bluuebunny/crossref_metadata_2025 huggingface dataset:
The Boss Iron-Copper Deposit, Missouri
Authors: Kisvarsanyi Geza
Published: August 2024

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

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

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

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

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

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

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

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

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 <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

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

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

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

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 <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

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

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

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

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

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
Geologic Overview of the Carlin Trend Gold Deposits and Descriptions of Recent Deep Discoveries
Authors: Teal Lewis , Jackson Mac
Published: August 2024

Including past production, reserves and resources, the Carlin Trend forms the largest and most prolific accumulation of gold deposits in North America. More than 40 separate deposits have been delineated since disseminated gold mineralization in carbonate rocks was discovered in 1961. From this discovery, a classification for this style of gold mineralization has come to be referred to as “Carlin-type” deposits. To date, more than 25 million ounces of gold have been mined on the Carlin Trend from 26 separate operating, or past producing mines (Table 1). Open pit mining on the Carlin Trend began in 1965 at the Carlin Mine, and underground mining began in 1993 on the same deposit.

The scope of this paper is to first present a regional overview of the Carlin Trend, followed by summary descriptions of some of the more recent discoveries of deep, predominantly refractory gold deposits. As part of a concluding discussion, a spectrum of Carlin Trend deposits are categorized on a quaternary diagram to illustrate the I relative influence of structural and stratigraphic controls on each deposit.
Breccia Types in the Betze Orebody, Goldstrike Mine, Eureka County, Nevada
Authors: Peters S.G. , Leonardson R.W. , Ferdock G.C. , Lauha E.A.
Published: August 2024

This paper describes outcrop- and hand specimen-scale breccias in the Betze orebody, which is the largest gold deposit on the Carlin trend (Bettles and Lauha, 1991; Leonardson and Rahn, 1996). The Betze orebody lies in the north-central part of the Carlin trend in the Goldstrike Mine (Fig. 1), and it is part of the Betze-Post deposits (Arehart et al., 1993; Lauha and Bettles, 1993; Smith and Sharon, 1994; Leonardson and Rahn, 1996). The orebody and much of the internal breccia bodies have a general WNW strike, with a sub-horizontal attitude (Peters, 1996; 1997). The open pit Goldstrike Mine exposes the Betze and Post orebodies, the Post anticline (Fig. 2), contacts between the Silurian and Devonian Roberts Mountains Formation, Devonian Popovich limestone and Devonian Rodeo Creek unit, and the northern contact of the Jurassic Goldstrike stock (Volk and Zimmerman (1991).

Breccia bodies host much of the Betze ore body. Breccias are common rock types in most Carlin-type deposits (Williams, 1992, 1993), and they are particularly common in ore bodies of the north-central Carlin trend (Clode, 1993; Griffin et al., 1993; Leach, 1993). The host rocks in the Betze orebody are altered and deformed. The complex descriptive geology of the Goldstrike Mine is detailed by Volk et al. (1996), Peters et al.(1996), and Leonardson and Rahn (1996). The WNW-striking Dillon deformation zone (DDZ) hosts the upper central Betze orebody (Fig. 2) and contains several ore types associated with breccia (Peters, 1996, 1997). Rock types that host the orebody include phyllonitic black to
Isotopic Composition of Sulfur in Carlin-type Gold Deposits
Authors: Hofstra Albert H.
Published: August 2024

The goal of this report is to consider new and existing sulfur isotope data from Carlin-type gold deposits within the context of a modem understanding of the geology of the region and processes of ore formation. Increased understanding of the source(s) of sulfur and mechanisms of H2S generation may help to discriminate between the various models proposed for the deposits. The source of reduced sulfur is very important because available evidence indicates the deposits formed from H2S-rich (SO4-poor) fluids that transported gold as a bisulfide complex. High H2S-concentrations in ore fluids are indicated by (1) the common occurrence of high sulfidation state minerals such as orpiment and realgar, (2) mass transfer studies which show that sulfur was one of the most abundant elements introduced by the hydrothermal fluids, (3) gas analyses of fluid inclusions which show the fluids contained 10-1 to 10-2m H2S, (4) petrographic and geochemical evidence which indicates that sulfidation of host rock iron was an important (but not the only) gold depositional mechanism in most of the deposits, and (5) chemical reaction path modeling which shows that sulfidation can produce the gold grades observed in the deposits (Hofstra et al., 1991; Hofstra, 1994). The predominance of H2S over sulfate is important because the isotopic composition of H2S is then representative of the bulk composition of sulfur in the ore fluids. Given that gold was transported as a bisulfide complex, knowledge of the sites of H2S production and migration pathways will also likely provide information on the source
Sterling Mine, Nye County, Nevada
Authors: Castor Stephen B.
Published: August 2024

