A potential barrier to deep Antarctic circumpolar flow until the late Miocene?

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

“…This requires that the E-W anomalies in the CSS represent Cretaceous oceanic or transitional crust formed during the early stages of spreading at the southern margin of South Georgia. This assertion was 'ground-truthed' in a new magnetic survey by Dalziel et al (2013), who confirmed both the presence of the E-W anomalies and the absence of any ridge axis. The re-interpretation of the anomalies as trapped, Cretaceous crust and not subduction-related, Miocene back-arc crust (e.g.…”

“…By using these new data, our goal is to fingerprint the tectonic evolution of the ASSA during its life cycle from subduction initiation to the cessation of volcanism. This in turn will provide a more rigorous test of the hypothesis of Dalziel et al (2013) and enable us to define more precisely the implications for deep ocean water and mantle flow, particularly that from the Pacific to the Atlantic. and South Georgia Passages.…”

“…The CSS segment was entirely unknown until the NBP0805 cruise reported in Dalziel et al (2013). They identified large volcanic edifices on the Central Scotia Sea floor.…”

Links between CO<sub>2</sub>, glaciation and water flow: reconciling the Cenozoic history of the Antarctic Circumpolar Current

“…Possible shutdown or slowdown of the ACC between approximately 29 and 22 Ma has also been suggested due to the temporary constriction of Drake Passage (Lagabrielle et al, 2009) and can be invoked to reconcile this apparent discrepancy in the timing of the ACC: after a period of shallow circulation in the middle to late Eocene (Scher and Martin, 2006), the first onset of the circumpolar current would have occurred close to the EO boundary (Borrelli et al, 2014;Katz et al, 2011;Latimer and Filippelli, 2002) following Antarctic glaciation and before a period of possible variations in its intensity under changes in pCO 2 , ice sheet size and tectonics; this development would have ended with a period of progressive slowdown (Lagabrielle et al, 2009). The Oligocene-Miocene boundary would then mark the second onset of the ACC (Lyle et al, 2007;Pfuhl and McCave, 2005), predating the evolution towards its modern features (Dalziel et al, 2013;Heinrich et al, 2011).…”

Patrones de diversidad y estructura genética en especies antárticas y subantárticas de Nacella (Nacellidae)

“…Estudios moleculares recientes indican que las separaciones entre especies congenéricas de invertebrados antárticos y subantárticos habría ocurrido mucho tiempo después de la separación física de los continentes. La divergencia molecular entre linajes de Antártica y Sudamérica estaría relacionada a cambios importantes ocurridos en el OA asociados a la evolución del Arco de Escocia y a la profundización del Paso de Drake a mediados del Mioceno (Dalziel et al 2013). Junto a todos estos procesos geológicos y oceanográficos, el cambio climático ha tenido un gran rol en el OA desde el Cenozoico modelando la abundancia, estructura y distribución de su biota (Clarke & Crame, 1989Aronson et al 2007).…”