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

研究成果: 雜誌貢獻文章

2 引文 (Scopus)

摘要

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.

原文英語
頁(從 - 到)567-590
頁數24
期刊Journal of Geology
122
發行號5
DOIs
出版狀態已發佈 - 2014 九月 1

指紋

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

引用此文

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.

於: Journal of Geology, 卷 122, 編號 5, 01.09.2014, p. 567-590.

研究成果: 雜誌貢獻文章

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. 於: Journal of Geology. 2014 ; 卷 122, 編號 5. 頁 567-590.
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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.",
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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.

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