Abstract Two thick turbidite sandstone units collectively form the basal Tres Pasos Formation sandstone exposed on the west face of the Sierra Contreras mountain range, Ultima Esperanza, chile ( Figures 1 , 2 ). Both sandstone units overlie and interact with thick mass-transport complexes (MTCs). These units are generically interpreted to represent infill of accommodation produced by slope failure, and may represent submarine fans, channel-fill units, crevasse-splay units, or units representing channel capture by slope failure. Extensive exposure of both coarse- and fine-grained strata make the Tres Pasos Formation an important analog system for hydrocarbon reservoirs in mud-rich, structurally complex, slope environments. This spectacular outcrop underscores the importance of slope failure on the preservation and stratigraphic architecture of deep-water sandstones.

Abstract The Magallanes Basin SEPM Field Conference, February 2009, showcases outcrops of Cretaceous deep-water clastic strata exposed in the Ultima Esperanza District of southernmost Chile from Puerto Natales northward to Torres del Paine National Park. Why travel to the ‘end of the Earth’ to see these deep-water deposits? We believe that the deep-water succession in the Magallanes Basin of Chilean Patagonia is destined to join a select set of outcrop systems such as the Tanqua Karoo of South Africa (e.g., Wickens and Bouma, 2000 ; Johnson et al., 2001 ) and Brushy Canyon Formation of west Texas (e.g., Beaubouef et al., 1999 ; Gardner et al., 2003 ) as a world-class outcrop analog for buried, petroliferous deep-water systems. Magallanes Basin outcrops are notable for several key features: (1) Involvement in a latest Cretaceous – early Tertiary fold-thrust belt, providing nearly continuous down-depositional-dip 2-D outcrops for ~100 km, with local 3-D exposures provided by folding and topography; (2) Deep excavation and many bare-rock surfaces created by Late Cenozoic glaciation; (3) Contrasting styles of deep-water systems stratigraphically stacked during basin evolution, from unconfined and/or weakly-confined turbidite systems through highly-confined channelized systems through progradational failure-dominated delta slope with numerous channels and sand-filled mini-basins. The variability of the Magallanes Basin fill over a relatively small area makes the exposures of the Ultima Esperanza District worthy of the attention of the international sedimentologic community. But it has not always been so. Cretaceous outcrops in the Magallanes Basin of the Ultima Esperanza District

Abstract The Tres Pasos Formation, Magallanes Basin, Chile, represents the deposit of a submarine slope depositional system. The formation is approximately 1500 m thick where exposed in the Ultima Esperanza district of southernmost Chile. It is characterized by a basal turbiditic sandstone unit up to 200 m thick that shows a north-to-south, proximal-to-distal facies evolution from turbidite channel-fill complexes to sheet-like sandstone units. This unit is interpreted as having been deposited at or near the base of slope. Overlying the basal sandstone unit is approximately 500 m of amalgamated mass transport complexes, fine-grained strata, and channelized and non-channelized turbidity current deposits, collectively comprising the middle part of the formation. Mass transport complexes exert a primary control on the character and grain size of turbidite sandstone bodies in the basal and middle part of the formation. In the southern part of the study area, a 300 m thick coarse-grained unit interpreted as a turbidite channel-fill complex partially replaces the middle part. The upper part of the formation is approximately 500 m thick and consists primarily of fine-grained strata. Failure scarps and thin turbidite channel-fill units are present in this upper part, interpreted as upper slope deposits.

Abstract Outcrop accessibility: extremely difficult Outcrop Coordinates: 50.7309°S, 72.6324°W Refer to outcrop 15 on location map The stratigraphic section at Cerro Escondido contains the most complete exposure of the Dorotea Formation in the Ultima Esperanza District ( Fig. 15.1 ). Cerro Escondido is located south of the Argentina-Chile border on an anticline between the Rio de las Chinas and the Rio Zamora (refer to outcrop location map). The contact between the Tres Pasos and Dorotea formations had not been formally mapped at Cerro Escondido, and we define it as the first contact between turbidites of the Tres Pasos Formation and overlying shallow-marine hummocky-cross stratified sandstone of the Dorotea Formation ( Fig. 15.1 ). Greater than 300 m of stratigraphy are exposed across >800 m of the Cerro Escondido outcrop ( Fig. 15.1 ). Two stratigraphic sections were recorded at cm-scale resolution (295 m thick in the east and 197 m thick in the west; Fig. 15.1C ).

Abstract 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.

Abstract Conglomeratic deep-water deposits of the Cerro Toro Formation are exposed for more than 100 km (62 mi) along a north–south trending outcrop belt in the Ultima Esperanza District of southern chile. The deposits accumulated within a broad channel belt (4–5 km [2.5–3.1 mi] wide) that occupied the axis of the Magallanes basin during the Late Cretaceous (Campanian). The elongate depocenter represented the foredeep to the fold-thrust belt presently exposed in the stucturally complex Patagonian Andes to the west of the study area. The Andes were actively uplifting during deposition of the Cerro Toro Formation, and have been interpreted to represent the source of the coarse-grained channel fill. Outcrops of the Cerro Toro Formation have long been studied as architectural analogs to hydrocarbon reservoirs, although the outcrop at Cerro Mocho that is the focus of this paper has not been documented before. The exceptional, seismic-scale exposure of the western channel margin at Cerro Mocho is an ideal place to document the relationship between conglomeratic channel fill and fine-grained, out-of-channel deposits. Structures associated with Andean tectonics are present in the study area but do not significantly hinder sedimentologic and stratigraphic interpretations. The channel margin at Cerro Mocho is complex, shaped by both constructional and erosional processes. Total relief of the margin is almost 300 m (984 ft) over a lateral distance of 1 km (0.6 mi). Deposition of predominantly sand and gravel in the channel axis was influenced by erosive gravity flows and traction processes (driven by overlying turbidity currents). Beds near

Abstract Large-scale vertical to subvertical clastic intrusions (as much as 67 m [219 ft] wide and >100 m [>330 ft] high) are present in Cretaceous strata (Cerro Toro Formation) of the Ultima Esperanza district, southern Chile. The injectites emanate from the margins of submarine-channel deposits that accumulated at water depths of 1000–2000 m (3300–6600 ft) in the Magallanes foreland basin. The remobilized sediment is very coarse, consisting of sandy matrix conglomerate, muddy matrix conglomerate, and poorly sorted sandstone. The injectite bodies sometimes bifurcate upward and are circular in plan view and, thus, are geometrically analogous in many respects to numerous injection features mapped seismically in the North Sea Basin. The remobilization of coarse sediment was likely induced after the burial of the parent deposit to at least a few hundred meters. The controlling factors on injection are difficult to discern; however, it is probable that the highly energetic process involved gas charging of the source body and, potentially, a seismic event trigger associated with the uplift of the Patagonian Andes.