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USGS1963

Hydrology of upper Black Earth Creek basin, Wisconsin, with a section on surface water

The upper Black Earth Creek drainage basin has an area of 46 square miles and is in Dane County in south-central Wisconsin. The oldest rock exposed in the valley walls is the sandstone of Late Cambrian age. Dolomite of the Prairie du Chien Group of Ordovician age overlies the sandstone and forms the. resistant cap on the hills. The St. Peter Sandstone, Platteville and Decorah Formations, and Galena Dolomite, all Ordovician in age, form a narrow belt along the southern boundary of the area. Outwash and alluvium of Pleistocene and Recent age fill the valleys. The eastern half of the area was glaciated and is covered with till. The sandstone of Late Cambrian age and the sand and gravel of the outwash deposits are hydraulically connected. Ground water occurs under unconfined (water-table) conditions in the western unglaciated part of the basin and under artesian conditions beneath the till locally in the eastern part. The source of most of the ground water is direct infiltration of precipitation; however, some ground water enters the area as underflow from the south. About 7 inches of the 30 inches of average annual precipitation recharges the ground-water reservoir. The ground water generally moves toward Black Earth Creek where it is discharged. Some ground water moves out of the basin as underflow beneath the valley of Black Earth Creek, and some is discharged by evapotranspiration or is withdrawn by pumping from wells. Water levels in shallow nonartesian wells respond rapidly to precipitation. The effect of precipitation on water levels in artesian wells is slower and more subdued. Water levels are generally highest in spring and lowest in fall and winter. The flow of upper Black Earth Creek is derived mostly from ground-water discharge, except during short periods of and immediately after precipitation when most of the flow is derived from surface runoff. The runoff from upper Black Earth Creek basin decreased from an average of 8.72 inches per square mile of drainage area in 1955 to 5.55 inches in 1958; the decrease reflects the generally decreasing precipitation and declining water levels in the basin during that period. On July 10, 1958, the discharge from the basin was 0.367 cubic feet per second per square mile, and the greatest discharge was 0.84 cubic feet per second per square mile from the southwest subbasin. The ground water has an average temperature of about 50°F. It is a calcium magnesium bicarbonate type water and is very hard.

Wisconsin↗

USGS2020

Book review: Rare earth element resources: Indian context

Rare Earth Element Resources: Indian Context. Yamuna Singh. 2020. ISBN 978-3-030-41353-8. Society of Earth Scientists Series, Springer, Cham, Switzerland, 269 Pp. Hardcover and eBook. €93.08 Rare Earth Element Resources: Indian Context by Yamuna Singh provides an excellent review of rare earth element (REE) deposits and occurrences in India with an emphasis on placer deposits, India’s most notable REE resource. This 269-page, 10-chapter book not only describes REE occurrences but also provides introductory material on REE geochemistry and discusses other potential industrial sources including recycling, fly ash, and mine waste products. The book concludes with a chapter on the state of the REE industry in India and discusses possible future trends and needs. Anyone interested in exploring for REEs in India will find this book from Springer’s Society of Earth Scientists series a useful reference.

Economic Geology↗

USGS1953

Method for determination of small amounts of rare earths and thorium in phosphate rocks

In laboratory investigations, interest developed in the possible rare-earth content of phosphate samples from Florida and the northwestern United States. Because of the difficulty of making chemical determinations of traces of individual rare earths, a combined chemical-spectrographic method was investigated. After removal of iron by the extraction of the chloride with ether, the rare earths and thorium are concentrated by double oxalate precipitation, using calcium as a carrier. The rare earths are freed from calcium by an ammonium hydroxide precipitation with a fixed amount of aluminum as a carrier. The aluminum also serves as an internal standard in the final spectrographic analysis. The method will determine from 0.02 to 2 mg. of each rare earth with an error no greater than 10%. The investigation has resulted in a fairly rapid and precise procedure, involving no special spectrographic setup. The method could be applied to other types of geologic materials with the same expected accuracy.

Analytical Chemistry↗

USGS1991

Satellite and earth science data management activities at the U.S. geological survey's EROS data center

The U.S. Geological Survey's Earth Resources Observation Systems (EROS) Data Center, the national archive for Landsat data, has 20 years of experience in acquiring, archiving, processing, and distributing Landsat and earth science data. The Center is expanding its satellite and earth science data management activities to support the U.S. Global Change Research Program and the National Aeronautics and Space Administration (NASA) Earth Observing System Program. The Center's current and future data management activities focus on land data and include: satellite and earth science data set acquisition, development and archiving; data set preservation, maintenance and conversion to more durable and accessible archive medium; development of an advanced Land Data Information System; development of enhanced data packaging and distribution mechanisms; and data processing, reprocessing, and product generation systems.

