Filters: Tags: lacustrine (X)19 results (139ms)
Sediment magnetic, paleomagnetic and geochemical results have beenobtained from lacustrine sediments recovered in a 30-meter coretaken by rotary drilling methods at Grass Lake, Siskiyou County,California. The data have been analyzed and interpreted in termsof environmental change in the Grass Lake catchment over the pastca. 100,000 years.
A previously unidentified major sequence boundary within the Eocene Green River Formation separates fluctuating profundal facies of the Tipton Shale Member from evaporative facies of the Wilkins Peak Member. During deposition of the Tipton Shale Member, rivers entered the basin from the north, across the subdued Wind River Mountains, and deposited the southward prograding deltaic complex of the Farson Sandstone Member. Boulder-rich alluvial fan deposits overlie the Farson Sandstone adjacent to the Continental Fault, and correlate basinward to hypersaline lacustrine deposits of the Wilkins Peak Member. The alluvial fan deposits record a period of reverse motion on the Continental Fault and uplift of the southeastern...
Geologic map of the Dalton Highway (Atigun Gorge to Slope Mountain) area, southern Arctic Foothills, Alaska
This report provides detailed mapping (1:63,360-scale) in the Dalton Highway area, from Atigun Gorge to Slope Mountain, in the west-central Philip Smith Mountains quadrangle. The map area extends from the northern flank of the Endicott Mountains into the Arctic Foothills province.
Digital Dataset for the Geomorphology of the Lower Mississippi River Valley in Missouri, Kentucky, Arkansas, Tennessee, Louisiana, and Mississippi
A digital dataset of the geomorphology of the Lower Mississippi River Valley in Missouri, Kentucky, Arkansas, Tennessee, Louisiana, and Mississippi was developed from Roger T. Saucier’s “Geomorphology and Quaternary Geologic History of the Lower Mississippi Valley, Volumes I and II” (1994) as part of the Mississippi Alluvial Plain (MAP) Regional Water Availability Study. The maps included in the 1994 reports provide a comprehensive overview of the previously misunderstood alluvial valley geology and characterize twenty-nine Pleistocene and Holocene alluvial deposits, such as point bars, abandoned channels, backswamps, and natural levees. Each map was georeferenced to North American Datum 1983 and projected to USA...
Complex, caddisfly-dominated (Insecta: Trichoptera) carbonate mounds up to 9 m tall and 40 m in diameter formed in the nearshore environment of Eocene Lake Gosiute. The mounds outcrop for 70 km in reef-like geometries along the northern margin of Lake Gosiute in Wyoming. The relationships among the caddisfly larvae, the benthic microbial mat and physicochemical nearshore processes of Eocene Lake Gosiute resulted in unique external and internal carbonate mound morphology. Externally, the large carbonate mounds are formed by the lateral and vertical coalescence of several layers of smaller columns. The smaller columns are generally 1?2 m tall and are 0.5?1 m in diameter. Each layer or generation of smaller columns...
Surficial geology of the Dalton Highway (Itkillik-Sagavanirktok rivers) area, southern Arctic foothills, Alaska
This report provides detailed (1:63,360-scale) surficial-geologic mapping in the Dalton Highway area, from the Sagavanirktok to the Itkillik Rivers, in the west-central Philip Smith Mountains quadrangle. The map area extends from the northern flank of the Endicott Mountains into the Arctic Foothills province.
In preparation for bottom sediment coring at Mother Goose Lake, bathymetric data was collected using a Lowrance Sonar "fishfinder" (model LcX-17M) in August 2006 and August 2007. A 5-meter bathymetric contour map of the lake bottom was constructed using the GPS-sonar data in conjunction with field observations. The contour data and GPS location and depth data are provided in ESRI shapefile format for use in Geographic Information System (GIS) software.
Microsatellite genotypes for Lake Sturgeon (Acipenser fulvescens) Eggs and Larvae from Constructed Reefs in the St. Clair-Detroit River System (2015-2016)
This dataset contains the physical collection information (e.g., sample location, date, gear type) and microsatellite DNA genotype of egg and larval Lake Sturgeon collected in the St. Clair and Detroit rivers in 2015 and 2016. Individuals were genotyped for 18 microsatellite loci (13 disomic and 5 polysomic). Alleles (base pair sizes) were recorded as presence absence scores (1:present, 2:absent, 0:missing data) for all previously observed alleles. Thus individual genotypes were recorded as pseudo diploid dominant phenotypes resulting in individual vectors of length n=205 for each genotyped egg or larval individual.
Lacustrine sedimentary record of human-induced gully erosion and land-use change at Providence Canyon, southwest Georgia, USA
This 1:50,000 scale geologic map describes the distribution of unconsolidated deposits, identifies local geologic hazards, and provides information about the depositional environment and basic engineering properties of common surficial-geologic materials in and around Shaktoolik, Alaska. Map units are the result of combined field observations and aerial imagery interpretation. A suite of local ground observations were collected over a two-week period in July 2011 by a helicopter-supported team of DGGS geologists and collaborators. Field investigations included soil test pits, sample collection, soil and rock description, oblique aerial photography, and documentation of landscape morphology.
The Alaska Division of Geological & Geophysical Surveys (DGGS), in partnership with the U.S. National Cooperative Geologic Mapping Program, mapped approximately 450 mi2 of the Talkeetna Mountains region of central Alaska at 1:50,000 scale over the course of six weeks in 2014. This area contains significant exposures of Late Triassic mafic volcanics and gabbro sills that have been the focus of region-wide exploration for the Strategic and Critical platinum-group elements (PGEs). The area also exposes numerous inactive and possibly active faults which project through the area of proposed hydropower development. The resulting geologic map offers an improved understanding of the geology, structural history, and mineral...
