Deep-Water, Shallow-Water, and Subaerial Island-Arc Volcanism: An Example from the Virgin Islands

1972 ◽  
pp. 401-414 ◽  
Author(s):  
Thomas W. Donnelly
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Virgin Islands ◽  
Island Arc ◽  
Arc Volcanism ◽  
Island Arc Volcanism

Detrital modes of the Riding Island Graywacke, north-central Newfoundland: evidence for deposition in a collisional successor basin in the Dunnage Zone

1994 ◽  
Vol 31 (1) ◽  
pp. 176-181 ◽  
Author(s):  
Gary G. Lash
Keyword(s):  
Volcanic Rocks ◽  
Island Arc ◽  
North Central ◽  
Arc Volcanism ◽  
Tectonic Environment ◽  
Complex Source ◽  
Island Arc Volcanism ◽  
Sandstone Provenance ◽  
Silicic Volcanic ◽  
Terrane Accretion

The Riding Island Graywacke (late Caradoc – Ashgill) crops out in Notre Dame Bay, north-central Newfoundland. Previous tectonic interpretations suggest that this succession of turbidites and hemipelagic mudstone accumulated in a basin adjacent to an active volcanic arc. The varied framework mineralogy of 29 Riding Island samples studied, however, records derivation from a complex source terrane composed of mafic and silicic volcanic rocks, sedimentary and metamorphic successions, and plutonic rocks. Assessment of the tectonic environment of deposition of the Riding Island Graywacke by use of popular sandstone provenance ternary diagrams yields ambiguous results. The mineralogy of the Riding Island samples reveals a change in tectonic scenario from one dominated by island-arc volcanism in pre-Caradoc time to a setting marked by tectonic shortening, transcurrent faulting, and terrane accretion near the end of the Ordovician. The complex composition of these sandstones and the fact that they accumulated after island-arc volcanism had ended argue for deposition in a collisional successor basin that formed during the early stages of mountain building along the proto-North American continental margin. This inferred Late Ordovician collisional successor basin may have also been the locus of deposition for other minera-logically complex late Caradoc – Ashgill units exposed in Notre Dame Bay, such as the Sansom Formation.

Geochronology and geochemistry of the South Scotia Ridge: Miocene island arc volcanism of the Scotia Sea

2021 ◽  
pp. 103615
Author(s):  
Teal R. Riley ◽  
Alex Burton-Johnson ◽  
Philip T. Leat ◽  
Kelly A. Hogan ◽  
Alison M. Halton
Keyword(s):  
Island Arc ◽  
The South ◽  
Scotia Sea ◽  
Arc Volcanism ◽  
Scotia Ridge ◽  
Island Arc Volcanism ◽  
South Scotia Ridge

The Twillingate Granite and nearby Volcanic Groups: An Island Arc Complex In Northeast Newfoundland

1975 ◽  
Vol 12 (6) ◽  
pp. 982-995 ◽  
Author(s):  
Harold Williams ◽  
John G. Payne
Keyword(s):  
Volcanic Rocks ◽  
Metamorphic Grade ◽  
Island Arc ◽  
Granitic Rocks ◽  
Arc Volcanism ◽  
Pillow Lavas ◽  
The North ◽  
Structural Style ◽  
Lower Ordovician ◽  
Island Arc Volcanism

The Twillingate Granite cuts mafic pillow lavas and silicic fragmental volcanic rocks of the Sleepy Cove Group. The granitic rocks are soda-rich and they vary from intensely foliated and mylonitic in the south to mildly foliated and massive toward the north. The Sleepy Cove volcanic rocks show similar structural and metamorphic variations from lineated amphibolitic pillow lavas, to elongated pillows of greenschist metamorphic grade, to slightly metamorphosed and relatively undeformed pillow lavas.The collective terrane occupied by the Twillingate Granite and Sleepy Cove Group is virtually surrounded by intrusive mafic dikes that are integral and coeval parts of the Moretons Harbour and Herring Neck Groups. The dikes decrease in abundance away from the contacts of the collective Twillingate – Sleepy Cove terrane. The essentially intrusive contact is modified by faults and locally, the profuse dike swarms are absent.Regional relationships, thickness, lithofacies, and petrochemistry all indicate that the Moretons Harbour and Herring Neck Groups relate to an episode of Lower Ordovician island arc volcanism. Intrusive relationships and contrasts in structural style and metamorphic grade indicate that the Twillingate Granite and Sleepy Cove Group are older. These older rocks are also interpreted as island arc derivatives, so that in their present position, they may represent the remnant of a partly deformed and metamorphosed older arc that is now bordered by relatively undeformed Lower Ordovician volcanic rocks.Similar relationships within transported sequences of western Newfoundland suggest a central Newfoundland island arc provenance for the transported Little Port Complex.

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