Ensialic origin for the Ngezi Group, Belingwe greenstone belt, Zimbabwe

Volcanic rocks of the Ngezi Group in the Belingwe greenstone belt have been interpreted as continental basalts extruded onto, or oceanic crust obducted onto, a succession of stable-shelf sedimentary rocks that nonconformably overlie continental basement. The volcanic succession locally contains quar...

Full description

Saved in:
Bibliographic Details
Published in:Geology (Boulder) 1993-12, Vol.21 (12), p.1135-1138
Main Authors: Blenkinsop, Tom G, Fedo, Christopher M, Bickle, Michael J, Eriksson, Kenneth A, Martin, Anthony, Nisbet, Euan G, Wilson, James F
Format: Article
Language:English
Subjects:
Africa
Archean
autochthons
Belingwe greenstone belt
continental crust
crust
folds
geochemistry
Geology
granitic layer
greenstone belts
igneous and metamorphic rocks
lithogeochemistry
lithostratigraphy
mapping
metamorphic belts
metamorphic rocks
metavolcanic rocks
Ngezi Group
Petrology
Precambrian
Southern Africa
Stratigraphy
Structural geology
subaerial environment
subaqueous environment
terrestrial environment
volcaniclastics
Volcanoes
Zimbabwe
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Volcanic rocks of the Ngezi Group in the Belingwe greenstone belt have been interpreted as continental basalts extruded onto, or oceanic crust obducted onto, a succession of stable-shelf sedimentary rocks that nonconformably overlie continental basement. The volcanic succession locally contains quartzose sandstones, and the stratigraphy is unlike ocean crust. Primary volcanic and sedimentary structures indicate a shallow-subaqueous to subaerial origin. All structural features are compatible with later refolding of an autochthonous successon; there is no structural manifestation of obduction. These criteria refute an oceanic setting for the volcanic rocks; rather, they are consistent with an ensialic origin for the Ngezi Group.
ISSN:0091-7613
1943-2682
DOI:10.1130/0091-7613(1993)021<1135:EOFTNG>2.3.CO;2