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At least 55 records · Page 3Linked to original sources
USGS1978

Preliminary report on the clay mineralogy of the Upper Devonian Shales in the southern and middle Appalachian Basin

The distribution of kaolinite in parts of the Devonian shale section is the most significant finding of this work. These shales are composed predominately of 2M illite and illitic mixed-layer clay with minor amounts of chlorite and kaolinite. Preliminary data indicate that kaolinite, the only allogenic clay mineral, is present in successively older beds of the Ohio Shale from south to north in the southern and middle parts of the Appalachian basin. This trend in the distribution of kaolinite shows a paleocurrent direction to the southwest. Three well-known methods of preparing the clay fraction for X-ray diffraction analysis were tested and evaluated. Kaolinite was not identified in two of the methods because of layering due to differing settling rates of the clay minerals. It is suggested that if one of the two settling methods of sample preparation is used, the clay film be thin enough for the X-ray beam to penetrate the entire thickness of clay.

Open-File Report↗
USGS1952

Preliminary report on the Passamaquoddy bedrock survey, July-August, 1951

In order to understand the results of the Passamaquoddy bedrock survey and the details of the method of obtaining them, it is desirable to have, in outline, a general idea of the methods and their application. In this part of the report a general account of the operation will be developed. The details will be found in subsequent parts of the report. At this point a statement of the general objective and some mention of the plans for reaching it are in order. The purpose of the Passamaquoddy survey was to determine the submarine geology in certain areas of Passamaquoddy and Cobscook Bays--the sea-bottom topography, the bedrock topography, the thickness of sediment overlying the bedrock beneath the sea, and the type of sediment. The information is needed for the planning of major engineering structures that may be built in the area. It developed in planning the study that detailed surveys could be limited to several areas where dams may be located. To determine bottom or bedrock topography, elevations of each were determined by sonic methods at a number of closely spaced locations (about 400 feet apart), evenly distributed on range lines 1,000 or 800 feet apart, in each of eight areas. Contour lines were then drawn to produce the desired topographic maps. Sonic soundings are necessarily referred to the existing water surface. To ascertain specific elevations in an area of large tidal variations is a complex problem. The details are discussed in the section on Vertical Control by Charles E. Knox (part 8). The basic datum is mean low water as determined by the U. S. Coast and Geodetic Survey. Equally important is the accurate positioning horizontally of each sounding location or fix. All such positioning was by the use of the standard three point fix procedure, using sextants. A net of shore points tied to the first-order control net of the Coast and Geodetic Survey was set up for this purpose, and all positions were thus accurately located. These problems are discussed in a section on Horizontal Control by Norman Duckworth (part 7). The general planning was done in conferences held in May 1951 at the Boston office of the Corps of Engineers, and in Eastport, Maine, after a brief reconnaissance of the area. A detailed account of the conferences is given in a memorandum by Herman J. Kropper of the New England Division, Corps of Engineers, reproduced in this report as part 4. Detailed survey procedures were developed on May 18, 1951, at a conference attended by P. J. A. Scott and Norman Duckworth of the Corps of Engineers and W. O. Smith of the Geological Survey. In order to make the necessary geophysical interpretation of the sound records, adequate geologic control had to be established. A preliminary field study of the geology was made by G. G. Parker of the Geological Survey during the period May 15-17, 1951. Subsequently Dr. T. E. Upson of the Geological Survey made the detailed geologic study required for the project. Two sonar units were used for the survey. One was a low-frequency high-power sonar unit developed by the Edo Corp. to meet specifications established by the Geological Survey. It was used to collect the bulk of the bedrock and bottom data. The other, of higher frequency and lower power, was manufactured by Bludworth Marine, Inc., end was required for adequate determination of water depths in shoal areas. The Edo equipment is described by Dr. Charles E. Mongan, Jr., in part 6 of this report.

