Hastings Natural History Reservation

04 Oct, 02 PM - 06 Oct, 02 AM

Understanding the origin of continents is a fundamental issue in geology. The average continental crust is intermediate in composition. Cordilleran-type batholiths represent aerially tremendous tracts of petrogenetically young sialic basement extending along the entire western margin of the Americas. Cordilleran-type batholiths also represent the best Phanerozoic analogues to the average upper-crustal composition of continental masses. Therefore it has been proposed that continental convergent margins represent the main sites of crustal differentiation and growth. Observations of magmatism in continental arcs and batholiths and derivative petrogenetic models come principally from upper- to mid-crustal levels exposed at the Earth's surface. These observations are complemented by experimental studies of the plausible sources and liquid line of descent of arc magmas. Many of the first order questions regarding the origin of large granitic batholiths and their relevance to crustal growth have not been uniquely answered by these constraints, in particular, the relative importance of contributions from the mantle wedge underlying arcs, pre-existing continental crust, or the subducting oceanic crust. This uncertainty leaves unresolved the extent to which the continental crust is internally differentiated or largely extracted from the mantle during arc magmatism. Whether continents grow at convergent sites, and by what mechanism and with what rates, remain open questions. Major batholithic belts of North and South America have been studied in great detail. What commonly escapes observation and prevents us from unique interpretations are the deeper crustal counterparts of the well-studied shallow batholithic exposures. Rare exposures of deeper crustal levels in arc terranes provide important insights into the nature of the lower crust of the North-American Cordillera and a testing ground for most hypotheses on the rates and mechanisms of continental growth in arcs. The current field trip focuses on one such exposure- the Salinian Arc of West-Central California. The field trip will bring together researchers from a number of Western U.S. institutions as well as German researchers, and it?s purpose is to explore the current issues of continental arcs in a field trip setting. LOCATION OF FIELD AREA The field area is a scattered throughout the Santa Lucia Range. Potential field trip stops within the reserve will depend on exposure and ease of access, and will be determined after discussion with reserve staff. ANIMAL AND PLANT POPULATIONS THAT MAY BE AFFECTED BY THE PROPOSED CLASS There are no expected affects on animal or plant populations as a result of this field trip. ANY POTENTIAL DISTURBANCES TO THE RESERVE'S ECOSYSTEM OR CULTURAL RESOURCES None expected. HOUSING OR OTHER RESOURCES NEEDED Housing for 15-16 is requested. No other special resources are requested.

Visit #1935 @Hastings Natural History Reservation

Approved

Under Project # 1556 | Class

University of Arizona - Geosciences

graduate_student - California Institute of Technology

Reservation Members(s)

Group of 24 Undergraduate Student Oct 4 - 6, 2003 (3 days)

Reserve Resources(s) | Create Invoice

Bunk House Cottage 24 Oct 4 - 6, 2003
Ranch House 24 Oct 4 - 6, 2003