Experience of petrochemical typification of acid volcanic rocks from different geodynamic settings

2013 ◽  
Vol 7 (3) ◽  
pp. 212-216 ◽  
Author(s):  
A. V. Grebennikov ◽  
V. K. Popov ◽  
A. I. Khanchuk
Author(s):  
A.I. Malinovsky ◽  

The article discusses the results of studying heavy clastic minerals from the Cretaceous sandy rocks of the West Sakhalin Terrane, and also presents their paleogeodynamic interpretation. It is shown that in terms of mineralogical and petrographic parameters, the terrane sandstones correspond to typical graywackes and are petrogenic rocks formed mainly by destruction of igneous rocks of the source areas. The sediments were found to contain both sialic, granite-metamorphic association minerals, and femic, formed by products of the destruction of basic and ultrabasic volcanic rocks. The interpretation of the entire set of data on the content, distribution and microchemical composition of heavy minerals was carried out by comparing them with minerals from older rocks and modern sediments accumulated in known geodynamic settings. The results obtained indicate that during the Cretaceous, sedimentation occurred along the continent-ocean boundary in a basin associated with large-scale left-lateral transform movements of the Izanagi Plate relative to the Eurasian continent. The source area that supplied clastic material to that basin combined a sialic landmass composed of granite-metamorphic and sedimentary rocks, a mature deeply dissected ensialic island arc, and fragments of accretion prisms, in the structure of which involved ophiolites.


1905 ◽  
Vol 2 (12) ◽  
pp. 541-549 ◽  
Author(s):  
J. R. Dakyns ◽  
Edward Greenly ◽  
J. R. Dakyns

There are several kinds of acid volcanic rocks in Wales. In the X neighbourhood of Snowdon there are at least five kinds, as follows:1. There are undoubted lavas, showing lines of viscous flow and sometimes vesicular, and weathering into cubical blocks. Such may be seen on Crib Goch and on Crib Yddysgl, on Cerrig Cochion, and elsewhere. These rocks are rarely cleaved.2. There are rocks like the last as to fracture and mode of weathering, but which are neither viscous nor vesicular. They are probably masses of felsitic dust or mud. Such may be seen in Cwm Llan.3. There are also massive felstones, rudely cleaved, such as form Moel Meirch. and Clogwyn Llwyd.4. There are the so-called ashes of various kinds, usually wellbedded and often highly cleaved.5. Lastly, there are highly cleaved felsitic rocks, which show no lines of viscous flow, are generally unbedded, and which are in many places fragmentary.


1980 ◽  
Vol 22 (12) ◽  
pp. 1437-1442
Author(s):  
N. V. Koronovskiy ◽  
E. D. Fromberg
Keyword(s):  

2007 ◽  
Vol 13 ◽  
pp. 53-56 ◽  
Author(s):  
Henrik Stendal ◽  
Anders Scherstén

During the field campaign in the Nuuk region, one of the objectives was to describe Archaean primary geological environments (Hollis et al. 2006). On Nunatak 1390, which is part of the Tasiusarsuaq terrane (Figs 1, 2), a bi modal volcanic succession is preserved and interpreted as former ocean floor. The field investigation included geological mapping and sampling of the volcanic sequence comprising mafic to ul tra mafic rocks, and associated acid volcanic rocks and granite intrusions.


1989 ◽  
Vol 145 ◽  
pp. 45-49
Author(s):  
L.M Larsen ◽  
A.K Pedersen

During field work in 1988 in eastern Disko we encountered redeposited volcanoclastic sediments with acid rocks at several localities between Rensdyrdalen and Charles Polaris Dal within lava sequences from the Nordfjord Member of the Maligât Formation. Some of the sediments were only observed during helicopter reconnaissance of steep inaccessible walls and corries, while other sites provided detailed information and samples through field visits. Fig.1 shows the area with newly discovered acid volcanic rocks in eastern Disko. Localities 1 and 2 denote localities investigated in some detail. In north-western Disko peraluminous rhyolite tuffs and conglomerates with almandine-bearing rhyolite blocks occur as widespread but minor deposits in the Nordfjord Member (Pedersen, 1977; Hansen & Pedersen, 1985; Pedersen & Pedersen, 1987). The acid rocks contain graphite and scarce sediment xenoliths and they are associated with contaminated basalts, andesites and dacites, same af which carry nativc iran. The distribution af airfall rhyolite tuff shows that the aciel rocks were erupted somewhere in north-western Disko or in the present shallow sea west af this arca. No eruption sites are exposed at present.


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