Maine↗
USGS2005

Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida

Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measures and targets for salinity and other water quality and quantity quality measures. Preliminary examination of the cores indicates significant changes have taken place over the last 1000-2000 years. The cores collected from the inner bays — the most landward bays — are distinctly different from other estuarine sediment cores examined in Florida Bay and Biscayne Bay. Peats in the inner-bay cores from Big Lostmans Bay, Broad River Bay, and Tarpon Bay were deposited at least 1000 years before present (BP) based on radiocarbon analyses. The peats are overlain by poorly sorted organic muds and sands containing species indicative of deposition in a freshwater to very low salinity environment. The Alligator Bay core, the most northern inner-bay core, is almost entirely sand; no detailed faunal analyses or radiometric dating has been completed on this core. The Roberts River core, taken from the mouth of the River where it empties into Whitewater Bay, is lithologically and faunally similar to previously examined cores from Biscayne and Florida Bays; however, the basal unit was deposited ~2000 years before the present based on radiocarbon analyses. A definite trend of increasing salinity over time is seen in the Roberts River core, from sediments representing a terrestrially dominated freshwater environment at the bottom of the core to those representing an estuarine environment with a strong freshwater influence at the top. The changes seen at Roberts River could represent a combination of factors including rising sea-level and changes in freshwater supply, but the timing and extent of the changes needs to be determined. The preliminary information on the cores collected in 2004 will be combined with data from cores collected in July 2005. The 2005 cores were collected along transects moving from the inner bays out towards the coast. These transects, combining information from the 2004 and 2005 cores, will allow us to examine long term trends in freshwater supply, sea-level rise, and potentially the impact of storms on the coastal ecosystem.

Florida↗
USGS2006

Descriptions and preliminary report on sediment cores from the southwest coastal area, Part II: Collected July 2005, Everglades National Park, Florida

Twelve cores were collected from six sites in the southwest coastal area of Everglades National Park, Florida, in July 2005. These six sites create transects up three river systems that are part of the complex network of channels and bays that form the mangrove and coastal glades – Lostmans River system, Harney River system, and Shark River system. The three transects are linked to two cores collected in 2004 from Big Lostmans Bay and Tarpon Bay. A preliminary model of changes in flow through the southwest coastal zone is proposed based on an examination of the sediments and an initial assessment of key indicator species of mollusks within the cores. Throughout the time period recorded by deposition of these cores, flow to the southwest coastal area has been predominantly through the Shark River channels, diminishing to the north toward the Lostmans River system. The Lostmans system was less influenced by freshwater flow and more emergent than the two systems to the south. Freshwater flow has periodically reached the mouths of the Harney and Shark River systems, but these areas have persistently been zones of mixed estuarine environments, typical of transition zones. Evidence for a substantial change in the flow regime is found in the mid-system cores from the Harney and Shark Rivers. The lower portions of both cores were deposited in freshwater environments, with no indication of estuarine influence; however, a shift towards more estuarine conditions occurs in the upper portions of the cores and a loss of the larger freshwater fauna. These results are preliminary. The next step will be to develop age models and to conduct quantitative analyses of the fauna, flora, and sediment geochemistry at these sites. Results of the quantitative analyses will provide information on the natural and anthropogenic changes that have occurred in the southwest coastal system that will allow resource managers to set targets for restoration.

Florida↗
USGS1985

Preliminary report on gold deposits at Meshaheed, Kingdom of Saudi Arabia

A fault-controlled, hydrothermal system deposited gold, stibnite, and quartz in metasediments, intrusive basalt, and diorite in an area approximately 3 by 5 km in the Meshaheed area of the northeastern Arabian Shield. Veins in metasediments appear to be lenticular and average less than 1 m thick. A related, quartz-pyrite stockwork in fractured, hydrothermally altered basalt is approximately 1 km long and at least 100 m wide. Poorly defined veins and veinlets bear gold, stibnite, and quartz, A few areas of ancient goldmining activity are in metasediments at the perimeter of a large diorite pluton. The arrangement of the pits also indicates that unexposed veinlet systems may be as much as 40 m wide. Small areas of diorite have also been hydrothermally altered where gold-stibnite-quartz veins were emplaced. A molybdenite-quartz stockwork and other quartz stockworks bearing traces of molybdenum, bismuth, and silver are in small diorite plutons. Large areas of moderately hydrothermally altered metasediments bearing trace molybdenum are also present. These mineralized zones are not cogenetic with the gold-stibnite-quartz deposits. A separate stream-sediment sampling program has shown the area southeast of Meshaheed to be anomalous in lead, copper, boron, tin, iron, and molybdenum, and a preliminary geophysical survey found resistivity anomalies coincident with the altered, intrusive basalt.

