Now showing items 71-80 of 82
Time scales of large volume silicic magma systems: Sr isotopic systematics of phenocrysts and glass from the Bishop Tuff, Long Valley, California
(Springer-Verlag, 1993-01)
The initial Sr isotopic compositions of glass and mineral separates from the 0.74 Ma Bishop Tuff ashflow in eastern California were determined to investigate the time scales of magmatic processes in a large silicic system. ...
Ion microprobe determination of sulfur isotope variations in iron sulfides from the Post/ Betze sediment-hosted disseminated gold deposit, Nevada, USA
(Elsevier, 1993-04)
Secondary ion mass spectrometric analyses of ore samples from the Post/Betze sedimenthosted disseminated gold deposit were utilized to constrain elemental distribution of Au and As in iron sulfide phases. Most of the Au ...
The europium anomaly of seawater: implications for fluvial versus hydrothermal REE inputs to the oceans
(Elsevier, 1991-10-25)
Seafloor hydrothermal vent fluids are characterized by rare earth element (REE) enrichments and large positive Eu anomalies; however, this input is not recorded by seawater. Hydrothermal sediments from the southeast Pacific ...
Geochemistry of eolian dust in Pacific pelagic sediments: Implications for paleoclimatic interpretations
(Elsevier, 1991-08)
Geochemical data (REEs, Th, Sc) were determined for the operationally defined eolian dust (ODED) fraction (n = 57) from the north and equatorial Pacific Ocean. Paleoclimate studies commonly have assumed that this sediment ...
Phyllosilicates in hydrothermally altered basalts from DSDP Hole 504B, Leg 83 — a TEM and AEM study
(Springer-Verlag, 1992-10)
Phyllosilicates occurring as replacements of olivine, clinopyroxene and interstitial materials and as veins or fracture-fillings in hydrothermally altered basalts from DSDP Hole 504B, Leg 83 have been studied using ...
40Ar/39Ar dating of very fine-grained samples: An encapsulated-vial procedure to overcome the problem of 39Ar recoil loss
(Elsevier, 1992-12-15)
40Ar/39Ar dating of very fine-grained materials is compromised by the loss of 39Ar by recoil, and also sometimes other Ar isotopes, during irradiation. An encapsulated sample 40Ar/39Ar procedure is described which overcomes ...
The Aurora volcanic field, California-Nevada: oxygen fugacity constraints on the development of andesitic magma
(Springer-Verlag; Springer-Verlag Berlin Heidelberg, 1996-10)
The Aurora volcanic field, located along the northeastern margin of Mono Lake in the Western Great Basin, has erupted a diverse suite of high-K and shoshonitic lava types, with 48 to 76 wt% SiO 2 , over the last 3.6 million ...
Magmatic modification of the uppermost mantle beneath the Basin and Range to Colorado Plateau Transition Zone; Evidence from xenoliths, Wikieup, Arizona
(Springer-Verlag; Springer-Verlag Berlin Heidelberg, 1997-06)
Upper mantle xenoliths from Wikieup, AZ, provide abundant evidence for magmatic modification of the uppermost mantle beneath the Transition Zone between the Colorado Plateau and the southern Basin and Range province. Upper ...
Heat capacities of TiO2-bearing silicate liquids: Evidence for anomalous changes in configurational entropy with temperature
(Elsevier, 1993-07)
The heat capacities of several TiO2-bearing silicate glasses and liquids containing Cs2O, Rb2O, Na2O, K2O, CaO, MgO, or BaO have been measured to 1100 K using a differential scanning calorimeter and to 1800 K using a Setaram ...