Time resolved construction of a bimodal laccolith (Torres del Paine, Patagonia)

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• 作者：Julien Leutholdp>ap>p> ; p>p>julien.leuthold@unil.chp>p> ; p>p>julien.leuthold@bristol.ac.ukp> ; Othmar Mü ; ntenerp>ap>p> ; p>p>othmar.muntener@unil.chp> ; Lukas P. Baumgartnerp>ap>p> ; p>p>lukas.baumgartner@unil.chp> ; Benita Putlitzp>ap>p> ; p>p>benita.putlitz@unil.chp> ; Maria Ovtcharovap>bp>p> ; p>p>maria.ovtcharova@unige.chp> ; Urs Schalteggerp>bp>p> ; p>p>urs.schaltegger@unige.chp>
• 关键词：laccolith growth ; sill accretion ; U&ndash ; Pb zircon geochronology ; Patagonian Andes
• 刊名：Earth and Planetary Science Letters
• 出版年：2012
• 出版时间：1 April, 2012
• 年：2012
• 卷：325-326
• 期：Complete
• 页码：85-92
• 全文大小：3887 K

文摘

Granitic and mafic magma pulses were sequentially accreted in the spectacularly exposed shallow crustal Torres del Paine laccolith, in southern Patagonia. This 12.5 Ma pluton forms a composite intrusion with a subvertical feeding system in the west and a laccolith in the east. A key unknown in the formation of sill complexes is how individual magma pulses are assembled over time and the geometry and localization of their feeding system. High resolution zircon CA-ID-TIMS U-Pb dating shows that the laccolith grew first by under-accretion of granitic sills over 90 ¡À 30 ka, linked to a ¡®sheet-like?feeding system, followed by underplating of mafic sills after ~ 20 ka of quiescence. In the mafic sills complex, individual sills were injected by over-accretion during 41 ¡À 11 ka. Our data show that successive granitic and mafic magmas emplacement generated a volume of ~ 88 kmp>3p> in 162 ¡À 11 ka.