Significant cooling during exhumation of UHP eclogite from the Taohang area in the Sulu region of eastern China and its tectonic significance

Daisuke Nakamura, Takao Hirajima

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The decompressional pressure-temperature (P-T) path was estimated for ultrahigh-pressure (UHP) eclogite from the Sulu region of eastern China by applying geo-thermobarometers to well-preserved equilibrium mineral pairs. The sample studied is a kyanite-bearing eclogite that was collected from the Taohang area of the Sulu region. Garnet is relatively homogeneous in chemical composition, but omphacite has a clear chemical zoning with decreasing jadeite content from core to rim. Assuming that peak-P equilibrium compositions are preserved in the cores of garnet (Grt) and omphacite (Omp), P-T conditions were calculated to be about 700°C and 3.4 GPa. On the other hand, the jadeite content of omphacite rims varies from 0.35 to 0.46 mol.%. Nevertheless, the variation in Fe/Mg ratios of omphacite rims is very small. Temperatures of 566 ± 54°C were obtained at 1.5 GPa for garnet rim and omphacite rim pairs. These petrological considerations indicate that temperatures should have significantly declined during the early decompression stage of this eclogite. In other areas of the Sulu region, isothermal decompression paths were proposed, and it was concluded that the UHP rocks were exhumed as a large mass tens of kilometers in thickness to avoid thermal effects from the surrounding materials. However, the newly identified decompression path accompanying the significant cooling may indicate that the Taohang outcrop was located at the margin of the Sulu UHP terrane. Thus, the decompressional P-T path is not unique in the Sulu region and varies depending on the location.

Original languageEnglish
Pages (from-to)707-717
Number of pages11
JournalIsland Arc
Volume19
Issue number4
DOIs
Publication statusPublished - Dec 2010

Fingerprint

eclogite
omphacite
exhumation
cooling
tectonics
decompression
jadeite
garnet
temperature
kyanite
temperature effect
zoning
terrane
outcrop
chemical composition
mineral
rock

Keywords

  • Eclogite
  • Garnet-clinopyroxene thermometer
  • Partial equilibrium
  • Sulu region
  • Ultrahigh-pressure

ASJC Scopus subject areas

  • Geology

Cite this

Significant cooling during exhumation of UHP eclogite from the Taohang area in the Sulu region of eastern China and its tectonic significance. / Nakamura, Daisuke; Hirajima, Takao.

In: Island Arc, Vol. 19, No. 4, 12.2010, p. 707-717.

Research output: Contribution to journalArticle

@article{9c4d5a263ca4486593396b0ec2fb3626,
title = "Significant cooling during exhumation of UHP eclogite from the Taohang area in the Sulu region of eastern China and its tectonic significance",
abstract = "The decompressional pressure-temperature (P-T) path was estimated for ultrahigh-pressure (UHP) eclogite from the Sulu region of eastern China by applying geo-thermobarometers to well-preserved equilibrium mineral pairs. The sample studied is a kyanite-bearing eclogite that was collected from the Taohang area of the Sulu region. Garnet is relatively homogeneous in chemical composition, but omphacite has a clear chemical zoning with decreasing jadeite content from core to rim. Assuming that peak-P equilibrium compositions are preserved in the cores of garnet (Grt) and omphacite (Omp), P-T conditions were calculated to be about 700°C and 3.4 GPa. On the other hand, the jadeite content of omphacite rims varies from 0.35 to 0.46 mol.{\%}. Nevertheless, the variation in Fe/Mg ratios of omphacite rims is very small. Temperatures of 566 ± 54°C were obtained at 1.5 GPa for garnet rim and omphacite rim pairs. These petrological considerations indicate that temperatures should have significantly declined during the early decompression stage of this eclogite. In other areas of the Sulu region, isothermal decompression paths were proposed, and it was concluded that the UHP rocks were exhumed as a large mass tens of kilometers in thickness to avoid thermal effects from the surrounding materials. However, the newly identified decompression path accompanying the significant cooling may indicate that the Taohang outcrop was located at the margin of the Sulu UHP terrane. Thus, the decompressional P-T path is not unique in the Sulu region and varies depending on the location.",
keywords = "Eclogite, Garnet-clinopyroxene thermometer, Partial equilibrium, Sulu region, Ultrahigh-pressure",
author = "Daisuke Nakamura and Takao Hirajima",
year = "2010",
month = "12",
doi = "10.1111/j.1440-1738.2010.00739.x",
language = "English",
volume = "19",
pages = "707--717",
journal = "Island Arc",
issn = "1038-4871",
publisher = "Wiley-Blackwell",
number = "4",

