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A layered intrusion is a large sill -like body of igneous rock which exhibits vertical layering or differences in composition and texture. These intrusions can be many kilometres in area covering from around 100 km 2 (39 sq mi) to over 50,000 km 2 (19,000 sq mi) and several hundred metres to over one kilometre (3,300 ft) in thickness. [1]
Setting. The Windimurra Igneous Complex is part of the c. 2813 Ma Meeline Suite of mafic-ultramafic layered intrusions of the central Murchison Domain, Yilgarn Craton of Western Australia. [1] It is a conical body, approximately 7 km thick, primarily composed of layered gabbroic rocks, which intrude into c. 2820 Ma Norie Group rocks of the ...
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta -igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are usually composed of greater than 90% mafic minerals (dark colored, high magnesium and iron content).
Secondly, large ultramafic intrusions are rarely sealed systems and may be subject to regular injections of fresh, primitive magma, or to loss of volume due to further upward migration of the magma (possibly to feed volcanic vents or dyke swarms). In such cases, calculating magma chemistries may resolve nothing more than the presence of these ...
The Great Dyke is a strategic economic resource with significant quantities of chrome and platinum. Chromite occurs to the base of the Ultramafic Sequence and is mined throughout the dyke. [ 4 ] Below the Ultramafic-Mafic sequences' contact, and in the uppermost pyroxenite (bronzitite and websterite) units are economic concentrations of nickel ...
Komatiite / koʊˈmɑːtiˌaɪt / is a type of ultramafic mantle -derived volcanic rock defined as having crystallised from a lava of at least 18 wt% magnesium oxide (MgO). [1] It is classified as a 'picritic rock'. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content.
Serpentinite is formed by near to complete serpentinization of mafic or ultramafic rocks. [8] Serpentinite is formed from mafic rock that is hydrated by carbon dioxide-deficient sea water that is pressed into the rock at great depths below the ocean floor. [9] This occurs at mid-ocean ridges and in the forearc mantle of subduction zones. [10] [11]
The largest layered mafic intrusions are tens of kilometers in size and almost all are Proterozoic in age, e.g. the Stillwater igneous complex (Montana), the Muskox intrusion (Canada), and the Great Dyke (Zimbabwe). Cumulate dunite may also be found in ophiolite complexes, associated with layers of wehrlite, pyroxenite, and gabbro.