scholarly journals Chrono- and lithostratigraphy of a Mesozoic–Tertiary fore- to intra-arc basin: Adelaide Island, Antarctic Peninsula

2011 ◽  
Vol 149 (5) ◽  
pp. 768-782 ◽  
Author(s):  
TEAL R. RILEY ◽  
MICHAEL J. FLOWERDEW ◽  
MARTIN J. WHITEHOUSE
Keyword(s):  
Antarctic Peninsula ◽  
Basaltic Andesite ◽  
West Coast ◽  
Volcanic Rocks ◽  
Volcanic Group ◽  
Volcaniclastic Rocks ◽  
Definition Of ◽  
The Antarctic ◽  
Adelaide Island

AbstractThe Mesozoic fore-arc of the Antarctic Peninsula is exposed along its west coast. On Adelaide Island, a 2–3 km succession of turbiditic coarse sandstones and volcanic rocks is exposed. Four U–Pb (zircon) ages are presented here that, in combination with a new stratigraphy, have permitted a robust chrono- and lithostratigraphy to be constructed, which in turn has allowed tentative correlations to be made with the Fossil Bluff Group of Alexander Island, where the ‘type’ fore-arc sequences are described. The lithostratigraphy of Adelaide Island includes the definition of five volcanic/sedimentary formations. The oldest formation is the Buchia Buttress Formation (149.5 ± 1.6 Ma) and is correlated with the Himalia Ridge Formation of Alexander Island. The sandstone–conglomerate dominated succession of the Milestone Bluff Formation (113.9 ± 1.2 Ma) is tentatively correlated with the Pluto Glacier Formation of Alexander Island. Three dominantly volcanic formations are recognized on Adelaide Island, akin to the volcanic rocks of the Alexander Island Volcanic Group; the Mount Liotard Formation is formed of 2 km of basaltic andesite lavas, whilst the Bond Nunatak Formation is also dominated by basaltic andesite lavas, but interbedded with volcaniclastic rocks. The Reptile Ridge Formation has been dated at 67.6 ± 0.7 Ma and is characterized by hydrothermally altered rhyolitic crystal-lithic tuffs. Tentative correlations between Adelaide Island and Alexander Island preclude the two areas forming part of distinct terranes as has been suggested previously, and a proximal source for volcaniclastic sediments also indicates an exotic terrane origin is unlikely.

Central volcanoes as sources for the Antarctic Peninsula Volcanic Group

1994 ◽  
Vol 6 (3) ◽  
pp. 365-374 ◽  
Author(s):  
Philip T. Leat ◽  
Jane H. Scarrow
Keyword(s):  
Antarctic Peninsula ◽  
Volcanic Rocks ◽  
Coarse Grained ◽  
North West ◽  
Magmatic Arc ◽  
Fine Grained ◽  
Volcanic Group ◽  
Land Sliding ◽  
High Level ◽  
The Antarctic

From at least the Early Jurassic to the Miocene, eastward subduction of oceanic crust took place beneath the Antarctic Peninsula. Magmatism associated with the subduction generated a N-S linear belt of volcanic rocks known as the Antarctic Peninsula Volcanic Group (APVG), and which erosion has now exposed at about the plutonic/volcanic interface. Large central volcanoes from the APVG are described here for the first time. The structures are situated in north-west Palmer Land within the main Mesozoic magmatic arc. One centre, Zonda Towers, is recognized by the presence of a 160 m thick silicic ignimbrite, containing accidental lava blocks up to 25 m in diameter. This megabreccia is interpreted as a caldera-fill deposit which formed by land sliding of steep caldera walls during ignimbrite eruption and deposition. A larger centre, Mount Edgell-Wright Spires, is dominated by coarse-grained debris flow deposits and silicic ignimbrites which, with minor lavas and fine-grained tuffs, form a volcanic succession some 1.5 km thick. Basic intermediate and silicic sills c. 50 m thick intrude the succession. A central gabbro-granite intrusion is interpreted to be a high-level magma chamber of the Mount Edgell volcano.

