Bangweulu Block
Encyclopedia
The Bangweulu Block is a craton
ic unit that forms part of the Congo craton
of central Africa. The Bangweulu Block however consists of Palaeoproterozoic granitoids and volcanics, and is overlain by a Palaeoproterozoic continental sedimentary succession, the Mporokoso Group
, and does not preserve much direct evidence of Archaean protolith
s.
Indirect evidence of an Archaean ancestry for the Bangweulu Block is provided by detrital
zircon
s within the Mporokoso Group
, which indicate a local source area with zircons of 3.2, 3.0. 2.7 and 2.5 Ga, but more importantly, by xenocrystic zircon found in volcanic and granitic lithologies
of the Bangweulu Block, and the area to the West, the Central African Copperbelt (Rainaud et al., 2003), which indicate the presence of a ca. 3.2 Ga terrane called the Likasi Terrane.
Craton
A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...
ic unit that forms part of the Congo craton
Congo craton
The Congo craton, covered by the Palaeozoic-to-recent Congo basin, is an ancient Precambrian craton that with four others makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time...
of central Africa. The Bangweulu Block however consists of Palaeoproterozoic granitoids and volcanics, and is overlain by a Palaeoproterozoic continental sedimentary succession, the Mporokoso Group
Mporokoso Group
The Mporokoso Group is the name given to a sedimentary succession of fluvial, lacustrine and aeolian sandstones and minor siltstones occurring on the Bangweulu Block of northern Zambia....
, and does not preserve much direct evidence of Archaean protolith
Protolith
Protolith refers to the precursor lithology of a metamorphic rock.For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other rock and thus have a wide variety of protoliths. Identifying a protolith is a major aim of metamorphic geology.Sedimentary...
s.
Indirect evidence of an Archaean ancestry for the Bangweulu Block is provided by detrital
Detrital
Detritus is a geological term used to describe particles of rock derived from pre-existing rock through processes of weathering and erosion. Detrital particles can consist of lithic fragments , or of monomineralic fragments...
zircon
Zircon
Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...
s within the Mporokoso Group
Mporokoso Group
The Mporokoso Group is the name given to a sedimentary succession of fluvial, lacustrine and aeolian sandstones and minor siltstones occurring on the Bangweulu Block of northern Zambia....
, which indicate a local source area with zircons of 3.2, 3.0. 2.7 and 2.5 Ga, but more importantly, by xenocrystic zircon found in volcanic and granitic lithologies
Lithology
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of...
of the Bangweulu Block, and the area to the West, the Central African Copperbelt (Rainaud et al., 2003), which indicate the presence of a ca. 3.2 Ga terrane called the Likasi Terrane.