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USGS1956

Floods of August 1955 in the Northeastern States

The floods of August 1955 were an unprecedented disaster in a arge area of the northeastern United States. They rank among the most destructive in the country's his ory. Augmented by the antecedent hurricane sto m of August 11-15, the rainfall of August 17-20 accompanying hurricane Diane reached maximum val es of 17 to 19 inches in south-central Massachusett • Record-breaking floods resulted within a broad re ion extending from southeastern Pennsylvania to east rn Massachusetts. The floods were outstanding in four categories: The large geogra hie area covered by floods of such magnitude; the ex ensive damage and loss .of life ranking with the grea est recorded in this country; the degree to which prio records were exceeded; and the distribution which as such that the greatest floods occurred predominate! on the smaller streams. Property damage has been stimated to be about half a billion dollars and was most~y concentrated in the heavily industrialized valleys f New England. A death toll of 179 persons was attr"buted to the floods. Peak discharges exceeded previ usly established maxima by 2. 2 and 2. 3 times respec ively, on Blackstone River at Woonsocket, R. I. , and Q inebaug River at Putnam, Conn.; 4. 1 times on Nau atuck River near Thomaston, Conn. ; and 4. 5 times on 1 ush Kill at Shoemakers, Pa. A unit runoff of 2, 300 c 1 hie feet per second per square mile occurred from ~· 50 square miles on Powdermill Brook near Westfiel , Mass. Although the floods were generally greate t on the smaller streams, Connecticut River at Hart ord reached the third highest stage since settlement an Delaware River between Port Jervis and Trenton exce ded the previous historic flood of 1903. This adv ce report has been prepared to supply preliminary · formation needed for immediate planning. It has been r leased pending preparation of a more comprehensive r port covering a three-month period of floods within an area from Massachusetts to North Carolina. In luded herein, for the region from Massachuset s to Pennsylvania, are general descriptions of the fEods, peak discharges for the present and previous rec rd floods at gaging stations, peak discharges at m y miscellaneous sites in the areas of greatest floo ing, and detailed stage and discharge data at 51 selecte gaging stations.

Circular↗

USGS2003

Metamorphic origin of ore-forming fluids for orogenic gold-bearing quartz vein systems in the North American Cordillera: constraints from a reconnaissance study of δ 15 N, δD, and δ 18 O

The western North American Cordillera hosts a large number of gold-bearing quartz vein systems from the Mother Lode of southern California, through counterparts in British Columbia and southeastern Alaska, to the Klondike district in central Yukon. These vein systems are structurally controlled by major fault zones, which are often reactivated terrane-bounding sutures that formed in orogens built during accretion and subduction of terranes along the continental margin of North America. Mineralization ages span mid-Jurassic to early Tertiary and encompass much of the evolution ofthe Cordilleran orogen. Nitrogen contents and δ15N values of hydrothermal micas from veins are between 130 and 3,500 ppm and 1.7 to 5.5 per mil, respectively. These values are consistent with fluids derived from metamorphic dehydration reactions within the Phanerozoic accretion-subduction complexes, which have δ15N values of 1 to 6 per mil. The δ18O values of gold-bearing vein quartz from different locations in the Cordillera are between 14.6 and 22.2 per mil but are uniform for individual vein systems. The δD values of hydrothermal micas are between -110 and -60 per mil. Ore fluids have calculated δ18O values of 8 to 16 per mil and δD values of -65 to -10 per mil at an estimated temperature of 300δC; δD values of ore fluids do not show any latitudinal control. These results indicate a deep crustal source for the ore-forming fluids, most likely of metamorphic origin. Low δDH2O values of -120 to -130 per mil for a hydrous muscovite from the Sheba vein in the Klondike district reflect secondary exchange between recrystallizing mica and meteoric waters. Collectively, the N, H, and O isotope compositions of ore-related hydrothermal minerals indicate that the formation of these gold-bearing veins involved dilute, aqueous carbonic, and nitrogen-bearing fluids that were generated from metamorphic dehydration reactions at deep crustal levels. These data are not consistent with either mantle-derived fluids or granitoid-related magmatic fluids, nor do they support a model involving deeply circulated meteoric water.

Economic Geology↗

USGS1992

Mid-Mesozoic (Mid-Jurassic to Early Cretaceous) evolution of the Georges Bank Basin, U.S. North Atlantic outer continental shelf: Sedimentology of the Conoco 145-1 well

The Conoco 145-1 exploratory well, located in the southeastern portion of the Georges Bank Basin, was drilled to a total depth of 4303 m below the sea floor. The oldest sedimentary rocks sampled are of Middle Jurassic age (Late Bathonian-Callovian). A dolomite-limestone-evaporite sequence dominates the section below 3917 m; limestone is the predominant lithology in the intervals of 3271-3774 m, 2274-3158 m, and 1548-1981 m. Siliciclastics dominate the remainder of the drilled section. Calcite tightly cements most of the rocks below 1548 m; dolomite, silica, siderite, and diagenetic clay cements are locally important. Restricted inner marine environments, representing lagoonal and tidal flat conditions, prevailed at the wellsite during much of the deposition recorded by the Callovian-Bathonian age Iroquois Formation. These environments gave way to a carbonate platform, which formed part of the > 5,000 km long Bahama-Grand Banks gigaplatform that lasted through the end of the Late Jurassic (encompassing the uppermost portion of the Iroquois Formation and the Scatarie Limestone and Bacarro Limestone Members of the Abenaki Formation). The absence of a skeletal-reef association and the dominance of muddy limestone fabrics are evidence that the 145-1 wellsite was located on the platform interior. Major periods of siticiclastic deposition interrupted carbonate deposition, and they are recorded by stratigraphic equivalents of the Mohican Formation, Misaine Shale Member of the Abenaki Formation, and the Mohawk and Mic Mac Formations. A series of sustained prograding delta systems, the earliest of which is preserved as the Missisauga Formation, buried the carbonate platform following its drowning in the Early Cretaceous (Berriasian-Valanginian). The sparser, primarily allochthonous lignite content and better-sorted, glauconite-bearing sands of the Missisauga strata at the 145-1 wellsite suggest that shallow marine or barrier-bar environments were more prevalent than the low delta-plain facies recorded farther shoreward at the COST G-1 wellsite.

Sedimentary Geology↗

USGS2022

Early Neoproterozoic gold deposits of the Alto Guaporé province, southwestern Amazon craton, western Brazil

The Alto Guaporé gold province, southwestern Amazon craton, contains gold deposits that have been mined since the beginning of the 18th century and these deposits, together, have modern-day, pre-mining gold resources of at least 1.8 Moz. The ore is associated with quartz vein systems along the southeastern part of the Aguapei belt, a ~35-km-wide and ~500-km-long, NNW-trending shear zone formed due to reactivation of a terrane-bounding suture. The Aguapei belt evolved by ca. 1150 to 1100 Ma rifting and deposition of siliciclastic sediments in an aulacogen basin, followed by deformation and low-grade metamorphism of the sedimentary sequences during 1100 to 900 Ma terrane collision along the craton margin. The deformation was characterized by a compressional regime until ca. 950 Ma and transition to a transpressional setting during the final 50 m.y. The gold deposits are hosted in a variety of structures that are second-order to the main Aguapei shear zone. The Ernesto and Pau-a-Pique deposits are located ~40 km apart and at jogs along the Aguapei belt. They are marginal to pre-ore igneous rocks, with Ernesto hosted in the basal part of the metasedimentary Fortuna Formation that overlies tonalite and Pau-a-Pique at the contact between metasedimentary rocks and diorite. Three deformational phases comprise the compressional (D 1 to D 2 ) to transpressional (D 3 ) tectonic events. In the Pau-a-Pique deposit and the deeper level of the Ernesto deposit, the ore-bearing veins are bedding parallel and follow D 2 strike-slip and reverse fault zones, respectively. However, the veins formed during D 3 reactivation of the older structures by an array of oblique accommodation faults. In contrast, ores at shallower levels of Ernesto, both in discordant and bedding-parallel veins, are hosted within a ~20-m-thick rigid metaconglomerate with associated dilation due to the structural complexity as sedimentary rocks of the Aguapei Group were folded around the dome-shaped roof of the pre-ore tonalite. The ores in both deposits, as well as in many other deposits of the province, are characterized by disseminated and vein-hosted pyrite. Gold occurs mainly as inclusions in the pyrite, with other hydrothermal phases comprising muscovite, Fe-Ti oxides, and minor apatite, chalcopyrite, and galena. Fluid inclusion data, coupled with stable isotope geochemistry and geothermometry, indicate that gold precipitated from a low-salinity, CO 2 -rich fluid at ~300°C and ~2.5 kbar. The source for the fluid and gold was the interbedded pelites during devolatilization of the Aguapei Group sequence. The aqueous-carbonic fluid inclusions and the narrow range of δ 18 O values of quartz (12 ± 1 ‰ ) from many auriferous veins from the central part of the province represent a regional ore-forming fluid. The broad range of δ D for hydrous minerals (–116 to –55 ‰ ) reflects influx of small amounts of meteoric water into the steeply dipping shear zones during postgold exhumation. The 40 Ar/ 39 Ar geochronology from hydrothermal muscovite indicates a widespread hydrothermal event along the belt between 928 and 920 Ma. Collectively, the geological, geochronological, and geochemical data suggest that metamorphic fluids migrated laterally into and then upward along the Aguapei belt and deposited gold in lower-order structures where strain gradients existed between lithounits. The province has many characteristics of large orogenic gold provinces worldwide and represents a highly prospective and underexplored target region for early Neoproterozoic gold, a time period that generally is not well endowed in gold ores.

Alto Guaporé gold province, Amazon craton↗

USGS2000

Age and Pb-Sr-Nd isotopic systematics of plutonic rocks from the Green Mountain magmatic arc, southeastern Wyoming: Isotopic characterization of a Paleoproterozoic island arc system

Three new U-Pb zircon ages and the Pb-Sr-Nd isotopic systematics of 24 whole-rock samples from mainly plutonic rocks of the Sierra Madre and Medicine Bow Mountains near the Colorado-Wyoming border help establish the Green Mountain magmatic arc as a Paleoproterozoic, variably eroded, island arc terrane. The Green Mountain magmatic arc, a terrane composed of variably metamorphosed volcanic and volcaniclastic rocks, minor metasedimentary rocks, high-grade gneisses, and plutons ranging from gabbro to granodiorite, was formed between ca. 1792 and 1744 Ma. It is the northernmost and oldest part of the Colorado province and is separated from Archean rocks to the north by the east-west-trending Cheyenne belt. New U-Pb zircon ages were determined for two dioritic samples of the Mullen Creek complex (1778 ±2 and 1778 ±17 Ma; an ultramafic/mafic layered intrusion) and for a sample of the Rambler granite (1771 ±3.4 Ma); both units are exposed in the Medicine Bow Mountains. A Sm-Nd internal isochron age of 1750 ±24 Ma (ϵ Nd i = + 3.8) was determined that is within error of the Sm-Nd whole-rock isochron age for the entire Lake Owen sample database (1775 ±45 Ma). Initial Nd signatures (+ 3.3 to 4.8) indicate that the bulk of the arc rocks was derived from a depleted mantle source at 1.78 Ga. Although the Rb-Sr systematics appear disturbed, data from extremely low Rb/Sr, non-hydrous, ultramafic layered units indicate an initial 87 Sr/ 86 Sr value of 0.7024. The range of initial Sr isotopic values for these rocks is elevated relative to depleted mantle sources at 1.78 Ga, an isotopic distinction of modern primitive oceanic island arc systems. The U-Pb data on the same mafic rock samples are consistent with the other isotopic results. The values define average initial Pb values of 206 Pb/ 204 Pb = 15.7 and 207 Pb/ 204 Pb = 15.3, indicative of a depleted mantle source at 1.78 Ga. Felsic plutonic arc rocks exhibit disturbed Pb and Sr isotopic behavior. They are characterized by the same depleted mantle signature with initial ϵ Nd values of ∼2.9–4.4, however, indicating little crustal contamination of source magmas for granites and precluding their derivation by subduction of Archean crustal components during collisional accretion of the arc.

Colorado, Wyoming↗

USGS1966

Hydrology of limestone terranes in the coastal plain of the Southeastern United States

T he very productive limestone aquifers of Tertiary and Quaternary age in the Coastal Plain of the Southeastern States contain a water-table circulation system where aquifers are at or near the land surface; the Tertiary limestone unit is a homoclinal artesian system confined beneath younger beds in coastal areas. The Tertiary limestone has a total thickness of several thousand feet and ranges in age from Paleocene to Pliocene. The part of the limestone that represents a hydrologic unit, as much as 1000 feet thick, ranges in age from middle Eocene to middle Miocene. That unit is the principal artesian aquifer in Florida and southeastern Georgia. It is also an aquifer, but of lesser importance, in South Carolina, North Carolina, and Alabama. In southeastern Florida the Quaternary limestone forms a shallow, although highly productive, aquifer. In general, the Tertiary formations dip gently toward the coast, except where the regional dip is interrupted by folds such as the Cape Fear arch, the Ocala uplift, and the Chattahoochee anticline, or by faults such as those on the Ocala uplift. A piezometric map showing the head of water in the principal artesian aquifer in Florida and southeastern Georgia reveals chief areas of recharge where limestone crops out in interstream areas and where sinkholes breach overlying beds; it reveals principal discharge areas in certain stream valleys, springs, and offshore. Lateral movement of the water in the limestone is generally controlled by the hydraulic gradient to the nearest discharge area. The movement may be either controlled by or independent of faults and folds; it may be along joints for short distances. Solution by downward movement of water in the zone of aeration to the water table has formed vertical tubular openings or shafts. Lateral movement of the water from areas of recharge to areas of discharge has formed caves and other solution channels, chiefly in the upper part of the zone of saturation. Since they were formed, some caves have been drowned, and others have been exposed in the zone of aeration as the water rose and fell, chiefly in Pleistocene time. The principal aquifer in Florida probably has caves and solution channels comparable in size and extent to those of Mammoth Cave, Kentucky; however, only a small percentage of these are above the water table at the present time. In a large part of the region the most noticeable change in chemical quality of the water in the limestone resulting from circulation of water is the freshening accompanying removal of salty water from the aquifer. Changes in sea level during Pleistocene time have raised and lowered the water table; thus the position of the upper part of the zone of saturation, in which conditions were most favorable for solution and for the formation of cavities, has changed repeatedly. At the lowest stand of the Pleistocene sea, it is conceivable that the water level in part of the limestone in north-central Florida was a few hundred feet lower than at present. The present pattern of solution openings probably was developed in Pleistocene time.

Southeastern United States↗

USGS2012

Reactivation of the Archean-Proterozoic suture along the southern margin of Laurentia during the Mazatzal orogeny: Petrogenesis and tectonic implications of ca. 1.63 Ga granite in southeastern Wyoming

The presence of ca. 1.63 Ga monzogranite (the “white quartz monzonite”) in the southern Sierra Madre, southeastern Wyoming, is anomalous given its distance from the nearest documented plutons of similar age (central Colorado) and the nearest contemporaneous tectonic margin (New Mexico). It is located immediately south of the Cheyenne belt—a ca. 1.75 Ga Archean-Proterozoic tectonic suture. New geochronological, isotopic, and geochemical data suggest that emplacement of the white quartz monzonite occurred between ca. 1645 and 1628 Ma (main pulse ca. 1628 Ma) and that the white quartz monzonite originated primarily by partial melting of the Big Creek Gneiss, a modified arc complex. There is no evidence that mafic magmas were involved. Open folds of the ca. 1750 Ma regional foliation are cut by undeformed white quartz monzonite. On a regional scale, rocks intruded by the white quartz monzonite have experienced higher pressure and temperature conditions and are migmatitic as compared to the surrounding rocks, suggesting a genetic relationship between the white quartz monzonite and tectonic exhumation. We propose that regional shortening imbricated the Big Creek Gneiss, uplifting the now-exposed high-grade rocks of the Big Creek Gneiss (hanging wall of the thrust and wall rock to the white quartz monzonite) and burying correlative rocks, which partially melted to form the white quartz monzonite. This tectonism is attributed to the ca. 1.65 Ga Mazatzal orogeny, as foreland shortening spread progressively into the Yavapai Province. Mazatzal foreland effects have also been described in the Great Lakes region and have been inferred in the Black Hills of South Dakota. We suggest that the crustal-scale rheologic contrast across the Archean-Proterozoic suture, originally developed along the southern margin of Laurentia, and including the Cheyenne belt, facilitated widespread reactivation of that boundary during the Mazatzal orogeny. This finding emphasizes the degree to which crustal heterogeneities can localize subsequent deformation in accretionary orogens, producing significant crustal melting in the distal foreland—a region not typically associated with orogenic magmatism.

