The Dehaj area, located in the southern part of the Urumieh-Dokhtar magmatic belt, is a well-endowed terrain hosting a number of world-class porphyry copper deposits. These deposits are all hosted in an acidic to intermediate volcano-plutonic sequence greatly affected by various types of the hydrothermal alterations, whether argillic, phyllic or propylitic. Although there are a handful of hithe...

The assessment of groundwater conditions within an unconfined aquifer with a periodic boundary condition is of interest in many hydrological and environmental problems. A two-dimensional numerical model for density dependent variably saturated groundwater flow, SUTRA (Voss, C.I., 1984. SUTRA: a finite element simulation model for saturated–unsaturated, fluiddensity dependent ground-water flow w...

In continuous permafrost regions, pathways for transport of sub-permafrost groundwater to the surface sometimes perforate frozen ground and result in formation a pingo. Explanations offered locations such have so far included hydraulically conductive geological units faults. On Svalbard, several pingos locate at valley flanks where these controls are apparently lacking. Intrigued by this observ...

The geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra-low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explored the melting properties of mid-oceanic ridge ...

In the deformation of layered materials such as geological strata, or stacks of paper, mechanical properties compete with the geometry of layering. Smooth, rounded corners lead to voids between the layers, while close packing of the layers results in geometrically induced curvature singularities. When voids are penalized by external pressure, the system is forced to trade off these competing ef...

The Neoproterozoic era was arguably the most revolutionary in Earth history. Extending from 1000 to 541 million years ago, it stands at the intersection of the two great tracts of evolutionary time: on the one side, some three billion years of pervasively microbial 'Precambrian' life, and on the other the modern 'Phanerozoic' biosphere with its extraordinary diversity of large multicellular org...

Ice cores through an ice sheet can be regarded as a sample of a unique natural deformation experiment lasting up to a million years. Compared to other geological materials forming the earth‘s crust, the microstructure is directly accessible over the full depth. Controlled sublimation etching of polished ice sections reveals pores, air bubbles, grain boundaries and subgrain boundaries at the sur...

GPS velocity data are used to estimate the Euler Argentina (LPGS; 1.2 years). Data spanning 2.0 years are vector describing rigid body motion of North America relative to South America. Assuming the boundary between the North and South American plates is located near the Fifteen Twenty fracture zone in the equatorial Atlantic, the Euler vector predicts extension across the Royal Trough up to 1 ...

Elena Nilsen, U.S. Geological Survey, Geologic Division Robert Rosenbauer, U.S. Geological Survey, Geologic Division Edward Furlong, U.S. Geological Survey, Methods Research and Development Program Mark Burkhardt, U.S. Geological Survey, Methods Research and Development Program Stephen Werner, U.S. Geological Survey, Methods Research and Development Program Lisa Greaser, U.S. Geological Survey,...

AASG/USGS Geologic Map Data Model Committee* Gary Raines, Chairman, US Geological Survey, [email protected] Boyan Brodaric, Geological Survey of Canada, [email protected] Jim Cobb, Kentucky Geological Survey, [email protected] Ralph Haugerud, US Geological Survey, [email protected] Greg Hermann, New Jersey Geological Survey, [email protected] Bruce Johnson,...