bluuebunny/crossref_metadata_2025_split huggingface dataset:
U-Th-Pb and 40Ar/39Ar Dating of the Mountain Pass Carbonatite and Alkalic Igneous Rocks, Southeastern California
Authors: DeWitt Ed , Kwak L.M. , Zartman R.E. 
Published: August 2024

Abstract
The age of the Mountain Pass carbonatite, the largest source of rare-earth elements in the world, is an important constraint in the search for similar bodies. Emplacement of the carbonatite was the last event in the intrusion of a 1400-Ma alkalic complex. Based on field relationships, the intrusive sequence was 1) shonkinite, 2) syenite and granite, and 3) carbonate bodies, dikes, and veins. Late shonkinite dikes cut syenite and granite, but not the carbonate bodies.
Alkalic igneous rocks were emplaced between 1410 and 1400 Ma. Apatite from the shonkinite has a U-Pb date of 1410±2 Ma. Phlogopite from the shonkinite has a 40Ar/39Ar plateau date of 1400±8 Ma. Arfvedsonite from the syenite has a 40Ar/39Ar plateau date of 1403±7 Ma. Zircon from the syenite are highly discordant and have Pb-Pb dates as old as 1330 Ma; their U-Pb dates were not made appreciably older by abrasion techniques.
Monazite from the carbonate body have Th-Pb dates of 1375±7 Ma and imply that the carbonatite was emplaced about 25 Ma after syenite and granite. Bastnaesite and parisite from the carbonatite contain considerable common lead and suggest that the body was open to lead migration after emplacement. Clear parisite has an older Th-Pb date (1332±7 Ma) than coexisting bastnaesite, but that date is anomalously young if compared to the Th-Pb dates from monazite. The least radiogenic common-lead ratios of galena from the carbonatite and potassium feldspar from alkalic igneous rocks (204:206:207:208 = 1:16.08:15.23;35.61) indicate that the parent magma for both rock types was
Road log and stop descriptions, Minturn to Leadville, Colorado
Authors: Beaty David W. 
Published: August 2024

Abstract
On the north side of the town of Minturn, the Leadville, Gilman, and Dyer Formations crop out. These rocks are most accessible in two places: in readouts along U.S. Highway 24, and in roadcuts along the railroad (Fig. 2). The northeast wall of the Eagle River canyon at this locality consists of a thick section of sandstones, siltstones, shales, and thin limestones of the Minturn Formation.
The Leadville Limestone/Dolomite consists of two members (Nadeau, 1971; Beaty et al., 1988a: this volume), the Red Cliff Member (below) and the castle Butte Member (above). The Red Cliff Member at Stop 1 consists bedded dolostone, principally of fine and medium grain size (Fig. 2). The dolomitization of these beds is regional in extent, and is interpreted by Horton (1985) to be of early diagenetic, sabkha origin. The Castle Butte Member at Stop 1 is limestone (Fig. 2), which has been described by De Voto (1985, p. 6-156) as “mixed-skeletal grainstones to packstones with readily visible echinoderm, brachiopod and solitary tetracoral fossils and abundant micritized foraminifera, green algae, and ostracods.” This is the southern limit of the limestone facies of the Castle Butte Member in this area.
Road log and stop descriptions, Leadville District, Colorado
Authors: Thompson Tommy B. 
Published: August 2024

Abstract
0.0 Begin mileage at Delaware Hotel, Leadville (Fig. 1) on East 7th and Harrison Avenue. Harrison Avenue is named for Edwin Harrison, a pioneer smelter entrepreneur. On the northwest comer of 7th and Harrison Avenue is the Tabor Grand Hotel, constructed by H.A.W. Tabor in 1885. Republican President Benjamin Harrison made a speech from the 2nd floor balcony (new removed) to the residents of the Cloud city (also referred to as the Magic City) in 1891 when there was major concern for the price of silver.
The Boss Iron-Copper Deposit, Missouri
Authors: Kisvarsanyi Geza 
Published: August 2024

Abstract
The Boss deposit was discovered by the American Zinc Company. A magnetic anomaly, mapped in 1943 near the towns of Boss and Bixby by the Missouri State Geological Survey, was drilled by the Company. The first exploratory holes started in 1956 and the discovery of a large iron-copper deposit was announced in 1964. The deposit has been well outlined with more than 100 diamond core holes drilled by American Zinc, Getty Oil and Granite City Steel companies. A Cominco American-Dresser joint venture obtained the property in 1979. The deposit occurs in the Precambrian basement beneath a cover of about 1,200 feet of Paleozoic sedimentary rocks (see Fig. 3, Kisvarsanyi and Kisvarsanyi, this volume).
Third Day
Authors: Kisvarsanyi Eva B. 
Published: August 2024