Assessing the potential of multispectral remote sensing for lithological mapping on the Antarctic Peninsula: case study from eastern Adelaide Island, Graham Land

2010 ◽  
Vol 22 (3) ◽  
pp. 299-318 ◽  
Author(s):  
C.E. Haselwimmer ◽  
T.R. Riley ◽  
J.G. Liu
Keyword(s):  
Remote Sensing ◽  
Antarctic Peninsula ◽  
Spectral Properties ◽  
Volcanic Rocks ◽  
Lithological Mapping ◽  
Aster Data ◽  
Intrusive Rocks ◽  
Multispectral Remote Sensing ◽  
The Antarctic ◽  
Adelaide Island

AbstractThe results of lithological mapping using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for the Wright Peninsula region of Adelaide Island, Antarctic Peninsula are compared with existing geological maps and recent field observations to assess the potential of multispectral remote sensing to undertake lithological mapping on the Antarctic Peninsula. The Wright Peninsula comprises calc-alkaline intrusive rocks ranging from granite to gabbro, volcanic rocks of acidic to intermediate composition, and arc-related sediments. The reflective and thermal bands of a single ASTER image were analysed with reference to reflectance spectra of rock samples from the study area. Assessment of the ASTER mapping outcomes was undertaken with a newly compiled geological map of Adelaide Island and observations made during recent fieldwork. The results demonstrate that ASTER can uniquely discriminate granitoid intrusive rocks and altered rhyolitic volcanic rocks that display distinctive spectral properties. The results are more ambiguous at discriminating more intermediate/mafic rocks such as diorite/gabbro, andesite/basalt and chlorite-bearing sediments due to the similarity in spectral properties. These results demonstrate that although ASTER data are limited in their ability to uniquely discriminate lithologies they can provide important lithological information in support of geological mapping on the Antarctic Peninsula.

Tectonic setting and geochemistry of Miocene alkalic basalts from the Jones Mountains, West Antarctica

1994 ◽  
Vol 6 (1) ◽  
pp. 85-92 ◽  
Author(s):  
M. J. Hole ◽  
B. C. Storey ◽  
W. E. LeMasurier
Keyword(s):  
Antarctic Peninsula ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
West Antarctica ◽  
Geochemical Composition ◽  
Crustal Block ◽  
Volcaniclastic Rocks ◽  
Geochemical Analyses ◽  
The Antarctic ◽  
Alkalic Basalts

Within the Jones Mountains, which form part of the Thurston Island crustal block, up to 700 m of Miocene (c. 10 Ma) pillow basalt and palagonitized volcaniclastic rocks unconformably overlie Jurassic granitic basement and Cretaceous volcanic rocks and dykes. New geochemical analyses demonstrate the alkalic nature of the basalts, which range in composition from alkali basalt to basanite. Unradiogenic Sr-isotope ratios (0.7031–0.7034), coupled with low LILE/HFSE ratios (e.g. Th/Ta c. 1.4, Rb/Nb 0.3–0.9) indicate a predominantly asthenospheric source for the basalts. The Jones Mountains basalts are geochemically similar to the alkalic basalts of Marie Byrd Land, but have consistently lower K/Ba and higher Ba/Nb ratios than Late Cenozoic alkalic basalts along the Antarctic Peninsula. These regional variations in geochemical composition apparently reflect differences in tectonic setting and are not the result of lithospheric interaction or partial melting/crystallization effects. The generation of alkalic magmas along the Antarctic Peninsula was causally related to the formation of slab windows following ridge crest-trench collision and the cessation of subduction, whereas the Jones Mountains alkalic basalts may represent the expression of the northward propagation of the head of the Marie Byrd Land plume.

The stratigraphy and geochronology of Adelaide Island

1998 ◽  
Vol 10 (4) ◽  
pp. 462-475 ◽  
Author(s):  
Chris J. Griffiths ◽  
Richard D. J. Oglethorpe
Keyword(s):  
Antarctic Peninsula ◽  
Volcanic Rocks ◽  
South Shetland Islands ◽  
The South ◽  
Shetland Islands ◽  
Step Heating ◽  
Show Evidence ◽  
Cretaceous Volcanism ◽  
The Antarctic ◽  
Adelaide Island

