragments and lesser amounts of volcanic and plutonic rock fragments; coarse-grained, older middle Miocene sands, from Sites 90 and 91, contain relatively few carbonate rock fragments, but are abundant in volcanic and plutonic rock fragments. Fine-grained, Pleistocene and younger Miocene sands, from Sites 85, 90, and 91, contain more quartz than coarse-grained older Miocene sands, from Sites 90 and 91; fine-grained (younger) sands are enriched in plagioclase. Authigenic minerals in the sands include gypsum and opal, zeolites, smectite, and pyrite. Volcanic rock fragments show evidence of dissolution, as do some feldspar grains. Diagenetic features are best seen in some coarse-grained Miocene age sands from Site 90, which are cemented by authigenic smectite and show porosity development by grain dissolution. Authigenic clinoptilolite also occurs in the smectite cemented sands. Textural relationships suggest that material needed for the formation of smectite cement and zeolites was supplied by the alteration and dissolution of volcanic rock fragments. Miocene age sands from Site 91 do not show development of smectite cement. Because of the similarity of cemented and uncemented sands in age, texture, composition, and initial pore-fluid composition, fluid flow probably controls the development of the smectite cement. Smectite has developed only in areas of low fluid flow. Clayey sediments from DSDP Sites 85, 90, and 91 are composed of variable amounts of illite, mixed-layer illite/smectite, chlorite, and kaolinite. Coarse clay (0.1-2.0 μm) fraction samples show that feldspars and quartz are also present. Fine clay (<0.2 μm) fraction samples of clayey sediment from Site 90 show evidence of progressive uptake of K from pore-water during burial. Because the low temperatures (no higher than 25°C) encountered by these clays precludes major changes in structure or chemistry, K is probably being removed from pore-water by high-charge smectite or by mica cores in degraded detrital material. (Abstract shortened with permission of author.) |
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| Item Description: | Typescript (photocopy). Vita. |
| Physical Description: | xi, 113 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 84-89). |