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Phanerozoic Androgenic Magmatism
Published in O.A. Bogatikov, R.F. Fursenko, G.V. Lazareva, E.A. Miloradovskaya, A. Ya, R.E. Sorkina, Magmatism and Geodynamics Terrestrial Magmatism Throughout the Earth’s History, 2020
Traps are very extensive areas of intrusive and volcanic rocks, mainly of basic composition, formed on stable cratons. Tholeiitic basalts are the predominant rock type, the composition of their major components being similar to those of MORB. As with other examples of intra-plate magmatism, they are associated with alkaline or even high-alkaline units. The boundary between continental flood basalts (CFB) and plateau basalts associated with the development of hot-spots is fairly arbitrary, being mainly determined by their scale of occurrence, which is relatively small in this case.
Scientific ocean drilling in the Australasian region: a review
Published in Australian Journal of Earth Sciences, 2022
Peirce et al. (1989) came to the following conclusions:The volcanism that built Ninetyeast Ridge probably formed topographically high centres, with lesser activity between these centres.The basaltic rocks are not primary magmas derived directly from the mantle, but moderately evolved (subalkaline) tholeiites, similar to those typical of many oceanic plateaus. Parenthetically, it is worth noting that the active volcanism on the Kerguelen Plateau is currently dominated by alkaline rocks (e.g. basanite and phonolite).All the sites received low sediment flux during the Eocene through middle Miocene. The sites were lying in paleopositions between 10° and 40°S and beneath the low-productivity, subtropical gyre.
Age and composition of dykes emplaced before and during the opening of the Tasman Sea—source implications
Published in Australian Journal of Earth Sciences, 2019
R. Offler, H. Zwingmann, J. Foden, F. L. Sutherland, I. T. Graham
The tholeiitic basalts are commonly amygdaloidal, show similar textures and mineralogy to the alkali basalts but lack kaersutite, biotite and analcime. Chlorite, mixed-layer clay (M/L; chlorite–smectite; Figure 2c) and calcite replace augite and the finer-grained minerals in the groundmass, and infill amygdules. Prehnite ± albite appears in some samples as aggregates replacing plagioclase.