TY - JOUR
T1 - Ultrahigh-pressure metamorphic records hidden in zircons from amphibolites in Sulu Terrane, eastern China
AU - Liu, Fulai
AU - Zhang, Zeming
AU - Katayama, Ikuo
AU - Xu, Zhiqin
AU - Maruyama, Shigenori
PY - 2003/9
Y1 - 2003/9
N2 - The amphibolites occur sporadically as thin layers and blocks throughout the Sulu Terrane, eastern China. All analyzed amphibolite from outcrop and drill cores from prepilot drill hole CCSD-PP1 and CCSD-PP2, Chinese Continental Scientific Drilling Project in the Sulu Terrane, are retrograded eclogites overprinted by amphibolite-facies retrograde metamorphism, with characteristic mineral assemblages of amphibole + plagioclase + epidote ± quartz ± biotite ± ilmenite ± titanite. However, coesite and coesite-bearing ultrahigh-pressure (UHP) mineral assemblages are identified by Raman spectroscopy and electron microprobe analysis as inclusions in zircons separated from these amphibolites. In general, coesite and other UHP mineral inclusions are preserved in the cores and mantles of zircons, whereas quartz inclusions occur in the rims of the same zircons. The UHP mineral assemblages consist mainly of coesite + garnet + omphacite + rutile, coesite + garnet + omphacite, coesite + garnet + omphacite + phengite + rutile ÷ apatite, coesite + omphacite + rutile and coesite + magnesite. Compositions of analyzed mineral inclusions are very similar to those of matrix minerals from Sulu eclogites. These UHP mineral inclusion assemblages yield temperatures of 631-780°C and pressures of ≥2.8 × 103 MPa, representing the P-T conditions of peak metamorphism of these rocks, which are consistent with those (T = 642-726°C; P ≥ 2.8 × 103 MPa) deduced from adjacent eclogites. These data indicate that the amphibolites are the retrogressive products of UHP eclogites.
AB - The amphibolites occur sporadically as thin layers and blocks throughout the Sulu Terrane, eastern China. All analyzed amphibolite from outcrop and drill cores from prepilot drill hole CCSD-PP1 and CCSD-PP2, Chinese Continental Scientific Drilling Project in the Sulu Terrane, are retrograded eclogites overprinted by amphibolite-facies retrograde metamorphism, with characteristic mineral assemblages of amphibole + plagioclase + epidote ± quartz ± biotite ± ilmenite ± titanite. However, coesite and coesite-bearing ultrahigh-pressure (UHP) mineral assemblages are identified by Raman spectroscopy and electron microprobe analysis as inclusions in zircons separated from these amphibolites. In general, coesite and other UHP mineral inclusions are preserved in the cores and mantles of zircons, whereas quartz inclusions occur in the rims of the same zircons. The UHP mineral assemblages consist mainly of coesite + garnet + omphacite + rutile, coesite + garnet + omphacite, coesite + garnet + omphacite + phengite + rutile ÷ apatite, coesite + omphacite + rutile and coesite + magnesite. Compositions of analyzed mineral inclusions are very similar to those of matrix minerals from Sulu eclogites. These UHP mineral inclusion assemblages yield temperatures of 631-780°C and pressures of ≥2.8 × 103 MPa, representing the P-T conditions of peak metamorphism of these rocks, which are consistent with those (T = 642-726°C; P ≥ 2.8 × 103 MPa) deduced from adjacent eclogites. These data indicate that the amphibolites are the retrogressive products of UHP eclogites.
KW - Amphibolite
KW - Cathodoluminescene image
KW - Laser Raman
KW - Outcrops and core samples
KW - Sulu Terrane
KW - Ultrahigh-pressure mineral inclusio
KW - Zircon
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U2 - 10.1046/j.1440-1738.2003.00398.x
DO - 10.1046/j.1440-1738.2003.00398.x
M3 - Article
AN - SCOPUS:0142009563
VL - 12
SP - 256
EP - 267
JO - Island Arc
JF - Island Arc
SN - 1038-4871
IS - 3
ER -