Abstract
SE 1/4 SE 1/4 NE 1/4 sec. 15, T. 34N., R. 3E., Elephant Rocks State Park, Iron County, Missouri; Graniteville 7 1/2-minute Quadrangle. Entrance to the park is from Missouri RA, 0.7 mi west of its junction with Missouri 21 (Fig. 1). From the parking lot, follow marked trail to the lookout point near the top of the hill. The site is on public land.
Recent Exploration History in Southeast Missouri
Authors: Ohle Ernest L. , Gerdemann Paul E. 
Published: August 2024

Abstract
Since the first recorded discovery of lead in Southeast Missouri near Fredericktown about 1720, knowledge of the deposits has advanced in spurts as a result of outlying discoveries:
The original discoveries at Bonne Terre consisted of residual galena in clay, similar to that in the previous finds at Fredericktown. Occurrences in solid dolomite were not noted until mining of the clay pits exposed the walls of the weathered depressions. The St. Joseph Lead Co. had been established to conduct the operations and it was J. Wyman Jones. first President of St. Joe, who at that time brought about the first of the technological advances that were to occur in the district. He proposed use of the newly-invented diamond drill to explore the bed-rock showings, after observing the machines in the Vermont Marble Belt.
Road log and stop descriptions, Cadillac tectonic zone and regional geology of Val d’Or
Authors: Desrochers Jean-Philippe , Dussault Chantal 
Published: August 2024

Abstract
The excursion begins with an examination of the stripped outcrop shown in figure 3 that exposes the various structural elements and mineralized veins described above in the text. This is followed by a N-S traverse on Oren ada Zone 2 to examine the boundaries of the Cadi11ac tectonic zone and its preserved lithologies.
The Chimo Mine
Authors: Viens François , Blouin Jean-Yves 
Published: August 2024

Abstract
The Chimo mine is located 40 km east of Val d’Or {Fig.1) in the eastern part of the Superior Province in the Canadian Shield. The deposit is hosted by mafic lava that forms part of the Trivio Group {Vogel, 1978). The Grenville Front is located only 12 km to the southeast. Although the first claims were staked in 1936, it was only in 1964 that Chimo Gold Mines started sinking a shaft to a depth of 190 m and deve1oped three 1eve1s. Production officia11y started in January 1966 and ended in August 1967. Up to this time, 63,162 ounces of gold had been produced from 140,000 metric tonnes of ore.
The Duvay Showing
Authors: Couture Jean-François 
Published: August 2024

Abstract
Recent exploration work by Société Minière Sphinx has exposed significant gold mineralization in a quartz vein system hosted by highly carbonatized mafic metavolcanics. A vast area of stripped outcrop permits the observation of severa1 fundamenta1 characteristics of Archean go1d-bearing hydrotherma1 systems. During this visit, several of these characteristics that document the evolution of the hydrothermal system will be examined.
Geological Setting of Volcanogenic Massive Sulfide Deposits in the Central Pyroclastic Belt, Val D’OR.
Authors: Chartrand Francis 
Published: August 2024

Abstract
Most copper-zinc volcanogenic massive sulfide deposits (herein designated by their common acronym, “VMSD”) in the Quebec segment of the Abitibi belt occur in volcanic complexes characterized by tholeiitic to calc-alkaline, mafic and felsic volcanic rocks, associated sediments and related igneous intrusives. These complexes were constructed upon extensive submarine plains composed of tholeiitic to komatiitic, mafic to ultramafic lava and intrusives. The volcanic complexes are generally comprised of multiple cycles which may be bimodal (ex., andesiterhyolite) or continuous (ex., andesite-dacite-rhyodacite-rhyolite). Essential elements of these volcanic successions are subaqueous felsic domes and associated volcaniclastic rock, massive sulfide deposits, and chemical sedimentary rock. VMSD generally accumulate during relatively quiet periods in low energy settings upon and/or immediately below the seafloor. Submarine topography controls in part the location of individual deposits (Lydon, 1984); they may form in depressions localized between domes, and on top or on the flanks of domes. “Noranda type” deposits (Morton and Franklin, 1987), formed at depths of greater than 500 m, are characterized by a host sequence dominated by mafic and felsic flows and hyaloclastite. VMSD of the Noranda and Matagami districts are typical deposits of this type. “Mattabi-type” deposits (Morton and Franklin, 1987), formed at shallow depths of less than 500 m, occur in a host sequence dominated by fragmental volcanic rock. VMSD of the Sturgeon Lake area, and the Kidd Creek deposit near Timmins, are examples of this type.
An Overview of the Geology and Geochemistry of the Coso Geothermal Area, Inyo County, CA.
Authors: Williams Alan E. 
Published: August 2024