Open-File Report↗
USGS1953

Preliminary report on the Little Susitna district, Matanuska coal field, Alaska

The Little Susitna district, as defined in this report, occupies an area roughly 25 miles long and 3 miles wide on the north side of the lower (western) extremity of the Matanuska Valley in south-central Alaska (fig. 1). The district is bounded on the north by the Talkeetna Mountains, on the south and east by the Little Susitna River, and on the west by the broad lowland of the Susitna River. (See pl. 1.) This report is based on field work done in the summer of 1952, in which the writer was assisted by Alfred Oestreich, Lewis Ladwig, and Richard Pack. Prior to the present investigation very little was known geologically of the district, except that it was largely covered with alluvial and glacial deposits and that coal-bearing rocks were exposed at three widely separated localities. The purpose of the investigation was to determine, if possible from scattered outcrops and shallow test pits, whether any parts of the district offered sufficient promise of containing minable coal deposits to warrant a more detailed investigation using sub-surface methods. As a result of this preliminary investigation, plans are being made to explore more thoroughly, by trenching and drilling, some of the more promising parts of the district.

Alaska↗
USGS1960

Preliminary report on ground water in the Salmon Falls area, Twin Falls County, Idaho

The Salmon Falls area contains about 80,000 acres of irrigable land, of which about 30,000 acres receives some water from the distribution system of Salmon River Canal Co., Ltd. This system utilizes virtually all the available surface water. A substantial amount of surface water, estimated to be about 70,000 acre-feet annually, is lost by leakage from the reservoir and the distribution system. Some of this water could be salvaged by lining sections of the canal where excessive losses occur. Ground water has not been extensively developed in the area, but some successful irrigation wells furnished supplemental irrigation water. Recharge to the area is from precipitation on the area, seepage from peripheral streams, seepage losses from the reservoir and canal system, irrigation seepage, and ground-water underflow. Ground water leaves the area by undertow to the north and northwest, and eventually reaches the Snake River. The total mount of underflow from the area was estimated by three different methods to be 17,000, 100,000, and 170,000 acre-feet per year. The preliminary estimate of 100,000 acre-feet was derived by the inventory of recharge and is probably more accurate than the other two methods. Calculations, based on estimates of transmissibility computed from specific capacities of wells, suggest that there may be some channels or conduits of higher than average transmissibility through which a large part of the undertow leaves the area, Possibly 25 percent of the ground-water outflow could be intercepted by wells. However, in part of the area the depth to water may be excessive for economic development. Chemical analyses of 25 samples of ground water indicate that most of the water sampled is suitable for irrigation. The samples found least suitable were of water occurring at shallow depth, south and east of Hollister.

Idaho↗
USGS2017

Sea turtles, light pollution, and citizen science: A preliminary report

Sea turtles are an important ecological resource for Gulf Islands National Seashore’s (Gulf Islands) waters and shorelines. Regionally, sea turtles face anthropogenic threats from situations such as entanglement in fishing gear and ingestion of marine debris, as well as possible changes in sex ratios due to increasing temperatures related to human-induced global warming. Locally, light pollution from residential, commercial, and industrial neighborhoods from nearby cities impacts the entirety of Gulf Islands, which spans 160 miles along the Gulf Coast, from Florida to Mississippi, and includes critical habitat for threatened and endangered sea turtles. Because light pollution has been hypothesized to negatively impact sea turtle nesting and hatchling survival, Gulf Islands undertook an effort to understand the relationship between light pollution and sea turtles and create unique educational and outreach opportunities by launching a citizen science program called Turtle Teens Helping in the Seashore (Turtle THIS). At the onset, the Turtle THIS program had two primary goals: quantify the association between light pollution and sea turtle nesting and hatching events using rigorous scientific methods; and initiate a citizen science volunteer program to provide youth with hands-on science and environmental stewardship roles, where they also gain employable skills and career opportunities. With multiple scientific hypotheses to consider, the development of a citizen science program became crucial. Such circumstances allowed Turtle THIS to grow a volunteer and intern program, quantify hypothesized light effects on sea turtles through developed methods, and begin to gather preliminary findings.

