Its geology consists of the formation known as the Old Volcanic Complex formed between 3 to 2 million years ago, it consists of basanite, tephrite and phonolite rocks.
22.
Formed of basanite, it's a remnant of a basaltic lake formed of solidified lava and is the site of the most recent volcanic activity in the range.
23.
Alkaline basalt, lesser hawaiite and basanite magmas from effusive eruptions create the massive shield volcanoes and small cinder cones throughout the volcanic province, several of which comprise lherzolite magma.
24.
The mineral assembly is usually abundant feldspathoids ( nepheline or leucite ), plagioclase, and augite, together with olivine and lesser iron-titanium oxides such as ilmenite and magnetite-ulvospinel; minor alkali feldspar may be present, as illustrated by the position of the field for basanite in the QAPF diagram.
25.
The term " basanite " has occasionally been used to refer to a variety of jasper, a black flinty or cherty jasper found in several New England states of the US . Such varieties of jasper are also informally known as " lydian stone " or " lydite " and have been used as touchstones in testing the purity of precious metal alloys.
26.
The Cenozoic platform ( which is also known as the " unconsolidated rock " level because the Cenozoic sedimentary rocks, due to their young age, have often not experienced intensive diagenesis and are therefore often not SiO 2-rich ) volcanic rocks of the transition level, the Cenozoic formations are mostly intermediate to very SiO 2-poor ( trachyte, basalt, phonolite, tephrite, nephelinite and basanite ).