Colorado;Wyoming↗

USGS1978

The hydrothermal system of Long Valley Caldera, California

Long Valley caldera, an elliptical depression covering 450 km 2 on the eastern front of the Sierra Nevada in east-central California, contains a hot-water convection system with numerous hot springs and measured and estimated aquifer temperatures at depths of 180?C to 280?C. In this study we have synthesized the results of previous geologic, geophysical, geochemical, and hydrologic investigations of the Long Valley area to develop a generalized conceptual and mathematical model which describes the gross features of heat and fluid flow in the hydrothermal system. Cenozoic volcanism in the Long Valley region began about 3.2 m.y. (million years) ago and has continued intermittently until the present time. The major event that resulted in the formation of the Long Valley caldera took place about 0.7 m.y. ago with the eruption of 600 km 3 or more of Bishop Tuff of Pleistocene age, a rhyolitic ash flow, and subsequent collapse of the roof of the magma chamber along one or more steeply inclined ring fractures. Subsequent intracaldera volcanism and uplift of the west-central part of the caldera floor formed a subcircular resurgent dome about 10 km in diameter surrounded by a moat containing rhyolitic, rhyodacitic, and basaltic rocks ranging in age from 0.5 to 0.05 m.y. On the basis of gravity and seismic studies, we estimate an aver- age thickness of fill of 2.4 km above the precaldera granitic and metamorphic basement rocks. A continuous layer of densely welded Bishop Tuff overlies the basement rocks, with an average thickness of 1.4 km; the fill above the welded Bishop Tuff consists of intercalated volcanic flows and tuffs and fluvial and lacustrine deposits. Assuming the average grain density of the fill is between 2.45 and 2.65 g/cm 3 , we calculate the average bulk porosity of the total fill as from 0.11 to 0.21. Comparison of published values of porosity of the welded Bishop Tuff exposed southeast of the caldera with calculated values indicates average bulk porosity for the welded tuff (including fracture porosity) from 0.05 to 0.10. Because of its continuity and depth and the likelihood of significant fracture permeability in the more competent rocks such as the welded tuff, our model of the hydrothermal system assumes that the Bishop Tuff provides the principal hot-water reservoir. However, because very little direct information exists from drill holes below 300 m, this assumption must be considered tentative. Long Valley caldera is drained by the Owens River and several tributaries which flow into Lake Crowley in the southeast end of the caldera. Streamflow and springflow measurements for water years 1964-74 indicate a total inflow to Lake Crowley of about 10,900 L/s. In contrast, the total discharge of hot water from the hydrothermal reservoir is about 300 L/s. For modeling purposes, the ground-water system is considered as comprising a shallow subsystem in the fill above the densely welded Bishop Tuff containing relatively cold ground water, and a deep subsystem or hydrothermal reservoir in the welded tuff containing relatively hot ground water. Hydrologic, isotopic, and thermal data indicate that recharge to the hydrothermal reservoir occurs in the upper Owens River drainage basin along the western periphery of the caldera. Temperature profiles in a 2.11- km-deep test well drilled by private industry in the southeastern part of the caldera suggest that an additional flux of relatively cool ground water recharges the deep subsystem around the northeast rim. Flow in the shallow ground-water subsystem is neglected in the model except in recharge areas and along Hot Creek gorge, where approximately 80 percent of the hot-water discharge from the hydrothermal reservoir moves upward along faults toward springs in the gorge. Heat-flow data from the Long Valley region indicate that the resurgent dome overlies a residual magma chamber more circular in plan than the original magma chamber that supplied the Bishop Tuff

California↗

USGS1968

Stratigraphy and structure of the tatum salt dome area, southeastern Mississippi and northeastern Washington Parish, Louisiana

In the 3000-square-mile area of southeastern Mississippi and northeastern Washington Parish , Louisiana , which has Tatum dome in its center, rocks of known Jurassic to Recent age are more than 20,000 feet thick. They are underlain by an unknown thickness of Louann Salt of Jurassic (?) age. The age, thickness, and nature of the sedimentary rocks between the salt and the basement, as well as the character of the basement, are unknown. The salt in the northern half of the area has moved upward to shallow depths as diapirs in overlying rocks. Outside of the area of shallow-piercement domes there are more deeply seated domes, ridges, and anticlines that may be the result of vertical movement of the salt . The Wiggins anticline in the south and, southwest of it, an area dipping more steeply to the southwest probably were not affected by salt movement. Structural maps of four horizons and isopach maps of rocks in the three intervals between them give information about the sedimentary and structural history of the region since the end of Early Cretaceous time. The horizons contoured mark either unconformities or the upper boundaries of zones of fairly uniform structural history. The top of the Lower Cretaceous rocks dips generally to the west. Upper Cretaceous rocks dip to the west-southwest and thicken to the northeast. Pre-Miocene Tertiary rocks dip to the southwest and thicken to the northwest. Miocene and later rocks dip and thicken to the south-southwest. The structure of the older formations is considerably more irregular than that of the younger ones; domes, ridges, and basins that were conspicuous in the Early Cretaceous became less pronounced as younger sediments progressively covered them. Of the eight shallow-piercement domes with which the author is familiar, three are known to have penetrated Oligocene rocks; two, middle Eocene; one, lower Eocene; one, Upper Cretaceous; and one, Lower Cretaceous. Some movement has taken place at Tatum dome since the sandy, gravelly Citronelle Formation was laid down.

Louisiana, Mississippi↗

USGS2001

Effects of ground-water withdrawals on flow in the Sauk River Valley Aquifer and on streamflow in the Cold Spring area, Minnesota