The Mesozoic-Cenozoic volcanic arc of the Antarctic Peninsula is represented on Adelaide Island by a sedimentary and volcanic succession intruded by plutons. 40Ar-39 Ar step-heating age spectra have been obtained from volcanic rocks and hornblende separates from sedimentary clasts of plutonic origin. These spectra show evidence for some argon loss, but, in general, have plateau ages which are consistent with the mapped stratigraphy and with other geochronological controls, suggesting that they approximate to original ages. As a result the following events in the evolution of Adelaide Island can be recognized:1) mostly marine Mesozoic sedimentation, 2) Early Cretaceous (c. 141 Ma) plutonism (recorded in clasts from conglomerates), 3) Cretaceous volcanism, 4) Late Cretaceous (possibly Tertiary) sedimentation, 5) Early Tertiary volcanism, which was acidic in eastern outcrops and intermediate elsewhere, and 6) Eocene intermediate volcanism and deposition of arc-derived conglomerates. Volcanism was possibly coeval with known Palaeocene-Eocene plutonic activity on Adelaide Island (part of the Antarctic Peninsula Batholith) and with volcanism of similar age in northern Alexander Island and the South Shetland Islands. The volcanism on Adelaide Island and the South Shetland Islands, at least, was associated with a westward migration of the Antarctic Peninsula arc.

A unifying lithostratigraphy of late Cretaceous–early Tertiary fore-arc volcanic sequences on Alexander Island, Antarctica

1997 ◽  
Vol 9 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Joe J. McCarron
Keyword(s):  
Antarctic Peninsula ◽  
Late Cretaceous ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Magmatic Arc ◽  
Ridge Subduction ◽  
Volcanic Group ◽  
Early Tertiary ◽  
Plutonic Rocks ◽  
The Antarctic

Late Cretaceous–early Tertiary subduction-related fore-arc volcanic rocks are exposed in a north–south linear belt along the length of Alexander Island. The age and tectonic setting of these rocks is well understood; they are not considered to represent “normal” arc magmas but were generated in the fore-arc as a result of ridge subduction. Due to their distinct composition and mode of formation, they are no longer considered to be genetically related to the Antarctic Peninsula magmatic arc. They are therefore removed from the Antarctic Peninsula Volcanic Group and placed in a newly defined Alexander Island Volcanic Group. The group is made up of the Monteverdi, Staccato, Walton, Colbert, Elgar and Finlandia formations, which vary widely in lithology, facies and age. The Colbert and Elgar formations are subdivided into nine and three members respectively. Type localities, representative lithologies and age of each of the formations are discussed. The Staccato and Colbert Magmatic complexes are defined to include volcanic and plutonic rocks that are considered to be coeval. The Rouen Intrusive complex combines the plutonic rocks from the Rouen Mountains and Rothschild Island on the basis of age and chemistry.

Middle Jurassic rhyolite volcanism of eastern Graham Land, Antarctic Peninsula: age correlations and stratigraphic relationships

2010 ◽  
Vol 147 (4) ◽  
pp. 581-595 ◽  
Author(s):  
TEAL R. RILEY ◽  
MICHAEL J. FLOWERDEW ◽  
MORAG A. HUNTER ◽  
MARTIN J. WHITEHOUSE
Keyword(s):  
Antarctic Peninsula ◽  
East Coast ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Silicic Volcanism ◽  
Volcanic Group ◽  
Silicic Volcanic ◽  
Eruption Age ◽  
Rhyolite Volcanism ◽  
The Antarctic

AbstractSilicic volcanism atc.168 Ma has been identified previously on the Antarctic Peninsula, and the Mapple Formation, which includes those volcanic rocks, has been defined and documented from one area of the east coast of Graham Land. Based on age and geochemical criteria, correlations have been made to the extensive Chon Aike Province of South America, which has been demonstrated to be one of the largest silicic volcanic provinces in the world. Rhyolitic and intermediate composition volcanic successions from six separate localities on the east coast of the Antarctic Peninsula are described here and are confirmed as correlatives of the Mapple Formation, based on newly acquired geochronology and field observations. They are dominantly rhyolitic crystal tuffs and/or ignimbrites with ages in the interval 162–168 Ma, overlapping with the age of the Mapple Formation (167–171 Ma) at the type locality. Andesitic agglomerates are also described, which are included in the same event and demonstrate the occurrence of rare intermediate volcanism, which is also seen in the Chon Aike Province. A new group, the Graham Land Volcanic Group, is defined here, and criteria are established which allow the separation of some volcanic successions out of the previously defined Antarctic Peninsula Volcanic Group, which takes no account of tectonic setting, eruption age or geochemistry.

