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USGS2008

Hydrogeochemical investigation of the Standard Mine Vicinity, Upper Elk Creek Basin, Colorado

Ground- and surface-water samples were collected in the vicinity of the Standard Mine in west-central Colorado in order to characterize the local ground-water flow system, determine metal concentrations in local ground water, and better understand factors controlling the discharge of metal-rich waters from the mine. The sampling program included a one-time sampling of springs, mine adits, and exploration pits in Elk Basin and Redwell Basin; repeated sampling throughout one year of Standard Mine Level 1 discharge and Elk Creek near its confluence with Coal Creek; and a one-time sampling of underground sites in Levels 3 and 5 of the Standard Mine. Samples were analyzed for major ions and trace elements, stable isotopes of hydrogen (2H/1H) and oxygen (18O/16O), strontium isotopes, and tritium and dissolved noble gases (including helium isotopes) for tritium/helium-3 age dating. No clear correlations were observed between natural ground-water discharge locations and map-scale faults and lithology. Surface observations and the location of ground-water discharge suggest that simple topography, rather than large-scale geologic features, primarily controls the occurrence and flow of shallow ground water in Elk Basin. Discrete inflows from cross faults or other features were not observed in Levels 3 and 5 of the Standard Mine. Instead, water entered the mine as relatively persistent dripping from gouge and breccia within the Standard fault, which both tunnels follow. Therefore, the Standard fault itself is probably the main pathway of ground-water flow from the shallow subsurface to the mine workings. Low pH (as low as 3.2) and elevated concentrations of zinc, lead, cadmium, copper, and manganese (commonly exceeding water-quality standards for Elk Creek) were measured in samples located within or immediately downgradient of areas where sulfides are abundant, including the Standard fault, the Elk Lode portal, and the breccia pipe in Redwell Basin. Concentrations of these metals were typically low and pH values were circumneutral at surrounding locations. Metal concentrations in samples collected from underground workings in the Standard Mine were also generally higher than in samples collected at aboveground sites located outside of sulfide-rich areas. Metal concentrations in discharge from the Level 1 tunnel were among the highest measured in Elk Basin. All of these observations suggest that sulfide-rich mineralized rock is the primary control on dissolved metal concentrations and pH in ground water in the Standard Mine vicinity. Waste-rock piles apparently exert another major control on metal concentrations and pH; the lowest pH and highest metal concentrations typically are found in discharge from waste-rock piles. Concentrations of several chemical constituents along with strontium isotope data indicate that none of the sampled waters could have been the primary source of metals in discharge from Level 1. Therefore, this study did not identify the primary source location for metals in Level 1 discharge. Possible sources must be located below Levels 3 and 5 or farther back into the mountainside than the ends of Levels 3 and 5. Apparent tritium/helium-3 ground-water ages ranged from 0 to 9 yr, and a considerable majority were <1 yr. Tritium data and computed initial tritium values (measured tritium plus measured tritiogenic helium-3) suggest that much of the ground water in the Standard Mine vicinity was weeks to months old rather than years old. Tritium, d2H, and d18O data from water entering into and discharging from the Standard Mine displayed spatial and temporal patterns indicating that these tracers were influenced by seasonal variations in their concentration in precipitation. The tracer data therefore suggest that ground water entering into and discharging from the Standard Mine was largely composed of water <1 yr old. Pronounced seasonal variations in geochemistry in Level 1 discharge also are consistent with short r

Colorado↗

USGS2013

Baseline groundwater quality from 20 domestic wells in Sullivan County, Pennsylvania, 2012

Water samples were collected from 20 domestic wells during August and September 2012 and analyzed for 47 constituents and properties, including nutrients, major ions, metals and trace elements, radioactivity, and dissolved gases, including methane and radon-222. This study, done in cooperation with the Pennsylvania Department of Conservation and Natural Resources, Bureau of Topographic and Geologic Survey (Pennsylvania Geological Survey), provides a groundwater-quality baseline for central and southern Sullivan County prior to drilling for natural gas in the Marcellus Shale. The analytical results for the 20 groundwater samples collected during this study indicate that only one constituent (gross-alpha radioactivity) in one sample was found to exceed the U.S. Environmental Protection Agency (USEPA) primary drinking water maximum contaminant level (MCL). Water samples from 85 percent of the sampled wells exceeded the proposed USEPA MCL of 300 picocuries per liter (pCi/L) for radon-222; however, only two water samples (10 percent of sampled wells) exceeded the proposed USEPA alternate maximum contaminant level (AMCL) of 4,000 pCi/L for radon-222. In a few samples, the concentrations of total dissolved solids, iron, manganese, and chloride exceeded USEPA secondary maximum contaminant levels (SMCL). In addition, water samples from two wells contained methane concentrations greater than 1 milligram per liter (mg/L). In general, most of the water-quality problems involve aesthetic considerations, such as taste or odor from elevated concentrations of total dissolved solids, iron, manganese, and chloride that develop from natural interactions of water and rock minerals in the subsurface. The total dissolved solids concentration ranged from 31 to 664 mg/L; the median was 130 mg/L. The total dissolved solids concentration in one water sample exceeded the USEPA SMCL of 500 mg/L. Chloride concentrations ranged from 0.59 to 342 mg/L; the median was 12.9 mg/L. The concentration of chloride in one water sample exceeded the USEPA SMCL of 250 mg/L. Concentrations of dissolved iron ranged from less than 3.2 to 6,590 micrograms per liter (µg/L); the median was 11.5 µg/L. The iron concentration in samples from 20 percent of the sampled wells exceeded the USEPA SMCL of 300 µg/L. Concentrations of dissolved manganese ranged from less than 0.13 to 1,710 µg/L; the median was 38.5 µg/L. The manganese concentration in samples from 35 percent of the sampled wells exceeded the USEPA SMCL of 50 µg/L. Activities of radon-222 ranged from 169 to 15,300 picocuries per liter (pCi/L); the median was 990 pCi/L. The gross alpha-particle radioactivity ranged from below detection to 33 pCi/L; the median was 1.5 pCi/L. The gross alpha-particle radioactivity of one water sample exceeded the USEPA MCL of 15 pCi/L. Concentrations of dissolved methane ranged from less than 0.001 to 51.1 mg/L. Methane was not detected in water samples from 13 wells, and the methane concentration was less than 0.07 mg/L in samples from five wells. The highest dissolved methane concentrations were 4.1 and 51.1 mg/L, and the pH of the water from both wells was greater than 8. Water samples from these wells were analyzed for isotopes of carbon and hydrogen in the methane. The isotopic ratio values fell in the range for a thermogenic (natural gas) source. The water samples from these two wells had the highest concentrations of arsenic, boron, bromide, chloride, fluoride, lithium, molybdenum, and sodium of the 20 wells sampled.

Pennsylvania↗

USGS2020

Spatially referenced models of streamflow and nitrogen, phosphorus, and suspended-sediment loads in the southeastern United States

Spatially Referenced Regression On Watershed attributes (SPARROW) models were applied to describe and estimate mean-annual streamflow and transport of total nitrogen (TN), total phosphorus (TP), and suspended sediment (SS) in streams and delivered to coastal waters of the southeastern United States on the basis of inputs and management practices centered near 2012, the base year of the model. Previously published TN and TP models for 2002 served as a starting point and reference for comparison. The datasets developed for the 2012 models not only represent updates of previous conditions but also incorporate new approaches for characterizing sources and transport processes that were not available for previous models. Variability in streamflow across the southeastern United States was explained as a function of precipitation adjusted for evapotranspiration, spring discharge, and municipal and domestic wastewater discharges to streams. Results from the streamflow model were used as input to the water-quality SPARROW models, and areas with large streamflow prediction errors—urban areas and karst areas—were used to provide guidance on where additional data are needed to improve routing of flow. Variability in TN transport in Southeast streams was explained by the following five sources in order of decreasing mass contribution to streams: atmospheric deposition, agricultural fertilizer, municipal wastewater, manure from livestock, and urban land. Variable rates of TN delivery from source to stream were attributed to variation among catchments in climate, soil texture, and vegetative cover, including the extent of cover crops in the watershed. Variability in TP transport in Southeast streams was explained by the following six sources in order of decreasing mass contribution to streams: parent-rock minerals, urban land, manure from livestock, municipal wastewater, agricultural fertilizer, and phosphate mining. Varying rates of TP delivery were attributed to variation in climate, soil erodibility, depth to water table, and the extent of conservation tillage practices in the watershed. Variability in SS transport in Southeast streams was explained by variable sediment export rates for different combinations of land cover and geologic setting (for upland sources of sediment) and by gains in stream power caused by longitudinal changes in channel hydraulics (for channel sources of sediment). Sediment yields for the transitional land cover (shrub, scrub, herbaceous, and barren) varied widely depending on geologic setting and on agricultural land cover. Varying rates of SS delivery, like those for TP, were attributed to variation in climate, soil erodibility, and the extent of conservation tillage practices in the watershed, as well as to areal extent of canopy land cover in the 100-meter buffer along the channel. Relatively large uncertainty, compared to the other three models, for almost all the SS source coefficients indicates the need for caution when interpreting the results from the sediment model. TN, TP, and SS inputs to streams from sources were balanced in the models with losses from physical processes in streams and reservoirs and with water withdrawals. The losses in streams and reservoirs along with withdrawals removed 35, 44, and 65 percent of the TN, TP, and SS load, respectively, that entered streams before reaching coastal waters.

Scientific Investigations Report↗

USGS1951

Summary of the research work of the Trace Elements Section, Geochemistry and Petrology Branch, for the period April 1, 1948-December 31, 1950

This report summarizes the research work of the Trace Elements Section, Geochemistry and Petrology Branch, from the organization of the Section in April 1948 to December 31, 1950. The research undertaken thus far consists of laboratory and related field studies in the following fields: 1. Mineralogic and petrologic investigations of radioactive rocks, minerals, and ores. 2. Investigations of chemical methods of analysis for uranium, thorium, and other elements and compounds in radioactive materials, and related chemical problems. 3. Investigations of spectrographic methods of analysis for a wide variety of elements in radioactive materials. 4. Investigations of radiometric methods of analysis as applied to radioactive materials. It should be emphasized that the work undertaken thus far, described under the headings "Future work", is almost entirely in the nature of investigations supporting the field appraisal of known important uraniferous deposits. A comprehensive program of more fundamental research was submitted in April 1949 in a report entitled "Proposed program of desirable research in the geochemistry of uranium," but funds for this work have not been authorized. It is hoped, however, that funds to support basic research of the type indicated in that report may be available in the future. This report does not cover the analytical work of the Section nor the public-sample program. The analytical work has been summarized for the fiscal year 1950 in the report, "Numerical summary of the analytical work of the Trace Elements Section, Geochemistry and Petrology Branch, for the fiscal year 1950," by John C. Rabbit, U.S. Geol. Survey Trace Elements Memorandum Rept. 174, October 1950. A report on the public-sample program is in preparation. Much of the material in this report has been paraphrased from reports prepared by members of the Section. My special thanks are due them; to Earl Ingerson, chief of the Geochemistry and Petrology Branch of the Survey, for his critical review; to my secretary, Marie Woolihan, for her aid in collecting material; and to Virginia Layne of the editorial staff of the Section for typing the manuscript and the multilith mats.