The U. S. Geological Survey, in cooperation with the city of Cold Spring, Minnesota conducted a study during 1998-99 to: (1) determine the contributing areas of groundwater flow to high-capacity wells, (2) delineate the 10-, 20-, and 30-year time-of-travel zones to high-capacity wells, and (3) determine changes in streamflow in the Sauk River due to ground-water withdrawals. Surficial aquifers underlie a portion of the uplands in the north-central part of the study area and the Sauk River Valley. The upland surficial aquifer is unconfined, with saturated thicknesses ranging from 6 to 37 feet. The Sauk River Valley aquifer consists of hydraulically connected sand and gravel units: (1) the generally continuous surficial unconfined unit underlying the Sauk River Valley and (2) buried confined units that are overlain by till or lake clays in the upland areas. Maximum saturated thickness of the Sauk River Valley aquifer is about 50 feet. Thicknesses of the buried units are generally 10 to 20 feet. Ground-water flow in the upland surficial aquifer is (1) to the south and southeast toward the margins of the aquifer and (2) toward an unnamed creek valley in the northwestern part of the study area. Ground-water flow in the Sauk River Valley aquifer is from upland areas toward the Sauk River and the connected chain of lakes. Based on hydrograph analysis, ground-water recharge rates to the aquifers during 1999 ranged from 5.3 to 8.6 inches per year, with an average value of 7.0 inches per year. Streamflow measurements indicated net gains of 44.8 and 25.8 cubic feet per second for the Sauk River from Cold Spring to Rockville during October 1998 and August 1999, respectively. In general, the Sauk River probably is a gaining stream in all reaches, except for the reach adjacent to the Gold'n Plump Poultry Processing Plant well field. Ground-water withdrawals from the well field induce infiltration of water from the Sauk River to the underlying aquifer. The measured gains in streamflow for Brewery Creek were 2.75 and 2.25 cubic feet per second during October 1998 and August 1999, respectively. A numerical ground-water-flow model was constructed and calibrated for steady-state conditions. Based on the calibrated model, areal recharge accounts for 51.5 percent of the sources of water to the aquifers in the Cold Spring area and inflow through constant-head boundaries contributes 45.8 percent. The largest discharges from the aquifers are leakage from the Sauk River Valley aquifer to the Sauk River and Brewery Creek (53.7 percent) and outflow through constant-head boundaries (33.1 percent). The simulated contributing areas for selected watersupply wells in the Cold Spring area generally extend to and possibly beyond the model boundaries to the north and to the southeast. The contributing areas for the Gold'n Plump Poultry Processing Plant supply wells extend: (1) to the Sauk River, (2) to the north to and possibly beyond to the northern model boundary, and (3) to the southeast to and possibly beyond the southeastern model boundary. The primary effects of projected increased ground-water withdrawals of 0.23 cubic feet per second (7.5 percent increase) were to: (1) decrease outflow from the Sauk River Valley aquifer through constant-head boundaries and (2) decrease leakage from the valley unit of the Sauk River Valley aquifer to the streams. No appreciable differences were discernible between the simulated steady-state contributing areas to wells with 1998 pumpage and those with the projected pumpage.

Minnesota↗

USGS1961

Distribution of uranium ore deposits in the elk ridge area, San Juan County, Utah

The Elk Ridge area of southeastern Utah contains uranium ore deposits in two lower members of the Chinle formation of Late Triassic age. Each member is mineralized in different parts of the area , and where both are present only the lower contains ore . Across the Elk Ridge area from southwest to northeast, successively younger beds lap onto the unconformity that separates the Chinle from the underlying Moenkopi formation of Triassic(?), Early and Middle(?) Triassic age. Important uranium deposits have been found only in sandstone beds of the Chinle that are in contact with the Moenkopi. Sandstone of the Chinle formation lies on the Moenkopi (or is separated from it by gray mudstone of the Chinle no thicker than the depths of most of the known paleostream channel scours) in two separate parts of the Elk Ridge area . These "favorable areas" contain all the mines and important prospects. The ore deposits are flat-lying tabular to lenticular bodies in fluvial sandstone beds of the Chinle with fine-grained black uranium minerals chiefly interstitial to sand grains and as replacement of carbonaceous material. Most of the ore -bearing sandstone beds are discontinuous lenses intertonguing with and overlain by relatively impermeable mudstone. Contact of the host sandstone with the underlying Moenkopi seems to be a prerequisite for ore as the ore bodies are generally within a few feet of such contact areas and sandstone lenses separated from the Moenkopi by gray mudstone are generally not ore bearing. The consistent association of ore deposits with the Chinle-Moenkopi contact suggests that mineralizing solutions were introduced into the host beds from their areas of contact with the Moenkopi formation. Impermeable barriers overlying ore -bearing parts of the host sandstones were probably an important control on the deposition of ore minerals from solution. Hypofiltration of metallic constituents from ascending ore solutions may have been important. It is also possible that the overlying barriers formed traps for H2S gas or fluid hydrocarbons and thus localized a reducing chemical environment in which ore minerals were later precipitated.

Utah↗

USGS1964

Geology and ground-water resources of Nobles County, and part of Jackson County, Minnesota

