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At least 1,261 records · Page 70Linked to original sources
USGS2007

Hydrostratigraphic Framework and Selection and Correlation of Geophysical Log Markers in the Surficial Aquifer System, Palm Beach County, Florida

The surficial aquifer system is the major source of freshwater for public water supply in Palm Beach County, Florida, yet many previous studies of the hydrogeology of this aquifer system have focused only on the eastern one-half to one-third of the county in the more densely populated coastal area (Land and others, 1973; Swayze and others, 1980; Swayze and Miller, 1984; Shine and others, 1989). Population growth in the county has resulted in the westward expansion of urbanized areas into agricultural areas and has created new demands on the water resources of the county. Additionally, interest in surface-water resources of central and western areas of the county has increased. In these areas, plans for additional surface-water storage reservoirs are being made under the Comprehensive Everglades Restoration Plan originally proposed by the U.S. Army Corps of Engineers and the South Florida Water Management District (1999), and stormwater treatment areas have been constructed by the South Florida Water Management District. Surface-water and ground-water interactions in the Everglades are thought to be important to water budgets, water quality, and ecology (Harvey and others, 2002). Most of the previous hydrogeologic and ground-water flow simulation studies of the surficial aquifer system have not utilized a hydrostratigraphic framework, in which stratigraphic or sequence stratigraphic units, such as those proposed in Cunningham and others (2001), are delineated in this stratigraphically complex aquifer system. A thick zone of secondary permeability mapped by Swayze and Miller (1984) was not subdivided and was identified as only being within the Anastasia Formation of Pleistocene age. Miller (1987) published 11 geologic sections of the surficial aquifer system, but did not delineate any named stratigraphic units in these sections. This limited interpretation has resulted, in part, from the complex facies changes within rocks and sediments of the surficial aquifer system and the seemingly indistinct and repetitious nature of the most common lithologies, which include sand, shell, sandstone, and limestone. Model construction and layer definition in a simulation of ground-water flow within the surficial aquifer system of Palm Beach County utilized only the boundaries of one or two major hydrogeologic zones, such as the Biscayne aquifer and surficial aquifer system; otherwise layers were defined by average elevations rather than geologic structure or stratigraphy (Shine and others, 1989). Additionally, each major permeable zone layer in the model was assumed to have constant hydraulic conductivity with no allowance for the possibility of discrete (thin) flow zones within the zone. The key to understanding the spatial distribution and hydraulic connectivity of permeable zones in the surficial aquifer system beneath Palm Beach County is the development of a stratigraphic framework based on a consistent method of county-wide correlation. Variability in hydraulic properties in the system needs to be linked to the stratigraphic units delineated in this framework, and proper delineation of the hydrostratigraphic framework should provide a better understanding and simulation of the ground-water flow system. In 2004, the U.S. Geological Survey, in cooperation with the South Florida Water Management District, initiated an investigation to develop a hydrostratigraphic framework for the surficial aquifer system in Palm Beach County.

Scientific Investigations Map↗
USGS2020

High-resolution airborne geophysical survey of the Shellmound, Mississippi area

In late February to early March 2018, the U.S. Geological Survey acquired 2,364 line-kilometers (km) of airborne electromagnetic, magnetic, and radiometric data in the Shellmound, Mississippi study area. The purpose of this survey is to contribute high-resolution information about subsurface geologic structure to inform groundwater models, water resource infrastructure studies, and local decision making. The Shellmound region hosts a managed aquifer recharge (MAR) pilot project, developed by the Agricultural Research Service of the U.S. Department of Agriculture. The MAR pilot project is investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline. Direct injection into the Mississippi River Valley Alluvial aquifer (MRVA) occurs about 3 km from the extraction gallery. Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot MAR study and may be even more important for potential future large-scale MAR projects and groundwater model development efforts.

Mississippi↗
USGS2010

Outcrops, fossils, geophysical logs, and tectonic interpretations of the Upper Cretaceous Frontier Formation and contiguous strata in the Bighorn Basin, Wyoming and Montana

