Abstract
A tonalitic vein from a representative traverse section from the Paleoarchean Sand River biotite-amphibole gneiss consists of two domains - orthopyroxene-bearing and orthopyroxcne-abscnt domains - which grade from center to the margin, along its length. The orthopyroxene-bearing domain is heavily altered with respect to the surrounding orthopyroxene-absent domain, which preserves a prominent magmatic texture typical of crystallized melt. Contrasting textures were observed in terms of monazite occurrence in fluorapatite in the two domains. While monazite occurs as inclusions in fluorapatite in the orthopyroxene-bearing domain, it prominently occurs as irregular rims along fluorapatite margins in the orthopyroxene-absent domain. The textural relation of monazite, occurring as both inclusions and irregular rims in the same fluorapatite grains, and different mineral chemical characteristics of both types of monazite, supports the operation of melting accompanying fluid-induced dehydration in the Sand River orthogneiss. T-H20 pseudosection modeling reproduced the mineral assemblages of the domain representing melt portion formed during dehydration. The Paleoproterozoic timing of the events is characterized by a '10Ar/39Ar amphibole age of 2037 ± 10 Ma from the dehydrated gneiss.
| Original language | English |
|---|---|
| Pages (from-to) | 237-254 |
| Number of pages | 18 |
| Journal | South African Journal of Geology |
| Volume | 117 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jan 1 2014 |
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All Science Journal Classification (ASJC) codes
- Geology
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Monazite-fluorapatite characteristics as evidence for interplay between 2.04 ga fluid-induced dehydration and melting of the sand river gneiss, limpopo complex, South Africa. / Rajesh, H. M.; Safonov, O. G.; Belyanin, G. A.; Kramers, J. D.
In: South African Journal of Geology, Vol. 117, No. 2, 01.01.2014, p. 237-254.Research output: Contribution to journal › Article
TY - JOUR
T1 - Monazite-fluorapatite characteristics as evidence for interplay between 2.04 ga fluid-induced dehydration and melting of the sand river gneiss, limpopo complex, South Africa
AU - Rajesh, H. M.
AU - Safonov, O. G.
AU - Belyanin, G. A.
AU - Kramers, J. D.
PY - 2014/1/1
Y1 - 2014/1/1
N2 - A tonalitic vein from a representative traverse section from the Paleoarchean Sand River biotite-amphibole gneiss consists of two domains - orthopyroxene-bearing and orthopyroxcne-abscnt domains - which grade from center to the margin, along its length. The orthopyroxene-bearing domain is heavily altered with respect to the surrounding orthopyroxene-absent domain, which preserves a prominent magmatic texture typical of crystallized melt. Contrasting textures were observed in terms of monazite occurrence in fluorapatite in the two domains. While monazite occurs as inclusions in fluorapatite in the orthopyroxene-bearing domain, it prominently occurs as irregular rims along fluorapatite margins in the orthopyroxene-absent domain. The textural relation of monazite, occurring as both inclusions and irregular rims in the same fluorapatite grains, and different mineral chemical characteristics of both types of monazite, supports the operation of melting accompanying fluid-induced dehydration in the Sand River orthogneiss. T-H20 pseudosection modeling reproduced the mineral assemblages of the domain representing melt portion formed during dehydration. The Paleoproterozoic timing of the events is characterized by a '10Ar/39Ar amphibole age of 2037 ± 10 Ma from the dehydrated gneiss.
AB - A tonalitic vein from a representative traverse section from the Paleoarchean Sand River biotite-amphibole gneiss consists of two domains - orthopyroxene-bearing and orthopyroxcne-abscnt domains - which grade from center to the margin, along its length. The orthopyroxene-bearing domain is heavily altered with respect to the surrounding orthopyroxene-absent domain, which preserves a prominent magmatic texture typical of crystallized melt. Contrasting textures were observed in terms of monazite occurrence in fluorapatite in the two domains. While monazite occurs as inclusions in fluorapatite in the orthopyroxene-bearing domain, it prominently occurs as irregular rims along fluorapatite margins in the orthopyroxene-absent domain. The textural relation of monazite, occurring as both inclusions and irregular rims in the same fluorapatite grains, and different mineral chemical characteristics of both types of monazite, supports the operation of melting accompanying fluid-induced dehydration in the Sand River orthogneiss. T-H20 pseudosection modeling reproduced the mineral assemblages of the domain representing melt portion formed during dehydration. The Paleoproterozoic timing of the events is characterized by a '10Ar/39Ar amphibole age of 2037 ± 10 Ma from the dehydrated gneiss.
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U2 - 10.2113/gssajg.117.2.237
DO - 10.2113/gssajg.117.2.237
M3 - Article
VL - 117
SP - 237
EP - 254
JO - South African Journal of Geology
JF - South African Journal of Geology
SN - 1012-0750
IS - 2
ER -