Abstract
The Coso Geothermal Project is a generation facility which produces 240 megawatts of electric power using turbine generators powered directly from geothermal steam. In this area, steam is provided by an active hydrothermal circulation system established in the fractured granitic basement rocks and extending upward into the overlying silicic volcanics and volcaniclastics. The geothermal reservoir has been tapped at depths of 1–2 km. and produces water and steam at temperatures of about 250–350°C. This active hydrothermal circulation may be quite analogous to fossil systems which have produced precious metal–bearing ore bodies in rhyolite-hosted environments. This paper will review the geologic setting of the Coso system and provide an overview of its reservoir chemistry.
Late Cenozoic basaltic magmatism in the Salton Trough
Authors: Herzig Charles T. , Jacobs David C. 
Published: August 2024

Abstract
The geochemistry of late Cenozoic basalts within the Salton Trough of southern California suggests that crustal extension has occurred in two very different tectonic settings. Initial extension of thick continental crust occurred during the Oligocene-Miocene, leading to the alkalic basalts now located along the trough margins. Following an ~10 Ma hiatus in igneous activity, tholeiitic basalts have been emplaced during the past 4 Ma along the trough axis as oceanic spreading centers of the East Pacific Rise – Gulf of California transtensional system exploited the previously extended and thinned crust of the North American continent. The correlation of basaltic xenoliths in the Quaternary rhyolite of Salton Buttes with oceanic rocks in the Gulf of California is strengthened in this study by new radiometric ages, and geochemical and isotopic data. In addition, a new U-Pb age of &lt;100,000 years for zircons from a granophyre xenolith in the rhyolite of Salton Buttes does not support the presence of pre-Tertiary, crystalline materials within this spreading center.
An Underground Guide to the Geology of the White Pine Mine, Michigan
Authors: Mauk J.L. , Seasor R. W. , Rews R. A. , Nelson W. S. , Robinson R. 
Published: August 2024

Abstract
In the past, we have not prepared an official "road log" for visitors to the White Pine mine. Aside from the fact that it requires a substantial amount of time to prepare such a guide, we have avoided the chore because often, we are not sure where we will take visitors when a tour arrives. A working mine is a dynamic entity, one that constantly changes shape and character as new workings are opened up and older workings are abandoned. Therefore, any underground guide will be obsolete before it is even published. Nonetheless, we have chosen to present a set of stops which reflect the geology of the White Pine mine as we understand it in 1992.
Thermal-Volcanic Evolution in the Northern California Coast Ranges
Authors: Liu Mian 
Published: August 2024

Abstract
Numerous late Tertiary and Quaternary volcanic centers are scattered in the vicinity of the San Andreas Fault system across the northern California Coast Ranges (Fig. 1). These volcanic rocks are characterized by a clear age progression. The youngest volcanic rocks are found in the Clear Lake volcanic center (2.1-0.01 Ma) (Donnelly-Nolan et al., 1981). To the south, volcanic rocks become progressively older. In an area about 60-70 km north of Clear Lake, seismic tomography suggests an “unerupted magma chamber” marked by relatively low crustal velocity similar to that under Clear Lake (Benz et al., 1992).
A number of causes have been suggested for the Coast Ranges volcanism. Hearn et al. (1981) proposed that the volcanism resulted from northward motion of the North American plate over a hotspot relatively fixed in the mantle. However, the trend of the Coast Ranges volcanism is difficult to reconcile with the relative motion of the North American plate derived from global inversion of plate kinematics (Minster et al., 1974). An origin of arc-volcanism is also unlikely, since volcanic rocks in the northern Coast Ranges were erupted within 50-60 km of the plate boundary, whereas the Cascades arc-volcanism typically occurs about 300 km inboard of the plate boundary (Fox et al., 1985).
Most workers relate the Coast Ranges volcanism to thermal perturbations associated with the northward migration of the Mendocino triple junction (MTJ) (Dickinson and Snyder, 1979; McLaughlin et al., 1981; Furlong, 1984; Johnson and O’Neil, 1984; Fox et al., 1985; Liu and Furlong, 1992). Both
Silica Carbonate Alteration of Serpentinite, Implications for the Association of Precious Metal and Mercury Mineralization in the Coast Ranges
Authors: Sherlock Ross L. , Amelia M. , Logan V. , Craig Jowett E. 
Published: August 2024

