نتایج جستجو برای: basalts

تعداد نتایج: 2061  

Journal: :journal of sciences islamic republic of iran 0

the kahnuj ophiolitic complex, a part of the jazmurian ophiolitic belt, is located on the western boundary of the jazmurian depression and is bounded by two major fault systems. there is a well-preserved, ophiolite pseudostratigraphy of early cretaceous to early palaeocene age and has a bearing on the mesozoic development of southeastern part of iran and adjacent region. the kahnuj ophiolitic c...

2005
R. P. VON

closed system grossly distorted sound calibration below 1 khz, whereas at frequencies higher than 6 khz calibration for the open loudspeaker was affected. This difficulty could be avoided by placing the loudspeaker close to the bird's ear (12 cm). 2. R. L. Boord and G. L. Rasmussen, J. Comp. Neurol. 120, 463 (1963). 3. For this reason, all data on single-unit thresholds and frequency range in t...

2005
Matthias Willbold

Trace elements (elements that constitute less than 0.1 wt.% of the analyzed sample) are important tracers for a great variety of processes in many research areas, such as biochemistry, medicine, semi-conductor and nano-technology, environmental science and geosciences (e.g., Anitha et al. [2002]; Becker et al. [2004]; Barbante et al. [2004]; Tibi and Heumann [2003]). Accordingly, much scientifi...

2006
A. K. Schmitt J. A. Vazquez

Rhyolite lavas and xenoliths from the Salton Sea geothermal field (Southern California) provide insights into crustal compositions and processes during continental rupture and incipient formation of oceanic crust. Salton Buttes rhyolite lavas contain xenoliths that include granophyres, fine-grained altered rhyolites (“felsite”), and amphibole-bearing basalts. Zircon is present in lavas and xeno...

2012
Michael E. Purucker James W. Head Lionel Wilson

[1] A new magnetic map of the Moon, based on Lunar Prospector magnetometer observations, sheds light on the origin of the South Pole-Aitken basin (SPA), the largest and oldest of the recognized lunar basins. A set of WNW-trending linear to arcuate magnetic features, evident in both the radial and scalar observations, covers much of a 1000 km wide region centered on the NW portion of SPA. The so...

2012
Xiao-Ming Liu Michael N. Evans

Title of Document: TRACING CONTINENTALWEATHERING USING LITHIUM AND MAGNESIUM ISOTOPES: INSIGHTS FROM THE CHEMICAL WEATHERING OF COLUMBIA RIVER BASALTS AND MASS BALANCE MODELING Xiao-Ming Liu, Ph.D., 2013 Directed By: Professors Roberta L. Rudnick & William F. McDonough, Department of Geology Chemical weathering is an important mechanism that changes the mass and composition of the continental c...

2010
V. Le Roux C.-T.A. Lee S. J. Turner

Oceanic basalts, such as mid-ocean ridge basalts (MORB) and ocean island basalts (OIB), are characterized by large isotopic and trace element variability that is hard to reconcile with partial melting of a peridotitic mantle alone. Their variability has been attributed to the presence of heterogeneities within the mantle, such as recycled crust, metasomatized material or outer core contribution...

2005
P. G. Lucey

Introduction: Lunar basalts exhibit obvious variations in ultraviolet-visible (UVVIS) color and these variations have been attributed to Ti content [1], the major compositional variable in mare basalts. Charette [2] first showed that Ti content in lunar samples is correlated with telescopic measurements of UVVIS ratio in mature (agglutinate rich) basaltic regolith, whereby samples with high TiO...

2002
C. D. K. Herd J. J. Papike

Synopsis: The oxygen fugacity of the basaltic martian meteorites has been calculated from thermodynamic models involving spinel-ilmenite equilibria. The wide range of estimates, from near the IW buffer to near QFM, may be explained by mixing of mantlederived melts with oxidized material in the martian crust. Possible oxidized crustal end-members are considered. Analytical Method and Results: Sp...

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