Mineral chemistry, reaction textures, thermobarometry and P-T path from orthopyroxene granulites of Rayagada, Eastern Ghats, India

Rajib Shaw, M. Arima

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Orthopyroxene granulites (charnockites, enderbites and associated rocks) form one of the major lithological units in Rayagada, in the north-central sector of the Eastern Ghats Granulite Belt of Peninsular India. Petrographic features show common occurrences of clinopyroxene lamella within orthopyroxene host, although reverse relations have also been observed in some cases. Two types of coronal garnet with different chemical compositions have been noted: one at the interface of orthopyroxene and plagioclase, and the other rimming magnetite, also at the contact of plagioclase. Garnet-orthopyroxene thermometry from these rocks show temperature variations from 840 to 700°C, whereas two-pyroxene and garnet-biotite thermometry yield temperatures around 750 and 700°C, respectively. Garnet-orthopyroxene-plagioclase-quartz barometry ranges from 8.1 to 6.8 kbar. A near-isobaric cooling from a thermal maxima of ∼840°C, followed by decompression is characteristic of the deduced pressure-temperature (P-T) path. This shows significant similarities with the P-T path derived from associated metapelites. Field and petrographic features collectively suggest that these orthopyroxene granulites have suffered at least the second deformation event (D2), which is the dominant ductile deformation of the area. This event presumably took place around 1000 Ma and might be coeval to the mid-Proterozoic events of East Antarctica and other fragments of Gondwanaland.

Original languageEnglish
Pages (from-to)175-184
Number of pages10
JournalJournal of Southeast Asian Earth Sciences
Volume14
Issue number3-4
Publication statusPublished - 1996
Externally publishedYes

Fingerprint

orthopyroxene
texture
garnet
mineral
plagioclase
temperature
barometry
metapelite
ductile deformation
Hypsithermal
granulite
decompression
rock
pyroxene
clinopyroxene
magnetite
biotite
Proterozoic
chemical composition
quartz

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Earth and Planetary Sciences(all)
  • Environmental Science(all)

Cite this

@article{9714dfcd906d48d29855e055050793ca,
title = "Mineral chemistry, reaction textures, thermobarometry and P-T path from orthopyroxene granulites of Rayagada, Eastern Ghats, India",
abstract = "Orthopyroxene granulites (charnockites, enderbites and associated rocks) form one of the major lithological units in Rayagada, in the north-central sector of the Eastern Ghats Granulite Belt of Peninsular India. Petrographic features show common occurrences of clinopyroxene lamella within orthopyroxene host, although reverse relations have also been observed in some cases. Two types of coronal garnet with different chemical compositions have been noted: one at the interface of orthopyroxene and plagioclase, and the other rimming magnetite, also at the contact of plagioclase. Garnet-orthopyroxene thermometry from these rocks show temperature variations from 840 to 700°C, whereas two-pyroxene and garnet-biotite thermometry yield temperatures around 750 and 700°C, respectively. Garnet-orthopyroxene-plagioclase-quartz barometry ranges from 8.1 to 6.8 kbar. A near-isobaric cooling from a thermal maxima of ∼840°C, followed by decompression is characteristic of the deduced pressure-temperature (P-T) path. This shows significant similarities with the P-T path derived from associated metapelites. Field and petrographic features collectively suggest that these orthopyroxene granulites have suffered at least the second deformation event (D2), which is the dominant ductile deformation of the area. This event presumably took place around 1000 Ma and might be coeval to the mid-Proterozoic events of East Antarctica and other fragments of Gondwanaland.",
author = "Rajib Shaw and M. Arima",
year = "1996",
language = "English",
volume = "14",
pages = "175--184",
journal = "Journal of Asian Earth Sciences",
issn = "1367-9120",
publisher = "Elsevier Limited",
number = "3-4",

}

TY - JOUR

T1 - Mineral chemistry, reaction textures, thermobarometry and P-T path from orthopyroxene granulites of Rayagada, Eastern Ghats, India

AU - Shaw, Rajib

AU - Arima, M.

PY - 1996

Y1 - 1996

N2 - Orthopyroxene granulites (charnockites, enderbites and associated rocks) form one of the major lithological units in Rayagada, in the north-central sector of the Eastern Ghats Granulite Belt of Peninsular India. Petrographic features show common occurrences of clinopyroxene lamella within orthopyroxene host, although reverse relations have also been observed in some cases. Two types of coronal garnet with different chemical compositions have been noted: one at the interface of orthopyroxene and plagioclase, and the other rimming magnetite, also at the contact of plagioclase. Garnet-orthopyroxene thermometry from these rocks show temperature variations from 840 to 700°C, whereas two-pyroxene and garnet-biotite thermometry yield temperatures around 750 and 700°C, respectively. Garnet-orthopyroxene-plagioclase-quartz barometry ranges from 8.1 to 6.8 kbar. A near-isobaric cooling from a thermal maxima of ∼840°C, followed by decompression is characteristic of the deduced pressure-temperature (P-T) path. This shows significant similarities with the P-T path derived from associated metapelites. Field and petrographic features collectively suggest that these orthopyroxene granulites have suffered at least the second deformation event (D2), which is the dominant ductile deformation of the area. This event presumably took place around 1000 Ma and might be coeval to the mid-Proterozoic events of East Antarctica and other fragments of Gondwanaland.

AB - Orthopyroxene granulites (charnockites, enderbites and associated rocks) form one of the major lithological units in Rayagada, in the north-central sector of the Eastern Ghats Granulite Belt of Peninsular India. Petrographic features show common occurrences of clinopyroxene lamella within orthopyroxene host, although reverse relations have also been observed in some cases. Two types of coronal garnet with different chemical compositions have been noted: one at the interface of orthopyroxene and plagioclase, and the other rimming magnetite, also at the contact of plagioclase. Garnet-orthopyroxene thermometry from these rocks show temperature variations from 840 to 700°C, whereas two-pyroxene and garnet-biotite thermometry yield temperatures around 750 and 700°C, respectively. Garnet-orthopyroxene-plagioclase-quartz barometry ranges from 8.1 to 6.8 kbar. A near-isobaric cooling from a thermal maxima of ∼840°C, followed by decompression is characteristic of the deduced pressure-temperature (P-T) path. This shows significant similarities with the P-T path derived from associated metapelites. Field and petrographic features collectively suggest that these orthopyroxene granulites have suffered at least the second deformation event (D2), which is the dominant ductile deformation of the area. This event presumably took place around 1000 Ma and might be coeval to the mid-Proterozoic events of East Antarctica and other fragments of Gondwanaland.

UR - http://www.scopus.com/inward/record.url?scp=0030403471&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030403471&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0030403471

VL - 14

SP - 175

EP - 184

JO - Journal of Asian Earth Sciences

JF - Journal of Asian Earth Sciences

SN - 1367-9120

IS - 3-4

ER -