Abstract
Silica carbonate alteration of serpentinite is ubiquitous in the Coast Ranges of northern California, occurring in barren, Hg-rich and auriferous hydrothermal systems. The alteration is formed by the low temperature reaction of CO2-rich fluids with serpentinite minerals. The alteration is considered to be an exchange of cations with little net gain or loss of oxygen. The major element flux is characterized by the addition of silica and CO2 and a depletion in all other cations. The trace element flux is different for each suite examined. Barren silica carbonate assemblages are not elevated in any of the trace elements analyzed. Mercury-rich suites are elevated in Hg and the auriferous suites are elevated in Au, As, Sb and Hg. The mineralogical changes resulting from the alteration is a halo of magnesite around a core of silicified serpentinite. The variation in alteration minerals may reflect variations in fluid temperature. Oxygen isotopes suggest that the alteration is low temperature around 20°C, and that the mineral-springs were likely active at the site of the McLaughlin deposit prior to and after the hot-spring activity, that formed the McLaughlin ore body. The sulfur isotopic composition from a variety of mercury deposits and active hydrothermal systems show fairly consistent values of about 0%o, indicating a magmatic source.
The Geysers Felsite and Associated Geothermal Systems, Alteration, Mineralization, and Hydrocarbon Occurrences
Authors: Hulen Jeffrey B. , Walters Mark A. 
Published: August 2024

Abstract
The Geysers “felsite” (a designation of common usage in the geothermal community and thus retained for this article) is a young, wholly concealed, hypabyssal intrusive complex of batholithic dimensions within and beneath The Geysers steam field in the Mayacmas Mountains of northwest-central California (Fig. 1). The felsite was first penetrated by geothermal wells in the 1970’s, but because these air-drilled boreholes yielded extremely minute (typically &lt;0.1 mm in diameter) cuttings, the igneous nature of the body long eluded recognition. Bailey (1946) speculated that fumaroles at The Geysers signaled such a hidden intrusive, but the first detailed descriptions and chemical analyses of the felsite were published by Schriener and Suemnicht of Unocal Corporation (1981).
The Geysers felsite shows a clear correlation with the extent and configuration of the currently exploited vapor-dominated geothermal system (Figs. 1 and 2). A portion of this system is actually hosted by the felsite (e.g. Beall and Box, 1992), and above the pluton the remainder of the steam reservoir occurs in rocks which are hydrothermally altered and mineralized in concentric zones centered on the deep intrusive (Hulen and Nielson, 1993; Hulen and others, 1992; Moore, 1992; Walters and others, 1992; Hebein, 1986; McLaughlin and others, 1983). This alteration records the prior presence of a high-temperature, liquid-dominated hydrothermal system which appears to have “dried out” to yield the modern vapor-dominant regime (e.g. Moore, 1992; McLaughlin and others, 1983). The surface projection of the steam field includes and is encircled by numerous but scattered, commonly hydrocarbon-rich mercury deposits (e.g.
Hot Springs and Deposits of Jviercury and Gold in the Clear Lake Volcanic Field: Road Log
Authors: Rytuba James J. , Donnelly-Nolan Julie M. , McLaughlin Robert J. 
Published: August 2024

Abstract
This tour begins and returns to Clearlake Highlands. The route for the trip is shown in Figure 1. Note that several stops on mis trip are described in detail in the field guide that is part of the Paper by Goff and Janik (this volume).
Geochemical Exploration of the Carlin Trend
Authors: Wakefield Todd 
Published: August 2024

Abstract
Geochemical exploration has always been a key to Newmont's success in gold exploration on the Carlin Trend. In the early 1960's, Newmont geologists John Livermore and Alan Coope discovered the Carlin gold deposit by systematic outcrop and float sampling of favorable areas defined by geologic mapping (Coope, 1991a). In the 30 years since that time, Newmont geologists have discovered many more gold deposits using the same exploration methods, thus defining the Carlin Trend.
The purpose of this paper is to relate both the history of geochemical exploration on the Carlin Trend and current practices in geochemical exploration on the Carlin Trend today. Several papers devoted to this subject have been published previously; most notably papers by Coope (1991b) and Craig and Wakefield (1991).
Nature and Origin of Mineral Resources in the Gulf Coast Basin
Authors: Kyle J. Richard , Saunders James A. 
Published: August 2024

