Deep structure of the central Lesser Antilles Island Arc: Relevance for the formation of continental crust

2011 ◽  
Vol 304 (1-2) ◽  
pp. 121-134 ◽  
Author(s):  
H. Kopp ◽  
W. Weinzierl ◽  
A. Becel ◽  
P. Charvis ◽  
M. Evain ◽  
...  
Keyword(s):  
Continental Crust ◽  
Deep Structure ◽  
Island Arc ◽  
Lesser Antilles

scholarly journals Deep structure of an island arc backstop, Lesser Antilles subduction zone

2003 ◽  
Vol 108 (B7) ◽  
Author(s):  
Gail L. Christeson ◽  
Nathan L. Bangs ◽  
Thomas H. Shipley
Keyword(s):  
Subduction Zone ◽  
Deep Structure ◽  
Island Arc ◽  
Lesser Antilles

scholarly journals The Hindu Kush slab break-off as revealed by deep structure and crustal deformation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofia-Katerina Kufner ◽  
Najibullah Kakar ◽  
Maximiliano Bezada ◽  
Wasja Bloch ◽  
Sabrina Metzger ◽  
...  
Keyword(s):  
Real Time ◽  
Penetration Depth ◽  
Continental Crust ◽  
Crustal Deformation ◽  
Deep Structure ◽  
Continental Collision ◽  
Variable Degree ◽  
Finite Frequency ◽  
Hindu Kush ◽  
Short Times

AbstractBreak-off of part of the down-going plate during continental collision occurs due to tensile stresses built-up between the deep and shallow slab, for which buoyancy is increased because of continental-crust subduction. Break-off governs the subsequent orogenic evolution but real-time observations are rare as it happens over geologically short times. Here we present a finite-frequency tomography, based on jointly inverted local and remote earthquakes, for the Hindu Kush in Afghanistan, where slab break-off is ongoing. We interpret our results as crustal subduction on top of a northwards-subducting Indian lithospheric slab, whose penetration depth increases along-strike while thinning and steepening. This implies that break-off is propagating laterally and that the highest lithospheric stretching rates occur during the final pinching-off. In the Hindu Kush crust, earthquakes and geodetic data show a transition from focused to distributed deformation, which we relate to a variable degree of crust-mantle coupling presumably associated with break-off at depth.

scholarly journals Ancient xenocrystic zircon in young volcanic rocks of the southern Lesser Antilles island arc

Lithos ◽  
2017 ◽  
Vol 290-291 ◽  
pp. 228-252 ◽  
Author(s):  
Yamirka Rojas-Agramonte ◽  
Ian S. Williams ◽  
Richard Arculus ◽  
Alfred Kröner ◽  
Antonio García-Casco ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Island Arc ◽  
Lesser Antilles

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.

Nd and Sr isotope geochemistry of island arc volcanics, Grenada, Lesser Antilles

1979 ◽  
Vol 45 (2) ◽  
pp. 237-248 ◽  
Author(s):  
C.J. Hawkesworth ◽  
R.K. O'Nions ◽  
R.J. Arculus
Keyword(s):  
Isotope Geochemistry ◽  
Island Arc ◽  
Lesser Antilles ◽  
Sr Isotope

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.

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