Admiralty Bay, King George Island (Soth Shetland Islands, West Antarctica): A geological monograph
Studia Geologica Polonica,
120: 5-73. (+ Geological Map and Cross-sections, 1:50 000, by Krzysztof
Institute of Geological Sciences,
Polish Academy of Sciences, Cracow Research Centre, ul. Senacka 1, 31-002
Kraków, Poland; ndbirken@cyf‑kr.edu.pl
Admiralty Bay is the largest
fjord system on King George Island, South Shetland Islands (West Antarctica).
Exposures along its coasts, and on nunataks, give a good insight into geological
history of the area, spanning more than 90 Ma, from Late Cretaceous to
King George Island is located in the
middle of the South Shetland Islands arc. To the north, it borders on the South
Shetland subduction trench, part of Drake Passage, to the south - it is divided
from crustal block of Antarctic Peninsula by a young rift and basin of Bransfield
The island consists of four
tectonic blocks/terranes bounded by longitudinal strike-slip faults of
Tertiary age. Three of these blocks, the Barton Horst (axial), the Warszawa
Block (southern, downthrown with respect to the Barton Horst), and the
Kraków Block (southernmost, downthrown with respect to the Warszawa Block,
bordering on Bransfield Rift) are present at Admiralty Bay. Geological
successions of stratiform volcanic/sedimentary and intrusive (hypabyssal
and plutonic) rocks markedly differ between these tectonic blocks/terranes,
suggesting considerable horizontal displacements between them along longitudinal
strike-slip faults. Geological age of stratiform and intrusive magmatic
successions is there generally well established on radiometric dating.
Terrestrial strata yielded numerous fossil plant assemblages of Late Cretaceous
and Early Tertiary ages. In the Admiralty Bay area, there occur also the
westernmost exposures of Oligocene marine/glaciomarine strata, whose principal
outcrops are located further east.
The paper is a monograph of
the Admiralty Bay area, the geological map of which, 1:50,000 scale (Pl.
I), and geological cross-sections (Pl. II), are attached under a separate
jacket. The monograph gives an outline of geological research on King George
Island since its beginnings in the 19th century, a concise description
of the Upper Cretaceous through Lower Oligocene rock successions within
each tectonic block/terrane, and of Quaternary strata, forms and events.