Mafic igneous rocks

Mafic igneous rocks
State Texas
Name Mafic igneous rocks
Geologic age preCambrian (Proterozoic)
Lithologic constituents
Major
Igneous > Plutonic > Gabbroic (Stock or pipe)metagabbro in stock or laccolith
Igneous > Plutonic > Dioritic (Laccolith)also metadiorite
Minor
Metamorphic > Amphibolite (Amphibolite)hornblendite
Comments Chiefly diorite, hornblendite, metagabbro, and metadiorite; occurs as linear to equidimensional bodies chiefly in SE part of Llano region (from Llano Sheet of Geologic Atlas of Texas, 1981)
References

Bureau of Economic Geology, 1981, Llano sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000.

Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.

NGMDB product
Counties Gillespie - Llano