Northward Extension of the Rancho San Marcos Dike Swarm: In Search of Silicic Dikes in Alta California Phil Farquharson SDSU - Geology 640 Spring 2000
Introduction n Rancho San Marcos Dike Swarm - a source for silicic volcanism? n If so, where are the resulting volcanic rocks? n What should we be looking for? n Swarm truncated on the north and south - may find continuation in bedrock windows
Topics of Discussion n SMDS Description u Location u Age u Structure u Chemistry u Petrography (to be done…) n Lake Jennings n South of the Agua Blanca fault in Baja California
San Marcos Dike Swarm Description n A densely intruded, northwest-striking, predominantly silicic regional dike swarm. n Exposed over an approximately 100 km-long segment in the west-central portion of the Cretaceous Peninsular Ranges batholith (PRB) in northern Baja California.
San Marcos Dike Swarm Location
San Marcos Dike Swarm Age
San Marcos Dike Swarm Structure
San Marcos Dike Swarm Chemistry
San Marcos Dike Swarm Petrography Work in progress...
San Marcos Dike Swarm Pictures Rancho San Marcos Area
San Marcos Dike Swarm Pictures Ojos Negros Area
San Marcos Dike Swarm Pictures Ojos Negros Area
San Marcos Dike Swarm Pictures Ojos Negros Area
San Marcos Dike Swarm Pictures Ojos Negros Area
San Marcos Dike Swarm Pictures El Alamo Area
Northernmost Extent in Baja California
Lake Jennings n Mapped by Gastil et al., 1961 n Sampled by Kimbrough
Lake Jennings Area Topo Map
Lake Jennings Area Geological Map
Other Possible Areas to Examine:
The BIG Picture: Shuttle Photo: STS
Finis...