Cerro Toro Formation: Outcrops Overview
Published:January 01, 2009
2009. "Cerro Toro Formation: Outcrops Overview", Stratigraphic Evolution of Deep-Water Architecture: Examples of controls and depositional styles from the Magallanes Basin, southern Chile, Andrea Fildani, Stephen M. Hubbard, Brian W. Romans, J.A. Covault, W.H. Crane, A. Bernhardt, Z.R. Jobe, D.A. Armitage, J.C. Fosdick, M.R. Shultz, J. Clark, D.R. Lowe, S.A. Graham
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A series of Cerro Toro Formation outcrops, presented along depositional dip, are featured in this fieldguide. The outcrop belt of the conglomeratic member of the formation is traced in red on the satellite image at left; the interpreted paleogeographic position of the various outcrops featured in this fieldguide are highlighted in the schematic basin diagram presented below left (Hubbard et al., 2008). Coarse-grained material of the Cerro Toro Formation is attributed to deposition in a foreland basin axial channel belt setting, with some outcrops proposed to record sedimentation in tributary conduits that fed the axial system. Levee deposits are recognized in outcrops associated with the axial channel belt (at outcrops 8, 9), whereas previous workers have debated a channel-levee complex versus an incised channel origin for deposits in the tributary conduit (at outcrops 4, 5).
The conglomerate-rich portion of the formation has a stratigraphic thickness up to 1200 m; from north (paleogeographically proximal) to south (distal), an increase in amalgamation of channel bodies and complexes is notable. With a higher proportion of siltstone and shale present separating conglomeratic units in the north, the formation has succumbed to folding. The result is exceptional three-dimensional exposures of channel deposits in the vicinity of the Silla Syncline in the Torres del Paine National Park (see map at left and photo below). Further south in the Cordillera Manuel Señoret, amalgamated coarse-grained channel deposits are present in packages up to 600 m thick; these erosionally
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Stratigraphic Evolution of Deep-Water Architecture: Examples of controls and depositional styles from the Magallanes Basin, southern Chile
This large format (11 × 17 inch) all color outcrop atlas and field guide was produced for the SEPM Research Conference held in Chile in February, 2009. It contains a wealth of information on the world class deep water outcrops of the Cretaceous of the Magallanes Basin in the Ultima Esperanza District, Chilean Patagonia. This book covers the significant outcrops in the region the Punta Barrosa Formation, CerroToro Fm., and the Tres Pasos Fm.