scholarly journals The Ordovician Thores volcanic island arc of the Pearya Terrane from northern Ellesmere Island formed on Precambrian continental crust

Lithos ◽  
2021 ◽  
Vol 386-387 ◽  
pp. 105999
Author(s):  
Jarosław Majka ◽  
Karolina Kośmińska ◽  
Jakub Bazarnik ◽  
William C. McClelland
Keyword(s):  
Continental Crust ◽  
Ellesmere Island ◽  
Island Arc ◽  
Volcanic Island

The Thores volcanic island arc of the Pearya Terrane from Ellesmere Island formed on Precambrian continental crust

2021 ◽  
Author(s):  
Jarosław Majka ◽  
Karolina Kośmińska ◽  
Jakub Bazarnik ◽  
William C. McClelland
Keyword(s):  
Continental Crust ◽  
High Arctic ◽  
Sensu Stricto ◽  
Ellesmere Island ◽  
Island Arc ◽  
Fault System ◽  
Published Data ◽  
Island Arcs ◽  
Volcanic Island ◽  
National Science

<p>We report on U-Pb zircon dating and bulk rock geochemistry results of intermediate to felsic rocks of the Thores Suite of the Pearya Terrane, northern Ellesmere Island (Arctic Canada).  Our new results together with the previously published data show that the Thores Suite was formed in the Early Ordovician (c. 490-470 Ma) as a part of an island arc. Some of the dated samples revealed common xenocrystic zircon. The latter yielded ages ranging between c. 2690 Ma and c. 520 Ma. The obtained ages of xenocrystic zircon are interpreted to be typical of Laurentia. We propose that the youngest obtained cluster of ages c. 580-570 Ma expresses a component typical for the Timanide Orogen, which is conventionally tied to Baltica. The newdataset sheds light on the history and understanding of the Thores Suite, which used to be explained as an effect of the M’Clintock orogenesis. The latter event was commonly presented as foreign to the major Caledonian orogenesis sensu stricto. In our view, the Thores Suite represents an island arc, which was formed on a fragment of continental crust dismembered during Iapetus opening. Importantly, the age of the Thores island arc is coeval with other island arcs and high pressure metamorphic units of the Scandinavian and Svalbard Caledonides. Thus, it is likely that the Thores volcanic island arc was a part of the larger arc system operating within northern Iapetus. The juxtaposition of the Thores arc with the other successions of the Pearya Terrane is ascribed to a major sinistral strike-slip escape fault-system developed along the northeastern margins of Baltica and Laurentia, broadly concurrent with the main Scandian collision between the two aforementioned continents. This crustal scale fault structure enabled the juxtaposition of numerous crustal blocks of different Precambrian ancestry that can be found in various regions of the current High Arctic, including Svalbard, Greenland and Ellesmere Island.</p><p>This research was supported by the National Science Centre (Poland) project no. 2015/17B/ST10/03114 and the internal AGH-UST funding to J. Majka, the internal grant of the Polish Geological Institute - NRI no. 62.9012.2014.00.0 to J. Bazarnik and the National Science Foundation (USA) grant EAR1650022 to J. Gilotti and W. McClelland.</p>

Observations in the South Sandwich Islands, 1962

Polar Record ◽  
1963 ◽  
Vol 11 (73) ◽  
pp. 394-405 ◽  
Author(s):  
M. W. Holdgate
Keyword(s):  
Island Arc ◽  
Deep South ◽  
Volcanic Island ◽  
The South ◽  
The West ◽  
Antarctic Region ◽  
South Sandwich Islands ◽  
Scotia Arc ◽  
The Antarctic ◽  
North And South

The South Sandwich Islands lie between lats. 56° 18′ S. and 59° 28′ S., and between longs. 26° 14′ W., and 28° 11′ W. There are eleven islands, of which ten form a curved chain stretching north and south while the eleventh, Leskov Island, lies to the west of the group near its northern end. The group is the only typical volcanic island arc in the Antarctic region and forms the easternmost section of the Scotia Arc; to the east it is bounded by the associated deep South Sandwich Trench.