Chapter 3.1b Antarctic Peninsula and South Shetland Islands: petrology

2021 ◽  
pp. M55-2018-68 ◽  
Author(s):  
Philip T. Leat ◽  
Teal R. Riley
Keyword(s):  
Antarctic Peninsula ◽  
Continental Margin ◽  
Volcanic Rocks ◽  
Oceanic Lithosphere ◽  
Contact Metamorphism ◽  
South Shetland Islands ◽  
Calc Alkaline ◽  
The Pacific ◽  
High K ◽  
The Antarctic

AbstractThe Antarctic Peninsula contains a record of continental-margin volcanism extending from Jurassic to Recent times. Subduction of the Pacific oceanic lithosphere beneath the continental margin developed after Late Jurassic volcanism in Alexander Island that was related to extension of the continental margin. Mesozoic ocean-floor basalts emplaced within the Alexander Island accretionary complex have compositions derived from Pacific mantle. The Antarctic Peninsula volcanic arc was active from about Early Cretaceous times until the Early Miocene. It was affected by hydrothermal alteration, and by regional and contact metamorphism generally of zeolite to prehnite–pumpellyite facies. Distinct geochemical groups recognized within the volcanic rocks suggest varied magma generation processes related to changes in subduction dynamics. The four groups are: calc-alkaline, high-Mg andesitic, adakitic and high-Zr, the last two being described in this arc for the first time. The dominant calc-alkaline group ranges from primitive mafic magmas to rhyolite, and from low- to high-K in composition, and was generated from a mantle wedge with variable depletion. The high-Mg and adakitic rocks indicate periods of melting of the subducting slab and variable equilibration of the melts with mantle. The high-Zr group is interpreted as peralkaline and may have been related to extension of the arc.

Chapter 4.1b Antarctic Peninsula: petrology

2021 ◽  
pp. M55-2018-40
Author(s):  
Malcolm J. Hole
Keyword(s):  
Antarctic Peninsula ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Passive Margin ◽  
Ridge Crest ◽  
Ridge Subduction ◽  
Simple Geometry ◽  
Key Issues ◽  
The Antarctic ◽  
Slab Window

AbstractScattered occurrences of Miocene–Recent volcanic rocks of the alkaline intraplate association represent one of the last expressions of magmatism along the Antarctic Peninsula. The volcanic rocks were erupted after the cessation of subduction which stopped following a series of northward-younging ridge crest–trench collisions. Volcanism has been linked to the development of a growing slab window beneath the extinct convergent margin. Geochemically, lavas range from olivine tholeiite through to basanite and tephrite. Previous studies have emphasized the slab-window tectonic setting as key to allowing melting of peridotite in the asthenospheric void caused by the passage of the slab beneath the locus of volcanism. This hypothesis is revisited in the light of more recent petrological research, and an origin from melting of subducted slab-hosted pyroxenite is considered here to be a more viable alternative for their petrogenesis. Because of the simple geometry of ridge subduction, and the well-established chronology of ridge crest–trench collisions, the Antarctic Peninsula remains a key region for understanding the transition from active to passive margin resulting from cessation of subduction. However, there are still some key issues relating to their tectonomagmatic association, and, principally, the poor geochronological control on the volcanic rocks requires urgent attention.

Ornithological observations at Eckener Point, Antarctic Peninsula

Polar Record ◽  
2009 ◽  
Vol 46 (3) ◽  
pp. 279-281 ◽  
Author(s):  
Eric J Woehler ◽  
Louise Blight ◽  
Ian Bullock
Keyword(s):  
Antarctic Peninsula ◽  
West Coast ◽  
Personal Communication ◽  
Avian Species ◽  
Nesting Habitat ◽  
The West ◽  
Lichen Diversity ◽  
Unpublished Report ◽  
Pygoscelis Antarctica ◽  
The Antarctic

Eckener Point (64° 26′S; 61° 36′W) lies on the northeast side of the entrance to Charlotte Bay and southeast of Murray Island, on the west coast of Graham Land, Antarctic Peninsula (Fig. 1). Data from a 1987 census (Woehler 1993) show 40 breeding pairs of chinstrap penguins Pygoscelis antarctica at the site. An unpublished report of 180 nests of blue-eyed cormorant Phalacrocorax atriceps/bransfieldensis (S Poncet, personal communication, 2004) in 1983 is the only other ornithological record for the site. Here we report on the results of a brief survey conducted to document the breeding seabirds for this locality. Suitable ice-free sites on the Antarctic Peninsula are limited, and Eckener Point, though small, provides nesting habitat for a high number of avian species. Plant and lichen diversity also appears unusually high.

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