Although relatively small, the sedimentary rock-hosted Sterling Mine has been the largest gold producer in the Bare Mountain district in southern Nye County, with total production of about 130,000 troy ounces between 1983 and 1996. Other gold production in the district has come from sedimentary and volcanic rock-hosted ore at the Mother Lode Mine (Mapa, 1990) and the Fluorspar Canyon deposits (Greybeck and Wallace, 1991) about 10 km north and northwest of the Sterling Mine. The district has also produced fluorspar and minor amounts of mercury.

At the Sterling Mine, mineralization is controlled by the intersection of north-northeast striking, high-angle normal faults with a thrust fault that separates siliciclastic rocks of the Late Proterozoic to Early Cambrian Wood Canyon Formation in the upper plate from carbonate rocks of the Middle Cambrian Bonanza King Formation in the lower plate. This mineralization is associated with an alteration assemblage that includes kaolinite, halloysite, illitesmectite, sericite, and alunite (Odt, 1983). Jarosite and limonite are present in most mineralized rock, but primary sulfide ore occurs in places and contains pyrite (Fig. 1 ), marcasite, arsenopyrite, and traces of sphalerite and galena (Joe Marr, personal communication, 1996). Samples ofunoxidized ore consist of quartz± dolomite± kaolinite and contain pyrite± marcasite± stibnite ±galena. On the basis of SEM examination, an unoxidized sample withl38 ppm gold contains pyrite with 1- to 2-micron-thick rims and veins of arsenian pyrite (see the figure below). Very rare micron-size gold is present, but the grade is too high to be accounted for by
Eocene Magmatism of the Tuscarora Volcanic Field, Elko County, Nevada, and Implications for Carlin-type Mineralization
Authors: Henry Christopher D. , Boden David R.
Published: August 2024

The Tuscarora volcanic field (TVF), the largest Eocene volcanic field in Nevada, lies just north of major gold deposits of the Carlin Trend and west of deposits in the Independence Mountains (Fig. 1). Ongoing detailed mapping documents at least five voluminous volcanic-intrusive centers in the southeastern part of the TVF (Figs. 1, 2). 40Ar39 Ar dates show that the five centers developed between 39.9 and 39.2 Ma during a brief, intense period of magmatism. Precious-metal mineralization at Tuscarora formed at about 39.3 Ma, contemporaneous with a major intrusive episode, and is the oldest Tertiary volcanic-hosted epithermal deposit in Nevada. Compilation of 40Ar39 Ar dates indicates that magmatism was particularly intense between 39 and 40 Ma throughout northeastern Nevada. Given that several Carlin-type deposits are now interpreted to have formed in the Eocene (Hofstra, 1995~ Emsbo, 1996~ Leonardson and Rahn, 1996~ Phinisey et al., 1996~ Rota, 1996), contemporaneous with this activity, we suggest that Eocene magmatism was directly or indirectly the heat source to drive hydrothermal circulation that generated Carlin-type deposits (see also Hofstra, 1995).
Blue Star Subdistrict Zoned Alteration Mineralogy and Gold Mineralization, Eureka County, Nevada
Authors: Williams Cindy L.
Published: August 2024

The Blue Star subdistrict in the Carlin Trend, Nevada, includes multiple gold mines with 2 million ounces in reserve and past production totaling 3. 9 million ounces. The deposits are characterized by zoned alteration mineralogy and gold grades. From orebody centers outward the zones include: 1) a silicified core with erratic gold grade; 2) adjacent mill-grade (>0.050 oz/st Au) intense quartz-sericite-pyrite alteration; 3) enveloping leach-grade (0.006 to 0.050 oz/st Au) weaker sericite-kaolinite-quartz-pyrite alteration; 4) surrounding decarbonatized and intensely argillized waste and leach grade ore; 5) pervasively decarbonatized waste rock; and 6) peripheral waste with weak decarbonatization
New K-Ar and 40Ar/39Ar Ages of Plutonism, Hydrothermal Alteration, and Mineralization in the Central Wasatch Mountains, Utah
Authors: John David A. , Turrin Brent D. , Miller Robert J.
Published: August 2024

