The Wolf Mountain Intrusion

• Several intrusive phases including two phases of coarse-grained porphyritic granites (I & II), fine to medium-grained pink equigranular granites and several distinct sets of pegmatitic, aplitic, or granitic dikes.
• Unusual chevron shape (phacolith)
• Higher percentage of mafic minerals than most granites in the Llano Uplift.
• Occurs in a southeast-plunging syncline at or near the boundary between two major lithological packages (Valley Spring Gneiss & Packsaddle Group)

The Principal Question:
What is the Timing Relationship between intrusion and folding?

possibilities:

1) Granite was intruded as a sill-like body and then folded.

2) Granite was passively intruded during folding, with folding producing space.

3) Granite was forcibly intruded after folding, merely taking the form of the beds it intruded.