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1998

Articles 1 - 2 of 2

Full-Text Articles in Geology

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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