Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications

© 2016 Elsevier B.V. New U-Pb geochronological, petrologic, elemental and Sr-Nd-Hf-O isotopic data for the granites from the Inthanon and Sukhothai zones in NW Thailand in conjunction with correlations with SW China are presented to constrain the age and position of the Paleotethys Ocean in this reg...

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Main Authors: Wang Y., He H., Cawood P., Srithai B., Feng Q., Fan W., Zhang Y., Qian X.
Format: Journal
Published: 2017
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spelling th-cmuir.6653943832-412792017-09-28T04:20:21Z Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications Wang Y. He H. Cawood P. Srithai B. Feng Q. Fan W. Zhang Y. Qian X. © 2016 Elsevier B.V. New U-Pb geochronological, petrologic, elemental and Sr-Nd-Hf-O isotopic data for the granites from the Inthanon and Sukhothai zones in NW Thailand in conjunction with correlations with SW China are presented to constrain the age and position of the Paleotethys Ocean in this region and the associated assembly of Southeast Asia. The geochronological data show that the granitic rocks in the Inthanon and Sukhothai zones, herein named Group 1 and Group 2 granites, respectively, yield similar crystallization ages of 230-200 Ma. Group 1 samples are characterized by monzogranite and granite with I- and S-type geochemical affinity and Group 2 samples by I-type monzogranite and granodiorite. They have generally similar chondrite-normalized REE and PM-normalized multi-element patterns but distinct Sr-Nd-Hf-O isotopic compositions. Group 1 samples have slightly higher initial 87 Sr/ 86 Sr ratios (0.7111-0.7293) but lower ε Nd (t) values (− 11.1 to − 14.1) than those of Group 2 samples ( 87 Sr/ 86 Sr (i) = 0.7073-0.7278 and ε Nd (t) = − 8.3 to − 11.0). Group 1 samples show the lower ε Hf (t) values (− 5.4 to − 18.2), older T DM (1.62-2.40 Ga) and higher δ 18 O values (+ 7.95 to + 9.94) than those of Group 2 samples (ε Hf (t) of − 11.1 to + 4.80, T DM of 0.96-1.95 Ga and δ 18 O of + 4.95 to + 7.98) for the Triassic crystallization zircons. These geochemical signatures are similar to the Kwangsian and Indosinian granites in the South China and Indochina blocks but distinct from those of the Gangdese I-type granite and Sibumasu Paleozoic granite. Our data suggest that Group 1 samples mainly originated from the early Paleozoic supracrustal rocks containing metapelite and metavolcanic components, which had previously experienced the surface weathering. Group 2 samples were derived from a hybridized source of an old metamorphic and a newly underplated mafic component. Synthesis of our data with available regional observations indicates that the Inthanon zone represents the main suture zone of the eastern Paleotethyan Ocean in NW Thailand and links with the Changning-Menglian suture zone in SW Yunnan (SW China). In NW Thailand, a switch from the eastward subduction of the Paleotethyan oceanic plate to the collision of the Sibumasu with Indochina blocks occurred at ~ 237 Ma, and syn- and post-collisional time being at ~ 237-230 Ma and ~ 200-230 Ma, respectively. The late Triassic granites in the Inthanon and Sukhothai zones are representative of the post-collisional magmatic products. 2017-09-28T04:20:21Z 2017-09-28T04:20:21Z 2016-12-01 Journal 00244937 2-s2.0-84995390445 10.1016/j.lithos.2016.09.012 https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84995390445&origin=inward http://cmuir.cmu.ac.th/jspui/handle/6653943832/41279
institution Chiang Mai University
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description © 2016 Elsevier B.V. New U-Pb geochronological, petrologic, elemental and Sr-Nd-Hf-O isotopic data for the granites from the Inthanon and Sukhothai zones in NW Thailand in conjunction with correlations with SW China are presented to constrain the age and position of the Paleotethys Ocean in this region and the associated assembly of Southeast Asia. The geochronological data show that the granitic rocks in the Inthanon and Sukhothai zones, herein named Group 1 and Group 2 granites, respectively, yield similar crystallization ages of 230-200 Ma. Group 1 samples are characterized by monzogranite and granite with I- and S-type geochemical affinity and Group 2 samples by I-type monzogranite and granodiorite. They have generally similar chondrite-normalized REE and PM-normalized multi-element patterns but distinct Sr-Nd-Hf-O isotopic compositions. Group 1 samples have slightly higher initial 87 Sr/ 86 Sr ratios (0.7111-0.7293) but lower ε Nd (t) values (− 11.1 to − 14.1) than those of Group 2 samples ( 87 Sr/ 86 Sr (i) = 0.7073-0.7278 and ε Nd (t) = − 8.3 to − 11.0). Group 1 samples show the lower ε Hf (t) values (− 5.4 to − 18.2), older T DM (1.62-2.40 Ga) and higher δ 18 O values (+ 7.95 to + 9.94) than those of Group 2 samples (ε Hf (t) of − 11.1 to + 4.80, T DM of 0.96-1.95 Ga and δ 18 O of + 4.95 to + 7.98) for the Triassic crystallization zircons. These geochemical signatures are similar to the Kwangsian and Indosinian granites in the South China and Indochina blocks but distinct from those of the Gangdese I-type granite and Sibumasu Paleozoic granite. Our data suggest that Group 1 samples mainly originated from the early Paleozoic supracrustal rocks containing metapelite and metavolcanic components, which had previously experienced the surface weathering. Group 2 samples were derived from a hybridized source of an old metamorphic and a newly underplated mafic component. Synthesis of our data with available regional observations indicates that the Inthanon zone represents the main suture zone of the eastern Paleotethyan Ocean in NW Thailand and links with the Changning-Menglian suture zone in SW Yunnan (SW China). In NW Thailand, a switch from the eastward subduction of the Paleotethyan oceanic plate to the collision of the Sibumasu with Indochina blocks occurred at ~ 237 Ma, and syn- and post-collisional time being at ~ 237-230 Ma and ~ 200-230 Ma, respectively. The late Triassic granites in the Inthanon and Sukhothai zones are representative of the post-collisional magmatic products.
format Journal
author Wang Y.
He H.
Cawood P.
Srithai B.
Feng Q.
Fan W.
Zhang Y.
Qian X.
spellingShingle Wang Y.
He H.
Cawood P.
Srithai B.
Feng Q.
Fan W.
Zhang Y.
Qian X.
Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications
author_facet Wang Y.
He H.
Cawood P.
Srithai B.
Feng Q.
Fan W.
Zhang Y.
Qian X.
author_sort Wang Y.
title Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications
title_short Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications
title_full Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications
title_fullStr Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications
title_full_unstemmed Geochronological, elemental and Sr-Nd-Hf-O isotopic constraints on the petrogenesis of the Triassic post-collisional granitic rocks in NW Thailand and its Paleotethyan implications
title_sort geochronological, elemental and sr-nd-hf-o isotopic constraints on the petrogenesis of the triassic post-collisional granitic rocks in nw thailand and its paleotethyan implications
publishDate 2017
url https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84995390445&origin=inward
http://cmuir.cmu.ac.th/jspui/handle/6653943832/41279
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