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Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

1998

Earth Sciences

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Full-Text Articles in Physical Sciences and Mathematics

Experimental Studies Of Fe-Mg Carbonates And Their Role In Petrogenesis Sep 1998

Experimental Studies Of Fe-Mg Carbonates And Their Role In Petrogenesis

Andrea M. Koziol

The occurrence of carbonate minerals in rocks and sediments is a mark of the interaction of the biosphere, hydrosphere, and atmosphere with the lithosphere. The studies described in this proposal will help geologists understand the conditions of formation of banded iron formations, carbonatites, and magnesite-bearing eclogites, among other parageneses.

The objectives of this study are to determine siderite (FeCO3), magnesite (MgCO3), and CO2 thermodynamic properties and the mixing relations of siderite-magnesite solid solutions. Selected carbonate univariant equilibria, experimentally reversed over a wide range of pressure and temperature, will provide this information. The equilibria siderite + hematite = magnetite + CO2, …

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Active Tectonics And Ultrahigh-Pressure Rocks, Ann Blythe Dec 1997

Active Tectonics And Ultrahigh-Pressure Rocks, Ann Blythe

Ann Blythe

This chapter compares modern exhumation and surface uplift rates with the rates needed for the preservation of ultrahigh pressure (UHP) metamorphic rocks. The highest recorded exhumation rates of ~ 5–10 mm/a are inferred from isotopic and fission-track analyses in the Himalaya, Southern Alps of New Zealand, and D’Entrecasteaux Islands. Similar rates (~7 mm/a) of surface uplift are measured from leveling surveys in Nepal and correlations of marine terraces in the Southern Alps. In Nepal, however, this surface uplift rate is occurring despite erosion, and the true rate of surface uplift is probably considerably higher. In restraining bends along the San …

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Longitudinal Study Of Dental Development In Chimpanzees Of Known Chronological Age: Implications For Understanding The Age At Death Of Plio-Pleistocene Hominids, Robert Anemone, Mark Mooney Dec 1997

Longitudinal Study Of Dental Development In Chimpanzees Of Known Chronological Age: Implications For Understanding The Age At Death Of Plio-Pleistocene Hominids, Robert Anemone, Mark Mooney

Robert L. Anemone

Reconstruction of life history variables of fossil hominids on the basis of dental development requires understanding of and comparison with the pattern and timing of dental development among both living humans and pongids. Whether dental development among living apes or humans provides a better model for comparison with that of Plio-Pleistocene hominids of the genus Australopithecus remains a contentious point. This paper presents new data on chimpanzees documenting developmental differences in the dentitions of modern humans and apes and discusses their significance in light of recent controversies over the human or pongid nature of australopithecine dental development. Longitudinal analysis of …

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