New Discovery and Tectonic Significance of Paleogene Volcanic Rocks in Nulei Area, Ritu County, Tibet

2019 ◽  
Vol 09 (10) ◽  
pp. 996-1005
Author(s):  
业斌 肖
Keyword(s):  
Volcanic Rocks ◽  
Tectonic Significance ◽  
New Discovery

The tectonic significance of Ordovician basic igneous rocks in the Southern Uplands, southwest Scotland

1995 ◽  
Vol 132 (5) ◽  
pp. 549-556 ◽  
Author(s):  
E. R. Phillips ◽  
R. P. Barnes ◽  
R. J. Merriman ◽  
J. D. Floyd
Keyword(s):  
Volcanic Rocks ◽  
Accretionary Prism ◽  
Igneous Rocks ◽  
Geochemical Data ◽  
Published Data ◽  
Volcanic Material ◽  
Tectonic Significance ◽  
Arc Setting ◽  
Back Arc ◽  
Midocean Ridge

AbstractIn the northern part of the Southern Uplands, restricted volumes of basic igneous rocks occur at or near the base of the Ordovician sedimentary strata. These rocks have previously been interpreted as ocean-floor tholeiites representative of the subducted Iapetus oceanic plate, preserved as tectonic slivers in a fore-arc accretionary prism. The alternative, back-arc basin model proposed for the Southern Uplands on sedimentological evidence raises questions over the origin of these rocks. New geochemical data and previously published data clearly indicate that the volcanic material does not have a simple single source. The oldest (Arenig) volcanic rocks from the Moffat Shale Group associated with the Leadhills Fault include alkaline within-plate basalts and tholeiitic lavas which possibly display geochemical characteristics of midocean ridge basalts. In the northernmost occurrence, alkaline and tholeiitic basalts contained within the Caradoc Marchburn Formation are both of within-plate ocean island affinity. To the south, in the Gabsnout Burn area, the Moffat Shale Group contains lenticular bodies of dolerite and basalt which have characteristics of island-arc to transitional basalts. This complex association of basaltic volcanic rocks is, at the present time, difficult to reconcile with either a simple fore-arc or back-arc setting for the Southern Uplands. However, the increasing arc-related chemical influence on basic rock geochemistry towards the southeast may tentatively be used in support of a southern arc-terrane, and as a result, a back-arc situation for the Southern Uplands basin. An alternative is that these volcanic rocks may represent the local basement to the basin and include remnants of an arc precursor to the Southern Uplands basin.

Deformational geometry and tectonic significance of a portion of the Chilliwack Group, northwestern Cascades, Washington

1988 ◽  
Vol 25 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Moira Smith
Keyword(s):  
High Pressure ◽  
Volcanic Rocks ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
North Cascades ◽  
Clastic Rocks ◽  
Tectonic Significance ◽  
Group A ◽  
Event Based

The northwestern Cascades structural province can be interpreted as an accretionary complex comprising fault-bounded blocks of pre-Tertiary metamorphic rocks of diverse age and lithologic type. This paper documents the deformation in a portion of the Chilliwack Group, a unit in this complex. The Chilliwack Group is a thick sequence of volcaniclastic sedimentary rocks, calc-alkaline volcanic rocks, and limestone that is metamorphosed to low-grade blueschist facies. The rocks underwent ductile deformation during a Late Cretaceous orogenic event, producing a subhorizontal foliation and, in appropriate lithologies, subhorizontal stretching lineations that trend N20°W. Finite strain sustained by coarse clastic rocks produced RXZ values averaging 3.5. The deformation at least partially postdates the high pressure metamorphic event, based on the presence of bent and broken high-pressure mineral grains. Although early studies postulated west-vergent thrust imbrication of units in the northwest Cascades, the N20°W direction of apparent elongation in the Chilliwack Group, consistent with the direction of motion along segments of the Shuksan fault elucidated in other more recent studies, may reflect significant, highly oblique components of convergence during formation of the western North Cascades collisional orogen.

Geochemistry, petrogenesis and tectonic significance of the volcanic rocks of the Las Tortolas Formation, Coastal Cordillera, northern Chile

2018 ◽  
Vol 87 ◽  
pp. 66-86 ◽  
Author(s):  
Paulina Fuentes ◽  
Juan Díaz-Alvarado ◽  
Natalia Rodríguez ◽  
Carlos Fernández ◽  
Christoph Breitkreuz ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Northern Chile ◽  
Coastal Cordillera ◽  
Tectonic Significance

Tectonic Significance of Upper Cambrian–Middle Ordovician Mafic Volcanic Rocks on the Alexander Terrane, Saint Elias Mountains, Northwestern Canada

2012 ◽  
Vol 120 (3) ◽  
pp. 293-314 ◽  
Author(s):  
Luke P. Beranek ◽  
Cees R. van Staal ◽  
Sarah M. Gordee ◽  
William C. McClelland ◽  
Steve Israel ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Middle Ordovician ◽  
Upper Cambrian ◽  
Tectonic Significance ◽  
Alexander Terrane
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