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At least 19 recordsLinked to original sources
USGS2026

Top-down targeted network analysis of critical mineral commodities applied to international geochemistry database

The global demand for critical mineral commodities is rapidly increasing, making domestic production an important factor in supporting the economy and national security. Large scale, publicly available geochemical databases allow for the application of data informatics methods to interrogate critical mineral commodities data for correlations in deposit formation and distribution, particularly for identifying enrichment of multiple critical mineral commodities at the same deposit. In this study, we applied network analysis to the Critical Minerals Mapping Initiative (CMMI) ore geochemistry (Critical Minerals in Ores, CMiO) database to identify the high concentration (defined as 10× bulk crustal abundance) co-occurrence of different critical mineral commodities across a mineral system hierarchy from deposit environments to individual deposits. Identifying patterns or unique outliers in enrichment in network communities will allow for the location of secondary critical mineral commodity resources from under-utilized deposits. We find trends in the enrichment of critical mineral commodities in network-communities between the elements praseodymium (Pr), neodymium (Nd), terbium (Tb), and dysprosium (Dy) across multiple CMiO database deposit environments and groups down to specific deposit types and sites. A separate trend in network community deposition is observed as well between iridium (Ir) and platinum (Pt) in deposit environments, groups, types, and sites. Network analysis focused on critical minerals in magmatic-hydrothermal deposits identified multiple deposit sites from different deposit types within the CMiO database with concentrations of Dy, Nd, Tb, Pr, Ir, and Pt that are at least ten times greater than the crustal average. This approach can be applied to any target element(s) or deposit(s) of interest, allowing broad investigation of co-enriched critical mineral commodities.

Journal of Geochemical Exploration↗
USGS1954

Progress report (1953) on the revision of Washington's Chemical analyses of igneous rocks (U.S.G.S. Prof. Paper 99), presented at the First International Symposium on Geochemistry, under the auspices of the International Union of Chemistry, in Zurich, August 11-13, 1953

In October of last year, vhen I was here in Zurich, it was my privilege to talk with Professor Niggli about the revision of Washington's "Chemical analysis of igneous rocks" which the United States Geological Survey is undertaking. It was then that he suggested the possibility of a progress report at this meeting in order that information about the revision would be available to those who are most interested. At the time that I talked with Professor Niggli the place or this meeting had not bean decided, but I think he hoped that it would be in Zurich,, Today, we must proceed without him, but I am sure that you must feel, as I do, that he is here sn spirit and that he expects us to continue the work as he would have, - with enthusiasm, with strength, and with happiness.

Open-File Report↗
USGS2012

Fifty years of IMOG (International Meetings on Organic Geochemistry)

IMOG2011 is the 25th of a series of international meetings on organic geochemistry that began in 1962. Thus, this 25th meeting marks the 50th anniversary year of IMOG, which has (a) had a rich history with meetings taking place in 11 different countries, (b) published Proceedings, titled “Advances in Organic Geochemistry,” from each meeting that now number 24 volumes totaling almost 18,000 pages, and (c) documented the content and development of the science of organic geochemistry. IMOG2011 adds a new milestone to the progress of organic geochemistry through time.

Organic Geochemistry↗
USGS2007

Elements of the iron and manganese cycles in Lake Baikal

Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time of renewal, etc.). Some previous results and common concepts were critically reevaluated. ?? Pleiades Publishing, Ltd. 2007.

Geochemistry International↗
USGS2016

Helium as a tracer for fluids released from Juan de Fuca lithosphere beneath the Cascadia forearc

The ratio between helium isotopes (3He/4He) provides an excellent geochemical tracer for investigating the sources of fluids sampled at the Earth's surface. 3He/4He values observed in 25 mineral springs and wells above the Cascadia forearc document a significant component of mantle-derived helium above Juan de Fuca lithosphere, as well as variability in 3He enrichment across the forearc. Sample sites arcward of the forearc mantle corner (FMC) generally yield significantly higher ratios (1.2-4.0 RA) than those seaward of the corner (0.03-0.7 RA). The highest ratios in the Cascadia forearc coincide with slab depths (40-45 km) where metamorphic dehydration of young oceanic lithosphere is expected to release significant fluid and where tectonic tremor occurs, whereas little fluid is expected to be released from the slab depths (25-30 km) beneath sites seaward of the corner.Tremor (considered a marker for high fluid pressure) and high RA values in the forearc are spatially correlated. The Cascadia tremor band is centered on its FMC, and we tentatively postulate that hydrated forearc mantle beneath Cascadia deflects a significant portion of slab-derived fluids updip along the subduction interface, to vent in the vicinity of its corner. Furthermore, high RA values within the tremor band just arcward of the FMC, suggest that the innermost mantle wedge is relatively permeable.Conceptual models require: (1) a deep fluid source as a medium to transport primordial 3He; (2) conduits through the lithosphere which serve to speed fluid ascent to the surface before significant dilution from radiogenic 4He can occur; and (3) near lithostatic fluid pressure to keep conduits open. Our spatial correlation between high RA values and tectonic tremor provides independent evidence that tremor is associated with deep fluids, and it further suggests that high pore pressures associated with tremor may serve to keep fractures open for 3He migration through ductile upper mantle and lower crust.