Conference Paper↗

USGS2006

Rare earths, the lanthanides, yttrium and scandium

In 2005, rare earths were not mined in the United States. The major supplier, Molycorp, continued to maintain a large stockpile of rare-earth concentrates and compounds. Consumption decreased of refined rare-earth products. The United States remained a major importer and exporter of rare earths in 2005. During the same period, yttrium was not mined or refined in the US. Hence, supply of yttrium compounds for refined yttrium products came from China, France and Japan. Scandium was not also mined. World production was primarily in China, Russia and Ukraine. Demand for rare earths in 2006 is expected to be closely tied to economic conditions in the US.

Mining Engineering↗

USGS1977

Rare earths, thorium, and other minor elements in sphene from some plutonic rocks in west-central Alaska

Sphene is an abundant accessory mineral in some abnormally radioactive plutonic rocks in west-central Alaska. Seven samples of sphene from four different areas in west-central Alaska contained from 20350 to 39180 parts per million total rare earths and 390 to 2000 ppm thorium. The lanthanide content in six of the seven sphenes is chiefly the light rare earths and is similar to that of crustal abundance; a seventh sphene from the Darby Mountains, however, contains above average amounts of the heavy rare earths. A comparison of the lanthanide distribution in sphene from several areas indicates that the structure of sphene will accommodate whatever lanthanides are available when the mineral crystallizes. The amount of thorium and rare earths in sphene is also affected by the presence of other accessory minerals. Sphene in rocks containing either allanite or zircon has a lower thorium content than in rocks that do not contain allanite or zircon. Sphene, because of its abundance, may contain the greater part of the rare earths and thorium in some of the plutonic rocks of west-central Alaska.

Alaska↗

USGS1968

Effects of selective fusion on the thermal history of the earth's mantle

A comparative study on the thermal history of the earth's mantle was made by numerical solutions of the heat equation including and excluding selective fusion of silicates. Selective fusion was approximated by melting in a multicomponent system and redistribution of radioactive elements. Effects of selective fusion on the thermal models are (1) lowering (by several hundred degrees centigrade) and stabilizing the internal temperature distribution, and (2) increasing the surface heat-flow. It was found that models with selective fusion gave results more compatible with observations of both present temperature and surface heat-flow. The results therefore suggest continuous differentiation of the earth's mantle throughout geologic time, and support the hypothesis that the earth's atmosphere, oceans, and crust have been accumulated throughout the earth's history by degassing and selective fusion of the mantle.

Earth and Planetary Science Letters↗

USGS2005

Identifying calcium sources at an acid deposition-impacted spruce forest: A strontium isotope, alkaline earth element multi-tracer approach

Depletion of calcium from forest soils has important implications for forest productivity and health. Ca is available to fine feeder roots from a number of soil organic and mineral sources, but identifying the primary source or changes of sources in response to environmental change is problematic. We used strontium isotope and alkaline earth element concentration ratios of trees and soils to discern the record of Ca sources for red spruce at a base-poor, acid deposition-impacted watershed. We measured 87 Sr/ 86 Sr and chemical compositions of cross-sectional stemwood cores of red spruce, other spruce tissues and sequential extracts of co-located soil samples. 87 Sr/ 86 Sr and Sr/Ba ratios together provide a tracer of alkaline earth element sources that distinguishes the plant-available fraction of the shallow organic soils from those of deeper organic and mineral soils. Ca/Sr ratios proved less diagnostic, due to within-tree processes that fractionate these elements from each other. Over the growth period from 1870 to 1960, 87 Sr/ 86 Sr and Sr/Ba ratios of stemwood samples became progressively more variable and on average trended toward values that considered together are characteristic of the uppermost forest floor. In detail the stemwood chemistry revealed an episode of simultaneous enhanced uptake of all alkaline earth elements during the growth period from 1930 to 1960, coincident with reported local and regional increases in atmospheric inputs of inorganic acidity. We attribute the temporal trends in stemwood chemistry to progressive shallowing of the effective depth of alkaline earth element uptake by fine roots over this growth period, due to preferential concentration of fine roots in the upper forest floor coupled with reduced nutrient uptake by roots in the lower organic and upper mineral soils in response to acid-induced aluminum toxicity. Although both increased atmospheric deposition and selective weathering of Ca-rich minerals such as apatite provide possible alternative explanations of aspects of the observed trends, the chemical buffering capacity of the forest floor-biomass pool limits their effectiveness as causal mechanisms.