Evidence for an incipient early Caledonian (Cambrian) orogenic phase in southwestern Norway

1983 ◽  
Vol 120 (6) ◽  
pp. 607-612 ◽  
Author(s):  
H. Furnes ◽  
H. Austrheim ◽  
K. G. Amaliksen ◽  
J. Nordas
Keyword(s):  
Continental Crust ◽  
Early Phase ◽  
Island Arc ◽  
Volcanic Complex ◽  
Northern Norway ◽  
Middle Ordovician ◽  
Minimum Age ◽  
Norwegian Caledonides

Summary. Quartz-keratophyres from an ensimatic island arc on Bømlo, southwest Norwegian Caledonides, resting on the Lykling ophiolite, have yielded a Rb/Sr whole rock age of 535 ± 46 Ma. This Cambrian age, which is a minimum age of formation for the ophiolite, indicates an early phase of subduction, corresponding with the orogenic activity known from northern Norway, i.e. the Finnmarkian. Before Middle Ordovician time, the ophiolite and ensimatic arc had been obducted onto continental crust and deformed, as they are unconformably overlain by a volcanic complex of subaerial rhyolites and andesites which have yielded Rb/Sr whole rock ages of 464 ± 16 and 468 ± 23 Ma respectively.

Timing of events in an Early Cretaceous island arc–marginal basin system on South Georgia

1979 ◽  
Vol 116 (3) ◽  
pp. 167-179 ◽  
Author(s):  
P. W. G. Tanner ◽  
D. C. Rex
Keyword(s):  
Continental Crust ◽  
Island Arc ◽  
Magmatic Arc ◽  
South Georgia ◽  
Marginal Basin ◽  
Early Mesozoic ◽  
Mafic Complex ◽  
Minimum Age ◽  
Radiometric Ages ◽  
Basin System

Summary19 new K–Ar mineral ages of 78-201 Ma and 3 Rb–Sr whole rock isochron ages of 81 ± 10, 127±4 and 181±30 Ma are presented from units of continental crust, mafic complex and island arc assemblage on South Georgia. The Drygalski Fjord Complex, part of the possible floor of the marginal basin in the southern part of the island, includes granodiorite and gabbro plutons of minimum age 180–200 Ma. Together with older metasediments they have been affected by a major thermal event at about 140 Ma, thought to have resulted from the emplacement of a mafic complex (Larsen Harbour Formation) during the initial opening of the marginal basin. Rocks of the Larsen Harbour Formation are cut by the Smaaland Cove intrusion dated by Rb–Sr whole rock isochron at 127±4 Ma. An island arc assemblage exposed to the SW of South Georgia consists of pyroclastic rocks cut by monzodiorite and andesite intrusions, which give radiometric ages of 81–103 Ma. These data suggest that the marginal basin opened during the late Jurassic (pre-140 Ma); that part of an earlier (early Mesozoic) magmatic arc is preserved in continental crust making up part of the floor of the basin; and that subduction continued beneath the island arc until at least the Senonian time. The younger plutons in the arc were emplaced at roughly the same time as turbidite facies rocks at deep levels in the marginal basin were being affected by penetrative deformation and metamorphism. The timing of events on South Georgia agrees closely with that deduced for the continuation of the same island arc–marginal basin system in South America. The 180–200 Ma plutons correlate with an older suite of plutonic rocks reported from the Antarctic Peninsula and southern Andes; they are part of a once-continuous magmatic arc related to subduction of the Pacific plate beneath Gondwanaland during the early Mesozoic.

