Heat-flow determinations of basement age in small oceanic basins of the southern central Scotia Sea

Abstract

Results are reported from seven heat flow stations in small basins of the southern part of the central Scotia Sea (CSS), undertaken in order to determine basement ages. The basins are small, which makes magnetic anomaly-based ages ambiguous and preserves basin subsidence that may have been anomalous as a result of local factors. The fact that these small basins formed in a back-arc setting adds additional uncertainty to depth-based age estimates. The results confirm that basin extension commenced in the Eocene, and indirectly support a relatively young, backarc origin for the northern CSS, but do not affect previously published suggestions of the age of onset of the Antarctic Circumpolar Current.

Tectonic reconstructions for paleobathymetry in Drake Passage

“…Based on this depth, after isostatic adjustment for around 1 km of sediment fill, and assuming that seafloor spreading there would not have occurred simultaneously with spreading elsewhere in the Scotia Sea, Eagles et al (2006) presented a model of magnetic anomaly isochrons 18-15 (41-35 Ma) for the basin. Consistent with this, Barker et al (2013) modelled heat flow values near the basin margins to suggest basement ages in the range 43-42 Ma.…”

Composition and evolution of the Ancestral South Sandwich Arc: Implications for the flow of deep ocean water and mantle through the Drake Passage Gateway

“…Barker et al (2013) support Eocene-Oligocene spreading using heat flow measurements, obtaining ages of 43-42 Ma for a site within the Dove Basin and one of 25.2Ma for a site within the Protector Basin. However, Maldonado et al (2006) use seismic stratigraphic methods to date the basins as Miocene (e.g., Protector Basin =17.6-14Ma) in which case these basins would not be relevant to the early history of deep water flow and more likely to be related to later westward subduction.…”

Tectonic activity evolution of the Scotia‐Antarctic Plate boundary from mass transport deposit analysis

“…Further bathymetric highs such as the South Orkney Microcontinent and continental blocks of the western SSR configure the physiography of the region, exposed at the South Orkney Islands and Elephant Island. Although debate surrounds the age and mechanisms of basin development [e.g., Eagles et al ., ; Barker et al ., ; Galindo‐Zaldívar et al ., , ], most authors agree that the oceanic spreading occurred prior to middle Miocene. Despite their age, these basins must have formed in a right‐lateral transcurrent regime of the SSR according to the eastward migration of the continental fragments [ Bohoyo et al ., ].…”