This legacy database lists occurrences of minerals identified in the Green River Formation in the Uinta and Piceance Basins, Utah and Colorado using X-ray diffraction (XRD). The database was compiled from data collected by the U.S. Geological Survey (USGS) and former U.S. Bureau of Mines (USBM). The database includes 1200 samples from 14 cores in the Uinta Basin and 9443 samples from 30 cores in the Piceance Basin; within that dataset over 40 mineral phases are represented between the two basins. Quartz, dolomite, and feldspars are the most common minerals. For nearly a century, these two agencies conducted extensive research on the oil shale deposits of the Eocene Green River Formation, Utah, Colorado, and Wyoming....
A multidisciplinary study of the Lower Cretaceous Cedar Mountain Formation, Mussentuchit Wash, Utah: a determination of the paleoenvironment and paleoecology of the Eolambia caroljonesa dinosaur quarry
A quarry within the Cedar Mountain Formation in Mussentuchit Wash, Emery County, Utah, produced a fossil assemblage containing the remains of at least eight juvenile iguanodontid dinosaurs (Eolambia caroljonesa). The Cedar Mountain Formation lies stratigraphically between the Tithonian?Berriasian (Upper Jurassic) Brushy Basin Member of the Morrison Formation and the Cenomanian (Upper Cretaceous) Dakota Formation. Detailed stratigraphic, sedimentological, geochronological, palynological, and paleontological data have been collected along a measured section at the site of the Cifelli #2 Eolambia caroljonesa Quarry. These data provide a chronostratigraphic and a biostratigraphic framework for the Cedar Mountain Formation...
Sediment Magnetic and Geochemical Data from Quaternary Lacustrine Sediment in Two Cores from Tule Lake, Siskiyou County, California
Sediment magnetic and geochemical results have been obtained fromthe top 60 meters of lacustrine sediments recovered in two coresfrom Tule Lake in northern California. The sediment magnetic andgeochemical data, presented here in tabular form, complementstudies of diatoms and pollen in the cores that are the bases forpublished paleoclimatic interpretations. This report alsodocuments the methods used to obtain the magnetic properties andgeochemical data.
The deposits of Eocene Lake Gosiute that constitute the Green River Formation of Wyoming contain numerous tuff beds that represent isochronous, correlatable stratigraphic markers. Tuff beds selected for 40Ar/39Ar analysis occur within laminated mudstone, are matrix supported, and lack evidence of reworking. These tuffs contain 2%?15% euhedral phenocrysts of quartz, plagioclase, sanidine, biotite, and minor amphibole, pyroxene, and zircon, encased in a matrix of altered glassy ash. Air abrasion and handpicking under refractive- index oils were required to obtain clean, unaltered phenocrysts of sanidine. 40Ar/39Ar age determinations from single-crystal and <1 mg multigrain aliquots of sanidine and biotite allowed...
Eocene calibration of geomagnetic polarity time scale reevaluated: Evidence from the Green River Formation of Wyoming
We reevaluate the Eocene geomagnetic polarity time scale on the basis of single-crystal 40Ar/39Ar ages for air-fall tuffs from the Wilkins Peak Member of the Green River Formation of Wyoming. Tuff 6 is dated as 49.1 � 0.2 Ma, and tuff 3 is dated as 50.4 � 0.3 Ma (maximum estimate). When combined with published magnetostratigraphic constraints, these age determinations suggest that the currently accepted age of chron C22r is 1.5?2.5 m.y. too old, which supports a significantly longer duration for the early Eocene, for the early Eocene climatic optimum, and the Wasatchian North American Land Mammal Age. Published in Geology, volume 32, issue 2, on pages 137 - 137, in 2004.
Stratigraphy, Sedimentology, Paleontology, and Paleomagnetism ofPliocene-Early Pleistocene Lacustrine Deposits in Two Cores fromWestern Utah
The data contained in this report represent our preliminary findingsof the analyses of two cores of Pliocene and early Pleistocenesediments from the eastern Great Basin. This is a collaborativeproject involving specialists from the USGS, Kansas State University,and the University of California-Davis in paleontology (Thompson,Buchner, Forester, Bradbury), stratigraphy and sedimentology (Oviatt,Kelsey, Bracht), and paleomagnetism and environmental magnetism(Roberts).
Sediment magnetic and paleomagnetic studies were conducted on a core fromBuck Lake, Klamath County, Oregon, that was collected as part of aninvestigation into the Quaternary climate history of the western UnitedStates. This report documents the methods used to obtain paleomagneticdirections, magnetic properties, and ancillary data, and presents thesedata in tabular form.
We developed a mapped classification of lakes and ponds based on variables that structure lacustrine natural communities and that could be mapped consistently across Northeastern US. The classification was built upon four key attributes: water temperature, trophic state, alkalinity, and depth. Water temperature was mapped into three classes (very cold, cold, and warm-cool) to reflect the requirements and limits of aquatic organisms. Trophic states, representing the productivity of a lake, were mapped into two classes (oligomesotrophic -mesotrophic and eutrophic- hypereutrophic). Alkalinity was grouped into three classes (high, medium, low) to reflect how well the lake system was buffered from acidification. Depth...