Twenty-one new K-Ar and 10 new 40Ar/39Ar ages are reported for igneous and hydrothermal minerals from intrusive rocks of the Wasatch igneous belt in the central Wasatch Mountains. Interpretation of our new data combined with previously published K-Ar ages and with new 40Ar/39Ar and U-Pb ages reported by Vogel et al. (1997) suggests that the Clayton Peak stock was emplaced at about 36 to 35 Ma, the Alta stock at about 35 to 33 Ma, and the Little Cottonwood stock at about 31 to 30 Ma. Biotite K-Ar ages progressively increase from west to east in the Little Cottonwood stock, which is consistent with more rapid cooling of the eastern part of the stock and with other evidence suggesting about 15 degrees of eastward tilting of the central Wasatch Mountains following emplacement of the Wasatch igneous belt. Most porphyry stocks in the Park City mining district were emplaced at about 41 to 40 Ma; the Ontario stock was emplaced at about 36 Ma. Vein deposits in the Park City mining district formed at about 36 to 33 Ma. The Park Premier stock was emplaced in several pulses between about 35 to 32 Ma. Alteration related to porphyry copper mineralization in the Park Premier stock formed at 33.5 Ma and advanced argillic alteration and gold mineralization formed at 31.4 Ma. Molybdenum mineralization in the eastern part of the Little Cottonwood stock formed between 26 to 23.5 Ma.
Distribution and Mineralogy of Gold and Silver in the Bingham Canyon Porphyry Copper Deposit, Utah
Authors: Ballantyne Geoffrey H. , Smith Tracy W. , Redmond Patrick B.
Published: August 2024

The Bingham Canyon porphyry copper deposit, prior to mining, is estimated to have contained 40.4 million ounces of gold and 289 million ounces of silver within 3,105 million tons of ore. The gold-mineralized zone mimics the shape of, and is coaxial with, the copper ore shell, but the zone of highest-grade gold mineralization lies at a slightly lower elevation than the zone of highest-grade copper mineralization. Geological observations suggest that high gold grades are associated with abundant bornite. The distribution of silver corresponds closely with that of copper.

Gold and silver recoveries for Bingham porphyry ore have averaged 68 and 81 percent, respectively, since the introduction of froth flotation in 1920. Electron microprobe examinations of head and concentrate samples suggest that most gold occurs as particles less than 25 microns across and is alloyed with less than 15 wt percent silver. Most gold particles occur on the boundaries of chalcopyrite and bornite grains and as inclusions within those minerals. Gold, silver, and bismuth tellurides are present but rare. The mode of occurrence of silver is not well established, but based on the high silver recovery and the response of concentrator products to leach tests, most of the silver is inferred to be present in solid solution in copper sulfide minerals. Sequential leach tests suggest that approximately 10 percent of the gold in the ore is encapsulated in pyrite and approximately 5 percent is encapsulated in silicate minerals.
Copper-Gold Skarn Deposits of the Bingham Mining District, Utah
Authors: Harrison Edwin D. , Reid Julia E.
Published: August 2024

Copper-gold skarns peripheral to the porphyry copper deposit in the Bingham mining district, Utah, contain a geologic resource of over 7 million tons of copper and 9 million ounces of gold. The skarn deposits, hosted by Pennsylvanian limestone beds within the contact metamorphic aureole of the Tertiary Bingham stock, have been mined intermittently since 1896. In the late 1960s, two large deposits were discovered at depth on the north side of the district by The Anaconda Company and Kennecott Copper Corporation: the Carr Fork mine, operated by Anaconda from 1979 to 1981, and the North Ore Shoot deposit, which has not entered production. Recent drilling by Kennecott on the eastern flank of the North Ore Shoot has resulted in discovery of the Fortuna deposit. These three areas are all part of the same, continuous skarn system.

A remarkable horizontal and vertical extent of skarn is displayed within the Bingham district. Mineralized skarn occurs in a zone roughly 2,000 feet wide around the quartz monzonite porphyry phase of the Bingham stock and extends over a mile vertically from surface exposures to the deepest drill-hole intersection. Skarn ore, delineated by the +1 percent copper grade contour, lies outside the porphyry copper ore shell and extends to a lower elevation. The Carr Fork orebodies consist predominantly of chalcopyrite in retrograde-altered garnetite skarn. In the North Ore Shoot and Fortuna deposits, massive sulfide replacement bodies are the principal ore type, although mineralized garnetite is also present. Pyrite-gold mineralization that crosscuts copper-gold skarn has been found in the Bingham skarn deposits, but its relationship to other gold mineralization in the district is unclear. Beyond the zone of copper-iron-gold mineralization, lead-zinc-silver deposits occur in limestone and other host rocks within a broad halo nearly one mile wide.
High-Sulfidation Epithermal Gold Deposit at Klokoč - Podpolom
Authors: Štohl Jaroslav , Žáková Eva , Lexa Jaroslav
Published: August 2024