Abstract
Salt domes, their cap rocks, and the adjacent sedimentary strata represent a major economic resource in the Gulf Coast and elsewhere. The resources and utilization of the salt dome setting are remarkably diverse. Major economic products of the salt dome environment are salt, cap rock-hosted native sulfur deposits, and oil and gas that occur on the dome flanks and in the cap rock. Some cap rocks are sources of limestone, gypsum, and anhydrite, and some host commercial concentrations of Zn and Pb. Uranium is concentrated in strata above or adjacent to some diapirs. Caverns, excavated within the salt, serve as product storage as diverse as crude oil, including the Strategic Petroleum Reserve, liquified petroleum gas, and hazardous waste.
In addition, the Gulf Coast is a geologically young basin with many components that commonly are regarded as critical for the development of sediment-hosted mineral deposits. Metalliferous formation waters are locally present in the Gulf Coast Basin and have been proposed as modern analogs for the ore-forming fluids for ore deposits in older sedimentary terranes. Synsedimentary growth faults are important features that control local depositional facies and subsequent fluid movement in the Gulf Coast. Zn-Pb-Ag sulfide concentrations in two principal host settings (salt dome cap rocks and shelf carbonates) have been identified in the Gulf Coast. These sulfides have the most direct genetic affinity with Mississippi Valley type ore deposits that typically occur in older sedimentary terranes, although the cap rock occurrences have similarities to SEDEX-style mineralization. Recently discovered barite mounds on
An Introduction to the Gold Deposits of the Carolina Slate Belt
Authors: Crowe Douglas E. 
Published: August 2024

Abstract
The gold deposits hosted in the Carolina Slate Belt (CSB) have been studied in great detail by university, government, and industry workers. Appendix A contains a brief compilation of work in which readers can find detailed descriptions of the structure, geochemistry, and geology of the deposits, as well as some idea of the overall architecture of the CSB. This brief introduction is summarized from several sources, including Feiss (1985) and Scheetz (1991). This guidebook contains chapters on each deposit to be visited, as well as a chapter discussing exploration techniques used in the southeastern U.S., where lack of exposure and deep weathering preclude the use of many traditional exploration methods.
The CSB can be traced regionally along strike from northern Georgia to southern Virginia (Fig. 1). The CSB in a general sense is composed of two major elements. The first is an older sequence of dominantly felsic volcanic rocks, including flows and tuffs. Age dating by Wright and Seiders (1980), Carpenter et al. (1982) and Butler and Fullagar (1975) yielded ages of 586 + 10 Ma (U/Pb on zircon), 566 ± 15 Ma (U/Pb) and 554 ± Ma (Rb/Sr), and 522 + 24 Ma (Rb/Sr whole rock), respectively. The second element is a younger sequence of predominantly epiclastic units including mudstones, quartz siltstones and sandstones, shales, slates and phyllites. Biostratigraphic age dates range from late Proterozoic (on the basis of Pteridium fragments, see Gibson el al., 1984; Gibson and Teeter, 1984) to middle Cambrian (on the basis of sponge spicules,
Detailed Mine Geology of the Brewer Gold Mine, Jefferson, South Carolina
Authors: Zwaschka Mark , Scheetz John W. 
Published: August 2024

Abstract
The Brewer Gold Mine is situated within the Carolina Slate Belt of the Piedmont physiographic province approximately 1 km west of Jefferson, SC and 13 km northeast of the Haile Gold Mine, Kershaw, SC (Figure 1). Regionally, the mine is located about 80 km southeast of Charlotte, NC and 80 km northeast of Columbia, SC.
The mine was discovered in 1828 and began as a placer operation. Butler (1985) provides a chronological history of production. Historic production was from four main pits that are, from largest to smallest, Brewer, Hartman, Hilford Cut, and Topaz. Minor underground workings were developed from these pits. Gold production occurred in various intervals with the last time period from 1934 to 1940. Pre-modern gold production is estimated at a minimum of 22,000 ounces.
A number of companies have prospected and drilled at the Brewer including the USBM. Exploration drilling on the property (core and rotary) totals 44,026 ms. Approximately three-quarters of the drilling was performed by Nicor/Westmont/Brewer both in pre-production exploration drilling and development drilling while in production.
In 1987, Westmont Mining Inc. formed the Brewer Gold Company and production began in mid-1987 as an open-pit, heap leach operation. The reserve base at the onset of mining was 5.1 million tons @ 0.042 opt Au (4.6 Mt @ 1.4 g/t). Mining continued from three different pits; Brewer, B6, and Northwest Trend (Figure 2) and ceased January 1993. A total of 5.66 million tons of ore was mined with 177,674 ounces of gold being recovered. Table