Evidence for cool extrusion of the North Indochina block along the Ailao Shan Red River shear zone, a Diancang Shan perspective

Meng-Wan Yeh, R. P. Wintsch, Yi Chen Liu, Ching Hua Lo, Sun Lin Chung, Yu Ling Lin, Tung-Yi Lee, Yee Chao Wang, M. R. Stokes

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Much debate surrounds the temporal-thermal-structural evolution of the >1000-km NW-SE-trending Ailao Shan–Red River (ASRR) shear zone. This mainly reflects the contradictory interpretations of the timing and P-T conditions for the occurrence of left-lateral shearing event due to a diverse data set of mineral ages. Our new microstructural, petrological, and geochronological data from the southern section of the Diancang Shan (DCS) block along the west wall of the ASRR support slow cooling from ∼300°C to ∼150°C from the Middle Eocene to the Late Miocene, accompanied by left-lateral shearing activity. This conclusion is based on the following: (1) The lower greenschist facies assemblages of biotite replaced by muscovite or chlorite, the albitized K-feldspar, and the stable association of K-feldspar + chlorite rather than muscovite + biotite are universally observed for the synkinematic Sn+1 and mylonitic S/C fabrics from both quartzofeldspathic and amphibolite domains. (2) New 40Ar/39Ar data for K-feldspar and muscovite of various structural domains such as the K-feldspar phenocrysts (∼20 to ∼40 Ma) from the early Triassic magmatic protolith (zircon U-Pb ages of 230–250 Ma), pre- to synkinematic muscovite (∼17 to ∼23 Ma) in mylonites, and K-feldspar (∼5 to ∼10 Ma) in postmylonitic cross-cutting veins produce an age spectrum that increases from ∼5 to ∼40 Ma under lower greenschist facies. Together these data indicate that the DCS block was slowly extruded along the ASRR shear zone through much of the Tertiary. These results contradict earlier interpretations of rapid cooling from synkinematic amphibolite metamorphic conditions caused by shear heating based in part on the assumption that all Miocene ages were cooling ages rather than crystallization ages.

Original languageEnglish
Pages (from-to)567-590
Number of pages24
JournalJournal of Geology
Volume122
Issue number5
DOIs
Publication statusPublished - 2014 Sep 1

Fingerprint

extrusion
shear zone
feldspar
muscovite
river
greenschist facies
amphibolite
cooling
chlorite
biotite
Miocene
P-T conditions
protolith
Eocene
zircon
crystallization
Triassic
heating
mineral

ASJC Scopus subject areas

  • Geology

Cite this

Evidence for cool extrusion of the North Indochina block along the Ailao Shan Red River shear zone, a Diancang Shan perspective. / Yeh, Meng-Wan; Wintsch, R. P.; Liu, Yi Chen; Lo, Ching Hua; Chung, Sun Lin; Lin, Yu Ling; Lee, Tung-Yi; Wang, Yee Chao; Stokes, M. R.

In: Journal of Geology, Vol. 122, No. 5, 01.09.2014, p. 567-590.

Research output: Contribution to journalArticle

Yeh, Meng-Wan ; Wintsch, R. P. ; Liu, Yi Chen ; Lo, Ching Hua ; Chung, Sun Lin ; Lin, Yu Ling ; Lee, Tung-Yi ; Wang, Yee Chao ; Stokes, M. R. / Evidence for cool extrusion of the North Indochina block along the Ailao Shan Red River shear zone, a Diancang Shan perspective. In: Journal of Geology. 2014 ; Vol. 122, No. 5. pp. 567-590.
@article{54805e8a4ee745bd901ac8943e939f1f,
title = "Evidence for cool extrusion of the North Indochina block along the Ailao Shan Red River shear zone, a Diancang Shan perspective",
abstract = "Much debate surrounds the temporal-thermal-structural evolution of the >1000-km NW-SE-trending Ailao Shan–Red River (ASRR) shear zone. This mainly reflects the contradictory interpretations of the timing and P-T conditions for the occurrence of left-lateral shearing event due to a diverse data set of mineral ages. Our new microstructural, petrological, and geochronological data from the southern section of the Diancang Shan (DCS) block along the west wall of the ASRR support slow cooling from ∼300°C to ∼150°C from the Middle Eocene to the Late Miocene, accompanied by left-lateral shearing activity. This conclusion is based on the following: (1) The lower greenschist facies assemblages of biotite replaced by muscovite or chlorite, the albitized K-feldspar, and the stable association of K-feldspar + chlorite rather than muscovite + biotite are universally observed for the synkinematic Sn+1 and mylonitic S/C fabrics from both quartzofeldspathic and amphibolite domains. (2) New 40Ar/39Ar data for K-feldspar and muscovite of various structural domains such as the K-feldspar phenocrysts (∼20 to ∼40 Ma) from the early Triassic magmatic protolith (zircon U-Pb ages of 230–250 Ma), pre- to synkinematic muscovite (∼17 to ∼23 Ma) in mylonites, and K-feldspar (∼5 to ∼10 Ma) in postmylonitic cross-cutting veins produce an age spectrum that increases from ∼5 to ∼40 Ma under lower greenschist facies. Together these data indicate that the DCS block was slowly extruded along the ASRR shear zone through much of the Tertiary. These results contradict earlier interpretations of rapid cooling from synkinematic amphibolite metamorphic conditions caused by shear heating based in part on the assumption that all Miocene ages were cooling ages rather than crystallization ages.",
author = "Meng-Wan Yeh and Wintsch, {R. P.} and Liu, {Yi Chen} and Lo, {Ching Hua} and Chung, {Sun Lin} and Lin, {Yu Ling} and Tung-Yi Lee and Wang, {Yee Chao} and Stokes, {M. R.}",
year = "2014",
month = "9",
day = "1",
doi = "10.1086/677263",
language = "English",
volume = "122",
pages = "567--590",
journal = "Journal of Geology",
issn = "0022-1376",
publisher = "University of Chicago",
number = "5",

