Showing papers in "Earth and Planetary Science Letters in 1992"

TL;DR: The most likely source for this "andesitic" water is recycled seawater as mentioned in this paper, which enters the subduction system in the form of porewater, or as the water of hydration in the clay minerals of accumulated marine sediments and is carried to the source region of arc magmas on the top of the subducting slab.

TL;DR: The trace element pattern and the isotopic composition of himu lavas can be quantitatively modelled using a mixture of ∼ 25% old recycled morb crust and 75% mantle peridotite as mentioned in this paper.

TL;DR: In this article, the authors use a high-resolution seawater Sr isotopic evolution curve for the last 100 m.y.d. in conjunction with modern riverine Sr flux measurements, and also geologic, tectonic and geochronological data, to make the case for a close relationship between seawater isotopic composition and the India Asia continental collision.

TL;DR: Variations in the carbon and nitrogen isotopic composition of bulk organic matter in the sediments of Lake Bosumtwi, Ghana reflect climatically induced changes to the lake and the catchment flora.

TL;DR: This paper measured the Li isotope composition of young, pristine basalts from active ocean ridge crests, of progressively older basalts along a dredging transect, and a limited number of hydrothermally altered basalts.

TL;DR: In this article, the UPb baddeleyite/zircon ages for gabbro sills and diabase dykes emplaced during Franklin igneous events in northern Canada were determined.

TL;DR: In this paper, a large scale fractionation of rare earth elements between colloidal and solution phases is found within the dissolved fraction of Connecticut River water, where colloidal particles carry a large part of the dissolved REE pool.

TL;DR: Garnet-whole rock and garnet-mineral isochrons were determined on granulite facies gneisses and amphibolites from the Archean Pikwitonei Granulite Domain of the Superior Province, and the Proterozoic Central Gneiss Belt and Adirondack Highlands of the Grenville orogen as mentioned in this paper.

TL;DR: The authors measured He, Sr, Nd, and Pb isotope ratios and concentrations in stratigraphically controlled lavas from the Pago shield volcano on Tutuila, American Samoa, and interpreted these lavas as products of mixing between two isotopically extreme mantle constituents.

TL;DR: This article determined the source area from which dusts from the last glacial maximum (LGM) section of the Dome C ice core were derived, by comparing their strontium and neodymium isotopic ratios with those of samples from potential source areas.

TL;DR: The rare gas isotopic compositions of residual harzburgite xenoliths from Savai'i (SAV locality) and an unnamed seamount south of the Samoan chain (PPT locality) provide important constraints on the rare gas evolution of the mantle and atmosphere as discussed by the authors.

TL;DR: The U-Th-Pb, Sm-Nd, and Rb-Sr isotopic systematics of mafic and ultramafic xenolithic rocks and associated megacrystic inclusions of aluminous augite and garnet, that occur in three alkalic volcanic suites: Kuandian in eastern Liaoning Province, Hanluoba in Hebei Province, and Minxi in western Fujian Province, China are described in this paper.

TL;DR: In this paper, the concentrations of Rb and Sr and87Sr/86Sr isotopic ratios have been measured in the dissolved load of the Ganga-Brahmaputra (G-B) river system.

TL;DR: In this paper, the origin of the Tertiary to Neogene Tibetan basic magmatism is investigated using high-K lavas sampled during the 1989 Sino-French Kunlun geotraverse.

TL;DR: In this paper, a synthetic Group I kimberlite was constructed using an MA-8 apparatus and at 16 GPa and 1650°C, majorite garnet (13% Al2O3) and β-M2SiO4 crystallized together on the liquidus, showing that this kimbersite magma could have been produced by a small degree of partial melting of a majorite +β-M 2 SiO4 assemblage in the transition zone (400-650 km).

TL;DR: In this paper, U-Pb isotopic analyses of individual detrital zircon, monazite, and xenotime grains separated from westerly derived clastic units in the Belt Supergroup as well as Sm-Nd isotopic data for the same grains where appropriate are provided.

TL;DR: In this article, the melting temperatures of FeO, FeS and FeS2 have been accurately determined in a hydrostatic, inert pressure environment up to about 0.5 Mbar using a new yttrium-lithium-fluoride (YLF) heating laser.

TL;DR: In this article, the peridotites were plastically deformed in low stress/high temperature conditions similar to those inferred for the asthenospheric mantle, and this deformation occurred during the tectonic uplift of the peridsotites throughout the lithosphere of the axial region.

TL;DR: In this paper, the relative magnetic field palaeointensities have been obtained from three marine cores in the Somali basin (western Indian Ocean) and a time versus depth correlation has been established from the δ18O record.

TL;DR: In this article, the authors investigated the role of metamorphic temperature in trace element compositions of volcanic arc versus intraplate magmas and found that the amount of B contained in a given subducted oceanic slab depends on the metamorphonic temperature.

TL;DR: In this article, the authors proposed that these and other, similar, magmas from the Arabian plate originated from a "fossilized" head of a mantle plume, which was unable to penetrate the continental lithosphere and was therefore trapped and stored beneath it.

TL;DR: In this paper, tourmalines of various chemical compositions, hosted in magmatic rocks with ages ranging from 3.8 Ga to the present were analysed for δ 11 B by ion microprobe.

TL;DR: In this paper, the air content of polar ice (V) is analyzed as a function of the atmospheric pressure, temperature, and porous volume of the ice, at which the air in the firn becomes isolated in terms of pressure from the atmosphere during the process of pore close-off.

TL;DR: In this article, multichannel seismic (MCS) data image both landward and seaward-vergent provinces along the central and northern Oregon margin is used to investigate the role of seafloor vent sites and potential fluid sources and migration paths.

TL;DR: The main objective of Leg 131 was to provide data on the deformational processes and associated hydrogeology of the Nankai prism toe as mentioned in this paper, which was the first time in the history of ocean drilling, in penetrating the complete sedimentary sequence to basaltic basement, reaching 1327 mbsf (metres below seafloor).

TL;DR: In this paper, a time-integrated fluid flux in excess of 2.9 × 107 kg m−2 is required to transport the strontium isotope composition of ∼ 0.7054 ± 7 (2σ) and fluid flow is inferred to have been pervasive with near-equilibrium fluid-rock exchange.

TL;DR: The variation of sea water during the Cenozoic has been determined by analyzing the hydrogenous Os released by acidic hydrogen peroxide leaching of layers in an abyssal North Pacific pelagic clay core as discussed by the authors.

TL;DR: In this paper, the authors determined the concentration and isotopic composition of Sr and Nd in waters from the Baltic Sea and found that seawater Sr is mixed with much more radiogenic components than seawater Nd.

TL;DR: The St. Helena and Walvis hot spot-plume systems were formed by the activity of the St Helena and Gough volcanic chains as mentioned in this paper, and they formed broad zones of diffuse volcanism (i.e., oceanic islands, seamounts and small ridges), at least 500 km in diameter.

TL;DR: The inherited 3 He/ 4 He/4 He ratio at St. Helena and Tubuaii is 4.3-5.9 R A, which is the highest known ratio for olivine and clinopyroxene phenocrysts.