Studia Geologica Polonica  vol. 110 (Abstracts)

Geology of the northern coast of King George Island, South Shetland Islands (West Antarctica)

Krzysztof BIRKENMAJER

Abstract
The northern coast of King George Island (South Shetland Islands, West Antarctica), between West Foreland (Fildes Peninsula) and North Foreland, is formed of volcanic and plutonic rocks of Lower Tertiary age belonging to two tectonic units. The Fildes Peninsula Group stratiform volcanics (Paleocene-Eocene) of basaltic, andesitic and, subordinately, dacitic composition occur in the downthrown Fildes Block. The Martel Inlet Group stratiform altered basaltic to andesitic volcanics (Paleocene), and the Wegger Peak Group moderate-size granodiorite plutons (Oligocene), occur in the upthrown Barton Horst. Hypabyssal basaltic and andesitic dykes and plugs of the Admiralty Bay Group (Upper Cretaceous and Palaeogene) cut the two stratiform complexes, sometimes also the Wegger Peak Group plutons. The present paper gives geological descriptions of exposures of these rocks scattered along highly glaciated northern coast of King George Island between West Foreland (Fildes Peninsula) in the west and North Foreland in the east.

Studia Geologica Polonica, 110: 27-45.

Thermal jointing in Tertiary volcanic plugs on King George Island, South Shetland Islands (West Antarctica) - a comparison with Tertiary volcanoes of Lower Silesia, Poland

Krzysztof BIRKENMAJER

Abstract
Selected Tertiary basaltic and andesitic plugs/vents are illustrated from King George Island (South Shetland Islands, West Antarctica). The plugs exhibit a very characteristic thermal jointing pattern that, together with other local data, allow us to reconstruct original structure and shape of the volcanoes. A comparison with internal structures of Tertiary basaltic volcanoes well exposed in quarries of Lower Silesia, Poland, is given.

Studia Geologica Polonica, 110: 47-59.

Polyphase tectonic deformation of the Trinity Peninsula Group (?Upper Permian-Triassic) at Paradise Harbour, Danco Coast (Antarctic Peninsula)

Krzysztof BIRKENMAJER

Abstract
Strongly tectonically deformed metasediments of the Trinity Peninsula Group (?Upper Permian-Triassic) occur at Paradise Harbour, Danco Coast (Antarctic Peninsula). They are represented by the Paradise Harbour Formation (PHF) more than 1000 m thick. The folding and thrusting occurred during two major phases. The first phase - Trinity phase of the Gondwanian orogeny (probably Triassic/Jurassic boundary) - caused strong folding and thrusting of the PHF rocks with a south-eastward vergence, i.e. retroarc with respect to the Mesozoic magmatic arc of Antarctic Peninsula. The Trinity orogen was deeply eroded and denuded during the Jurassic. The Lower Cretaceous basaltic-andesitic lavas (Antarctic Peninsula Volcanic Group, APVG), some 2000 m thick, rest with a strong angular unconformity upon pre-Lower Cretaceous peneplain surface.
The second phase of deformation post-dated the Lower Cretaceous APVG pile, the mid-Cretaceous plutons, and the ?late Cretaceous hypabyssal dykes of the Andean Intrusive Suite. It could be related to the Tertiary (mid-Miocene) collision of the Aluk Ridge with the Antarctic Peninsula. During this phase, a large asymmetric anticline was formed, its core consisting of the PHF, and the limbs of the APVG rocks. The anticline is cut in its south-eastern limb by a reverse fault along which the PHF rocks are thrust retroarc over the APVG lavas.

Studia Geologica Polonica, 110: 61-90.

A turbidite sedimentary log of the Trinity Peninsula Group (?Upper Permian-Triassic) at Paradise Harbour, Danco Coast (Antarctic Peninsula): sedimentology and petrology

Krzysztof BIRKENMAJER, Marek DOKTOR & Anna ŚWIERCZEWSKA

Abstract
A continuous sedimentary log about 40 m long of the Trinity Peninsula Group metasediments (?Upper Permian-Triassic), was studied at Paradise Harbour, Danco Coast (Antarctic Peninsula). It includes the Skontorp Cove Member and an upper part of the underlying Almirante Brown Member, both belonging to the Paradise Harbour Formation. This is a succession of ripplemarked rhythmites (sandstone-siltstone-mudstone/clayshale), with small and larger channels filled with cross-bedded sandstone. These deposits probably represent distal part of a deep submarine turbidite fan. Petrological study of the sandstones indicate provenance of their clastic components from an uplifted basement at Pacific margin of the Gondwanaland. The rocks of the Paradise Harbour Formation were affected by advanced diagenesis and anchimetamorphism, however to a lesser degree than the Trinity Peninsula Group rocks further north on Antarctic Peninsula.

Studia Geologica Polonica, 110: 91-104.

Quaternary geology at Arctowski Station, King George Island, South Shetland Islands (West Antarctica)

Krzysztof BIRKENMAJER

Abstract
A detailed Quaternary geology map, 1:2,500 scale, of the area of H. Arctowski Station, King George Island (South Shetland Islands, West Antarctica), was prepared in 1979. It is being published now with description of its elements, the most important being: palaeoglacial (Pleistocene) and neoglacial (Holocene) moraines and associated deposits and forms; raised marine terraces/ beaches and cliffs (Pleistocene and Holocene).