Trace Elements Investigations↗

USGS1951

Summary of the research work of the Trace Elements Section, Geochemistry and Petrology Branch, for the period January 1-March 31, 1951

This report summarized the research work of the Trace Elements Section, Geochemistry and Petrology Branch for the period January 1 - March 31, 1951. Work before that is summarized in an earlier report, "Summary of the research work of the Trace Elements Section, Geochemistry and Petrology Branch, for the period April 1, 1948 - December 31, 1950," by John C. Rabbitt (U.S. Geol. Survey Trace Elements Investigations Rept. 148, January 1951). This report will be referred to as TEIR 148. In TEIR 148 the purpose of each project was described and it is not thought necessary to repeat that material. The research work of the section consists of laboratory and related field studies in the following fields: 1. Mineralogic and petrologic investigations of radioactive rocks, minerals, and ores. 2. Investigations of chemical methods of analysis for uranium, thorium, and other elements and compounds in radioactive materials, and related chemical problems. 3. Investigations of spectographic method of analysis for a wide variety of elements in radioactive materials. 4. Investigation of radiometric methods of analysis is applied to radioactive materials. It should be emphasized that the work undertaken so far is almost entirely in the nature of investigations supporting the field appraisal of known uraniferous deposits. A program of more fundamental research, particularly in the mineralogy and geochemistry of uranium, is now being drawn up and will be submitted for approval soon. This report does not deal with the routine analytical work of the Section nor the public-sample program. The analytical work will be summarized in a report to be issued after the end of fiscal year 1951, and a report on the public-sample program is in process. Special thanks are due members of the Section who are engaged in the research work and who have supplied material for this report, the Early Ingerson, Chief of the Geochemistry and Petrology Branch for his critical review, to Jane Titcomb of the editorial staff of the Section for editing the report, and to Virginia Layne of the same staff, for typing the manuscript and the multilith mats.

Trace Elements Investigations↗

USGS1955

Geology of the Copper King uranium mine, Larimer County, Colorado

The Copper King mine in Larimer County, Colo., in the northern part of the Front Range of Colorado, was opened in World War I in an unsuccessful attempt to mine copper and zinc ore. In 1949, following the discovery of pitchblende on the dump, the mine was reopened, and it was worked until 1953 for uranium. A total of 652 tons of ore that contained an average of 0.28 percent U 3 O 8 was shipped. The bedrock consists predominantly of biotite granite, part of the Precamblian Log Cabin batholith, and minor metasedimentary rocks -- biotite-quartz-plagioclase gneiss, amphibole skarn, biotite schist, quartzite, amphibolite, and biotite sköls. The metasedimentary rocks occur as inclusions that trend northeast, essentially parallel to the prevailing foliation in the granite. In places the metasedimentary rocks are crosscut sharply by the granite and form angular, steep-walled blocks in the granite. Faults, confined to a narrow easterly-trending zone through the mine, cut all the Precambrian rocks. Mineral deposits of two types are present at the mines 1) sulfide-magnetite ore and 2) a uranium deposit in a filled fissure that cuts the skarn. The sulfide-magnetite deposits are small and consist of pyrite, sphalerite, chalcopyrite, pyrrhotite, and at places magnetite. Alpha-helium age determinations on ore magnetite by Hurley indicate that the mineral assemblage is late Precambrian in age. The deposits are pyrometasomatic in origin and possibly related to the granite. The uranium deposit consists of pitchblende and associated vein-forming minerals that occur in the Copper King fault and locally in pyrite boxwork adjacent to the fault. Three phases of black pitchblende have been identified -- uraninite, "coffinite", and UO 3 -rich pitchblend. Colored secondary minerals are absent. The pitchblende occurs in a steeply plunging, tabular shoot between 45 and 135 feet below the surface that has a horizontal length of about 50 feet. Within the shoot the pitchblende occurs in pods or layers generally only a few feet in height and length and as much as a foot thick that are separated by nearly barren vein. The grade of the ore within the pods ranges from 0.2 percent uranium to as much as 20 percent but averages about 1 to 2 percent. Age determinations by the Pb 206 /U 238 and Pb 207 /U 235 methods on two samples of hard pitchblende from the vein, not from the pyrite boxwork, gave ages by the two methods after suitable common lead corrections, ranging from 55 to 76 million years, corresponding to an early Tertiary age. Diamond core drilling and reconnaissance for radioactivity have not disclosed other uranium deposits the Prairie Divide region; nevertheless, it seems likely that other deposits are present.

