Constraints on the timing of multiple thermal events and re-equilibration recorded by high-U zircon and xenotime : case study of pegmatite from Piława Górna (Góry Sowie Block, SW Poland)
PBN-AR
Instytucja
Wydział Geologii, Geofizyki i Ochrony Środowiska (Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie)
Informacje podstawowe
Główny język publikacji
EN
Czasopismo
Lithos (Oslo) (45pkt w roku publikacji)
ISSN
0024-4937
EISSN
1872-6143
Wydawca
Elsevier Science BV
DOI
Rok publikacji
2018
Numer zeszytu
Strony od-do
65--85
Numer tomu
310-311
Link do pełnego tekstu
Identyfikator DOI
Liczba arkuszy
1.5
Autorzy
(liczba autorów: 7)
Pozostali autorzy
+ 5
Słowa kluczowe
EN
dissolution-reprecipitation
uraninite
geochronology
hingganite-(Y)
secondary textures
mineral-fluid reactions
diffusion-reaction
Streszczenia
Język
EN
Treść
The application of zircon and xenotime geochronometers requires knowledge of their potential and limitations related to possible disturbance of the age record. The alteration of the intergrown zircon and xenotime in pegmatite from the Góry Sowie Block (SW Poland) was studied using the electron microprobe analysis, X-ray WDS compositional mapping, micro-Raman analysis, and LA-ICP-MS U-Pb dating of zircon and xenotime, as well as the U-Th-total Pb dating of uraninite. These microanalytical techniques were applied to understand the formation mechanisms of the secondary textures related to post-magmatic processes in the zircon and xenotime intergrowth, and to constrain their timing. Textural and compositional features combined with U-Pb data indicate that the pegmatite-related crystallization of the zircon and xenotime intergrowth occurred ca. 2.09 Ga (2086 ± 35 Ma for zircon and 2093 ± 52 Ma for xenotime), followed by the re-equilibration of zircon and xenotime ca. 370 Ma (373 ± 18 Ma and 368 ± 6 Ma, respectively) during the formation of the younger pegmatite. The zircon and xenotime were most likely derived from Precambrian basement rocks and emplaced in the pegmatite as a restite. The zircon preserved textures related to diffusion-reaction processes that affected its high-U core (up to ca. 9.6 wt% UO2), which underwent further metamictization and amorphization due to self-radiation damage. The zircon rim and xenotime were affected by coupled dissolution-reprecipitation processes that resulted in patchy zoning, age disturbance and sponge-like textures. Xenotime was also partially replaced by fluorapatite or hingganite-(Y) and Y-enriched allanite-(Ce). The termination of the low-temperature alteration was constrained by the U-Th-total Pb age of the uraninite inclusions that crystallized in zircon at 281 ± 2 Ma, which is consistent with the age of 278 ± 15 Ma obtained from the youngest cluster of U-Pb ages in the re-equilibrated high-U zircon domains. This study demonstrates the importance of the careful examination of compositional, microtextural and geochronological data obtained using microanalytical techniques to reconstruct the complex thermal histories recorded by accessory minerals. © 2018 Elsevier B.V.
Cechy publikacji
original article
peer-reviewed
Inne
System-identifier
idp:113739
CrossrefMetadata from Crossref logo
Cytowania
Liczba prac cytujących tę pracę
Brak danych
Referencje
Liczba prac cytowanych przez tę pracę
Brak danych