BH250-114
Title
Subject
Description
Minor Mineral: chlorite
BH250-114 chemically plots in the basaltic andesite field on a TAS (Total Alkali-Silica) diagram. Basaltic andesite is an intermediate volcanic rock that bridges the compositional gap between basalt and andesite. It plays a significant role in igneous petrology, particularly in subduction-related volcanic arcs.
This rock type is characterized by an intermediate silica content, typically ranging from 52–57 wt% SiO₂—richer in silica than basalt, but less than true andesite. Other key chemical features include moderate alkali levels and variable magnesium and iron contents, reflecting processes like fractional crystallization and magma mixing.
Sample BH250-114 exhibits a fine-grained (aphanitic) texture, consistent with rapid cooling at or near the Earth’s surface. This texture, along with its chemistry, supports its classification as a basaltic andesite and highlights its origin from a volcanic arc tectonic setting.