The area described in this report is in southwestern Minnesota, about 130 miles southwest of Minneapolis and St. Paul. It includes; Nobles County and the western tier of townships in Jackson County, a total of 864 square miles. Worthington, the Nobles County seat, is the largest city in the area, having a population of 9,015 persons (1960 census). Farming is the leading occupation, and food processing is the major industry. Critical water shortages have occurred in several parts of the area. The climate is characterized by mild, subhumid summers and relatively long, severe winters. Mean monthly temperatures range from 15.1 °F in January to 73.3 °F in July. The mean annual precipitation is 26.75 inches. The crest of the Coteau des Prairies, a broad highland belt, traverses Nobles County from northwest to southeast. Three glacial end moraines and their associated ground moraines trend south to southeast across the area. Altitudes range from about 1,820 feet on the crest of the coteau in the northwestern part of the area to about 1,390 feet above mean sea level in the Jack and Okabena Creek valleys in the northeast. The Mississippi-Missouri River drainage divide crosses the area from north to east. The Gary outer end moraine trends southeast through central Nobles County. East of this moraine the land is poorly drained and contains numerous lakes and swamps; west of this moraine the land is well drained and contains few, if any, undrained depressions. Within the area, granite and Sioux Quartzite of Precambrian age are overlain by Cretaceous strata, except locally in the northeast and northwest parts of the area where the quartzite is directly overlain by glacial drift. The Cretaceous strata are composed of interbedded shale, siltstone, and sandstone. The surface of the area is composed of Pleistocene deposits of glacial drift and some thin, patchy deposits of Recent age. Bedrock is not known to crop out in the area. The drift ranges in thickness from about 150 feet in the southwest and northeast corners to about 500 feet on the highest part of the Coteau des Prairies. The Precambrian granite is not a source of ground water in this area. The Sioux Quartzite yields moderate supplies in adjacent counties to the north and west, but because of its sporadic occurrence it does not constitute an important water source in this area. The Cretaceous sandstone units are a secondary source of ground water and yield adequate supplies 'to at least 24 farm wells, which range in depth from 283 to 586 feet below land surface. The primary source of ground water in the Nobles-Jackson County area is the glacial drift. Buried outwash deposits supply water to 7 of the 10 municipalities and to most of the farms in the area. Two Worthington city wells, completed in a buried outwash deposit underlying East Okabena dry lake bed, were tested for short periods at 500 gallons per minute. The estimated coefficient of transmissibility for the aquifer at one of the wells was 70,000 gpd (gallons per day) per ft. The buried outwash deposits may occur anywhere within the drift from about 15 feet below land surface to bedrock which is as much as 500 feet below land surface. The outwash ranges from a fraction of a foot to more than 25 feet in thickness where permeable; below the water table it generally will supply ample quantities of water to properly constructed wells. Surflcial outwash deposits fill the valley bottoms and form the terrace deposits associated with the present-day drainage channels. The thicker, more extensive, and continuous deposits occur in the proglacial stream channels that drained the fronts of the ice sheets rather than in those channels that now drain the backs of the moraines. The surflcial outwash deposits generally are made up of sand, gravel and some silt and clay, and range in thickness from 0 to more than 60 feet; they range in width from a few feet in the narrow tributaries to about one mile in the larger stream valleys. Four municipalities and many farms obtain part or all of their water supplies from surficial outwash. An Adrian municipal well, completed in this source, was pumped at a rate of 400 gpm. At the confluence of two streams which drain Ocheda Lake in southeastern Nobles County, the sand and gravel section is more than 60 feet thick in places. Results of a pumping test here showed an average coefficient of transmissibility of 150,000 gpd per ft. Coefficients of transmissibility may be as much as 500,000 gdp per ft in the thickest part of the deposit if the permeability of the sand and gravel is uniform. Recharge to the surflcial outwash deposits is relatively rapid; it is slower to the buried outwash deposits where the descending water must percolate through till of low permeability before entering the aquifers. The quality of water in the Precambrian crystalline rocks, the Cretaceous strata, and the buried Pleistocene aquifers is poor. Chemical analyses of 22 water samples showed that dissolved solids ranged from 1,100 ppm (parts per million) to 3,050 ppm. Water from the surficial outwash deposits is good by comparison; dissolved solids in water from these aquifers ranged from 425 to 870 ppm.

Minnesota↗

USGS2010

Kinetics of selenium release in mine waste from the Meade Peak Phosphatic Shale, Phosphoria Formation, Wooley Valley, Idaho, USA

Phosphorite from the Meade Peak Phosphatic Shale member of the Permian Phosphoria Formation has been mined in southeastern Idaho since 1906. Dumps of waste rock from mining operations contain high concentrations of Se which readily leach into nearby streams and wetlands. While the most common mineralogical residence of Se in the phosphatic shale is elemental Se, Se(0), Se is also an integral component of sulfide phases (pyrite, sphalerite and vaesite–pyrite ss ) in the waste rock. It may also be present as adsorbed selenate and/or selenite, and FeSe 2 and organo-selenides. Se release from the waste rock has been observed in field and laboratory experiments. Release rates calculated from waste rock dump and column leachate solutions describe the net, overall Se release from all of the possible sources of Se listed above. In field studies, Se concentration in seepage water (pH 7.4–7.8) from the Wooley Valley Unit 4 dump ranges from 3600 µg/L in May to 10 µg/L by Sept. Surface water flow, Q , from the seep also declines over the summer, from 2 L/s in May to 0.03 L/s in Sept. Se flux ([Se] ⁎ Q ) reaches a steady-state of < 150 mg/day in 1–4 months, depending upon the volume of Q . Se release (mg/L) follows a first order reaction with a rate constant, k , = 1.35 – 6.35e−3 h − 1 (11.8–55.6 yr − 1 ). Laboratory experiments were performed with the waste shale in packed bed reactors; residence time varied from 0.09 to 400 h and outlet pH ∼ 7.5. Here, Se concentration increased with increasing residence time and release was modeled with a first order reaction with k = 2.19e−3 h − 1 (19.2 yr − 1 ). Rate constants reported here fall within an order of magnitude of reported rate constants for oxidation of Se(0) formed by bacterial precipitation. This similarity among rate constants from both field and laboratory studies combined with the direct observation of Se(0) in waste shales of the Phosphoria Formation suggests that oxidation of Se(0) may control steady-state Se concentration in water draining the Wooley Valley waste dump.

Idaho↗

USGS1989

Hydrogeology of Wood County, Wisconsin

The presence of low-permeability Precambrian rocks near land surface limits ground-water availability in the northern two-thirds of Wood County. Sand and gravel deposits provide large amounts of water (more than 500 gallons per minute) to some wells in the southeastern part of the county. Fine-grained unconsolidated deposits generally are less than 20 feet thick in the northern two-thirds of the county, but sand and gravel deposits 40- to 100-feet thick underlie the extreme southeastern part of the county. Horizontal hydraulic conductivity of the sand and gravel deposits ranges from about 155 to about 280 feet per day. The horizontal hydraulic conductivity of fine-grained unconsolidated deposits in the northern part of the county ranges from about 0.02 to 2 feet per day. Where unconsolidated deposits do not yield dependable water supplies, wells are finished in Precambrian rocks. Fractures occurring at shallow depths are the primary source of water for wells finished in Precambrian rocks. Because the number of fractures tends to decrease with depth, the horizontal hydraulic conductivity of these rocks generally decreases from about 11 feet per day in wells less than 50-feet deep to about 0.02 foot per day in wells greater than 160 feet deep. Estimates of ground-water recharge to sand and gravel deposits in the southeastern part of the county range from about 7 to 12 inches per year. Recharge estimates for the central and northern parts of the county range from about 1 to 4 inches per year. The total dissolved-solids concentration in ground water in Wood County is relatively low. Concentrations in water samples from 124 wells ranged from 21 to 578 milligrams per liter, with a median concentration of about 190 milligrams per liter. Major dissolved constituents are calcium, magnesium, and bicarbonate; sodium, potassium, chloride, and sulfate are present in low concentrations. The most common water-quality problem in Wood County is elevated iron concentrations. Iron concentrations greater than 300 micrograms per liter were found in 54 of 124 samples, and 15 samples contained iron concentrations greater than 5,000 micrograms per liter. Nitrate as nitrogen concentrations exceeded Wisconsin's drinking-water standard (10 milligrams per liter) in water from just 4 of 124 wells. The pesticide aldicarb was detected in 7 of 36 samples, and various volatile organic compounds were detected in 24 of 102 ground-water samples collected by the Wisconsin Department of Natural Resources since 1980. Wells in which these chemicals were detected are near irrigated agricultural fields and in commercially developed areas where buried gasoline-storage tanks and chemical spills are more likely to occur. A reconnaissance approach combining electromagnetic surveys and sampling for water-quality indicators was used to assess effects of leachate on ground water near seven landfills. Results of the electromagnetic surveys were used to site water-quality observation wells. Total dissolved-solids concentrations and concentrations of volatile organic compounds, chloride, sulfate, iron, chemical oxygen demand, and organic carbon are some of the chemical constituents analyzed in samples collected from these wells. The average rate of ground·water pumpage in Wood County in 1985 was 9.7 million gallons per day. Of this rate, about 6 million gallons per day is pumped from municipal-supply wells in seven communities.An additional 1.08 million gallons per day is pumped for agricultural irrigation.

