نتایج جستجو برای: geochemical

تعداد نتایج: 12072  

2011
R. H. Cary J. F. Dowd

Investigating storm runoff generation in watersheds is an area of ongoing hydrologic research. Geochemical tracer studies, such as static end-member mixing analysis (EMMA) and hysteresis loop analysis, have been used to evaluate these processes. While EMMA can assess the relative input of flow pathways for individual stream water quality samples collected during a storm, it cannot quantify thei...

2017
Daniel R. Muhs Vance T. Holliday

Mostly stabilized late Holocene eolian sands on the Southern High Plains of the United States were studied to determine their origins and to assess whether present dune stability depends more strongly on sediment supply, sediment availability, or transport limitations. Geomorphic, sedimentological, and geochemical trends indicate that late Holocene dunes formed under westerly paleowinds, broadl...

2017
Stanley R. Herwitz Daniel R. Muhs Joseph M. Prospero Shannon Mahan Bruce Vaughn

Red clayey paleosols that are chiefly the product of aerosolic dust deposition are interbedded in the Quaternary carbonate formations of the Bermuda oceanic island system. These paleosols provide a basis for reconstructing Quaternary atmospheric circulation patterns in the northwestern Atlantic. Geochemical analyses were performed on representative paleosol samples to identify their parent dust...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2015
Shuichang Zhang Xiaomei Wang Emma U Hammarlund Huajian Wang M Mafalda Costa Christian J Bjerrum James N Connelly Baomin Zhang Lizeng Bian Donald E Canfield

Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe tw...

2017
Heather C. Olins Daniel R. Rogers Christina Preston William Ussler Douglas Pargett Scott Jensen Brent Roman James M. Birch Christopher A. Scholin M. Fauzi Haroon Peter R. Girguis

Despite years of research into microbial activity at diffuse flow hydrothermal vents, the extent of microbial niche diversity in these settings is not known. To better understand the relationship between microbial activity and the associated physical and geochemical conditions, we obtained co-registered metatranscriptomic and geochemical data from a variety of different fluid regimes within the...

2013
Henderson James Cleaves

The origin of life on Earth is widely believed to have required the reactions of organic compounds and their self- and/or environmental organization. What those compounds were remains open to debate, as do the environment in and process or processes by which they became organized. Prebiotic chemistry is the systematic organized study of these phenomena. It is difficult to study poorly defined p...

2009
D. S. Ebel H. C. Connolly N. T. Kita T. Ushikubo

Weisberg, D. S. Ebel, H. C. Connolly Jr., N. T. Kita and T. Ushikubo. Dept. Phys. Sci., Kingsborough College, City University New York, Bklyn, NY 11235 and Dept. Earth and Environmental Sci., The Graduate Center of CUNY 365 5 Ave., NY, NY. ([email protected]). Dept. Earth Planet. Sci., American Museum Natural History, NY, NY 10024. Dept. Geology and Geophys., University Wisconsin-Madison,...

2014
Kolawole Bello Mileva Radonjic Patrick F. Taylor

Geopressured reservoirs can serve as ample source of geothermal energy with temperatures as high as 140 0C. Salinities are typically high in these reservoirs due to the dissolution of surrounding salt domes. Cement retrogression can occur under these geopressured geothermal conditions resulting from calcium silicate hydrate [3CaO2SiO23H2O] phase in hydrated cement converting to alpha dicalciu...

Requisite programs soil conservation and sediment control is requires identification of areas prone to erosion and today used fingerprinting method around the world to determine the contribution of sediments transported. In this study, in order to gain optimized share of the estimated sediment resources, used of tracking feature and finally presented the map susceptibility to erosion in the Fas...

Behnam Sadeghi Masoumeh Khalajmasoumi Parviz Moarefvand Peyman Afzal

GIS is considered an important technique as well as a prerequisite for cost effective mineral exploration and determination of high potential areas. The purpose of this research is to determine high potential iron zones for detailed exploration using index overlay GIS method. Index Overlay was used to combine the geology, topography (scale: 1:1,000), lineaments, remote sensing (ASTER and ETM+) ...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید