Showing papers in "Earth and Planetary Science Letters in 1975"

TL;DR: In this paper, a two-stage model for terrestrial lead isotope evolution is proposed, which permits the age of the earth to be that of the meteorite system and also yields good model ages for samples of all ages.

TL;DR: In this paper, a critical re-assessment of the construction of simple ore lead isotopic development curves is followed by three fresh approximations, all designed to involve the minimum possible number of assumptions.

TL;DR: In this paper, five minor and trace elements have been variously combined to produce a set of binary diagrams in addition to total alkali-SiO2 diagrams, that discriminate between fresh tholeiitic and alkali basalts.

TL;DR: Theoretical blocking curves for hematite and magnetite are given over temperature ranges from room temperatures to Curie temperature and over time scales from 1 second to 109 years as mentioned in this paper.

TL;DR: In this paper, seawater reacted with basalt at 200°C and 500 bars for 4752 hours, and the results showed that aqueous composition and alteration minerals were similar to those in the Iceland geothermal fields; sufficient heavy metals were solubilized to account for the deep-sea heavy-metal deposits.

TL;DR: The calcite compensation depth (CCD) in the world oceans was shallow from the late Jurassic to early Cenozoic time as discussed by the authors, reaching a very shallow peak 10−15 m.y.

TL;DR: In this article, the authors show that water on the crest and flanks of the East Pacific Rise has the highest enrichment in 3He so far observed in the oceans; the 3He/4He ratio anomaly relative to atmospheric helium is + 32% at the mid-depth maximum in the profiles.

TL;DR: In this paper, rare earths (RE) in basalts erupted within the rift of the Mid-Atlantic Ridge show a progressive change from light-RE enriched to depleted patterns from the Azores Platform (40°N) down to 33°30′N.

TL;DR: In this paper, the authors used regression analysis to find the relationship between the dielectric constant of a soil or solid at a density of pg/cm3 and the loss tangent.

TL;DR: The TiO2-K2O-P2O5 ternary diagram as discussed by the authors was proposed as a method of discriminating between oceanic and non-oceanic (continental) basalts.

TL;DR: The 3 He/4 He ratio in basalt glass is the same as the isotope ratio of the excess helium in Pacific Ocean deep water, supporting the theory that the atmospheric escape rate of 3 He is balanced by a flux of primordial 3 He from the mantle as discussed by the authors.

TL;DR: In this paper, a cubic perovskite-type 3olymorph of CaSiO 3 has been obtained from synthetic crystalline (wollastonite) and glass forms of the material and has been compressed to loading pressures above 160 kbar and heated to about 1500° C by a laser in a diamond anvil cell.

TL;DR: In this paper, the activity coefficients of deuterated and light water (Γ) are given in chloridic saline solutions as a function of the molality of the salt components by the expression: ( 1 − 1 Γ ) x 10 3 ≡ − Δ δ = 6.1 M CaC l 2 + 5.4 M KCl + 0.4 m NaCl

TL;DR: In this article, the authors examined the relationship between group velocities of Rayleigh waves and the ocean bottom age in the Pacific and found that a significant change in the group velocity was observed for these four regions by the use of the least-squares method from data for 27 paths in a period range of 40-90 s.

TL;DR: In this paper, the authors attributed the alteration of basalt in Layer II of the ocean floor and secondarily to alteration of volcanic ash in the sediments to increase the seawater concentration in pore water.

TL;DR: In this paper, an extensive compilation of recently acquired geophysical reconnaissance data has allowed the Mesozoic magnetic lineations (The Eastern Keathley sequence) to be identified and mapped in detail for the area off northwest Africa lying between Madeira and the Cape Verde Islands.

TL;DR: The evidence for hot spot origin for the Canary Islands is reviewed in this paper, and it is found that the geochronological and geophysical data do not support this model and the propagating fracture hypothesis explains in a more convincing way the location and chronology of the Archipelago, whose three main periods of activity corresponding to basal complexes, table-land basalts and recent emissions are suggested to be related in time and genetically to the three main tensional phases in the nearby High Atlas Mountains.

TL;DR: The Belingwe greenstone belt, Rhodesia, contains a succession of Archaean lavas and sedimentary rocks which display features of critical importance for an understanding of their genesis as mentioned in this paper.

TL;DR: In this paper, a global heat flow map has been derived from existing observations supplemented in areas without data by an empirical predictor based on tectonic setting and age, and the predictor was used to assign mean heat flow values to 5° × 5° grid areas on the globe, weighted according to the relative area of Tectonic provinces represented.

TL;DR: The magnetic fabric has been measured of specimens from 16 laboratory-deposited sediments and the results from the running-water depositions confirm the existence of a characteristic style of magnetic fabric and hint at the possibility of estimating the magnitude of depositing currents.

TL;DR: The distribution of the ash and of mica percentage in the ash form a W-shaped pattern opening towards the west as discussed by the authors, which suggests that two branches of the Cromwell current, one moving along the equator and one along 3°S, had a significant influence on the distribution of ash.

TL;DR: In this article, magnetic lineations in the Shikoku marginal basin were identified and the authors inferred that the Palau-Kyushu ridge and the Izu-Bonin island arc began separating about 27 m.y.b.p.

TL;DR: In this paper, six pairs of coexisting garnets and clinopyroxenes were separated from the sheared and granular garnet lherzolite nodules in kimberlites and analyzed for rare earth elements (REE).

TL;DR: The results in this paper indicate that tholeiites and andesites of the calc-alkaline series with compositions similar to the rocks studied are not primary magmas from mantle peridotite at depths greater than about 50 km.

TL;DR: In this article, the authors suggest that an in-situ titration of some of the alkalinity by protons derived from the redox changes associated with organic decomposition of organic matter may explain an apparent excess of calcium in seawater.

TL;DR: In this article, an experimental determination of the reaction MgCO 3 + MgSiO 3 = Mg 2 SiO 4 + CO 2 between 20 and 40 kbars and in the range 1000-1500°C yields an average pressure effect on the equilibrium of 44 bars/°C.

TL;DR: In this paper, the authors used a two-stage model for the U-Pb system with an average 238 U/ 204 Pb (μ 1 ) value of 9.3 ± 0.2 for the source region.

TL;DR: In this paper, an analysis of the magnetic anomaly profiles in the Bay of Biscay provides evidence for the former existence of an E-W trending sea-floor spreading axis in Biscays.

TL;DR: The reaction between enstatite (En 95.3 Fs 4.7 ) and CaCO 3 has been studied at pressures between 23 and 77 kbars and at temperatures between 800° and 1400°C.

TL;DR: In this article, the effects of temperature, f O2 and composition on the electrical conductivity of silicate liquids have been experimentally determined from 1200 to 1550°C under a range of f O 2 conditions sufficient to change the oxidation state of Fe from predominantly Fe 2+ to Fe 3+.