}

TY - JOUR

T1 - Significant cooling during exhumation of UHP eclogite from the Taohang area in the Sulu region of eastern China and its tectonic significance

AU - Nakamura, Daisuke

AU - Hirajima, Takao

PY - 2010/12

Y1 - 2010/12

N2 - The decompressional pressure-temperature (P-T) path was estimated for ultrahigh-pressure (UHP) eclogite from the Sulu region of eastern China by applying geo-thermobarometers to well-preserved equilibrium mineral pairs. The sample studied is a kyanite-bearing eclogite that was collected from the Taohang area of the Sulu region. Garnet is relatively homogeneous in chemical composition, but omphacite has a clear chemical zoning with decreasing jadeite content from core to rim. Assuming that peak-P equilibrium compositions are preserved in the cores of garnet (Grt) and omphacite (Omp), P-T conditions were calculated to be about 700°C and 3.4 GPa. On the other hand, the jadeite content of omphacite rims varies from 0.35 to 0.46 mol.%. Nevertheless, the variation in Fe/Mg ratios of omphacite rims is very small. Temperatures of 566 ± 54°C were obtained at 1.5 GPa for garnet rim and omphacite rim pairs. These petrological considerations indicate that temperatures should have significantly declined during the early decompression stage of this eclogite. In other areas of the Sulu region, isothermal decompression paths were proposed, and it was concluded that the UHP rocks were exhumed as a large mass tens of kilometers in thickness to avoid thermal effects from the surrounding materials. However, the newly identified decompression path accompanying the significant cooling may indicate that the Taohang outcrop was located at the margin of the Sulu UHP terrane. Thus, the decompressional P-T path is not unique in the Sulu region and varies depending on the location.

AB - The decompressional pressure-temperature (P-T) path was estimated for ultrahigh-pressure (UHP) eclogite from the Sulu region of eastern China by applying geo-thermobarometers to well-preserved equilibrium mineral pairs. The sample studied is a kyanite-bearing eclogite that was collected from the Taohang area of the Sulu region. Garnet is relatively homogeneous in chemical composition, but omphacite has a clear chemical zoning with decreasing jadeite content from core to rim. Assuming that peak-P equilibrium compositions are preserved in the cores of garnet (Grt) and omphacite (Omp), P-T conditions were calculated to be about 700°C and 3.4 GPa. On the other hand, the jadeite content of omphacite rims varies from 0.35 to 0.46 mol.%. Nevertheless, the variation in Fe/Mg ratios of omphacite rims is very small. Temperatures of 566 ± 54°C were obtained at 1.5 GPa for garnet rim and omphacite rim pairs. These petrological considerations indicate that temperatures should have significantly declined during the early decompression stage of this eclogite. In other areas of the Sulu region, isothermal decompression paths were proposed, and it was concluded that the UHP rocks were exhumed as a large mass tens of kilometers in thickness to avoid thermal effects from the surrounding materials. However, the newly identified decompression path accompanying the significant cooling may indicate that the Taohang outcrop was located at the margin of the Sulu UHP terrane. Thus, the decompressional P-T path is not unique in the Sulu region and varies depending on the location.

KW - Eclogite

KW - Garnet-clinopyroxene thermometer

KW - Partial equilibrium

KW - Sulu region

KW - Ultrahigh-pressure

UR - http://www.scopus.com/inward/record.url?scp=78649718430&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78649718430&partnerID=8YFLogxK

U2 - 10.1111/j.1440-1738.2010.00739.x

DO - 10.1111/j.1440-1738.2010.00739.x

M3 - Article

AN - SCOPUS:78649718430

VL - 19

SP - 707

EP - 717

JO - Island Arc

JF - Island Arc

SN - 1038-4871

IS - 4

ER -