The paleohydrothermal systems in the central zone of the Javorie stratovolcano are represented at the surface by conspicuous outcrops of secondary quartzites (residual quartz) and much less conspicuous argillized rocks. These zones of advanced argillic alteration were assumed during the early seventies to reflect porphyry copper systems at depth. Subsequent drilling at Banisko (Konecný et al., 1997), and a systematic metallogenetic survey in the central zone of the Javorie stratovolcano (Štohl at al., 1981) confirmed this assumption and provided extensive information concerning the geology, mineralogy, geochemistry and geophysics of this area. The next stage of metallogenetic investigation (Štohl et al., 1985, 1986) was then devoted to the detailed study of individual hydrothermal systems. Geochemical sampling as well as drilling was used to explore for a possible enargite-type Cu mineralization; with the exception of a few occurrences the results were negative. Nobody was aware of the possibility for gold potential at that time. In addition, gold was not analyzed for since sufficiently sensitive analytical methods were not available to carry out systematic gold geochemistry.

In the early nineties the advanced argillic zones of alteration were recognized to represent high-sulfidation epithermal systems with a possible gold potential. In February, 1996, Rhodes mining company began to explore the area. Portions of drill cores from the preceding exploration campaign which were enriched in pyrite were sampled and analyzed for gold; however, the results were mostly negative, with only two samples showing values close to 1 g/t. The discovery of gold mineralization at Klokoc —
Overview of Epithermal Gold Mineralization in Kyushu, Japan
Authors: Izawa Eiji , Watanabe Koichiro
Published: August 2024

Epithermal gold deposits are the principal source of gold in Japan, and mesothermal vein gold or by-product gold from skarn deposits, VMS (the Kuroko type and the Besshi type), and polymetallic veins contribute historically only 10 percent of domestic gold production. Gold production from epithermal gold deposits of Kyushu amounts to 284 tonnes and comprises about 40 percent of total Japanese gold production, 576 tonnes, from the Meiji Restoration (1868) to present (1999). The silver/gold ratio of ores in Kyushu is less than three and differs from the value that exceeds 10 in other areas (Fig. 1). The Yamagano mine in the Edo era and later the Taio and Kushikino mines were the largest gold-silver mines in Kyushu before the discovery of the Hishikari deposit. At present the Hishikari underground operation and three opencut mines of the Nansatsu-type gold deposits at Kasuga, Iwato, and Akeshi are producing gold.

The major gold deposits in Kyushu, typically of the low- sulfidation vein type and locally the high-sulfidation Nansatsu type, occur in extinct or waning geothermal systems of the Pliocene and Pleistocene volcanic areas. The young formation ages relate to the well-preserved shallow bonanza zones and overlying thick argillic alteration zones, and in places surface expression of hydrothermal activity, such as sinters and nearby acid alteration related to steam- heated acid hot springs.

This contribution aims to present supplementary data to a previous review paper (Izawa and Urashima, 1989), which described the relationship
Geology of Sakurajima Volcano, Southern Kyushu, Japan
Authors: Kobayashi Tetsuo
Published: August 2024

Sakurajima is an andesitic stratovolcano situated on the southern rim of Aira caldera, southern Kyushu, Japan. The first eruption from Sakurajima volcano is estimated (using tephrochronology) to have occurred circa 23 ka B.P., following a large ignimbrite eruption from Aira caldera at circa 24.5 ka B.P. The oldest eruption in historic times occurred in the eighth century, and eruptions since the fifteenth century are well documented. They include five flank eruptions and many small-scale summit eruptions. The latest big eruption occurred in 1914 and produced large volumes of pyroclastics and lava flows. Current activity is represented by intermittent explosive eruptions from the summit crater that began in 1955. More than several million cubic meters of volcanic products have been ejected every year, and debris flows occur regularly, especially in the rainy season.
Field Trip Day One
Authors: McLelland James M.
Published: August 2024

