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- 저자 : Ching-Ying Lan (검색결과 4 건)
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Detrital zircon evidence for the antiquity of Taiwan
Ching-Ying Lan,Tadashi Usuki,Kuo-Lung Wang,Tzen-Fu Yui,Kazuaki Okamoto,Yuan-Hsi Lee,Takafumi Hirata,Yoshitaka Kon,Yuji Orihashi,Juhn G. Liou,Chun-Sun Lee 한국지질과학협의회 2009 Geosciences Journal Vol.13 No.3
In-situ U–Pb geochronology and Hf isotopic studies of zircons from the Pre-Tertiary basement complex and Eocene rocks of the Central Range of Taiwan were carried out to elucidate the history of detrital zircons older than 2.3 Ga. Zircons from the eastern Backbone Range and Eastern Central Range show Paleoproterozoic to late Neoarchean ages (2.3 –³2.5 Ga), whereas those from the Hsuehshan Range yield Neoarchean to Mesoarchean ages (2.6–3.2 Ga). The εHf(T) for the Paleoproterozoic to late Neoarchean zircons varies from –7.4 to +5.1, implying both juvenile crustal growth and reworking of old crusts. This dual origin could extend back to Mesoarchean–Paleoarchean (3.0–3.4 Ga) based on Hf isotopic model ages. Consistent but narrower εHf(T) values and Hf crustal model ages for zircons from Taiwan compared to Cathaysia suggest a possible common origin for these zircons, although Taiwan has a generally younger crustal evolution history than SE China.
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Tadashi Usuki,Ching-Ying Lan,Tzen-Fu Yui,Yoshiyuki Iizuka,Van Tich Vu,Tuan Anh Tran,Kazuaki Okamoto,Joseph L. Wooden,Juhn G. Liou 한국지질과학협의회 2009 Geosciences Journal Vol.13 No.3
To constrain the timing of collisional event in the Indochina block, SHRIMP U–Pb dating and REE analyses of zircon were carried out for two paragneiss samples of the Kham Duc Complex, central Vietnam. Both samples contain kyanite, staurolite, and zoisite as relics from an early metamorphic stage (M1), and biotite and sillimanite as major minerals constituting the foliation formed during the late metamorphic stage (M2). The change in mineral assemblages indicates a clockwise P-T path composed of a high- or medium-P + low-T stage (M1) and a subsequent low-P + high-T stage (M2). The U−Pb concordia ages of zircon rims are 447 ± 6 Ma and 452 ± 6 Ma for the two samples, respectively. These results are distinctly different from the available Ar–Ar mineral ages of 254–225 Ma. Following the clockwise P-T path and phase equilibrium analyses of the Complex, we suggest that the zircon rims were formed near peak temperatures during the decompression. The ~450 Ma zircon rim thus gives the minimum age constraint for a possible crustal thickening event during Early Paleozoic, whereas the reported Permo-Triassic Ar–Ar ages would result from an Indosinian overprint. This Early Paleozoic event is most likely related to a collisional orogeny between the Indochina and South China blocks. Late Neoproterozoic to Neoarchean ages are recorded from detrital zircon cores of the Kham Duc Complex, the Kontum Massif and Truong Son Belt, suggesting that their protoliths might have derived from sediments at the Gondwana margin.
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권성택,남정영,Kwon, Sung-Tack,Lan, Ching-Ying 대한자원환경지질학회 1991 자원환경지질 Vol.24 No.3
We applied Sm-Nd isotopic system to so-called amphibolites occurring within the Ogcheon group to provide constraints on the age of the metasedimentary rocks and to characterize tectonic environment of basaltic magmatism. An internal mineral isochron age of $677{\pm}91Ma({\sigma})$ was obtained from a coarse-grained, intrusive, amphibolite near Mungyeong. Considering previous studies on the age of the Ogcheon group, we interpret that the isochron represents either early metamorphic or emplacement age. The depositional age of the metasedimentary rocks intruded by the amphibolite would be prior to late Proterozoic. The present study and Cambro-Ordovician fossil evidences of previous workers suggest that both Precambrian and Phanerozoic rocks are present in the Ogcheon group. Positive ${\varepsilon}$ Nd values(+2.4 to +3.5) of four whole rocks indicate mantle origin for the amphibolite. These isotopic data, along with published immobile trace element data of Cluzel et al.(1989), strongly suggest that parental rocks of the amphibolite formed in an intraplate environment rather than in island arc or midocean ridge. The age and tectonic environment of amphibolites in the Ogcheon belt suggest that the basaltic magmatism may be related to the late Proterozoic break-up of a presumed supercontinent, but not to the Triassic(?) collision between North and South China continents.
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