Earth and Planetary Science Letters
About: Earth and Planetary Science Letters is an academic journal. The journal publishes majorly in the area(s): Mantle (geology) & Subduction. It has an ISSN identifier of 0012-821X. Over the lifetime, 18373 publication(s) have been published receiving 1266164 citation(s). The journal is also known as: EPSL.
Papers published on a yearly basis
Abstract: On August 24, 1976 the IUGS Subcommission on Geochronology (FOOTNOTE 4) met in Sydney, Australia, during the 25th International Geological Congress. They unanimously agreed to recommend the adoption of a standard set of decay constants and isotopic abundances in isotope geology. Values have been selected, based on current information and usage, to provide for uniform international use in published communications. The Subcommission urges that all isotopic data be reported using the recommended values (see appendix). The recommendation represents a convention for the sole purpose of achieving interlaboratory standardization. The Subcommission does not intend to endorse specific methods of investigation or to specifically select the works of individual authors, institutions, or publications. All selected values are open to and should be the subjects of continuing critical scrutinizing and laboratory investigation. Recommendations will be reviewed by the Subcommission from time to time to bring the adopted conventional values in line with significant new research data.
Abstract: Parameters on which models for terrestrial lead isotope evolution are based have recently been revised. These parameters are the isotopic composition of troilite lead, the age of the meteorite system and the decay constants of uranium and thorium. As a result, the normal single-stage model in which the age of the earth is taken to be that of the meteorite system is now untenable. A two-stage model has been constructed which permits the age of the earth to be that of the meteorite system and which also yields good model ages for samples of all ages. The new model postulates that lead developed initially from a primordial composition assumed to be that of troilite lead beginning at 4.57 b.y. ago. The average values of 238 U/ 204 Pb and 232 Th/ 204 Pb for this first stage were 7.19 and 32.21 respectively. At approximately 3.7 b.y. ago differentiation processes brought about the conditions of a second stage, in which 238 U/ 204 Pb ≈ 9.74 and 232 Th/ 204 Pb ≈ 37.19 in those portions of the earth which took part in mixing events, giving rise to average lead.
Abstract: A simple model for the development and evolution of sedimentary basins is proposed. The first event consists of a rapid stretching of continental lithosphere, which produces thinning and passive upwelling of hot asthenosphere. This stage is associated with block faulting and subsidence. The lithosphere then thickens by heat conduction to the surface, and further slow subsidence occurs which is not associated with faulting. The slow subsidence and the heat flow depend only on the amount of stretching, which can be estimated from these quantities and from the change in thickness of the continental crust caused by the extension. The model is therefore easily tested. Preliminary investigations of the Great Basin, the Aegean, the North Sea and the Michigan Basin suggest that the model can account for the major events in their evolution.
Abstract: Analyses for Ti, Zr, Y, Nb and Sr in over 200 basaltic rocks from different tectonic settings have been used to construct diagrams in which these settings can usually be identified. Basalts erupted within plates (ocean island and continental basalts) can be identified using a Ti-Zr-Y diagram, ocean-floor basalts, and low-potassium tholeiites and calc-alkali basalts from island arcs can be identified using a Ti-Zr diagram (for altered samples) and a Ti-Zr-Sr diagram (for fresh samples). Y/Nb is suggested as a parameter for indicating whether a basalt is of tholeiitic or alkalic nature. Analyses of dykes and pillow lavas from the Troodos Massif of Cyprus are plotted on these diagrams and appear to the tholeiitic ocean-floor rocks
Abstract: Hydrothermal experiments in the temperature range 750–1020°C have defined the saturation behavior of zircon in crustal anatectic melts as a function of both temperature and composition. The results provide a model of zircon solubility given by: In D Zr zircon/melt = −3.80−[0.85(M−1)]+12900/T where D Zr zircon/melt is the concentration ratio of Zr in the stoichiometric zircon to that in the melt, T is the absolute temperature, and M is the cation ratio (Na + K + 2Ca)/(Al · Si). This solubility model is based principally upon experiments at 860°, 930°, and 1020°C, but has also been confirmed at temperatures up to 1500°C for M = 1.3. The lowest temperature experiments (750° and 800°C) yielded relatively imprecise, low solubilities, but the measured values (with assigned errors) are nevertheless in agreement with the predictions of the model. For M = 1.3 (a normal peraluminous granite), these results predict zircon solubilities ranging from ∼ 100 ppm dissolved Zr at 750°C to 1330 ppm at 1020°C. Thus, in view of the substantial range of bulk Zr concentrations observed in crustal granitoids (∼ 50–350 ppm), it is clear that anatectic magmas can show contrasting behavior toward zircon in the source rock. Those melts containing insufficient Zr for saturation in zircon during melting can have achieved that condition only by consuming all zircon in the source. On the other hand, melts with higher Zr contents (appropriate to saturation in zircon) must be regarded as incapable of dissolving additional zircon, whether it be located in the residual rocks or as crystals entrained in the departing melt fraction. This latter possibility is particularly interesting, inasmuch as the inability of a melt to consume zircon means that critical geochemical “indicators” contained in the undissolved zircon (e.g. heavy rare earths, Hf, U, Th, and radiogenic Pb) can equilibrate with the contacting melt only by solid-state diffusion, which may be slow relative to the time scale of the melting event.