Appearance: Dark green or greenish black coloured, medium or coarse grained intrusive igneous rock. Compositionally similar to diorite but the anorthite content of plagioclases is more than 50mol%.
Essential minerals: Ca-rich plagioclase, clino- and/or orthopyroxene, olivine, amphibole
Accessory minerals: apatite, magnetite, ilmenite; and may contain less amount of quartz, alkali feldspar or olivine and feldspathoids
Secondary minerals: chlorite, titanite, serpentine group minerals, epidote
Rock types (variations):
norite: orthopyroxene and plagioclase bearing gabbro
troctolite: olivine and plagioclase bearing, pyroxene poor gabbro
anorthosite: gabbro containing more than 90% Ca-rich plagioclase
Considering the presence of quartz or feldspathoid, and the relative proportion of alkali feldspar and plagioclase we can differentiate varieties of gabbros such as monzogabbro, quartz-gabbro and quartz-monzogabbro as well as foid-gabbro, foid-bearing gabbro, foid-bearing monzogabbro and foid-monzogabbro.
Locations in the Carpathian-Pannonian region: Tardos and Tóbérc quarries (SW-Bükk, close to Szarvaskő; Early Jurassic), boreholes around Darnó-hill (Triassic), ophiolites at the Maros valley (Apuseni Mts., Jurassic).
Appearance: Dark, mostly aphyric rock with minor amount of phenocrysts (mostly olivine, rarely clinopyroxene and/or plagioclase). The effusive equivalent of gabbro. It occurs almost every plate-tectonic setting.
Essential minerals: olivine, Ca-rich plagioclase, clinopyroxene
Accessory minerals: spinel (usually as inclusions in olivine and clinopyroxene), apatite, magnetite, ilmenite, nepheline and leucite (in alkaline basalts), K-feldspars (in Si-saturated basalts), rarely amphibole
Secondary minerals: serpentine group minerals, chlorite, carbonate materials
alkali basalt: Si-undersaturated basalt with feldspathoids (nepheline or leucite). Olivine often occurs as phenocrysts occasionally with clinopyroxenes
tholeiitic basalt: Si-saturated or oversaturated basalts. Ol-tholeiites contain olivine phenocrysts along with clinopyroxene and plagioclase, whereas quartz-tholeiite does not contain olivine but instead orthopyroxene appears. Quartz may be present in the groundmass.
calc-alkaline basalt: the most frequent phenocrysts are clinopyroxene, occasionally with orthopyroxene and/or amphibole with fairly abundant plagioclase. Olivine could be also present.
basanite: Si-undersaturated alkaline mafic rocks with typically less SiO2 content then the basalts. The normative olivine content is higher than 10 wt%. Feldspathoids are usually present in the groundmass.
tephrite: Si-undersaturated alkaline mafic rocks with normative olivine content less than 10 wt%. Feldspathoids are usually present in the groundmass.
trachybasalt: plagioclase-phyric basalts with higher alkaline content than the normal basalts. The sodic trachybasalt is called hawaiite (plagioclase, anorthoclase, olivine, clinpyroxene, biotite). It is often difficult to recognize them petrographically, therefore bulk rock major element compositional data are necessary.
Pcrite: olivine-rich basaltic rocks. Although their major element composition, particularly the relatively low SiO2 content, indicates ultrabasic character, it is not the effusive equivalent of the peridotites, but rather a rare primitive variety of basaltic rocks. The high MgO and the low SiO2 contents can be explained by the abundance of olivines, both phenocrysts and xenocrysts. Picritic magmas are usually formed at high pressure and high temperature with high degree of melting of the upper mantle rocks.
Ankaramite: clinopyroxene and olivine-phyric (clinopyroxene>>olivine) varity of basalt
Formation of basaltic rocks:
Locations in the Carpathian-Pannonian region: Boreholes at Darnó hill and Bódva valley (Triassic to Jurassic); Szarvaskő (Early Jurassic); Maros valley (Apuseni; Jurassic); Eastern Mecsek and basement of the Great Hungarian Plain (Early Cretaceous); Miocene-Quaternary alkali basalt volcanic fields: Styrian basin (4.9-1.9 Ma), Burgenland (11.5-11.0 Ma), Kemenesalja (5.5-4.5 Ma), Bakony-Balaton Upland (7.9-2.6 Ma), Nógrád-Gömör (7-0.4 Ma), Selmec (7 és 100 ezer év), Persány (1.2-0.6 Ma). Calc-alkaline basalts: Vlchi vrch, Ziar nad Hronom (Central Slovakian volcanic field; 9-10 Ma), Sárospatak borehole (9 Ma)
Miocene-Quaternary basalts – Styrian basin
Miocene-Quaternary basalts – Kemenesalja and the Bakony-Balaton Upland: