The U.S. Geological Survey conducted an environmental assessment of 198 catchments in a 54,000-km area of central Colorado, much of which is on Federal land. The Colorado Mineral Belt, a northeast-trending zone of historical baseand precious-metal mining, cuts diagonally across the study area. The investigation was intended to test the hypothesis that degraded water and sediment quality are res...

Isotopic signatures are used to distinguish Group I, Transition, and Group II kimberlites, and provide information on the origin of melts parental to the final intrusion. Kimberlitic rocks are often weathered and altered, making them potentially unsuitable for whole rock isotopic studies. We therefore have explored the alternative use of the isotopic signatures of resistant minerals in kimberli...

To study the coupled thermo-hydrologic-geomechanical processes and their influence on gas and nuclide transport in a two phase flow through the porous medium, a coupling of the thermo-hydrodynamic code TOUGH2 and the thermo-mechanic code FLAC3D is described and applied to analyze three dimensional gas, heat and nuclide transport in a repository for disposal of heat generating nuclear waste in a...

Magmatic sheet intrusions (dykes) constitute the main form of magma transport in the Earth's crust. The size distribution of dykes is a crucial parameter that controls volcanic surface deformation and eruption rates and is required to realistically model volcano deformation for eruption forecasting. Here we present statistical analyses of 3,676 dyke thickness measurements from different tectoni...

biotite samples from different units of boroujerd granitoid complex (bgc) of the sanandaj-sirjan zone, western iran, have beenanalyzed by electron microprobe for major elements. biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof bgc have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (...

Evidence of life on Earth is manifestly preserved in the rock record. However, the microfossil record only extends to ∼ 3.5 billion years (Ga), the chemofossil record arguably to ∼ 3.8 Ga, and the rock record to 4.0 Ga. Detrital zircons from Jack Hills, Western Australia range in age up to nearly 4.4 Ga. From a population of over 10,000 Jack Hills zircons, we identified one >3.8-Ga zircon that ...

As a part of a broader effort to determine the status of Paragonimus species infection in Lao PDR, an epidemiological survey was conducted on villagers and schoolchildren in Namback District between 2003 and 2005. Among 308 villagers and 633 primary and secondary schoolchildren, 156 villagers and 92 children evidenced a positive reaction on a Paragonimus skin test. Only 4 schoolchildren out of ...