Biogeochemistry↗

USGS1953

Systematic variation of rare earths in monazite

Ten monazites from widely scattered localities have been analyzed for La, Ce, Pr, Nd, Sm, Gd, Y and Th by means of a combined chemical and emission spectrographic method. The analytical results, calculated to atomic percent of total rare earths (thorium excluded), show a considerable variation in the proportions of every element except praseodymium, which is relatively constant. The general variation trends of the elements may be calculated by assuming that the monazites represent different stages in a fractional precipitation process, and by assuming that there is a gradational increase in the precipitability of rare earth elements with decreasing ionic radius. Fractional precipitation brings about an increase in lanthanum and cerium, little change in praseodymium, and a decrease in neodymium, samarium, gadolinium, and yttrium. Deviations from the calculated lines of variation consist of a simultaneous, abnormal increase or decrease in the proportions of cerium, praseodymium, and neodymium with antipathetic decrease or increase in the proportions of the other elements. These deviations are ascribed to abnormally high or low temperatures that affect the precipitability of the central trio of elements (Ce, Pr, Nd) relatively more than that of the other elements. The following semiquantitative rules have been found useful in describing the composition of rare earths from monazite: 1. The sum of lanthanum and neodymium is very nearly a constant at 42 ± 2 atomic percent. 2. Praseodymium is very nearly constant at 5 ± 1 atomic percent. 3. The sum of Ce, Sm, Gd, and Y is very nearly a constant at 53 ± 3 atomic percent. No correlation could be established between the content of Th and that of any of the rare earth elements.

Geochimica et Cosmochimica Acta↗

USGS2026

The Sedimentary Geochemistry and Paleoenvironments Project Phase 2 data release: An open data resource for the study of Earth's environmental history

Geochemical data from sedimentary rocks are the primary source of information regarding Earth's surface evolution through time, including its air and water envelopes and interactions with life and deep Earth processes. The Sedimentary Geochemistry and Paleoenvironments Project (SGP) is a scientific consortium centered around open data and community-driven development of cyberinfrastructure tools and resources for sedimentary geochemistry and Earth history. Here we describe the SGP Phase 2 data release, which focused on incorporating Paleoproterozoic and Mesoproterozoic (2500–1000 million years ago) data and better accommodating carbonate data. This data release was built through the involvement of >200 researchers worldwide in academia, government, and industry, and provides the largest available public data resource for our user community in the academic fields of geochemistry, sedimentology, tectonics, paleontology, Earth history, and paleoclimate, as well as the petroleum and minerals industries. The dataset now encompasses 126,006 samples and 4,132,371 geochemical analyses. In addition to direct entry by SGP Team Members, we have ingested and incorporated datasets from the Geoscience Australia OZCHEM database, the Alberta Geological Survey, and the Deep-Time Marine Sedimentary Element Database (DM-SED) compilation. This paper details sampling in the Phase 2 dataset with respect to age, geography, lithology, and other geological characteristics, documents access via our search website and API, discusses possible issues and/or biases in the dataset that could impact analyses, describes plans for governance and stewardship of data from Indigenous lands, and serves as the citable reference paper for the data release.

Chemical Geology↗

USGS2021

Developing bare-earth digital elevation models from structure-from-motion data on barrier islands