Colorado↗

USGS2002

Metal concentrations and sources in the Miller Creek watershed, Park County, Montana, August 2000

Miller Creek is a tributary of Soda Butte Creek in south-central Montana near the northeast corner of Yellowstone National Park. Surface-water and streambed-sediment samples were collected from streams and seeps throughout the Miller Creek watershed during low-flow conditions on August 28-31, 2000, to characterize metal concentrations and identify possible sources contributing metal to Miller Creek. Most water in Miller Creek appears to be unaffected by mining disturbances or natural weathering of mineralized rocks, although such effects are common elsewhere in the New World Mining District. Values for pH were near neutral to basic. Total-recoverable copper, lead, and zinc concentrations were low, relative to State of Montana water-quality standards, with many concentrations less than the analytical minimum reporting levels. Metal concentrations in Miller Creek during this study ranged from 1 to 6 micrograms per liter (?g/L) for total-recoverable copper, <1 to 5 ?g/L for total-recoverable lead, and <1 to 26 ?g/L for total-recoverable zinc. Concentrations of cadmium, copper, lead, and zinc in all samples from Miller Creek were less than the chronic aquatic-life criteria, except for one total-recoverable lead value (5 ?g/L) just downstream from the Black Warrior Mine inflow. Leachable lead and zinc concentrations in streambed-sediment samples collected during this study were highest at the Black Warrior Mine inflow. Leachable concentrations at this site were about 20 times greater for lead and 11 times greater for zinc than concentrations in the streambed-sediment sample collected from Miller Creek upstream from this inflow. However, these elevated concentrations had little effect on the leachable metal concentrations in the streambed-sediment sample collected downstream from the Black Warrior Mine inflow. Metal loading to Miller Creek during this low-flow study was relatively small. Three small left-bank inflows having elevated copper concentrations entered Miller Creek near the middle of the study reach and their combined total-recoverable copper load accounted for about 96 percent of the copper load in Miller Creek. Small loads of lead (about 2 micrograms per second) entered Miller Creek from the Black Warrior Mine inflow and a right bank inflow. None of the loads entering Miller Creek had an appreciable effect on mainstem metal concentrations. In addition, substantial differences between mining related areas and areas influenced by local geology could not be determined.

Montana↗

USGS1950

Spectrographic analysis of coal and coal ash

Coal can be analyzed on the spectrograph for per cent ash and composition of ash in a matter of a few minutes, using the total energy method. The composition of the ash so determined can be used to calculate ash softening temperatures. This analysis can be made in sufficiently short a time to control tipple and washing operations for preparation of coal to meet specifications. This spectrographic method can be readily adapted to the analysis of rocks, minerals, and inorganic chemicals of all kinds.

Analytical Chemistry↗

USGS1991

Origins of acid fluids in geothermal reservoirs

Acid fluids in geothermal reservoirs are rare. Their occurrence in geothermal systems associated with recent volcanism (Tatun, Sumikawa, Miravalles) probably indicates that the geothermal reservoir fluid was derived from volcanic fluid incompletely neutralized by reaction with feldspars and micas. Superheated steam containing HCl (Larderello, The Geysers) forms acid where it condenses or mixes with liquid at moderate temperatures (<300??C). The origin of steam with HCl is reaction of NaCl solid with rock minerals at high temperatures (>325??C). Cryptoacidity occurs at Los Humeros where HCl acidity is formed and neutralized without reaching the surface.

Conference Paper↗

USGS1883

Geology of Wisconsin: Survey of 1873-1879, Volume I

The leading purpose df this volume was determined by the following enactment, being section 1, chapter 121, of the Laws of 1876. " The people of the State of Wisconsin, represented in Senate and Assembly, do enact as follows: Section 1. That in the preparation of his final report, the chief geologist be, and he is hereby authorized to collate the general geology and the leading facts and principles relating to the material resources of the State, together with practical suggestions as to the methods of detecting and utilizing the same, so as to constitute the material for a volume suited to the wants of explorers, miners, land owners, and manufacturers, who use crude native products, and to the needs of the schools of the State, and the masses of intelligent people who are not familiar with the principles of geology; said volume to be written in clear, plain language, with explanations of technical terms, and to be properly illustrated with maps and diagrams, and to be so arranged as to constitute a key to the more perfect understanding of the whole report." To subserve the purposes thus legally defined, the volume will be found to consist of three distinct portions; Part I, embracing the General Geology of the State, with explanatory matter; Part II, consisting of lists of the minerals, rocks and life-products of the State, with descriptions and auxiliary discussions; and Part III, embracing industrial descriptions and practical suggestions with reference to the leading natural resources of the State.

