Structure and emplacement of Buena Vista Crest Intrusive Suite, California

The 100 to 95 Ma Buena Vista Crest Intrusive Suite (BVCS) intruded slightly older plutons of the central Sierra Nevada batholith, including the intrusive suite of Yosemite Valley (YVIS). The main results of this study are: (1) Mingling of diorite host rock with the oldest phase of the BVCS and youngest phase of the YVIS implies that the two suites overlap in age. (2) There are two magmatic foliations in the granodiorite of Illilouette Creek of the BVCS; the dominant northwest foliation records regional strain and weaker east-west foliation records internal processes. Regional foliation in 92 Ma rocks to the north is east-west, indicating the regional strain field changed between 99 and 92 Ma. (3) Sharp truncation of host rock markers, irregular contacts between the BVCS and host rocks, and xenoliths in the BVCS indicate stoping was an important material transfer process during emplacement. Roof uplift also likely aided emplacement.