Florida↗
USGS2000

Preliminary report on the 16 October 1999 M 7.1 Hector mine, California, earthquake

The M w 7.1 Hector Mine, California, earthquake occurred at 9:46 GMT on 16 October 1999. The event caused minimal damage because it was located in a remote, sparsely populated part of the Mojave Desert, approximately 47 miles east-southeast of Barstow, with epicentral coordinates 34.59°N 116.27°W and a hypocentral depth of 5 ± 3 km. Twelve foreshocks, M 1.9-3.8, preceded the mainshock during the previous twelve hours. All of these events were located close to the hypocenter of the mainshock. The Hector Mine earthquake occurred within the Eastern California Shear Zone (ECSZ). By virtue of its remote location, the societal impact of the Hector Mine earthquake was, fortunately, minimal in spite of the event's appreciable size. The ECSZ is characterized by high seismicity, a high tectonic strain rate, and a broad, distributed zone of north-northwest-trending faults (ECSZ; Figure 1 ; Dokka and Travis, 1990 ; Sauber et al., 1986 ; Sauber et al., 1994 ; Sieh et al., 1993 ). Data regarding the slip rates of faults within the ECSZ suggest that on the order of 15% of the Pacific-North American plate motion occurs along this zone ( Sauber et al., 1986 ; Wesnousky, 1986 ). Most of the faults in the ECSZ have low slip rates and long repeat times for major earthquakes, on the order of several thousands to tens of thousands of years. The occurrence of the Hector Mine earthquake within seven years and only about 30 km east of the 1992 M w 7.3 Landers earthquake suggests that the closely spaced surface faults in the ECSZ are mechanically related. The Hector Mine event involved rupture on two previously mapped fault zones—the Bullion Fault and an unnamed, more northerly-trending fault that is informally referred to in this paper as the Lavic Lake Fault (Dibblee, 1966 , 1967a , b ). Traces of the Bullion Fault exhibit evidence of Holocene displacement and were zoned as active in 1988 under California's Mquist-Priolo Earthquake Fault Zoning Act ( Hart and Bryant, 1997 ). The pattern of rupture along more than one named fault was also observed from the 1992 Landers earthquake ( Hauksson et al., 1993 ; Sieh et al., 1994). Much of the fault zone that produced the Hector Mine earthquake had been buried by relatively young stream deposits, and the fault scarps in bedrock have a subdued morphology. It appears that these faults have not experienced significant offset for perhaps 10,000 years or more ( Hart, 1987 ). Planned future investigations will refine the age of the last event on these faults. The portion of the Lavic Lake Fault that ruptured between the northern end of the Bullion Mountains and Lavic Lake had not previously been mapped. However, our field investigations have identified ancient, subdued fault scarps along portions of the 1999 rupture zone in this area. It thus appears that the entire segment of the Lavic Lake Fault that was involved in the 1999 event had ruptured in the past. As is typical for most faults within the Eastern California Shear Zone, the rate of movement along the Lavic Lake Fault may be quite slow (<1 mm/yr) and should produce earthquakes only infrequently. This event is a reminder that faults that have ruptured in late Quaternary time, but that lack evidence of Holocene displacement, can still produce earthquakes in this low-slip-rate tectonic setting. Additionally, the Hector Mine earthquake is noteworthy for a couple of other reasons. First, it clearly produced triggered seismicity over much of southern California, from the rupture zone toward the south-southwest in particular. Second, as we will discuss, the event may provide new data and insight into recently developed paradigms concerning earthquake interactions and the role of static stress changes. Questions such as these will, of course, be the subject of extensive detailed analyses in years to come. Fortunately, the Hector Mine sequence will provide one of the best data sets obtained to date for a significant earthquake in the United States. Because it occurred when major upgrades to both the regional seismic network (TriNet) and the regional geodetic network (SCIGN) were well underway, the Earth science community will have abundant high-quality data with which to explore the important and interesting questions that have been raised. In this paper, we present and discuss the basic data and preliminary results from the Hector Mine earthquake.

