Collections > Electronic Theses and Dissertations > Understanding plutonism in three dimensions: Field and geochemical relations on the southeast face of El Capitan, Yosemite Valley, CA

Detailed mapping of the spatial extents of exposed rock units on the vertical southeast face of El Capitan was completed to determine the chronology and geometry of emplacement. Field relations display a complex intrusive history at the point of interaction between two intrusive suites and two mafic dike swarms. Mapping revealed two sets of aplite dikes with trace element compositions suggestive of derivation from intrusive suite of Yosemite Valley or Buena Vista Crest magmas. Within the El Capitan and Taft Granites, 62 samples from multiple km-tall transects were analyzed for major- and trace-element abundances. Texture analysis was completed on 78 scale photographs of El Capitan Granite. No systemic variations in texture, mineralogy or chemistry were found in either the Taft or El Capitan Granites. These observations are consistent with incremental pluton assembly and are hard to reconcile with models for magma chambers that are envisioned as large, convecting, fractionating bodies.