Wisconsin↗

USGS2009

Occurrence of Pesticides in Ground Water of Wyoming, 1995-2006

Little existing information was available describing pesticide occurrence in ground water of Wyoming, so the U.S. Geological Survey, in cooperation with the Wyoming Department of Agriculture and the Wyoming Department of Environmental Quality on behalf of the Wyoming Ground-water and Pesticides Strategy Committee, collected ground-water samples twice (during late summer/early fall and spring) from 296 wells during 1995-2006 to characterize pesticide occurrence. Sampling focused on the State's ground water that was mapped as the most vulnerable to pesticide contamination because of either inherent hydrogeologic sensitivity (for example, shallow water table or highly permeable aquifer materials) or a combination of sensitivity and associated land use. Because of variations in reporting limits among different compounds and for the same compound during this study, pesticide detections were recensored to two different assessment levels to facilitate qualitative and quantitative examination of pesticide detection frequencies - a common assessment level (CAL) of 0.07 microgram per liter and an assessment level that differed by compound, referred to herein as a compound-specific assessment level (CSAL). Because of severe data censoring (fewer than 50 percent of the data are greater than laboratory reporting limits), categorical statistical methods were used exclusively for quantitative comparisons of pesticide detection frequencies between seasons and among various natural and anthropogenic (human-related) characteristics. One or more pesticides were detected at concentrations greater than the CAL in water from about 23 percent of wells sampled in the fall and from about 22 percent of wells sampled in the spring. Mixtures of two or more pesticides occurred at concentrations greater than the CAL in about 9 percent of wells sampled in the fall and in about 10 percent of wells sampled in the spring. At least 74 percent of pesticides detected were classified as herbicides. Considering only detections using the CAL, triazine pesticides were detected much more frequently than all other pesticide classes, and the number of different pesticides classified as triazines was the largest of all classes. More pesticides were detected at concentrations greater than the CSALs in water from wells sampled in the fall (28 different pesticides) than in the spring (21 different pesticides). Many pesticides were detected infrequently as nearly one-half of pesticides detected in the fall and spring at concentrations greater than the CSALs were detected only in one well. Using the CSALs for pesticides analyzed for in 11 or more wells, only five pesticides (atrazine, prometon, tebuthiuron, picloram, and 3,4-dichloroaniline, listed in order of decreasing detection frequency) were each detected in water from more than 5 percent of sampled wells. Atrazine was the pesticide detected most frequently at concentrations greater than the CSAL. Concentrations of detected pesticides generally were small (less than 1 microgram per liter), although many infrequent detections at larger concentrations were noted. All detected pesticide concentrations were smaller than U.S. Environmental Protection Agency (USEPA) drinking-water standards or applicable health advisories. Most concentrations were at least an order of magnitude smaller; however, many pesticides did not have standards or advisories. The largest percentage of pesticide detections and the largest number of different pesticides detected were in samples from wells located in the Bighorn Basin and High Plains/ Casper Arch geographic areas of north-central and southeastern Wyoming. Prometon was the only pesticide detected in all eight geographic areas of the State. Pesticides were detected much more frequently in samples from wells located in predominantly urban areas than in samples from wells located in predominantly agricultural or mixed areas. Pesticides were detected distinctly less often in sa

Scientific Investigations Report↗

USGS1970

The structure and origin of the large submarine canyons of the Bering Sea

Three exceptionally large and long submarine canyons — Bering, Pribilof, and Zhemchug — incise the continental slope underlying the southeastern Bering Sea. Bering Canyon, the world's longest known slope valley, is approximately 400 km long and has a volume of 4,300 km 3 . The volume of Pribilof Canyon is 1,300 km 3 and that of Zhemchug is 8,500 km 3 ; Zhemchug Canyon may well be the world's largest slope valley; most other large submarine canyons have volumes less than 500 km 3 . Pribilof and Zhemchug canyons are further distinguished by the headward bifurcation of their slope axes to form elongated trough-shaped basins behind the regionally projected position of the shelf edge. These troughs are superimposed over structural depressions formed by down-faulted basement rocks of Mesozoic and older ages. Prior to canyon cutting these depressions were filled with as much as 2,600 m of shallow-water diatomaceous, tuffaceous, and detrital sediments largely of Tertiary age. Deposition of these sediments took place concurrently with general margin subsidence of at least 2,000 m. The data and conclusions presented in this paper stress that the location, trend, and shape of the enormous submarine canyons cutting the Bering margin are structurally determined. However, axial cutting and headward erosion within the relatively unconsolidated Tertiary strata and the older, lithified basement rock is thought to have been caused by basinward-sliding masses of sediment; these unstable sediment bodies accumulated on the upper continental slope and outer shelf, probably near the mouths of major Alaskan rivers. Bering Canyon was periodically cut and filled by axial sedimentation during Late Tertiary and Quaternary time. Pribilof and Zhemchug canyons, however, are thought to have been excavated entirely during the Pleistocene. It is presumed that, during one or more periods of glacially lowered sea level, the Kuskokwim and Yukon rivers emptied into or near the heads of Pribilof and Zhemchug canyons. The enormous size and unusual shape of Zhemchug Canyon resulted from the breaching of the seaward wall of an outer-shelf basement depression and the subsequent removal of nearly 4,500 km 3 of Tertiary deposits filling it.

