ION MICRO-PROBE U-PB ZIRCON GEOCHRONOLOGY OF PEAK AND RETROGRADE STAGES OF ULTRAHIGH-PRESSURE METAMORPHIC ROCKS FROM THE KOKCHETAV MASSIF, NORTHERN KAZAKHSTAN
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dc.contributor.author | Katayama I. | |
dc.contributor.author | Maruyama S. | |
dc.contributor.author | Parkinson C.D. | |
dc.contributor.author | Terada K. | |
dc.contributor.author | Sano Y. | |
dc.date.accessioned | 2021-04-05T12:39:55Z | |
dc.date.available | 2021-04-05T12:39:55Z | |
dc.date.issued | 2001 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=14052511 | |
dc.identifier.citation | Earth and Planetary Science Letters, 2001, 188, 1-2, 185-198 | |
dc.identifier.issn | 0012-821X | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/27428 | |
dc.description.abstract | Sensitive high resolution ion micro-probe (SHRIMP) U–Pb analyses of zoned zircons were performed to constrain the age and geodynamic significance of the Kokchetav ultrahigh-pressure (UHP) metamorphic rocks, which recrystallized at P>60 kbar and T>1000°C. Cathodoluminescence images were correlated with micro-assemblages of mineral inclusions in zircons from diamond-bearing gneisses. These revealed UHP mineral-bearing cores and low-pressure mineral-bearing rims, some zircons also retain inherited cores. Our SHRIMP data identified four discrete stages: Middle Proterozoic protolith age, 537±9 Ma for UHP metamorphic conditions, 507±8 Ma for the late-stage amphibolite facies overprint, and 456–461 Ma for post-orogenic thermal events. Thus, we conclude that Middle Proterozoic supracrustal protoliths of the Kokchetav UHP–HP rocks were subducted to mantle depths in the Middle Cambrian, and exhumed to mid-crustal levels in the Late Cambrian. The exhumation rate calculated from the SHRIMP data and relative P–T conditions is approximately 5 km/Ma. The rapid exhumation rate for the massif is in the same range as other UHP metamorphic terranes, and suggests that slab decoupling may be a driving force for exhumation of UHP metamorphic rocks from mantle depths. | |
dc.subject | Proterozoic | en |
dc.subject | Cambrian | en |
dc.title | ION MICRO-PROBE U-PB ZIRCON GEOCHRONOLOGY OF PEAK AND RETROGRADE STAGES OF ULTRAHIGH-PRESSURE METAMORPHIC ROCKS FROM THE KOKCHETAV MASSIF, NORTHERN KAZAKHSTAN | |
dc.type | Статья | |
dc.subject.age | Докембрий::Протерозой | ru |
dc.subject.age | Paleozoic::Cambrian | en |
dc.subject.age | Precambrian::Proterozoic | en |
dc.subject.age | Палеозой::Кембрийская | ru |
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