Geochemistry International↗
USGS2003

Geochemistry of carbonatites of the Tomtor massif

Carbonatites compose sheet bodies in a 300-m sequence of volcanic lamproites, as well as separate large bodies at depths of >250-300 m. An analysis of new high-precision data on concentrations of major, rare, and rare earth elements in carbonatites shows that these rocks were formed during crystallization differentiation of a carbonatite magma, which resulted in enrichment of the later melt fractions in rare elements and was followed by autometasomatic and allometasomatic hydrothermal processes. Some independent data indicate that the main factor of ore accumulation in the weathered rock zone (also known as the "lower ore horizon" comprising metasomatized volcanics with interbedded carbonatites) was hydrothermal addition of Nb and REEs. The giant size of the Tomtor carbonatite-nepheline syenite massif caused advanced magma differentiation, extensive postmagmatic metasomatism and recrystallization of host rocks, and strong enrichment of carbonatites in incompatible rare and rare earth elements (except for Ta, Zr, Ti, K, and Rb) compared to the rocks of many other carbonatite massifs. We suggest that a wide range of iron contents in carbonatites-2 can be related to extensive magnetite fractionation at the magmatic stage in different parts of the huge massif.

Tomtor Massif↗
USGS2001

Environmental geochemistry at the global scale

Land degradation and pollution caused by population pressure and economic development pose a threat to the sustainability of the earth's surface, especially in tropical regions where a long history of chemical weathering has made the surface environment particularly fragile. Systematic baseline geochemical data provide a means of monitoring the state of the environment and identifying problem areas. Regional surveys have already been carried out in some countries, and with increased national and international funding they can be extended to cover the rest of the land surface of the globe. Preparations have been made, under the auspices of the International Union of Geological Surveys (IUGS) and the International Association of Geochemistry and Cosmochemistry (IAGC) for the establishment of just such an integrated global database. ?? 2001 NERC. Published by Elsevier Science Ltd.

Conference Paper↗
USGS2012

The IUGS/IAGC Task Group on Global Geochemical Baselines

The Task Group on Global Geochemical Baselines, operating under the auspices of both the International Union of Geological Sciences (IUGS) and the International Association of Geochemistry (IAGC), has the long-term goal of establishing a global geochemical database to document the concentration and distribution of chemical elements in the Earth’s surface or near-surface environment. The database and accompanying element distribution maps represent a geochemical baseline against which future human-induced or natural changes to the chemistry of the land surface may be recognized and quantified. In order to accomplish this long-term goal, the activities of the Task Group include: (1) developing partnerships with countries conducting broad-scale geochemical mapping studies; (2) providing consultation and training in the form of workshops and short courses; (3) organizing periodic international symposia to foster communication among the geochemical mapping community; (4) developing criteria for certifying those projects whose data are acceptable in a global geochemical database; (5) acting as a repository for data collected by those projects meeting the criteria for standardization; (6) preparing complete metadata for the certified projects; and (7) preparing, ultimately, a global geochemical database. This paper summarizes the history and accomplishments of the Task Group since its first predecessor project was established in 1988.

Earth Science Frontiers↗
USGS2006

Organic geochemistry - A retrospective of its first 70 years

Organic geochemistry had its origin in the early part of the 20th century when organic chemists and geologists realized that detailed information on the organic materials in sediments and rocks was scientifically interesting and of practical importance. The generally acknowledged "father" of organic geochemistry is Alfred E. Treibs (1899-1983), who discovered and described, in 1936, porphyrin pigments in shale, coal, and crude oil, and traced the source of these molecules to their biological precursors. Thus, the year 1936 marks the beginning of organic geochemistry. However, formal organization of organic geochemistry dates from 1959 when the Organic Geochemistry Division (OGD) of The Geochemical Society was founded in the United States, followed 22 years later (1981) by the establishment of the European Association of Organic Geochemists (EAOG). Organic geochemistry (1) has its own journal, Organic Geochemistry (beginning in 1979) which, since 1988, is the official journal of the EAOG, (2) convenes two major conferences [International Meeting on Organic Geochemistry (IMOG), since 1962, and Gordon Research Conferences on Organic Geochemistry (GRC), since 1968] in alternate years, and (3) is the subject matter of several textbooks. Organic geochemistry is now a widely recognized geoscience in which organic chemistry has contributed significantly not only to geology (i.e., petroleum geochemistry, molecular stratigraphy) and biology (i.e., biogeochemistry), but also to other disciplines, such as chemical oceanography, environmental science, hydrology, biochemical ecology, archaeology, and cosmochemistry.

