United States Geological Survey

About: United States Geological Survey is a government organization based out in Reston, Virginia, United States. It is known for research contribution in the topics: Population & Groundwater. The organization has 17899 authors who have published 51097 publications receiving 2479125 citations. The organization is also known as: USGS & US Geological Survey.

Geology and resources of some world oil-shale deposits

Abstract: Oil-shale deposits are found in many parts of the world. They range in age from Cambrian to Tertiary and were formed in a variety of marine, continental, and lacustine depositional environments. The largest known deposit is the Green River oil shale in western United States. It contains an estimated 215 billion tons of in-place shale oil (1.5 trillion U.S. barrels). Total resources of a selected group of oil-shale deposits in 33 countries is estimated at 411 billion tons of in-place shale oil which is equivalent to 2.9 trillion U.S. barrels of shale oil. This figure is very conservative because several deposits mentioned herein have not been explored sufficiently to make accurate estimates and other deposits were not included in this survey.

Evidence for early life in Earth’s oldest hydrothermal vent precipitates

Abstract: Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite-haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.

The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Body Unit and Combined System Tests

Abstract: The ChemCam instrument suite on the Mars Science Laboratory (MSL) rover Curiosity provides remote compositional information using the first laser-induced breakdown spectrometer (LIBS) on a planetary mission, and provides sample texture and morphology data using a remote micro-imager (RMI). Overall, ChemCam supports MSL with five capabilities: remote classification of rock and soil characteristics; quantitative elemental compositions including light elements like hydrogen and some elements to which LIBS is uniquely sensitive (e.g., Li, Be, Rb, Sr, Ba); remote removal of surface dust and depth profiling through surface coatings; context imaging; and passive spectroscopy over the 240–905 nm range. ChemCam is built in two sections: The mast unit, consisting of a laser, telescope, RMI, and associated electronics, resides on the rover’s mast, and is described in a companion paper. ChemCam’s body unit, which is mounted in the body of the rover, comprises an optical demultiplexer, three spectrometers, detectors, their coolers, and associated electronics and data handling logic. Additional instrument components include a 6 m optical fiber which transfers the LIBS light from the telescope to the body unit, and a set of onboard calibration targets. ChemCam was integrated and tested at Los Alamos National Laboratory where it also underwent LIBS calibration with 69 geological standards prior to integration with the rover. Post-integration testing used coordinated mast and instrument commands, including LIBS line scans on rock targets during system-level thermal-vacuum tests. In this paper we describe the body unit, optical fiber, and calibration targets, and the assembly, testing, and verification of the instrument prior to launch.

Magnitude and significance of carbon burial in lakes, reservoirs, and peatlands

Abstract: Globally, lakes are currently accumulating organic carbon (OC) at an estimated annual rate of about 42 Tgṁyr −1 . Most of the OC in all but the most oligotrophic of these lakes is autochthonous, produced by primary production in the lakes. The sediments of reservoirs accumulate an additional 160 Tg annually, and peatlands contribute 96 Tg annually. These three carbon pools collectively cover less than 2% of the Earth9s surface and constitute a carbon sink of about 300 Tgṁyr −1 . Although the oceans cover 71% of the Earth9s surface, they accumulate OC at a rate of only about 100 Tgṁyr −1 .