نتایج جستجو برای: paleo temperature
تعداد نتایج: 454922 فیلتر نتایج به سال:
Paleoclimatology requires the analysis of paleo time-series, obtained from a number of independent techniques and instruments, produced by several researchers and/or laboratories. Analytical reasoning techniques that combine the judgment of paleoceanographers with automated reasoning techniques are needed to gain deep insights about commplex climatic phenomena. This paper presents an interactiv...
IMPLICATIONS FOR PALEO-GROUNDWATER GEOCHEMISTRY AND HEMATITE ON MARS. B. Beitler, and M. A. Chan, W. T. Parry, J. Ormö, G. Komatsu, University of Utah, Department of Geology and Geophysics, (135 South 1460 East, Salt Lake City, UT 84112-0111, [email protected]), Centro de Astrobiología (INTA/CSIC), (Instituto Nacional de Técnica Aeroespacial, Ctra de Torrejón a Ajalvir, km 4, 28850 Torrej...
Flowers and Farley (Reports, 21 December 2012, p. 1616; published online 29 November 2012) use thermochronometry to propose that the western paleo–Grand Canyon was nearly as deep 70 million years ago (Ma) as today. However, lithologies, facies relations, geomorphology, and paleotopography of Miocene interior-basin deposits near the mouth of the Grand Canyon show that no paleocanyon existed in t...
We present a new method to incorporate paleo-surface temperature effects in steady state 3D conductive models. The workflow approximates the transient and incorporates these into models, using appropriate source sink terms for radiogenic heat production. This allows rapid which can be easily used ensemble approaches data assimilation of high-resolution models geothermal resource assessment. is ...
Large volcanic eruptions are one of the dominant perturbations to global and regional atmospheric temperatures on timescales years decades. Discrepancies remain, however, in estimated magnitude persistence surface temperature cooling caused by eruptions, as characterized paleoclimatic proxies climate models. We investigate these discrepancies context large tropical over Last Millennium using tw...
Wildfire is a dominant disturbance agent in forest ecosystems, shaping important biogeochemical processes including net carbon (C) balance. Long-term monitoring and chronosequence studies highlight a resilience of biogeochemical properties to large, stand-replacing, high-severity fire events. In contrast, the consequences of repeated fires or temporal variability in a fire regime (e.g., the cha...
This paper primarily reviews our recent work on the biology and geochemistry of foraminifera with respect to their use as paleoceanographic proxies. Our approach to proxy validation and development is described, primarily from a modeler’s point of view. The approach is based on complementary steps in understanding the inorganic chemistry, inorganic isotope fractionation, and biological controls...
It was not known until recently whether the endemic of cholesterol gallstones among certain southwestern American Indian tribes was unique among this ethnic group. With use of ultrasonography of the gallbladder and standard diagnostic criteria, gallstones are now found in epidemic proportions in 13 diverse American Indian tribes and communities living in Arizona, Oklahoma, and the Dakotas. We s...
The precision of spectrophotometric measurements of indicator absorbance ratios is sufficient to allow evaluation of small isotopically induced differences in the dissociation constant of boric acid (KB). The quotient of KB and KB, obtained using isotopically X99% pure borate/boric acid buffers, provides an equilibrium constant for the reaction B(OH)3+ B(OH)4 3B(OH)3+ B(OH)4 which heretofore ha...
Pan-American mitochondrial DNA (mtDNA) haplogroup C1 has been recently subdivided into three branches, two of which (C1b and C1c) are characterized by ages and geographical distributions that are indicative of an early arrival from Beringia with Paleo-Indians. In contrast, the estimated ages of C1d--the third subset of C1--looked too young to fit the above scenario. To define the origin of this...
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