This First day of the field trip visits Proterozoic iron deposits at the Podunk and Skiff Mountain iron mines, in the eastern Adirondack Mountains of New York state. Included are roadcuts to see representative lithologies and structures in the region surrounding the iron deposits. The origin of these iron deposits has been controversial, but studies by Foose and McLelland (1995) and more recently by McLelland et al. (2001b, 2001c) provide strong evidence for a high-temperture, intramagmatic origin related to late stages the Lyon Mountain Granite and correlative intrusions during the latter part of the 1090 to 1030 Ma Ottawan orogeny. The great majority of the deposits consist of low Ti magnetite ore accompanied by apatite and aegerine-augite. The apatite has high concentrations of rare-earth elements (REE) indicating to Foose and McLelland (1995) that the deposits are of Kiruna (REE-Au-U-Cu) type. This is further supported by persistent sodic (i.e., albitic) alteration associated with the ores. Most of the iron ores appear to be undeformed although they may occur in strained host rocks. Deposits are intimately associated with late tectonic to posttectonic Lyon Mountain Granitic Gneiss that was emplaced at ca. 1055 Ma, during the waning stages of the ca. 1090 to 1030 Ma Ottawan Orogeny.
Field Trip Day Two
Authors: McLelland James M. , Slack John F. , DeLorraine William F.
Published: August 2024

This Day of the field trip visits the large Chateaugay open pit of the Lyon Mountain group of iron mines, in the northern Adirondack Mountains, following by visits to roadcuts in the Adirondack Lowlands to the west, in the vicinity of the Balmat zinc mine. The Chateaugay open pit has superb exposures of iron ore remaining on walls and in the entrances to stopes, which clearly establish the geologic and paragenetic relations of the magnetite ores and yield compelling evidence for their high-temperature, intramagmatic origin via hydrothermal fluids (McLelland et al., 2001b, 2001c). A wide variety of rock types ranging from leucogranite to mineralized skarns are present.

In the afternoon this day features stops at five roadcuts between the town of Gouverneur, New York, and the Balmat zinc mine to the east. These roadcuts provide a good overview of the regional geologic setting of the Balmat deposit, including stratigraphy, structure, deformation, and metamorphism. Whereas the geochronology in the Adirondack Highlands to the east is well established (e.g., McLelland et al., 2001c), the Lowlands is underlain mostly by metasedimentary rocks hence its precise age range is difficult to determine. One constraint is provided by U-Pb zircon ages of 1284 ±7 Ma, 1236 ± 6 Ma, and 1230 ± 33 Ma for the Gouverneur, Fish Creek, and Hyde School alaskite bodies, respectively, that occur in the Lowlands (Grant et. al., 1986; McLelland and Chiarenzelli, 1990; McLelland et al., 1992). Although these alaskite bodies were interpreted by Carl and Van Diver (1975) to
Introduction
Authors: Seal Robert R. , Hammarstrom Jane M. , Slack John F. , Hathaway Edward M. , Lovely William P. , Kierstead Matthew A.
Published: August 2024

The Purpose of this trip is to examine relations of the economic geology and mining history of the Vermont copper belt to the environmental behavior of these deposits and their potential future reclamation. In contrast, the 1993 Society of Economic Geologists field trip focused on the regional and economic geology of the copper belt (Slack etal., 1993).

The Vermont copper belt, like many other mining districts, has had a long and colorful history (Abbott, 1973). This history spans the period of active mining from the discovery of the Elizabeth deposit in 1793 through its closure in 1958, to the present, as plans to reclaim the site are being made. Like other districts, the history is intimately intertwined with the economic development and early settlement of the region. Production was dominated by three main mines: Elizabeth, near South Strafford; Ely, near West Fairlee; and Pike Hill, near Corinth. In addition, several other smaller mines and prospects are found in the belt. All mines exploited copper-rich massive sulfide deposits, or their weathered equivalents. The earliest mining from Elizabeth was for iron from the gossan zone, followed by mining of pyrrhotite for the manufacture of copperas (hydrated ferrous sulfate). Copperas was produced by roasting the ores to oxidize the pyrrhotite. Resulting ferrous sulfate was leached from the roast beds with water, and concentrated in evaporating vats. During the late 18th and early 19th centuries, copperas was used for curing and setting colors in hides and pelts, and for making dyes, treating timbers and
Sources of Metals and Acidity at the Elizabeth and Ely Mines
Authors: Hammarstrom Jane M. , Seal Robert R. , Ouimette Andrew P. , Foster Scot A.
Published: August 2024

The Elizabeth and Ely mines are developed in pyrrhotite-rich, Besshi-type massive sulfide deposits in the Orange County copper district of east-central Vermont. Mine waste and flotation mill tailings have been exposed to weathering for 50 years or more, resulting in acid mine drainage. The Elizabeth mine became a Superfund site in 2001; the Ely mine is proposed. Geochemical and mineralogical characterization of historical mine waste and modern flotation tailings show that despite differences in mine site history, the mines share many similarities. The Elizabeth site includes metal-rich mine waste piles associated with 19th century copperas (melanterite) production, remnants of copper smelter operations, as well as 1.5 million m3 of pyrrhotite-rich flotation tailings. Total base metal concentrations in the surface material on the historically significant Elizabeth mine wastes are higher (as much as 7,000 ppm) than in oxidized parts of flotation mill tailings piles (1,000 ppm or less). Cu >Zn>Pb throughout historic waste piles; Zn>Cu >Pb throughout much of the flotation tailings piles. Variations in Cu/Zn ratios reflect changes in efficiency of chalcopyrite processing over time. Ely ore was smelted for copper on-site after partial roasting, leaving roast beds, mine waste piles, and slag. Oxidized surface materials at both sites are goethite- and jarosite-rich, and locally hematite-rich in roast bed areas. Fine-grained, unoxidized pyrrhotite- and mica-rich tailings lie within 30 cm of the oxidized tailings surfaces. Highly soluble efflo-rescent sulfate salts (melanterite, rozenite, chalcanthite) form intermittently on historic mine waste piles and locally on flotation tailings surfaces at both mines and contribute metals and acidity to surface runoff during rainstorms and spring snowmelt. Water quality in streams draining both mine sites will improve only if the established cycles of weathering of exposed ore, efflorescent sulfate salt formation and dissolution, and release of metals and acidity to the surface runoff, are broken.
PENGARUH LAJU PERTUMBUHAN EKONOMI DAN TINGKAT INFLASI TERHADAP PENERIMAAN PAJAK DAERAH DI PROVINSI DI INDONESIA PERIODE 2017-2021
Authors: TB AGUNG AMALUDIN  , Romadhina Anggun Putri
Published: August 2024

Penelitian ini bertujuan untuk mengetahui pengaruh laju pertumbuhan ekonomi dan tingkat inflasi terhadap penerimaan pajak daerah di provinsi di Indonesia periode 2017-2021. Jenis penelitian yang digunakan yaitu kuantitatif dengan menggunakan metode pengumpulan data menggunakan data sekunder. Teknik penentuan sampel yang digunakan adalah metode sampel jenuh, yakni metode penentuan sampel dengan seluruh populasi dijadikan sampel penelitian. Populasi dalam penelitian ini adalah 34 provinsi di Indonesia periode 2017-2021. Hasil penelitian membuktikan bahwa secara simultan laju pertumbuhan ekonomi dan tingkat inflasi berpengaruh secara signifikan terhadap penerimaan pajak daerah, secara parsial laju pertumbuhan ekonomi berpengaruh signifikan terhadap penerimaan pajak daerah dan variabel tingkat inflasi juga berpengaruh secara signifikan terhadap penerimaan pajak daerah di provinsi di Indonesia.
PENGARUH VOLATILITAS PENJUALAN, DAN TINGKAT HUTANG TERHADAP PERSISTENSI LABA DENGAN TAX AVOIDANCE SEBAGAI MODERASI
Authors: SANI M. KHAIRUL , NADI LUH
Published: August 2024

The purpose of this study was conducted to examine and analyze the influence of sales volatility and debt levels on earnings persistence. Moderating Variables are useful for knowing whether these variables can strengthen or weaken the independent variable on the dependent variable. The research population is 118 companies in the Primary Consumer Goods (Consumer Non-Cyclicals) sector which are listed on the Indonesia Stock Exchange in 2017 – 2021. The type of research used is quantitative using secondary data. The method of determining the sample using purposive sampling. The number of samples is 56 companies. The research results show that sales volatility and debt levels moderated by tax avoidance simultaneously affect earnings persistence. Sales volatility affects earnings persistence. The level of debt has no effect on earnings persistence. Partially, the tax avoidance moderating variable has no effect on earnings persistence. In this study, tax avoidance was not able to moderate the relationship between sales volatility and earnings persistence, as well as the debt level variable, which was moderated by tax avoidance, proving that tax avoidance was not able to moderate the relationship between debt levels and earnings persistence.