Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6430673 | Earth and Planetary Science Letters | 2012 | 8 Pages |
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 ± 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 ± 11 ka. Our data show that successive granitic and mafic magmas emplacement generated a volume of ~ 88 km3 in 162 ± 11 ka.
⺠High resolution zircon CA-ID-TIMS U-Pb dating on Torres del Paine mafic rocks. ⺠Granite-mafic laccolith and stock-like feeding system construction over 162 ± 11 ka. ⺠Mafic sill complex over-accretion over 41 ± 11 ka, overlain by older granite. ⺠Pluton construction rate decreases from 0.0008 km3 yâ 1 to 0.0002 km3 yâ 1.