Abstract The highly irregular and localized distribution of tungsten deposits worldwide constitutes a supply challenge for basic industries such as steel carbides. Over Earth's history, has preferentially accumulated at paleocontinental margins formed during the breakup supercontinents. Later crustal thickening these paleogeographic regions magmas they produce are associated with large district...

High-resolution paleoclimate reconstructions are often restricted by the difficulties of sampling geologic archives in great detail and the analytical costs of processing large numbers of samples. Using sediments from Lake Braya Sø, Greenland, we introduce a new method that provides a quantitative high-resolution paleoclimate record by combining measurements of the alkenone unsaturation index (...

Vast quantities of natural gas are held in hydrate form in geologic reservoirs in sub-oceanic sediments and arctic permafrost zones (KVENVOLDEN, 1988; SLOAN, 1998), where conditions of high pressure and low temperature are within the hydrate stability region. In 1995, the U.S. Geological Survey (USGS) conducted a study to assess the quantity of natural gas hydrate resources in the United States...

Interferometric synthetic aperture radar (InSAR) has great potential to detect and quantify land subsidence caused by aquifer system compaction. InSAR maps with high spatial detail and resolution of range displacement (610 mm in change of land surface elevation) were developed for a groundwater basin (;10 km) in Antelope Valley, California, using radar data collected from the ERS-1 satellite. T...

Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features inc...

Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the Earth system through the stratigraphic record. The appearance of manufactured materials in sediments, including aluminum, plastics, and concre...

Osedax is a recently discovered group of siboglinid annelids that consume bones on the seafloor and whose evolutionary origins have been linked with Cretaceous marine reptiles or to the post-Cretaceous rise of whales. Here we present whale bones from early Oligocene bathyal sediments exposed in Washington State, which show traces similar to those made by Osedax today. The geologic age of these ...

Selenium (Se) in irrigation drainage water became a major concern after it was implicated in deaths and deformities of waterfowl at Kesterson Reservoir (Presser and Ohlendorf 1987; Ohlendorf 1989). Subsequently, other areas with irrigationinduced Se problems (or potential problems) have been identified in several western U.S. states (Seiler 1995), reinforcing the status of Se as a U.S. Environm...

Recently, the need of the geologic information has been rising in many fields such as environmental geology, disaster mitigation, and urban geological applications. For these fields, it is effective to provide geologic information as a three dimensional(3-D) model that can be generated and visualized in general purpose GIS software. The present work aims at introducing a basic theory, implement...