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1	Paleocurrent Analysis of the Upper Miocene Formation, Los Angeles Basin, California Bennett, John Newton, Jr. January 1967 (has links) Almost all sandstone beds occurring in the Upper Miocene formations at the Los Angeles basin were deposited by turbidity currents. Primary textures and structures indicative of turbidites occur in fair abundance throughout all three Upper Miocene formations. All accessible outcrops of the Puente, Modelo, and Upper Miocene portion of the Monterey and Capistrano Formations were scrutinized for sandstone beds containing primary sedimentary structures. Through study of these structures, the direction of current movement was determined. The pattern of current movement displayed reveals that sediment was being transported into the Los Angeles basin from all sides. Current directions and mineralogic studies indicate that essentially three source areas were supplying sediment into the basin. These source areas are 1) the San Gabriel Mountains, 2) an area to the east of the Santa Ana Mountains, and 3) a ridge of metamorphic rock paralleling the present coast line. The majority of sediment was derived from an area in the San Gabriel Mountains located northeast or the basin. This is evidenced by the fact that the thickness, grain size, and total sand content of the Upper Miocene units decrease southwestward across the basin. bedding plane irregularities California Cenozoic current markings current transport Los Angeles Basin Miocene Neogene paleocurrents paleocurrent analysis provenance sedimentary petrology sedimentary structures sedimentation sediments stratigraphy structure Tertiary United States upper Miocene
2	Paleocurrents and Depositional Environments of the Dakota Group (Cretaceous), San Miguel County, New Mexico Bejnar, Craig Russel January 1975 (has links) The Dakota Group surrounding Las Vegas, New Mexico, consists of three units: 1) a basal, predominately trough cross-stratified, conglomeratic sandstone, 2) middle intercalated, thin-bedded sandstone and carbonaceous shale, and 3) upper, predominately tabular-planar cross-stratified, sandstone containing trace fossils. These units represent, respectively, 1) a fluvial piedmont plain, 2) fluvial coastal plain, and 3) a beach, littoral, and shallow marine complex. The cross-stratification in the lower sandstone unit indicates an easterly paleoslope. The cross-stratification in the upper sandstone unit has a bimodal distribution almost at right angles to the paleoslope, suggesting deposition by longshore currents. The standard deviation of the cross-stratification in the lower sandstone unit of 78° is typical of fluvial deposits. The standard deviation in the upper sandstone unit of 97° indicates a marine origin. algae bedding plane irregularities biostratigraphy clastic rocks Cretaceous cross-stratification Dakota Formation depositional environment environment environmental analysis indicators lithostratigraphy marine Mesozoic microfossils Mora County New Mexico nannofossils nearshore New Mexico northeast paleocurrents palynomorphs planar bedding structures Plantae provenance ripple marks San Miguel County New Mexico sandstone sedimentary petrology sedimentary rocks sedimentary structures sedimentation shale shallow stratigraphy streams terrigenous thallophytes United States

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Paleocurrent Analysis of the Upper Miocene Formation, Los Angeles Basin, California

Paleocurrents and Depositional Environments of the Dakota Group (Cretaceous), San Miguel County, New Mexico