Oliv-Cpx-Qtz Pseudo-ternary Diagram with 1 atm. Petrography and chemistry of minerals show that rocks of Upper Eocene in northeast of Tafresh are composed mostly of andesitic basalt, basaltic andesite and andesite volcanic rocks. Mg is thus relatively abundant in mafic/basic igneous rocks, but also in granite and granodiorite in form of biotite. the Callahan Lava Flow, a Basaltic Andesite from Medicine Lake Shield Volcano, California. olivine and (ortho-)pyroxene, or under ‘wet’ conditions (high water and oxygen fugacity) as amphibole and mica. In magmatic rocks, Mg has crystallized relatively early as high-temperature minerals, e.g. However, calcite (CaCO 3) can incorporate Mg into its crystal lattice to a certain amount leading to the differentiation of low-Mg calcite ( 5 mol% MgCO 3) (which is reflected in the ‘calcite – aragonite sea’ cycles, e.g., Sandberg, 1983, Stanley et al., 2010). One rock sample is not allowed to contain both of them. Note that quartz and feldspathoids are mutually exclusive. Q, A, P, and F correspond to quartz, alkali feldspar, plagioclase, and feldspathoids, respectively. Andesite (Ab70-50) Labradorite (Ab50-30) Bytownite (Ab30-10) Anorthite (Ab10-0) All members of the plagioclase series, however, crystallize in the triclinic symmetry. QAPF diagram for plutonic rocks is a double ternary plot. Mg-bearing carbonate minerals are mainly dolomite (CaMg(CO 3) 2), ankerite (Ca(Fe,Mg,Mn)(CO 3) 2), and magnesite (MgCO 3). A ternary diagram, based on these three endmembers, can therefore represent the feldspar compositions accordingly (Figure 1). Authigenic minerals may include carbonate minerals, such as dolomite, ankerite, and magnesite.ĭue to its strong affinity with phyllosilicates (clay and mica minerals) and the instability of most of the igneous minerals (olivine, amphibole, pyroxene), Mg concentrations are commonly higher in ‘shales’ than in sandstones. Mg is commonly associated with clay minerals, such as chlorite and smectite, mica e.g., biotite and glauconite (the latter an indicator for marine origin), as well as olivine (e.g., forsterite), amphibole, pyroxene, spinel, and garnet (e.g., pyrope). In siliciclastic sediments, the mineral assemblage can comprise detrital and authigenic minerals.
#ANDESITE TERNARY DIAGRAM SERIES#
A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. The drawing to the left has only the skeleton of the triangle present as we concentrate on point A. The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. We are going to take the diagram apart to see how it works.
For the moment they are labeled A, B, and C. Most common element – mineral associations: Sedimentary rocks can have a diverse range of Mg-bearing minerals. A ternary diagram is a triangle, with each of the three apexes representing a composition, such as sandstone, shale, and limestone. Mg has one main oxidation stage, +2, and is the eighth-most abundant element in the Earth’s crust. Magnesium (symbol Mg atomic number 12 relative atomic mass 24.305)