Conference Paper↗
USGS2010

Episodic intrusion, internal differentiation, and hydrothermal alteration of the Miocene Tatoosh intrusive suite south of Mount Rainier, Washington

The Miocene Tatoosh intrusive suite south of Mount Rainier is composed of three broadly granodioritic plutons that are manifestations of ancestral Cascades arc magmatism. Tatoosh intrusive suite plutons have individually diagnostic characteristics, including texture, mineralogy, and geochemistry, and apparently lack internal contacts. New ion-microprobe U-Pb zircon ages indicate crystallization of the Stevens pluton ca. 19.2 Ma, Reflection-Pyramid pluton ca. 18.5 Ma, and Nisqually pluton ca. 17.5 Ma. The Stevens pluton includes rare, statistically distinct ca. 20.1 Ma zircon antecrysts. Wide-ranging zircon rare earth element (REE), Hf, U, and Th concentrations suggest late crystallization from variably evolved residual liquids. Zircon Eu/Eu*–Hf covariation is distinct for each of the Reflection-Pyramid, Nisqually, and Stevens plutons. Although most Tatoosh intrusive suite rocks have been affected by weak hydrothermal alteration, and sparse mineralized veins cut some of these rocks, significant base or precious metal mineralization is absent. At the time of shallow emplacement, each of these magma bodies was largely homogeneous in bulk composition and petrographic features, but, prior to final solidification, each of the Tatoosh intrusive suite plutons developed internal compositional variation. Geochemical and petrographic trends within each pluton are most consistent with differential loss of residual melt, possibly represented by late aplite dikes or erupted as rhyolite, from crystal-rich magma. Crystal-rich magma that formed each pluton evidently accumulated in reservoirs below the present level of exposure and then intruded to a shallow depth. Assembled by episodic intrusion, the Tatoosh intrusive suite may be representative of midsized composite plutonic complexes beneath arc volcanoes.

Washington↗
USGS2008

Bjørn Bølviken - 2008 IAGC Vernadsky medalist

Prof. Bjørn Bølviken, 80, formerly with the Geological Survey of Norway, was the 2nd recipient of the IAGC's Vernadsky Medal. The IAGC Vernadsky Medal is awarded biennially to a single person for a distinguished record of scientific accomplishment in geochemistry over the course of a career. Dr. David Smith of the US Geological Survey and Leader of the IAGC Working Group on ‘Global Geochemical Baselines’ was the citationist for the award.

Newsletter of the International Association of Geo↗
USGS2013

The distribution of uranium over Europe: Geological and environmental significance

The variation of baseline levels of uranium in soil and stream sediments over Europe is described, based on new data prepared by the Forum of European Geological Surveys (FOREGS). The samples have been collected and analysed according to the protocols established for the International Union of Geological Sciences/International Association of Geochemistry and Cosmochemistry (IUGS/IAGC) Working Group on Global Geochemical Baselines. The baseline levels of U vary between 0??21 to 53 mg kg-1 in topsoils, 0??19 to 30 mg kg-1 in subsoils and < 1 to 59 mg kg-1 in stream sediments. There is generally good agreement between the levels of U in the three sample types, and the median concentration in all three media is approximately 2 mg kg-1. The most anomalous baseline levels occur over the Variscan orogen, especially areas into which late post-orogenic radiothermal high heat production (HHP) granites were emplaced. Spiderdiagrams based on trace element levels and rare earth element (REE) plots, confirm the association between the highest U anomalies and evolved radiothermal granites. High values are also associated with parts of the Alpine terrain especially in Slovenia, where there are historical U workings, and Southern Italy, where high values of U reflect contemporary volcanism. In contrast, much of the Caledonides of North West Europe and the Precambrian of the Baltic Shield and East European craton and its overlying sedimentary cover have very low values, generally < 4 mg kg-1. The results suggest that the main concern for the environment and human health from U, and the Th and K with which it is generally associated, is the naturally occurring total gamma radiation and radon potential associated with radiothermal granites. This is likely to be especially important where the granites are mineralised and have been worked historically, for example in the North West of the Iberian Peninsula where U and its decay products are likely to be more dispersed in the surface environment. The study also indicates the value of multi-element data in distinguishing between anthropogenic and naturally occurring anomalies.

Transactions of the Institution of Mining and Meta↗
USGS1998

Geochemistry of coalbed gas - a review

Coals are both sources and reservoirs of large amounts of gas that has received increasing attention in recent years as a largely untapped potential energy resource. Coal mining operations, such as ventilation of coalbed gas from underground mines, release coalbed CH4 into the atmosphere, an important greehouse gas whose concentration in the atmosphere is increasing. Because of these energy and environmental issues, increased research attention has been focused on the geochemistry of coalbed gas in recent years. This paper presents a summary review of the main aspects of coalbed gas geochemistry and current research advances.Coals are both sources and reservoirs of large amounts of gas that has received increasing attention in recent years as a largely untapped potential energy resource. Coal mining operations, such as ventilation of coalbed gas from underground mines, release coalbed CH4 into the atmosphere, an important greenhouse gas whose concentration in the atmosphere is increasing. Because of these energy and environmental issues, increased research attention has been focused on the geochemistry of coalbed gas in recent years. This paper presents a summary review of the main aspects of coalbed gas geochemistry and current research advances.

International Journal of Coal Geology↗