Triassic-Jurassic sediments and multiple volcanic events in North Victoria Land, Antarctica: A revised stratigraphic model

Abstract

Field investigations in North Victoria Land, Antarctica during GANOVEX IX (2005/2006) allow the revision of the Triassic-Jurassic stratigraphy of ~300 m thick continental deposits in between the crystalline basement and the Kirkpatrick lava flows of the Ferrar Group. The lower stratigraphic unit (Section Peak Formation) is characterised by braided river-type quartzose sandstone deposits with intercalations of shale and coal occurring at the top. It is overlain by a homogeneous unit of reworked tuffs composed of fine-grained silicic shards, quartz and feldspar (new name: "Shafer Peak Formation"). These deposits can be correlated with parts of the Hanson Formation in the Central Transantarctic Mountains and require a distal yet unknown source of massive silicic volcanism. Clastic products of mafic volcanic eruptions, formerly described as a separate stratigraphic formation (Exposure Hill Formation), occur within local diatreme structures as well as intercalated at various stratigraphic levels within the sedimentary succession. These dominantly hydroclastic eruptions are the first subaerial expression of Ferrar magmatism. The initial Kirkpatrick lavas/pillow lavas were generated from local eruptive centres and again may be overlain by thin sediments, which are covered by the thick plateau lava succession known throughout the Transantarctic Mountain Range.

The geological and tectonic evolution of the Transantarctic Mountains: a review

“…By contrast, a more extensive record is present north of the Priestley Glacier in north Victoria Land (Schöner et al 2007;Viereck-Goette et al 2007). There, the siliciclastic Section Peak Formation passes up into a silicic shard-bearing sandstone sequence informally named the Shafer Peak Formation.…”

“…All were Barrett (1991); Falla Formation, Elliot (1996) ;Hanson Formation, Elliot et al (2007); Prebble Formation, Hanson & Elliot (1996); unnamed strata, south Victoria Land, Elliot & Grimes (2011); Mawson Formation, Ross et al (2008); north Victoria Land glacial beds and Takrouna Formation, Collinson et al (1986); Section Peak and 'Shafer Peak' formations, Schöner et al (2007Schöner et al ( , 2011; Exposure Hill Formation, Viereck-Goette et al (2007); Kirkpatrick Basalt, Elliot & Fleming (2008).…”

“…These rocks are exposed primarily in the central Transantarctic Mountains (Hanson Formation;Elliot 1996) and in north Victoria Land (Shafer Peak Formation; Schöner et al 2007). In the central Transantarctic Mountains the sequence, disconformable on the Falla Formation, consists of tuffaceous sandstones and finer-grained beds and tuffs.…”

Long‐Term Geochemical and Geodynamic Segmentation of the Paleo‐Pacific Margin of Gondwana: Insight From the Antarctic and Adjacent Sectors

“…The Hanson Formation consists of tuffs, tuffaceous sandstones, arkosic grits and sandstones, and lapillistones that comprise a 235 m thick section at the type locality at Mount Falla (Figure ; Elliot, ; Elliot, Fanning, et al, ; Elliot, Larsen, et al, ). The only other section of correlative Early Jurassic reworked silicic tuffs with exposed upper and lower contacts, the Shafer Peak Formation, occurs in the Deep Freeze Range in northern Victoria Land (NVL, Figure b; Schöner et al, ; Elsner et al, ). Tuffs of the Hanson Formation are dacitic to rhyolitic in composition (~67 to 78 wt % SiO 2 ) with the majority containing evidence for fluvial reworking, with relatively few primary tuffs that, where present, are interpreted to represent unmodified airfall deposits resulting from distal (super)plinian eruptions (Elliot, ; Elliot et al, ; Elliot, Fanning, et al, ; Elliot, Larsen, et al, ).…”

Cheirolepidiaceous diversity: An anatomically preserved pollen cone from the Lower Jurassic of southern Victoria Land, Antarctica

“…Fossil plants of Jurassic age on the continent are found only in a few, exceptional sites where sedimentary interbeds occur within the volcanics. Compression and permineralized plant fossils have been described from the Lower Jurassic Shafer Peak Formation in northern Victoria Land (Bomfleur and Kerp, 2010;Bomfleur et al, 2007Bomfleur et al, , 2011aBomfleur et al, , 2011bSchöner, et al 2007). In addition, several examples of silicified conifers have been described from the Jurassic of Antarctica, including trees engulfed by lava flows from northern Victoria Land (Jefferson et al, 1983), silicified tree trunks from Brebbia and Ramírez Nunataks (Antarctic Peninsula;del Valle et al, 1997), a single tree stump from the Coombs Hills in southern Victoria Land (Garland et al, 2007), and permineralized woody axes from Suture Bench east of the Gair Mesa in northern Victoria Land (Bomfleur et al, 2011b;Harper et al, 2012).…”