Wisconsin↗

USGS2013

Mineral resource of the month: Phosphate rock

As a mineral resource, “phosphate rock” is defined as unprocessed ore and processed concentrates that contain some form of apatite, a group of calcium phosphate minerals that is the primary source for phosphorus in phosphate fertilizers, which are vital to agriculture.

Earth↗

USGS1960

Mineral paragenesis of precambrian rocks in the Tenmile Range, Colorado

A Precambrian complex of granulite, gneiss, and migmatite, intruded by numerous plutons of granitic rocks correlated with the Silver Plume granite, is exposed in a long narrow belt along the crest and upper slopes of the Tenmile Range , Colorado . The metamorphic rocks are predominantly felsic; bands, lenses, and irregular bodies of mafic rocks rich in biotite, hornblende, and locally in sillimanite and garnet, are interlayered with the felsic rocks . The major lithologic variations in the metamorphic rock complex are believed to be due chiefly to variations in the original sedimentary rocks , which probably were interbedded sandstone, shale, and limestone. The metamorphic rocks and the Silver Plume granite reveal the age relations of quartz and the feldspars, and these relations afford considerable information on the origin and progressive transformation of the rocks . Quartz is the earliest mineral in the metamorphic rocks and is probably a relict mineral of a sandstone. It has been partially replaced by feldspar. It occurs chiefly in irregular clusters, some of which show sutured grains, enclosed in a ramifying network of feldspar. Irregular small apophyses, barbs, and prongs of feldspar penetrate the quartz clusters along grain boundaries and healed fractures in the quartz. In some of the least feldspathized quartzose metamorphic rocks the feldspar is clearly interstitial to the quartz. Quartz also occurs in feldspar as small spherical inclusions. The relations of the quartz to the feldspars show clearly that a quartzose host rock was replaced by feldspar along quartz grain boundaries, pre-existing healed fractures, and margins of shadowy areas in strained quartz grains. The textural relations of the other principal minerals in the metamorphic rocks show that plagioclase formed earlier than the microcline and that the micas were the last of the principal minerals to form. Identical paragenetic relations are found in the Silver Plume granite, and the writer concludes that the Silver Plume granite was derived by partial fusion of quartzose metamorphic rocks .

Colorado↗

USGS1999

Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206 Pb/ 204 Pb = 17.34 to 22.66, 207 Pb/ 204 Pb = 15.43 to 15.96, and 208 Pb/ 204 Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206 Pb/ 204 Pb and higher model Th/U, and the southern subprovince has higher 206 Pb/ 204 Pb and lower model Th/U. These Pb isotope differences are inferred to result from differences in their respective post-1.7 Ga magmatic histories. Throughout Arizona, Pb isotope compositions of Late Cretaceous and early Tertiary plutons and associated sulfide minerals are distinct from those of Jurassic plutons and also middle Tertiary igneous rocks and sulfide minerals. These differences most likely reflect changes in tectonic setting and magmatic sources. Within Late Cretaceous and early Tertiary igneous complexes that host economic porphyry copper deposits, there is commonly a decrease in Pb isotope composition from older to younger plutons. This decrease in Pb isotope values with time suggests an increasing involvement of crust with lower U/Pb than average crust in the source(s) of Late Cretaceous and early Tertiary magmas. Lead isotope compositions of the youngest porphyries in the igneous complexes are similar to those in most sulfide minerals within the associated porphyry copper deposit. This Pb isotope similarity argues for a genetic link between them. However, not all Pb in the sulfide minerals in porphyry copper deposits is magmatically derived. Some sulfide minerals, particularly those that are late stage, or distal to the main orebody, or in Proterozoic or Paleozoic rocks, have elevated Pb isotope compositions displaced toward the gross average Pb isotope composition of the local country rocks. The more radiogenic isotopic compositions argue for a contribution of Pb from those rocks at the site of ore deposition. Combining the Pb isotope data with available geochemical, isotopic, and petrologic data suggests derivation of the young porphyry copper-related plutons, most of their Pb, and other metals from a hybridized lower continental crustal source. Because of the likely involvement of subduction-related mantle-derived basaltic magma in the hybridized lower crustal source, an indiscernible mantle contribution is probable in the porphyry magmas. Clearly, in addition, Pb was contributed from the local country rocks. This is most evident in sulfide minerals in veins that are late stage, hosted in Proterozoic gneiss, and/or peripheral to the porphyry copper deposit.