Alaska↗

USGS2002

Place vs. time and vegetational persistence: A comparison of four tropical mires from the Illinois Basin during the height of the Pennsylvanian Ice Age

Coal balls were collected from four coal beds in the southeastern part of the Illinois Basin. Collections were made from the Springfield, Herrin, and Baker coals in western Kentucky, and from the Danville Coal in southwestern Indiana. These four coal beds are among the principal mineable coals of the Illinois Basin and belong to the Carbondale and Shelburn Formations of late Middle Pennsylvanian age. Vegetational composition was analyzed quantitatively. Coal-ball samples from the Springfield, Herrin, and Baker are dominated by the lycopsid tree Lepidophloios, with lesser numbers of Psaronius tree ferns, medullosan pteridosperms, and the lycopsid trees Synchysidendron and Diaphorodendron. This vegetation is similar to that found in the Springfield and Herrin coals elsewhere in the Illinois Basin, as reported in previous studies. The Danville coal sample, which is considerably smaller than the others, is dominated by Psaronius with the lycopsids Sigillaria and Synchysidendron as subdominants. Coal balls from the Springfield coal were collected in zones directly from the coal bed and their zone-by-zone composition indicates three to four distinct plant assemblages. The other coals were analyzed as whole-seam random samples, averaging the landscape composition of the parent mire environments. This analysis indicates that these coals, separated from each other by marine and terrestrial-clastic deposits, have essentially the same floristic composition and, thus, appear to represent a common species pool that persisted throughout the late Middle Pennsylvanian, despite changes in baselevel and climate attendant the glacial interglacial cyclicity of the Pennsylvanian ice age. Patterns of species abundance and diversity are much the same for the Springfield, Herrin, and Baker, although each coal, both in the local area sampled, and regionally, has its own paleobotanical peculiarities. Despite minor differences, these coals indicate a high degree of recurrence of assemblage and landscape organization. The Danville departs dramatically from the dominance-diversity composition of the older coals, presaging patterns of tree-fern and Sigillaria dominance of Late Pennsylvanian coals of the eastern United States, but, nonetheless, built on a species pool shared with the older coals. ?? 2002 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗

USGS1943

The Basin and Range Province in Utah, Nevada, and California

In this report an attempt has been made to summarize and in places to interpret the published information that was available through 1938 on the geology of those parts of Nevada, California, and Utah that are included in the geologic province known as the Basin and Range province. This region includes most of the Great Basin, from which no water flows to the sea, as well as part of the drainage basin of the lower Colorado River. It is characterized by numerous parallel, linear mountain ranges that are separated from one another by wide valleys or topographic basins. All the major divisions of geologic time are represented by the rocks exposed in this region. The oldest are of pre-Cambrian age and crop out chiefly along the eastern and southern borders. They have been carefully studied at only a few localities, and the correlation and extent of the subdivision so far recognized is uncertain. There appear to be at least three series of pre-Cambrian rocks which are probably separated from one another by profound unconformities. Large masses of intrusive igneous rocks have been recognized only in the oldest series. During the Paleozoic era the region was a part of the Cordilleran geosyncline, and sediments were deposited during all of the major and most of the minor subdivisions of the era. There are thick and widespread accumulations of Cambrian and Ordovician strata, the maximum aggregate thickness possibly exceeding 23,000 feet. The eastern and western boundaries of the province were approximately those of the area of rapid subsidence within the geosyncline, though the axes of maximum subsidence oscillated back and forth during the two periods. The Silurian and Devonian seas, on the other hand, extended beyond the province and, possibly as a consequence, are represented by much thinner sections - of the order of 6,000 feet. At the end of the Devonian period the geosyncline was split by the emergence of a geanticline in western Nevada, and Mississippian and Pennsylvanian sedimentary rocks are known only in the central and eastern part of the province. They locally attain considerable thicknesses, however, as the combined thickness of the two series in western Utah approaches 24,000 feet. The geanticline appears to have been eroded by Permian time, as Permian strata have been recognized in most parts of the province except the southern, where another geanticline, which persisted into the Mesozoic era, began to rise coincidentally with the disappearance of the older one. Igneous activity was at a minimum throughout the Paleozoic era. Some volcanism appears to have occurred locally in the Carboniferous period, but the lavas and sills cannot yet be accurately dated and may be somewhat younger. The second geanticline, which began to form in Permian time, was greatly extended during the Mesozoic era and eventually caused the disappearance of the geosynclinal seas that had persisted throughout most of Paleozoic time. Its axis lay east of the earlier geanticline, and its gradual emergence resulted in the development of two depositional troughs within the province. The western trough was filled with more than 30,000 feet of sediments and interbedded volcanic deposits, which range in age from basal Lower Triassic through the Lower Jurassic. Deposition in this trough was terminated by a period of intense orogeny near the end of Lower Jurassic time. The deposits of the eastern trough are found only along the eastern border of the province; they consist largely of nonmarine sedimentary beds ranging in age from Triassic to Upper Cretaceous. Marine Lower Triassic, possible Middle Triassic, and Upper Jurassic sedimentary rocks have been found in a few places, and some pyroclastic rocks occur in Lower Triassic and Upper Cretaceous beds. The eastern seaway appears to have been closed to the south, for lagoonal deposits, such as salines, characterize the southern and southeastern extensions of the marine formations. In addition to the sur

Professional Paper↗