In the Bighorn Basin of north-central Wyoming and south-central Montana, the Frontier Formation of early Late Cretaceous age consists of siliciclastic, bentonitic, and carbonaceous beds that were deposited in marine, brackish-water, and continental environments. Most lithologic units are laterally discontinuous. The Frontier Formation conformably overlies the Mowry Shale and is conformably overlain by the Cody Shale. Molluscan fossils collected from outcrops of these formations and listed in this report are mainly of marine origin and of Cenomanian, Turonian, and Coniacian ages. The lower and thicker part of the Frontier in the Bighorn Basin is of Cenomanian age and laterally equivalent to the Belle Fourche Member of the Frontier in central Wyoming. Near the west edge of the basin, these basal strata are disconformably overlain by middle Turonian beds that are the age equivalent of the Emigrant Gap Member of the Frontier in central Wyoming. The middle Turonian beds are disconformably overlain by lower Coniacian strata. Cenomanian strata along the south and east margins of the basin are disconformably overlain by upper Turonian beds in the upper part of the Frontier, as well as in the lower part of the Cody; these are, in turn, conformably overlain by lower Coniacian strata. Thicknesses and ages of Cenomanian strata in the Bighorn Basin and adjoining regions are evidence of regional differential erosion and the presence of an uplift during the early Turonian centered in northwestern Wyoming, west of the basin, probably associated with a eustatic event. The truncated Cenomanian strata were buried by lower middle Turonian beds during a marine transgression and possibly during regional subsidence and a eustatic rise. An uplift in the late middle Turonian, centered in north-central Wyoming and possibly associated with a eustatic fall, caused the erosion of lower middle Turonian beds in southern and eastern areas of the basin as well as in an adjoining region of north-central Wyoming. Similarly, in east-central Wyoming and an adjacent area to the south, Cenomanian strata are disconformably overlain by upper middle and lower upper Turonian strata that probably reflect uplift and erosion in that region during the interim period of middle Turonian time. During later subsidence and a marine transgression, upper Turonian deposits buried Cenomanian beds in areas along the south and east margins of the Bighorn Basin and buried lower middle Turonian beds in much of northern Wyoming. Upper Turonian and lower Coniacian strata are apparently conformable in eastern and southern areas of the basin as well as near Riverton, Kaycee, and Casper in central Wyoming. Upper Turonian strata are absent on the west flank of the Bighorn Basin and in outcrops west of the basin, where middle Turonian beds are disconformably overlain by lower Coniacian beds . The conformable upper Turonian and lower Coniacian beds apparently transgressed an eroded middle Turonian surface in the region, but only Coniacian strata overlie middle Turonian beds on the west side of the basin and areas farther west. Coniacian strata onlap the truncated lower middle Turonian surface west of the basin, indicating a region that had higher elevation possibly resulting from tectonic uplift. In east-central Wyoming and an adjoining region to the south, upper middle Turonian and lower upper Turonian strata are disconformably overlain by lower and middle Coniacian beds. That region apparently was uplifted and eroded during the latest Turonian.

Montana, Wyoming↗
USGS2010

Borehole Geophysical, Water-Level, and Water-Quality Investigation of a Monitoring Well Completed in the St. Francois Aquifer in Oregon County, Missouri, 2005-08

A deep (more than 2,000 feet) monitoring well was installed in an area being explored for lead and zinc deposits within the Mark Twain National Forest in southern Missouri. The area is a mature karst terrain where rocks of the Ozark aquifer, a primary source of water for private and public supplies and major springs in the nearby Eleven Point National Wild and Scenic River and the Ozark National Scenic Riverways, are exposed at the surface. The potential lead deposits lie about 2,000 feet below the surface within a deeper aquifer, called the St. Francois aquifer. The two aquifers are separated by the St. Francois confining unit. The monitoring well was installed as part of a series of investigations to examine potentiometric head relations and water-quality differences between the two aquifers. Results of borehole flowmeter measurements in the open borehole and water-level measurements from the completed monitoring well USGS-D1 indicate that a seasonal upward gradient exists between the St. Francois aquifer and the overlying Ozark aquifer from about September through February. The upward potentiometric heads across the St. Francois confining unit that separates the two aquifers averaged 13.40 feet. Large reversals in this upward gradient occurred during the late winter through summer (about February through August) when water levels in the Ozark aquifer were as much as 138.47 feet higher (average of 53.84 feet) than water levels in the St. Francois aquifer. Most of the fluctuation of potentiometric gradient is caused by precipitation and rapid recharge that cause large and rapid increases in water levels in the Ozark aquifer. Analysis of water-quality samples collected from the St. Francois aquifer interval of the monitoring well indicated a sodium-chloride type water containing dissolved-solids concentrations as large as 1,300 milligrams per liter and large concentrations of sodium, chloride, sulfate, boron, and lithium. In contrast, water in the overlying Ozark aquifer interval of the monitoring well was a calcium-magnesium-bicarbonate type water containing less than 250 milligrams per liter dissolved solids and substantially smaller concentrations of major and trace elements.

Scientific Investigations Report↗
USGS2019

Lithologic descriptions, geophysical logs, and source-rock geochemistry of the U.S. Geological Survey Alcova Reservoir AR–1–13 Core Hole, Natrona County, Wyoming

In 2013, a continuous 624-foot core hole was drilled and logged by the U.S. Geological Survey in Natrona County, Wyoming, with the goal to better understand Cretaceous source rocks in the Wind River Basin. The core hole, named the Alcova Reservoir AR–1–13, penetrated the interval extending from the upper part of the Lower Cretaceous Cloverly Formation to the lower part of the Upper Cretaceous Frontier Formation. The lithologies are predominantly mudrock, with minor amounts of sandstone and altered volcanic ash beds that were deposited in open marine, nearshore marine, and fluvial settings. Samples were collected from open marine clay-rich, dark-colored mudrocks, and these were analyzed for total organic carbon content and by programmed pyrolysis analysis. The results show that the lower part of the Frontier Formation, Shell Creek Shale equivalent, and the Thermopolis Shale contain Type III gas-prone kerogen, with poor to fair generative source rock potential. The upper part of the Mowry Shale has good to excellent generative potential, with organic matter composed mainly of Type II oil-prone kerogen with some mixed Type II/III kerogen capable of generating oil and gas.

Wyoming↗
USGS1959

A Summary interpretation of geologic, hydrologic, and geophysical data for Yucca Valley, Nevada test site, Nye County, Nevada

This report summarizes an interpretation of the geology of Yucca Valley to depths of about 2,300 feet below the surface, the characteristics features of ground water in Yucca and Frenchman Valleys, and the seismic, gravity, and magnetic data for these valleys. Compilation of data, preparation of illustrations, and writing of the report were completed during the period December 26, 1958 to January 10, 1959. Some of the general conclusions must be considered as tentative until more data are available. This work was done by the U.S. Geological Survey on behalf of Albuquerque Operations Office, U.S. Atomic Energy Commission.

Nevada↗