Economic Geology↗

USGS2011

Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons, are included here in the AGDB and will be added to the NGDB. The AGDB data provided here are the most accurate and complete to date, and should be useful for a wide variety of geochemical studies. The AGDB data provided in the linked database may be updated or changed periodically. The data on the DVD and in the data downloads provided with this report are current as of date of publication.

Data Series↗

USGS2013

Alaska Geochemical Database, Version 2.0 (AGDB2)–Including “best value” data compilations for rock, sediment, soil, mineral, and concentrate sample mediaI

The Alaska Geochemical Database Version 2.0 (AGDB2) contains new geochemical data compilations in which each geologic material sample has one “best value” determination for each analyzed species, greatly improving speed and efficiency of use. Like the Alaska Geochemical Database (AGDB, http://pubs.usgs.gov/ds/637/) before it, the AGDB2 was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This relational database, created from the Alaska Geochemical Database (AGDB) that was released in 2011, serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables in several different formats describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey personnel and analyzed in U.S. Geological Survey laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various U.S. Geological Survey programs and projects from 1962 through 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy-mineral concentrate samples are included in this database. The AGDB2 includes historical geochemical data originally archived in the U.S. Geological Survey Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the U.S. Geological Survey PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all U.S. Geological Survey geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest U.S. Geological Survey geochemical databases, or were once excluded for programmatic reasons, are included here in the AGDB2 and will be added to the NGDB. The AGDB2 data provided here are the most accurate and complete to date, and should be useful for a wide variety of geochemical studies. The AGDB2 data provided in the linked database may be updated or changed periodically.

Alaska↗

USGS1999

Geochemical data for stream-sediment, heavy-mineral-concentrate, and rock samples collected from the Fortyseven Creek gold-arsenic-antimony-tungsten prospect, southwestern Alaska

In the summer of 1991, we conducted a reconnaissance geochemical survey around the Fortyseven Creek Au-As-Sb-W prospect that is located in the southwestern part of the Sleetmute quadrangle. At that time, this project was a small part of a more comprehensive Alaska Mineral Resource Assessment Program (AMRAP) study of the Sleemute quadrangle. AMRAP studies were conducted by the U.S. Geological Survey (USGS) to fulfill requirements of the Alaska National Interests Lands Conservation Act (Public Law 96-487, 1980) to survey certain federal lands to determine their mineral potential. Although AMRAP is no longer in operation, this study represents a small topical study that was conducted during the Sleetmute quadrangle AMRAP study. The objective of the Fortyseven Creek work was to characterize the geochemistry of samples collected downstream from the Fortyseven Creek prospect, as well as mineralized and altered rock samples collected from the prospect. In this report, we describe the samples collected in 1991, the methods used for the analysis of the samples, and the geochemical data for these samples. The data in this report are also available in digital form on computer diskette in Gray and others (1999). An interpretation of these data appears in Gray and others (1998).