California↗
USGS1981

Storm-built sand ridges on the Maryland inner shelf: a preliminary report

Several aspects of the Maryland ridge field are pertinent to the problem of ridge genesis in response to Holocene sea-level rise. There is a systematic morphologic change from shoreface ridges through nearshore ridges to offshore ridges, which reflects the changing hydraulic regime. Grain size is 90?? out of phase with topography, so that the coarsest sand lies between the axis of each trough and the adjacent seaward ridge crest, while the finest sand lies between each ridge crest and the axis of the adjacent seaward trough. Finally, analysis over a 43-year period on an outer ridge reveals a systematic pattern of landward flank erosion, seaward flank deposition, and seaward crest migration. These relationships support a model which explains the ridges as consequences of the up-current shift of maximum bottom shear stress with respect to the crests of initial bottom irregularities. The oblique orientation of the ridges with respect to the beach may be at least partly due to the more rapid migration rate of the ridges' inshore ends. ?? 1981 A.M. Dowden, Inc.

Geo-Marine Letters↗
USGS1976

Concentration and mineralogical residence of elements in rich oil shales of the Green River Formation, Piceance Creek basin, Colorado, and the Uinta Basin, Utah - A preliminary report

Ten samples from drillcore of two rich oil-shale beds from the Parachute Creek Member of the Eocene Green River Formation, Piceance Creek basin, Colorado, and Uinta Basin, Utah, were analyzed for 37 major, minor, and trace elements. For 23 of these elements, principal mineralogical residence is established or suggested and such studies may provide data which are useful for predicting the kinds and amounts of elements and compounds that might be released into the environment by oil-shale mining operations. ?? 1976.

Chemical Geology↗
USGS2009

Preliminary report on the commercial viability of gas production from natural gas hydrates

Economic studies on simulated gas hydrate reservoirs have been compiled to estimate the price of natural gas that may lead to economically viable production from the most promising gas hydrate accumulations. As a first estimate, $CDN 2005 12/Mscf is the lowest gas price that would allow economically viable production from gas hydrates in the absence of associated free gas, while an underlying gas deposit will reduce the viability price estimate to $CDN 2005 7.50/Mscf. Results from a recent analysis of the simulated production of natural gas from marine hydrate deposits are also considered in this report; on an IROR basis, it is $US 2008 3.50-4.00/Mscf more expensive to produce marine hydrates than conventional marine gas assuming the existence of sufficiently large marine hydrate accumulations. While these prices represent the best available estimates, the economic evaluation of a specific project is highly dependent on the producibility of the target zone, the amount of gas in place, the associated geologic and depositional environment, existing pipeline infrastructure, and local tariffs and taxes. ?? 2009 Elsevier B.V.

Energy Economics↗
USGS1969

Potassium-argon ages bearing on the igneous and tectonic history of the Elk Mountains and vicinity, Colorado: A preliminary report

K-Ar ages for epizonal plutonic rocks together with field studies indicate that uplift of the Sawatch Range began at least 72 m.y. ago. Vertical uplift of the Sawatch Range was followed or accompanied by gravity sliding of sedimentary rocks along the Elk Range thrust fault. The greatest volume of exposed intrusive rocks in the Elk Mountains, Ruby Range, and West Elk Mountains consists of granodioritic rocks of Oligocene age which are younger than the Elk Range thrust. Miocene and Pliocene(?) mafic dikes were emplaced after most of the structural features in the area had developed. The Treasure Mountain dome near Marble was formed by emplacement of a unique soda granite pluton about 12.5 m.y. ago. Discordant K-Ar and Rb-Sr ages for biotite from the Twin Lakes stock in the Sawatch Range suggest that this large pluton is of Late Cretaceous or early Tertiary age and lost argon during Oligocene plutonism, or is of Eocene age and represents a separate event not yet supported by other radiometric dates from the area.

Colorado↗
USGS1956

A preliminary report on model studies of magnetic anomalies of three-dimensional bodies

Model experiments were made to devise a rapid method for calculating magnetic anomalies of three-dimensional structures. The magnetic fields of the models were determined using the equipment at the Naval Ordnance Laboratory, White Oaks, Md. An irregularly shaped mass was approximated by an array of prismatic rectangular slabs of constant thickness and varying horizontal dimensions. Contoured maps are being prepared for these magnetic models at different depths and for several magnetic inclinations. The fields of these three-dimensional structures are obtained by superimposing the appropriate contoured maps and adding numerically the effects at each point. The equipment and laboratory methods are described. Theoretical and practical examples are given.

Geophysics↗