}

TY - JOUR

T1 - Evidence for cool extrusion of the North Indochina block along the Ailao Shan Red River shear zone, a Diancang Shan perspective

AU - Yeh, Meng-Wan

AU - Wintsch, R. P.

AU - Liu, Yi Chen

AU - Lo, Ching Hua

AU - Chung, Sun Lin

AU - Lin, Yu Ling

AU - Lee, Tung-Yi

AU - Wang, Yee Chao

AU - Stokes, M. R.

PY - 2014/9/1

Y1 - 2014/9/1

N2 - Much debate surrounds the temporal-thermal-structural evolution of the >1000-km NW-SE-trending Ailao Shan–Red River (ASRR) shear zone. This mainly reflects the contradictory interpretations of the timing and P-T conditions for the occurrence of left-lateral shearing event due to a diverse data set of mineral ages. Our new microstructural, petrological, and geochronological data from the southern section of the Diancang Shan (DCS) block along the west wall of the ASRR support slow cooling from ∼300°C to ∼150°C from the Middle Eocene to the Late Miocene, accompanied by left-lateral shearing activity. This conclusion is based on the following: (1) The lower greenschist facies assemblages of biotite replaced by muscovite or chlorite, the albitized K-feldspar, and the stable association of K-feldspar + chlorite rather than muscovite + biotite are universally observed for the synkinematic Sn+1 and mylonitic S/C fabrics from both quartzofeldspathic and amphibolite domains. (2) New 40Ar/39Ar data for K-feldspar and muscovite of various structural domains such as the K-feldspar phenocrysts (∼20 to ∼40 Ma) from the early Triassic magmatic protolith (zircon U-Pb ages of 230–250 Ma), pre- to synkinematic muscovite (∼17 to ∼23 Ma) in mylonites, and K-feldspar (∼5 to ∼10 Ma) in postmylonitic cross-cutting veins produce an age spectrum that increases from ∼5 to ∼40 Ma under lower greenschist facies. Together these data indicate that the DCS block was slowly extruded along the ASRR shear zone through much of the Tertiary. These results contradict earlier interpretations of rapid cooling from synkinematic amphibolite metamorphic conditions caused by shear heating based in part on the assumption that all Miocene ages were cooling ages rather than crystallization ages.

AB - Much debate surrounds the temporal-thermal-structural evolution of the >1000-km NW-SE-trending Ailao Shan–Red River (ASRR) shear zone. This mainly reflects the contradictory interpretations of the timing and P-T conditions for the occurrence of left-lateral shearing event due to a diverse data set of mineral ages. Our new microstructural, petrological, and geochronological data from the southern section of the Diancang Shan (DCS) block along the west wall of the ASRR support slow cooling from ∼300°C to ∼150°C from the Middle Eocene to the Late Miocene, accompanied by left-lateral shearing activity. This conclusion is based on the following: (1) The lower greenschist facies assemblages of biotite replaced by muscovite or chlorite, the albitized K-feldspar, and the stable association of K-feldspar + chlorite rather than muscovite + biotite are universally observed for the synkinematic Sn+1 and mylonitic S/C fabrics from both quartzofeldspathic and amphibolite domains. (2) New 40Ar/39Ar data for K-feldspar and muscovite of various structural domains such as the K-feldspar phenocrysts (∼20 to ∼40 Ma) from the early Triassic magmatic protolith (zircon U-Pb ages of 230–250 Ma), pre- to synkinematic muscovite (∼17 to ∼23 Ma) in mylonites, and K-feldspar (∼5 to ∼10 Ma) in postmylonitic cross-cutting veins produce an age spectrum that increases from ∼5 to ∼40 Ma under lower greenschist facies. Together these data indicate that the DCS block was slowly extruded along the ASRR shear zone through much of the Tertiary. These results contradict earlier interpretations of rapid cooling from synkinematic amphibolite metamorphic conditions caused by shear heating based in part on the assumption that all Miocene ages were cooling ages rather than crystallization ages.

UR - http://www.scopus.com/inward/record.url?scp=84907236619&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84907236619&partnerID=8YFLogxK

U2 - 10.1086/677263

DO - 10.1086/677263

M3 - Article

AN - SCOPUS:84907236619

VL - 122

SP - 567

EP - 590

JO - Journal of Geology

JF - Journal of Geology

SN - 0022-1376

IS - 5

ER -