Showing papers in "Earth and Planetary Science Letters in 1997"

TL;DR: In this paper, the authors obtained a new set of present-day mean values in chondrites of176Hf/177Hf = 0.282772 ± 29 and176Lu/177 Hf= 0.0332 ± 2.

TL;DR: In this paper, it was shown that the very high Pb isotopic ratios observed in some ocean island basalts, known as HIMU, can be readily achieved by incorporation of ancient subducted crust into their mantle source.

TL;DR: In this paper, a two-box model was used to estimate the fractionation factor of Y and Ho in seawater, rivers and rain, and the mean oceanic residence time was estimated to be 5100 years for Y and 2700 years for Ho.

TL;DR: In this paper, the authors show the first case of highly significant correlations of Nb/U, Ba/Nb and Ba/Th with87Sr/86Sr for Indian Ocean mid-ocean ridge basalts and confirm and strengthen a previously detected correlation with Ce/Pb (or Nd/PB) in nine hand picked MORB glasses from the Central Indian and Carlsberg Ridge.

TL;DR: Gabbroic sills intruding dunite in the crust-mantle transition zone (MTZ) of the Oman ophiolite have textures and compositions very similar to those in modally layered gabbros that form the lower part of the gabbro section in the oophiolite as mentioned in this paper.

TL;DR: In this article, the age of the Dabie-shan metamorphic rocks is estimated to be 218.5 ± 1.7 Ma using U/Pb in zircon separated from host gneisses.

TL;DR: In this paper, trace element data for 80 samples from about 50 seamounts in the east equatorial Pacific near the East Pacific Rise was presented, and it was shown that the seamount source consists of two components: (1) an extremely depleted component, much more depleted than estimates of the source of depleted MORB; and (2) an enriched component even more enriched than average OIB.

TL;DR: In this paper, the isotopic composition (87 Sr 86 Sr and 143 Nd 144 Nd ) of the ice-core dust has been compared with the isotope composition of the potential source areas: Antarctica, New Zealand, Southern Africa, Australia and South America.

TL;DR: In this paper, the authors explore the mid-Pleistocene climate transition in the time and frequency domains by new methods of time series analysis and find that the ice volume-related increase in δ18O mean (amplitude: 0.29 ± 0.05 (1 − σμ) ) significantly preceded the abrupt increase in the amplitude of the ∼ 100 ka cycle at 641 ± 9 ka.

TL;DR: In this paper, the authors show that microlites grow in the melt phase as a consequence of undercooling caused by gas loss and that microlite growth can cause large excess fluid pressures to develop at shallow levels.

TL;DR: In this paper, high resolution benthic δ 18 O and δ 13 C records from North Atlantic sediment cores were used to monitor the impact of Heinrich events on thermohaline circulation and to estimate the sensitivity of deep oceanic circulation to changes in freshwater input to the North Atlantic surface waters.

TL;DR: In this paper, a new ion microprobe method for dating magmatic zircon growth was proposed based on in situ measurement of the magnitude of 238U-230Th disequilibrium.

TL;DR: The earliest known occurrence of an inverted metamorphic sequence is that found immediately beneath the Himalayan Main Central Thrust (MCT), generally thought to have been active during the Early Miocene as discussed by the authors.

TL;DR: In this paper, a detailed study of size distributions of framboidal pyrite in Holocene Black Sea sediments is presented, showing that framboid size distributions are remarkably uniform (mean diameter = 5 μm).

TL;DR: In this paper, the four longest European pollen records were linked and a terrestrial sequence of vegetation events and a coherent stratigraphic scheme for the last 500,000 years was derived, showing that the pollen sequences contain a higher degree of climate sensitivity than the oxygen isotope record.

TL;DR: In this paper, the authors compare the 14C/12C measurements obtained on tree rings with an independent record of cosmogenic 10Be measured in ice from the South Pole to check the solar origin of the observed 14C /12C variations, which strongly suggests the dominance of solar modulation on the cosmonuclide production variations during the last millennium.

TL;DR: Trace element relationships of near-primary alkalic lavas from La Grille volcano, Grande Comore, in the Indian Ocean, as well as those of the Honolulu volcanic series, Oahu, Hawaii, show that their sources contain amphibole and/or phlogopite as mentioned in this paper.

TL;DR: In this paper, the inverse relationship between recrystallization and trace-element enrichment results from km-scale variation in volume and composition of melts pervasively infiltrated in the lithosphere.

TL;DR: Oxygen diffusion in natural, nonmetamict zircon was characterized under both dry and water-present conditions at temperatures ranging from 765°C to 1500°C.

TL;DR: In this article, the authors applied additive-dose and regenerative-dose single-aliquot methods to estimate the radiation dose received during burial for individual quartz grains from an aeolian deposit of known age (10,000 year old).

TL;DR: In this paper, a large non-riverine source of Ra and Ba is suggested to explain the high fluxes during low river discharge, and the total annual fluxes of226Ra and Ba to the ocean from this system are significantly greater than estimated previously.

TL;DR: In this paper, the authors measured the concentration of in situ produced cosmogenic 10Be and 26Al from bare bedrock surfaces on summit flats in four western U.S. mountain ranges.

TL;DR: In this article, detrital zircons extracted from three flysch samples collected in the central part of the belt were analyzed grain-by-grain using the U-Pb method.

TL;DR: In this paper, the authors show that the presence of serpentinite can reduce the integrated strength of the oceanic lithosphere by up to 30% and that if serpentinization is isolated to fault zones, strain localization should be enhanced, providing an explanation for variations in the style of normal faulting along slow-spreading ridge segments.

TL;DR: In this article, the authors used depth profiles of three Pacific ferromanganese crusts to obtain growth rates which are between 1.4 and 3.8 mm/Ma, indicating that eNd stratification in Pacific seawater, as demonstrated for the present day, has been maintained for at least 20 Ma.

TL;DR: Osmium, strontium, neodymium, and lead isotopic data have been obtained for 30 hand picked samples of basaltic glass from the Pacific, Atlantic and Indian mid-oceanic ridges as mentioned in this paper.

TL;DR: In this article, the authors provided new constraints on the crystallization conditions of the 3.49 Ga Barberton komatiites and compared the compositions of pyroxene preserved in Barberton KOMatiites with pyroxenes produced in laboratory experiments at 0.1 MPa under anhydrous conditions and at 100 and 200 MPa (1 and 2 kbar) under H2O-saturated conditions on an analog Barberton composition.

TL;DR: In this paper, the authors present major and trace-element analyses, Sr, Nd and Pb isotope data, and 40Ar/39Ar dates on basalt samples from above and below the unconformity in northwest Iceland.

TL;DR: In this article, a high-resolution record from northwest Argentina in which the S13C values of soil carbonate rise above a threshold of - 8%0, suggesting the presence of C, plants, starting at 7.3-6.7 Ma.

TL;DR: In this article, structural analysis suggests that current motions along both the active faults and eruptive fissures are kinematically compatible and simply linked with ongoing, WNW-ESE-directed regional extension.