Unoccupied aerial systems can collect aerial imagery that can be used to develop structure-from-motion products with a temporal resolution well-suited to monitoring dynamic barrier island environments. However, topographic data created using photogrammetric techniques such as structure-from-motion represent the surface elevation including the vegetation canopy . Additional processing is required for estimating bare-earth elevation, which is critical for understanding the underlying geomorphology of these islands. In this study, we used a vegetation and elevation survey to produce bare-earth digital elevation models from structure-from-motion-derived elevation products for two sites on Dauphin Island, Alabama (USA). One site was exposed to high wave energy and included a mix of beach, dune, and barrier flat habitats that were dominated by supratidal/upland herbaceous vegetation. The second site was exposed to low wave energy and was dominated by intertidal marsh. Aerial imagery was collected in late fall of 2018 and spring of 2019. We tested several machine learning algorithms for predicting and removing elevation bias for vegetated areas using predictors that included spectral indices from unoccupied aerial systems-based multispectral imagery and landscape position information (e.g., relative topography and distance from shore). Models were developed for each site and season. We also explored how well the model from one season generalized to data from a different season for the same site. For developing initial digital surface models, we found that utilizing a minimum bin algorithm, as opposed to interpolation, led to lower elevation bias. For bias removal, Gaussian process regression performed the best and led to a root mean square error for the bare-earth digital elevation models of around 0.10 m for the high energy site and 0.15 m for the low energy site. Compared to the digital surface models, the root mean square error for the bare-earth digital elevation models was reduced by at least 29 percent for the high energy site and 69 percent for the low energy site. For all models, common predictors included surface elevation, vegetation greenness, and distance from the shoreline. The models produced comparable results when trained using data from a different season. The error estimates for all analyses were within published elevation standards for lidar data for vegetated areas. With calibration, this approach could be portable to other areas or data, such as aerial lidar (conventional or unoccupied), to provide an efficient and repeatable framework for monitoring geomorphology or provide baseline elevations for predicting changes to these environments under future conditions.

Alabama↗

USGS1997

Loparite, a rare-earth ore (Ce, Na, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3

The mineral loparite (Ce, NA, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3 is the principal ore of the light-group rare-earth elements (LREE) in Russia. The complex oxide has a perovskite (ABO3) structure with coupled substitutions, polymorphism, defect chemistry and a tendency to become metamict. The A site generally contains weakly bonded, easily exchanged cations of the LREE, Na and Ca. The B site generally contains smaller, highly charged cations of Ti, Nb or Fe+3. Mine production is from Russia's Kola Peninsula. Ore is beneficiated to produce a 95% loparite concentrate containing 30% rare-earth oxides. Loparite concentrate is refined by either a chlorination process or acid decomposition process to recover rare-earths, titanium, niobium and tantalum. Rare-earths are separated by solvent extraction and selective precipitation/dissolution. The concentrate is processed at plants in Russia, Estonia and Kazakstan.

Journal of Alloys and Compounds↗

USGS2011

Plan for living on a restless planet sets NASA's solid Earth agenda

What are the most important challenges facing solid Earth science today and over the next two decades? And what is the best approach for NASA, in partnership with other agencies, to address those challenges? A new report, Living on a Restless Planet, provides a blueprint for answering these questions. The top priority for a new spacecraft mission in the area of solid Earth science over the next 5 years, according to this report, is a satellite dedicated to Interferometric Synthetic Aperture Radar (InSAR). At the request of NASA, the Solid Earth Science Working Group (SESWG) developed a strategy for the highest priority objectives in solid Earth science for the space agency over the next 25 years. The strategy addresses six challenges that are of fundamental scientific importance, have strong implications for society, and are amenable to substantial progress through a concerted series of scientific observations from space.

Eos Science News↗

USGS1961

Palæomagnetic evidence relevant to a change in the earth's radius

INTEREST in the hypothesis that the Earth's radius has increased during geological history has been renewed in recent years because of several sets of independent observations and interpretations. From studies of the deformation of mountain ranges and the distribution of faults and oceans, Carey 1 proposes an increase in the Earth's area of 45 per cent since the Palæozoic era. Heezen 2 similarly interprets submarine topography as indicating that the oceans may be immense rift valleys formed by a pulling apart of the continents as the Earth expanded. Using a different approach, Egyed 3,4 infers a rate of increase of the Earth's radius of 0.4–0.8 mm. per year. This calculation is based on a decrease in the total amount of continental area covered by oceans during the past 400 million years, as determined palæographically. Egyed 4 has also pointed out the desirability of using palæomagnetic data to test this hypothesis.

Nature↗

USGS2021

Past abrupt changes, tipping points and cascading impacts in the Earth system

The geological record shows that abrupt changes in the Earth system can occur on timescales short enough to challenge the capacity of human societies to adapt to environmental pressures. In many cases, abrupt changes arise from slow changes in one component of the Earth system that eventually pass a critical threshold, or tipping point, after which impacts cascade through coupled climate–ecological–social systems. The chance of detecting abrupt changes and tipping points increases with the length of observations. The geological record provides the only long-term information we have on the conditions and processes that can drive physical, ecological and social systems into new states or organizational structures that may be irreversible within human time frames. Here, we use well-documented abrupt changes of the past 30 kyr to illustrate how their impacts cascade through the Earth system. We review useful indicators of upcoming abrupt changes, or early warning signals, and provide a perspective on the contributions of palaeoclimate science to the understanding of abrupt changes in the Earth system.