Alaska↗

USGS2009

Delineation of Magnesium-rich Ultramafic Rocks Available for Mineral Carbon Sequestration in the United States

The 2005 Intergovernmental Panel on Climate Change report on Carbon Dioxide Capture and Storage suggested that a major gap in mineral carbon sequestration is locating the magnesium-silicate bedrock available to sequester CO2. It is generally known that silicate minerals with high concentrations of magnesium are suitable for mineral carbonation. However, no assessment has been made covering the entire United States detailing their geographical distribution and extent, or evaluating their potential for use in mineral carbonation. Researchers at Columbia University and the U.S. Geological Survey have developed a digital geologic database of ultramafic rocks in the continental United States. Data were compiled from varied-scale geologic maps of magnesium-silicate ultramafic rocks. These rock types are potentially suitable as source material for mineral carbon-dioxide sequestration. The focus of the national-scale map is entirely on suitable ultramafic rock types, which typically consist primarily of olivine and serpentine minerals. By combining the map with digital datasets that show non-mineable lands (such as urban areas and National Parks), estimates on potential depth of a surface mine, and the predicted reactivities of the mineral deposits, one can begin to estimate the capacity for CO2 mineral sequestration within the United States. ?? 2009 Elsevier Ltd. All rights reserved.

Conference Paper↗

USGS2024

Hyperspectral (VNIR-SWIR) analysis of roll front uranium host rocks and industrial minerals from Karnes and Live Oak Counties, Texas Coastal Plain

VNIR-SWIR (400–2500 nm) reflectance measurements were made on the surfaces of various cores, cuttings and sample splits of sedimentary rocks from the Tertiary Jackson Group, and Catahoula, Oakville and Goliad Formations. These rocks vary in composition and texture from mudstone and claystone to sandstone and are known host rocks for roll front uranium occurrences in Karnes and Live Oak Counties, Texas. Spectral reflectance profiles, 569 in total, were reduced to 125 representative spectral signatures, which were analyzed using the U.S. Geological Survey's (USGS) Material Identification and Characterization Algorithm (MICA). MICA uses an automated continuum-removal procedure together with a least-squares linear regression to determine the fit of observed sample spectral absorption features to those of reference mineral standards in a spectral library. The reference minerals include various clay, mica, carbonate, ferric and ferrous iron minerals and their mixtures. In addition, absorption feature band-depth analysis was done to identify rock surfaces exhibiting absorption features related to uranium and zeolite minerals, which were not included in the command files used to execute MICA. Rocks from each of the four geologic units produced broadly similar spectral signatures as a result of comparable mineral compositions, but there were some notable differences. For example, Ca- and Na-montmorillonite was matched most frequently to the spectral absorption features in 2-μm (∼2000–2500 nm) wavelengths, while goethite occurred often at 1-μm (∼400–1000 nm) wavelengths. The latter is related to limonitic iron-staining in and around oxidized zones of the uranium roll front as described in previous papers. Rocks of the Jackson Group differed from those of the Catahoula, Oakville and Goliad units in that the former exhibited spectral features we interpret as being due to the presence of lignite-bearing mudstone layers. Goliad rocks exhibit spectral features related to dolomite, gypsum, anhydrite, and an unidentified green clay mineral that is possibly glauconite . Jackson Group rocks also exhibit weak but well-resolved absorption features at 964 and 1157 nm related to either or both zeolite minerals clinoptilolite and heulandite. These zeolite minerals and a few spectra exhibiting hydrous silica absorption features are indicative of alteration of volcanic glass in tuffaceous mudstone and claystone layers. A few sample spectra exhibited strong absorption features at around 1135 nm related to the uranium mineral coffinite. Both the 1135 nm coffinite and 1157 nm zeolite absorption features overlap somewhat, potentially making them difficult to distinguish without additional hyperspectral field, laboratory or remote sensing data. The results of this study were compared to mixtures of minerals described for ore, gangue and alteration minerals in deposit models for sandstone-hosted uranium, sedimentary bentonite and sedimentary zeolite. Use of these spectra can help facilitate mapping of both waste materials from the legacy mining of the above commodities, as well as future exploration and resource assessment activities.

Texas↗