Metamorphic Evolution of a Tremolite Marble from the Dabie UHP Terrane, China: A Focus on Zircon.
In: Journal of Earth Science, Jg. 33 (2022-04-01), Heft 2, S. 493-506
Online
academicJournal
Zugriff:
In this study, a tremolite marble from the Dabie ultrahigh-pressure (UHP) terrane, east-central China was investigated for its metamorphic evolution by focusing on zircon. The marble contains an amphibolite-facies assemblage of dolomite, Mg-calcite, tremolite, biotite, and plagioclase, while zircon in the marble witnesses a complex recrystallization and growth history under both amphibolite-and eclogite-facies conditions. Cathodoluminescence reveals eight characteristic zones for zircon. As indicated by mineral inclusions in zircon, two zones formed no earlier than amphibolite-facies retrogression and are too thin to date. The other six zones contain inclusions of dolomite, aragonite, diopside (XNa=Na/(Na+Ca)=0.11–0.14), garnet (XCa=0.51–0.62, XMg=0.21–0.23, XFe=0.17–0.26, XMn=0.01), phengite and rutile, and formed under eclogite-facies conditions. Phase equilibria calculations illustrat that the Na-richest diopside formed under UHP conditions. Being an accessory eclogite-facies mineral in the marble, the analyzed chemistry of garnet inclusions cannot be reproduced by phase equilibria calculations because solid-solution models for many other minerals don't incorporate Mn-endmembers. The eclogite-facies zircon zones show low HREE contents and flat MREE-HREE distribution patterns, which are interpreted to have been determined by the low bulk-rock HREE content instead of the presence of accessary garnet in the marble. U-Pb dating yielded a large age dataset ranging from about 250 to 210 Ma for the eclogite-facies zircon zones. Statistically, the eclogite-facies ages are characterized by a Gaussian distribution with a median peak at 232 Ma. We propose that zircon experienced a "protracted" recrystallization and/or growth history in the tremolite marble during the Triassic subduction and exhumation. [ABSTRACT FROM AUTHOR]
Titel: |
Metamorphic Evolution of a Tremolite Marble from the Dabie UHP Terrane, China: A Focus on Zircon.
|
---|---|
Autor/in / Beteiligte Person: | Liu, Penglei ; Jin, Zhenmin |
Link: | |
Zeitschrift: | Journal of Earth Science, Jg. 33 (2022-04-01), Heft 2, S. 493-506 |
Veröffentlichung: | 2022 |
Medientyp: | academicJournal |
ISSN: | 1674-487X (print) |
DOI: | 10.1007/s12583-020-1363-1 |
Schlagwort: |
|
Sonstiges: |
|