Nature Geoscience↗

USGS2011

The human dimension of fire regimes on Earth

Humans and their ancestors are unique in being a fire‐making species, but ‘natural’ (i.e. independent of humans) fires have an ancient, geological history on Earth. Natural fires have influenced biological evolution and global biogeochemical cycles, making fire integral to the functioning of some biomes. Globally, debate rages about the impact on ecosystems of prehistoric human‐set fires, with views ranging from catastrophic to negligible. Understanding of the diversity of human fire regimes on Earth in the past, present and future remains rudimentary. It remains uncertain how humans have caused a departure from ‘natural’ background levels that vary with climate change. Available evidence shows that modern humans can increase or decrease background levels of natural fire activity by clearing forests, promoting grazing, dispersing plants, altering ignition patterns and actively suppressing fires, thereby causing substantial ecosystem changes and loss of biodiversity. Some of these contemporary fire regimes cause substantial economic disruptions owing to the destruction of infrastructure, degradation of ecosystem services, loss of life, and smoke‐related health effects. These episodic disasters help frame negative public attitudes towards landscape fires, despite the need for burning to sustain some ecosystems. Greenhouse gas‐induced warming and changes in the hydrological cycle may increase the occurrence of large, severe fires, with potentially significant feedbacks to the Earth system. Improved understanding of human fire regimes demands: (1) better data on past and current human influences on fire regimes to enable global comparative analyses, (2) a greater understanding of different cultural traditions of landscape burning and their positive and negative social, economic and ecological effects, and (3) more realistic representations of anthropogenic fire in global vegetation and climate change models. We provide an historical framework to promote understanding of the development and diversification of fire regimes, covering the pre‐human period, human domestication of fire, and the subsequent transition from subsistence agriculture to industrial economies. All of these phases still occur on Earth, providing opportunities for comparative research.

Journal of Biogeography↗

USGS1981

Rare-earth element geochemistry of the island-arc volcanic rocks of Rabaul and Talasea, New Britain

The island-arc volcanic rocks of Rabaul and Talasea, New Britain, range in composition from basalt through rhyolite. Rare-earth elements have been determined by mass-spectrometric isotope dilution in 16 samples. Chondrite-normalized rare-earth element patterns are distinct for each volcanic center, but all are relatively flat (Ce/Yb E.F. = 1.1 to 3.0). Within each center, rare-earth element concentrations increase from basalt to dacite, and Eu anomalies become progressively more negative from basalt to dacite (Eu/Eu* = 1.0 to 0.8). Lavas inferred to contain cumulate phenocrysts show positive Eu anomalies (Eu/Eu* of up to 1.2). The observed variations are consistent with fractional crystallization of basalt or basaltic andesite by removal or accumulation of the observed phenocrysts, including olivine, plagioclase, pyroxene, and opaque minerals. Quantitative trace-element models for Talasea lavas indicate precipitation of 50 wt percent of phenocrysts from basalt to produce andesite and an additional 22 wt percent to produce dacite. A total-equilibrium model provides the best approximation to observed concentrations, implying that the process took place at a depth sufficient to allow slow cooling of the magma as precipitation proceeded. The “least fractionated” basalts and basaltic andesites are similar in rare-earth element pattern to those of corresponding type suites in other oceanic-island arcs, implying a widespread uniformity of source and process in the production of each magma type.

Geological Society of America Bulletin↗

USGS1982

Collision of astronomically observable bodies with the Earth

There are at present about 1,000 Earth-crossing bodies of asteroidal appearance that have diameters greater than 1 km. It is calculated that on the average about 3 of these bodies impact the Earth every million years. Because there are many more small bodies than large ones, impacts of 10-km-diameter objects, as postulated by Alvarez and others to explain the Cretaceous/Tertiary extinction, occur less frequently. Nevertheless, it is expected that the frequency of impact of these larger bodies will be about once every 40 million years. The cratering record on the Earth and the Moon is in agreement with this estimate. It is likely that bodies as large as 20 km in diameter have struck the Earth during the last 3 billion years. A somewhat smaller but possibly comparable impact rate of active comet nuclei of similar size is also expected. The bodies of asteroidal appearance represent a quasi-steady-state population. Losses by collision and perturbation out of the solar system are balanced by supply on a 10 7 to 10 8 year time scale of new objects: asteroidal fragments and extinct comet nuclei. The relative importance of these two sources is at present uncertain.

Special Papers of the Geological Society of Americ↗