Continental rift to back‐arc basin: Jurassic–Cretaceous stratigraphical and structural evolution of the Larsen Basin, Antarctic Peninsula

Abstract

The Larsen Basin developed in Jurassic times as a result of continental rifting during the early stages of Gondwana break‐up. Lower‐?Upper Jurassic non‐marine sedimentary and volcanic rocks constitute a syn‐rift megasequence recording initial largely amagmatic extension and subsequent widespread extension‐related silicic volcanism. A succeeding, Kimmeridgian–early Berriasian transgressive megasequence, consisting largely of anoxic‐dysoxic hemipelagic mudstones, is thought to have been deposited during a thermal subsidence phase when relative magmatic quiescence and peak Jurassic eustatic sea levels served to maximize sediment starvation. The fragmentary record for late Berriasian–Barremian times suggests that a ?regressive megasequence may have developed in the earlier part of this period, recording increased sediment yield to the Larsen Basin from the increasingly emergent Antarctic Peninsula arc. Subsequently, strata in the southern, but not the northern, part of the basin underwent relatively intense eastward‐verging deformation, possibly during the formation of a retro‐arc fold‐thrust belt. Where exposed, the lower part of the succeeding Aptian–Eocene megasequence consists of a deep‐marine clastic wedge deposited along the fault‐bounded western basin margin during a phase of arc uplift and related differential subsidence. Following partial basin inversion in Late Cretaceous times, regression took place as reduced basinal subsidence rates allowed shallow marine facies to prograde basinward.

Valdivian ecosystems in the Late Cretaceous and Early Tertiary of Antarctica: further evidence from myrtaceous and eucryphiaceous fossil wood

“…This lithostratigraphic framework forms an important basis for the regional tectonic (Hathway, 2000), palaeoclimatic (e.g. Dingle and Lavelle, 2000) and palaeobiological studies (e.g.…”

Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

“…The southern South America was subject to crustal extension associated with the breakup of the Gondwana supercontinent during the Middle to Late Jurassic (Dalziel et al 1987). As a result of the extension, isolated continental rift basins and a back-arc basin (Rocas-Verdes Basin) developed along the Pacific margin (Hathway 2000). During the early Cretaceous, deformation style changed from extension to compression because of the onset of the Andean orogeny, which led to the closure of the back-arc basin and partial obduction of the basin floor onto the craton margin (Dalziel and Brown 1989).…”

Inferências paleoambientais a partir de análise de palinofácies da Formação Hidden Lake (Coniaciano, Cretáceo), Bacia Larsen, Ilha James Ross, Antártica

“…A Bacia Larsen, a principal bacia sedimentar a oeste da Península Antártica (Macdonald et al, 1988;Hathway, 2000), é subdividida nas sub-bacias Sul e James Ross (Figura 1).…”

“…Esta megassucessão vulcano-sedimentar foi dividida formalmente em três unidades litoestratigráficas: a Formação Nordenskjöld, o Grupo Gustav e o Grupo Marambio (Hathway, 2000;Hathway & Riding, 2001;Riding & Crame, 2002). Os depósitos do Grupo Gustav são caracterizados por conglomerados e brechas com clastos tamanho até matacão e arenitos seixosos, com ocorrência subordinada de arenitos mais finos, siltitos e lamitos.…”