A Late Mesozoic island arc in the southern Andes, Chile

1979 ◽  
Vol 116 (3) ◽  
pp. 181-190 ◽  
Author(s):  
M. Suárez
Keyword(s):  
Continental Crust ◽  
Rift Zone ◽  
Volcanic Rocks ◽  
Upper Jurassic ◽  
Island Arc ◽  
Volcanic Complex ◽  
Late Mesozoic ◽  
Marginal Basin ◽  
The Pacific ◽  
Pacific Side

SummaryThe Hardy Formation, a sequence of Upper Mesozoic volcanic rocks exposed in Peninsula Hardy (Isla Hoste) in the southernmost archipelago of Chile represents, at least in part, the island-arc assemblage of an island-arc-marginal-basin system related to an eastward dipping subduction zone. This island arc was founded on South American continental crust and is also represented in the island of South Georgia 2000 km to the E. The island-arc assemblage includes pyroclastic rocks, characterized by a high proportion of vitric material, and lava intercalations ranging in composition from rhyolite to basalt. These rocks underwent zeolite and prehnite-pumpellyite facies metamorphism and are gently folded, in contrast with the intense folding exhibited by the rocks exposed to the north of Peninsula Hardy. Silicic volcanics assigned to this assemblage underlie pillow lavas, and are intruded by dolerites and gabbros probably related to a Late Jurassic-Early Cretaceous ophiolite magmatism associated with the generation of a quasioceanic marginal basin. Volcanic turbidites (Yahgan Formation) were deposited into the marginal basin.It is suggested that in pre-marginal basin times the Hardy Formation interfingered towards the Atlantic with the silicic volcanics of the Tobifera Formation. However, recent geochemical work on the Tobifera Formation suggest an origin by continental crust anatexis in a volcano-tectonic rift zone related to upper mantle diapirism, whereas an island arc origin is favoured for at least the andesitic and basaltic components of the Hardy Formation. Therefore, the geology of Peninsula Hardy as presented here, confirms early assumptions of the splitting apart of a Middle–Upper Jurassic volcanic terrain along the Pacific margin of South America during the generation of a marginal basin. The spreading axis of the latter seems to have been located at the boundary of two somewhat overlapping petrotectonic assemblages: and island arc on the Pacific side and a silicic volcano-tectonic rift zone towards the Atlantic. A probably Cenozoic volcanic complex discordantly overlies the Yahgan and Hardy formations.

scholarly journals PENENTUAN PROVENANCE SATUAN BATUPASIR FORMASI NANGGULAN DENGAN MENGGUNAKAN METODE DICKINSON (1985)

2018 ◽  
Vol 2 (1) ◽  
pp. 25
Author(s):  
Yohanes Arifin De Sousa
Keyword(s):  
Island Arc ◽  
Volcanic Island

Daerah penelitian secara administratif terletak di daerah Kalisongo, Kecamatan Nanggulan, Kabupaten Kulon Progo. Penelitian ini bertujuan untuk mengetahui keadaan geologi seperti provenance, iklim, relief dan kemiringan satuan batupasir Formasi Nanggulan, mengacu pada beberapa ahli seperti Dickinson (1985)Metode penelitian yang digunakan adalah pemetaan geologi permukaan yang meliputi beberapa tahapan, yaitu tahap pra-lapangan, tahap pemetaan geologi permukaan, tahap analisis laboratorium, dan tahap penyusunan laporan. Dari beberapa data diatas dilakukan analisis  provenance dengan menggunakan mineral kuarsa, feldspar dan fragmen batuan atau lithic yang di plotkan dalam segitiga QFL.Berdasarkan hasil pengeplotan mineral penyusun batuan dari Formasi Nanggulan bahwa kedudukan umum tektonik daerah asal batuan adalah Transition Arc (Volcanic Island Arc), Sedangkan batuan asalnya besaral dari pencampuran antara batuan plutonik, batuan vulkanik maupun batuan piroklastik. Dan juga iklim, topografi dan kemiringan daerah asal batuan yaitu beriklim panas dan lembab, sedangkan bentuk topografi dan kemiringan asal batuan yaitu sedang-curam, dilihat dari bentuk mineral kuarsa dan fragmen.Kata Kunci: Provenance, Formasi Nanggulan, Metode Dickinson (1985)

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