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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The sedimentation, tectonics and stratigraphy of the cretaceous/tertiary sequence of northwest Santander, northern Spain

Hines, Frederick Michael January 1986 (has links)
The facies evolution of the Cretaceous/Tertiary sequence of NW Santander is considered in relation to the Cretaceous rifting and drifting, and Tertiary partial closure of the Bay of Biscay. Overlying the Palaeozoic basement are the fluvial Lower Triassic Buntersandstone and Upper Triassic Keuper evaporitic mudstone, deposited in a failed rift, extensional basin. Overlying Lower Jurassic carbonates are the syn-rift, continental elastics of the Vealden deposited in halfgrabens cut by transfer faults. The Vealden consists of two formations:- the lower, arenaceous-rich Barcena Mayor Fm. (braided stream environment) and the upper, argillaceous-rich Vega de Pas Fm. (meandering river). Overlying it is the Aptian Umbrera Fm. (calcarenite sheet), the Patrocinio Fm. (shoaling-up ward sandstone/marl alternation), the San Esteban Fm. (requienid/foraminiferal biomicrite of the internal platform) and the marls of the Rodezas Fm. The Upper Aptian Reocin Fm. is a requienid/foraminiferal biomicrite with thinned calcarenites deposited over active, diapiric palaeohighs. After initial marine and then equant calcite (meteoric phreatic) cementation, invasion of meteoric-derived groundwater over palaeohighs generated lenses of sucrosic dolomite in the Reocin Fm. Local mixing of further groundwater and Keuper-derived, sulphate-rich waters in karstic caverns precipitated sparry, baroque dolomite and Pb/Zn sulphides (by bacterial sulphate reduction). The clastic Lower Albian is a transgressive fluvial/estuarine/inner shelf sequence with tidal estuarine channels and sandwaves. The Middle/Upper Albian (syn-drift) has basal calcarenitic tidal sandwaves and is followed by storm/wave-reworked carbonates deposited on a homoclinal ramp. The clastic Lower Cenomanian is an estuarine/inner shelf deposit with tidal sandwaves and sandbars. The Middle/Upper Cenomanian is a storm/tide-dominated calcarenite. Outer shelf marls occur in the Turonian to Middle Campanian and the Upper Campanian to Middle Eocene is a sandy, foraminiferal inner shelf limestone. The Upper Eocene/Oligocene (syn-compression) is a carbonate slope-apron-reefal flysch deposit. It includes hemipelagic marl, neritic-derived calcarenitic turbidites and rudaceous mass flow deposits with highly polymict conglomerates. These were deposited coevally with Keuper piercement and thrust reactivation and date the Pyrenean compressional deformation here.
22

Carbonate shelf and basin sedimentation, late Proterozoic Wonoka Formation, South Australia /

Haines, Peter W. January 1987 (has links) (PDF)
Thesis (Ph. D.)--University of Adelaide, 1987. / Five folded ill. in pocket. Includes bibliographical references (leaves 141-152).
23

Use of selected macroinvertebrates as indicators of sedimentation effects on Huntington River, Utah

Reichert, Michael Kenneth 18 March 1975 (has links)
Benthic macroinvertebrate communities of Huntington River, Emery County, Utah were studied to determine effects of sedimentation from construction of Electric Lake Dam, a state highway, and two bridges. Approximately 900 benthic samples were collected from riffle areas above, in, and below the construction zone from January, 1971 to December, 1973. Two settling basins below construction sites were effective in limiting scouring of downstream communities. Heavy silt deposition was limited to a 1-km stream reach. Number of indicators, density, and biomass were reduced in the construction zone during periods of sediment input. During periods of scouring, density and biomass were reduced; however, community diversity (d̅) increased due to a reduction of the more populous taxa. The mean d̅ value in the construction zone was 2.05 compared to 2.81 outside. Ordination analysis revealed dissimilarity in communities in, above, and below the construction zone. Specific indicators showed varying response to sedimentation. Recovery was rapid following scouring but slow following sedimentation.
24

Sedimentology and depositional history of the Chapel Island Formation (late Precambrian to early Cambrian) southeast Newfoundland /

Myrow, Paul Michael. January 1987 (has links)
Thesis (Ph.D.) -- Memorial University of Newfoundland, 1987. / Typescript. Bibliography: leaves 448-477. Also available online.

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