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Title: Theoretical studies of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in young lavas produced by mantle melting

Abstract

This paper provides ready-to-use equations to describe variations in uranium-series (U-series) disequilibrium as a function of elemental distribution coefficients, melting porosity, melting rate, and melting time. The effects of these melting parameters on U-series disequilibria are quantitatively evaluated in both an absolute and relative sense. The importance of net elemental fractionation and ingrowth of daughter nuclides are also described and compared in terms of their relative contributions to total U-series disequilibrium. In addition, the authors compare the production of U-series disequilibrium during mantle melting to trace element fractionations produced by melting in a similar context. Trace element fractionations depend externally on the degree to which a source is melted, whereas U-series disequilibrium depends upon both the degree and rate of melting. In contrast to previous models, their approach to modeling U-series disequilibrium during dynamic melting collapses simply to a description of trace element behavior during dynamic melting when the appropriate decay terms are omitted. Their formulation shows that extremely small degrees of melting, sometimes called upon to explain observed extents of U-series disequilibrium, are not always required.

Authors:
;
Publication Date:
Research Org.:
Univ. of California, Los Angeles, CA (US)
OSTI Identifier:
20076121
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Volume: 64; Journal Issue: 10; Other Information: PBD: May 2000; Journal ID: ISSN 0016-7037
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; 58 GEOSCIENCES; LAVA; GEOCHEMISTRY; URANIUM 238; THORIUM 230; RADIUM 226; URANIUM 235; PROTACTINIUM; EQUILIBRIUM; ECOLOGICAL CONCENTRATION; EARTH MANTLE; MELTING; MATHEMATICAL MODELS

Citation Formats

Zou, H., and Zindler, A. Theoretical studies of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in young lavas produced by mantle melting. United States: N. p., 2000. Web. doi:10.1016/S0016-7037(00)00350-1.
Zou, H., & Zindler, A. Theoretical studies of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in young lavas produced by mantle melting. United States. doi:10.1016/S0016-7037(00)00350-1.
Zou, H., and Zindler, A. Mon . "Theoretical studies of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in young lavas produced by mantle melting". United States. doi:10.1016/S0016-7037(00)00350-1.
@article{osti_20076121,
title = {Theoretical studies of {sup 238}U-{sup 230}Th-{sup 226}Ra and {sup 235}U-{sup 231}Pa disequilibria in young lavas produced by mantle melting},
author = {Zou, H. and Zindler, A.},
abstractNote = {This paper provides ready-to-use equations to describe variations in uranium-series (U-series) disequilibrium as a function of elemental distribution coefficients, melting porosity, melting rate, and melting time. The effects of these melting parameters on U-series disequilibria are quantitatively evaluated in both an absolute and relative sense. The importance of net elemental fractionation and ingrowth of daughter nuclides are also described and compared in terms of their relative contributions to total U-series disequilibrium. In addition, the authors compare the production of U-series disequilibrium during mantle melting to trace element fractionations produced by melting in a similar context. Trace element fractionations depend externally on the degree to which a source is melted, whereas U-series disequilibrium depends upon both the degree and rate of melting. In contrast to previous models, their approach to modeling U-series disequilibrium during dynamic melting collapses simply to a description of trace element behavior during dynamic melting when the appropriate decay terms are omitted. Their formulation shows that extremely small degrees of melting, sometimes called upon to explain observed extents of U-series disequilibrium, are not always required.},
doi = {10.1016/S0016-7037(00)00350-1},
journal = {Geochimica et Cosmochimica Acta},
issn = {0016-7037},
number = 10,
volume = 64,
place = {United States},
year = {2000},
month = {5}
}