Batholiteina

Batholiteina is a term found in certain geological discussions to describe a proposed category of very large intrusive igneous bodies, analogous to batholiths, but not recognized as an official rock or mineral category by major reference works. The name blends batholith with a suffix that signals a collective or class, but its usage is informal and not standardized.

Definition and usage: In informal usage, batholiteina refers to granitoid plutons of exceptional size and crustal significance, typically spanning many tens to hundreds of square kilometers and emplaced at considerable depth. There is no universally accepted set of criteria, and the term has varied usage across studies.

Composition and texture: Rocks described as batholiteina, when discussed conceptually, resemble granitic to granodioritic compositions, with dominant quartz and feldspar, and common mafic minerals such as biotite or amphibole. They are expected to be coarse-grained due to slow cooling, reflecting prolonged crystallization at depth. Accessory minerals may include zircon and allanite; isotopic systems can record late-stage crystallization or magmatic differentiation.

Occurrence and examples: Batholiteina is not an officially recognized category, so there are no formal exemplars. In some regional syntheses, authors use the term loosely to refer to prominent batholith-scale complexes in orogenic belts, but these are typically described using standard terminology.

Formation and significance: The concept implies long-lived crystallization of a large magma chamber at crustal depths, followed by uplift and exposure. If formalized, batholiteina could help distinguish unusually large plutons from smaller intrusions in studies of crustal evolution.

See also: Batholith, Pluton, Intrusive rock, Granitoid.