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Weathering-related origin of widespread monazite in S-type granites

Abstract

The S-type granite suites comprising more than a quarter of the extensively developed granites in the Lachlan Fold Belt, Australia, contain monazite which may be related to the chemical weathering of the sedimentary source rocks. We report a process whereby chemical weathering fixes mobile rare-earth elements (REE) in hydrous phosphate phases such as florencite and rhabdophane. This material contains up to 50 wt.% LREE and occurs as very small particles (approx. 3 ..mu..m). Dehydration of these hydrous REE phases during anatexis directly yields monazite. The low solubility of phosphorus in S-type granite melts inhibits dissolution of both monazite and apatite. Refractory monazite may be thus entrained and transported in S-type granites in a manner similar to processes resulting in inherited zircon. Since both Th and the light REE are major components in monazite, materials containing this minute phase may be of widespread geochemical significance in both granites and metamorphic rocks.
Publication Date:
Jan 01, 1986
Product Type:
Journal Article
Reference Number:
AIX-17-039152; EDB-86-115141
Resource Relation:
Journal Name: Geochim. Cosmochim. Acta; (United Kingdom); Journal Volume: 50:1
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 58 GEOSCIENCES; GRANITES; GEOCHEMISTRY; MONAZITES; MINERALIZATION; ORIGIN; AUSTRALIA; GEOLOGIC MODELS; RARE EARTHS; WEATHERING; ACTINIDE COMPOUNDS; AUSTRALASIA; CHEMISTRY; ELEMENTS; IGNEOUS ROCKS; MATERIALS; METALS; MINERALS; OXYGEN COMPOUNDS; PHOSPHATES; PHOSPHORUS COMPOUNDS; PLUTONIC ROCKS; RADIOACTIVE MATERIALS; RADIOACTIVE MINERALS; RARE EARTH COMPOUNDS; ROCKS; THORIUM COMPOUNDS; THORIUM MINERALS; THORIUM PHOSPHATES; 050100* - Nuclear Fuels- Reserves, Exploration, & Mining; 580400 - Geochemistry- (-1989)
OSTI ID:
5757965
Research Organizations:
Australian National Univ., Canberra. Dept. of Geology
Country of Origin:
United Kingdom
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: GCACA
Submitting Site:
INIS
Size:
Pages: 171-175
Announcement Date:
Jun 01, 1986

Citation Formats

Sawka, W N, Banfield, J F, and Chappell, B W. Weathering-related origin of widespread monazite in S-type granites. United Kingdom: N. p., 1986. Web. doi:10.1016/0016-7037(86)90062-1.
Sawka, W N, Banfield, J F, & Chappell, B W. Weathering-related origin of widespread monazite in S-type granites. United Kingdom. doi:10.1016/0016-7037(86)90062-1.
Sawka, W N, Banfield, J F, and Chappell, B W. 1986. "Weathering-related origin of widespread monazite in S-type granites." United Kingdom. doi:10.1016/0016-7037(86)90062-1. https://www.osti.gov/servlets/purl/10.1016/0016-7037(86)90062-1.
@misc{etde_5757965,
title = {Weathering-related origin of widespread monazite in S-type granites}
author = {Sawka, W N, Banfield, J F, and Chappell, B W}
abstractNote = {The S-type granite suites comprising more than a quarter of the extensively developed granites in the Lachlan Fold Belt, Australia, contain monazite which may be related to the chemical weathering of the sedimentary source rocks. We report a process whereby chemical weathering fixes mobile rare-earth elements (REE) in hydrous phosphate phases such as florencite and rhabdophane. This material contains up to 50 wt.% LREE and occurs as very small particles (approx. 3 ..mu..m). Dehydration of these hydrous REE phases during anatexis directly yields monazite. The low solubility of phosphorus in S-type granite melts inhibits dissolution of both monazite and apatite. Refractory monazite may be thus entrained and transported in S-type granites in a manner similar to processes resulting in inherited zircon. Since both Th and the light REE are major components in monazite, materials containing this minute phase may be of widespread geochemical significance in both granites and metamorphic rocks.}
doi = {10.1016/0016-7037(86)90062-1}
journal = {Geochim. Cosmochim. Acta; (United Kingdom)}
volume = {50:1}
journal type = {AC}
place = {United Kingdom}
year = {1986}
month = {Jan}
}