Showing papers in "Earth and Planetary Science Letters in 1976"

TL;DR: In this paper, the possibility of using 143Nd/146Nd as a natural tracer was examined by analyzing two Hercynian granitic rocks, one carbonatite, three alkali basalts and nine tholeiites.

TL;DR: In this article, five minor and trace elements, known to be chemically stable during alteration and metamorphism, have been combined in a set of binary diagrams that distinguish fresh tholeiites from alkali basalts.

TL;DR: A primordial neon component in neon from Kilauea Volcano and deep-sea tholeiite glass has been identified by the presence of excess 20Ne; relative to atmospheric neon the 20Ne enrichments are 54% in Kilea neon and about 25% in the basalts The 20Ne anomalies are associated with high 3He/4He ratios.

TL;DR: In this article, the water column and the sediments of the Cariaco Trench were measured and the results showed that CH4 is non-conservative in both environments, and the concentrations of CH4 were found to be non-consistency.

TL;DR: The absolute values of the 18 O/16 O ratio (R s ) and the relative 18 O content ( X s ) in SMOW have been determined by comparing SMOW mass spectrometrically with well-defined synthetic mixtures of pure D 2 18 O and H 2 16 O as discussed by the authors.

TL;DR: In this paper, the C1/(C2 + C3) ratios of the seep gas samples ranged from 68 to greater than 1000, whereas δPDB13C values varied from −39.9 to −65.5

TL;DR: In this paper, a 2.5-year residence time was calculated for 210 Pb and a 0.6-year resident time for 210 Po in the mixed-layer.

TL;DR: On the basis of 18O/16O and 17O/ 16O ratios, meteorites and planets can be grouped into at least six categories, as follows: (1) the terrestrial group, consisting of the earth, moon, differentiated meteorites, and enstatite chondrites; (2) types L and LL ordinary chondrite; (3) type H ordinary chonderes; (4) anhydrous minerals of C2, C3, C4 carbonaceous chondites; (5) hydrous matrix minerals of c2 carbonaceous

TL;DR: In this article, a simple technique for the etching of fission tracks in zircon has been developed which overcomes the practical difficulties of previously described techniques, which is a low melting-point binary eutectic of KOH and NaOH which is used at 200-220°C.

TL;DR: The distribution of 234Th(t 1/2 = 24.1 days) in excess of its parent 238U in the upper layers of near-shore sediment makes possible the evaluation of short-term sediment reworking and diagenetic rates as mentioned in this paper.

TL;DR: The authors showed that saddle-shaped age spectra are diagnostic of excess 40 Ar in igneous minerals as well as in the igneous rocks, but do not reach the crystallization age.

TL;DR: In this article, a method has been developed for the analysis of D/H ratios of non-exchangeable hydrogen in plant cellulose and the overall relationship is linear with slope of one and intercept of −22%.

TL;DR: In this article, a 6m sediment core from Lake St. Croix, Minnesota, spanning the time range from 445 to 1740 years B.P. was used to obtain relative paleointensities.

TL;DR: Nickel has been measured on four Geosecs profiles from the Atlantic and Pacific as discussed by the authors, and the resulting distribution is oceanographically consistent: the concentration levels are over a factor of five lower than any previously reported.

TL;DR: In this article, the spinifex-textured peridotites (STP) and high-magnesian basaltic basaltics are considered to belong to the komatiite suite, despite their low CaO/Al2O3 ratios.

TL;DR: In this paper, the authors modeled the observed distribution of 210 Pb and 210 Po in surface waters of the Pacific, and determined the residence times relative to particulate removal relative to particle removal.

TL;DR: Using thin elastic plate theory and neglecting horizontal applied forces, a universal deflection profile applicable to many oceanic trenches is derived in this paper, where the thickness of the elastic lithosphere is found to vary between 20 and 29 km for the trench profiles considered.

TL;DR: In this article, the authors concluded that there is a close agreement between the plate-tectonic predictions and the South Island Cainozoic geological history, and that the period 10 m.y. B.P.

TL;DR: In this paper, a tentative history of the Southwest Pacific is proposed for the last 40 m.y. from magnetic anomaly studies and major tectonic events on land, and the Hawkes Bay Crustal Microplate is deduced to have been “floating” while Pacific plate lithosphere passed beneath it throughout the Upper Cenozoic.

TL;DR: In this paper, three groups of spinels have been identified in dredged basalts from the Mid-Atlantic Ridge in the Azores region (30-40°N): (1) magnesiochromites with 0.4-0.5 Cr/(Cr + Al) are most common and characteristic of olivine tholeiites of the region; (2) titaniferous spinels are found in an olivinite basalt with alkali affinities, of local occurrence and evolved in relatively high fugacity of oxygen; (3) chromian

TL;DR: Serpentinite may be a significant component of the oceanic crust, not as a continuous layer, but as vertical tectonic protrusions and sills emplaced from the upper mantle into fault zones parallel to the axis of spreading ridges as discussed by the authors.

TL;DR: In this article, the distribution of points in the plot of Ti, Zr, Y, Sr, K, P and Nb has been investigated at 55 sample sites within a single basaltic flow, the Cliefden Outcrop, which has adjusted to low-grade metamorphism of the prehnite-pumpellyite facies.

TL;DR: In this paper, field, petrographic and geochemical criteria identify the Eocambrian, 500 km 2, mafic-ultramafic complex of Jabal al Wask as an ophiolite possibly formed in a back arc environment.

TL;DR: In this paper, temperature-depth profiles are computed to account for the development of sharply inverted metamorphic zonations and estimated P-T conditions under deep-seated thrust faults, with particular reference to the metamorphism of the Pelona Schist-Vincent Thrust system of southern California.

TL;DR: In this paper, a mantle plume model is proposed for the Barberton region in South Africa, which has the advantages of including both moderate and high geothermal gradients and accounting for the observed episodisity of magmatism.

TL;DR: In this article, the authors discussed the known δ13C variations in rocks of deep-seated origin and interpreted the −7.6 ± 0.5% value as a reasonable estimate of the primary value of deepseated carbon in the ridge area.

TL;DR: In this paper, the iodine content of marine suspended matter obtained from thirteen stations in the Atlantic between 75°N and 55°S has been measured, and the concentration of particulate iodine is high in the surface, up to 127 ng/kg of seawater being observed.

TL;DR: The Lau Basin is a marginal sea, located between the Tonga and Lau Ridges, in the southwestern Pacific as mentioned in this paper, and the data for Lau Basin basalt (LBB) show close similarity to data of typical oceanic ridge basalt.

TL;DR: In this article, a small particle (ca. 10−6 g) was magnetically separated from a Ca,Al-rich inclusion of the Allende meteorite, and a polished section of the grain showed that it consisted mainly of silicates, with a rounded particle of metal and sulfide attached to it.

TL;DR: In this paper, the authors show a general linear correlation in the oceanic water column within the uncertainties of the data: the slope of the line is about 4.6 nanomoles (nmoles) Ra/mole Ba, the intercept being at about 4 nmoles Ba/kg.