February 18, 2006 Vol. 2, N o. 3 BENEATH THE SOUTHERN CALIFORNIA REGION EVOLUTION OF THE DEEP CRUST AND UPPER MANTLE

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1 Newsletter Inland Empire Chapter News Southern Section, Association of Environmental and Engineering Geologists Newsletter Editor: Rick Gundry, POB 8944 Moreno Valley, CA (951) February 18, 2006 Vol. 2, N o. 3 BENEATH THE SOUTHERN CALIFORNIA REGION EVOLUTION OF THE DEEP CRUST AND UPPER MANTLE Thursday 2-Mar-2006 (Not Wednesday 15-Mar-06) 5:30-6:30 Geologist Orientation Restaurant Bar/Banquet Room 6:30-6:45 Meeting Opening (Business) Banquet Room 6:45-7:30 Dinner Banquet Room 7:30-8:45 Speaker Presentation Banquet Room Marie Calender Restaurant Banquet Meeting Cost: $23 (includes tax/gratuity/special desert) (Fund-raising donation suggested is $5.00, or more) (RSVP/Directions below) Dear AEG Members: This months meeting is a joint meeting with the Inland Geological Society on the 1 st Thursday of the month (2-Mar-05) and not the 3 rd Wednesday (please take Note of this!). We anticipate a very large number of professionals attending! RSVP: please COB 23-Feb-06 (Thursday) rick.gundry@verizon.net or call: voice This Months Guest Speaker: Dr. Jason Saleeby Professor of Geology Division of Geological and Planetary Sciences Institute of Technology Evolution of the Deep Crust and Upper Mantle Beneath the southern region Page 1

2 Abstract Deep-level basement exposures (30-35 km) into the Cretaceous magmatic arc of the SW Cordillera are preserved in the southernmost Sierra Nevada, Santa Lucia Range (Salinia), central Mojave Desert and eastern San Gabriel Mountains areas. Lower crust-upper mantle xenoliths that were entrained in late Cenozoic lavas are widespread in the southern Sierra Nevada, Owens Valley and Mojave Desert regions. Integration of regional structural and petrogenetic data on the deep-level exposures, and petrogenetic data on the xenoliths offer an opportunity to reconstruct the evolution of the southern arc-generated lithosphere. Further integration with regional geophysical data bring to focus the current evolutionary state of the lithosphere, and further reveal a complex tectonic history during which structural inheritance in the basement plays a crucial role. The xenolith data in conjunction with batholith petrogenetic data record the production of a highdensity mantle lithosphere beneath the batholithic belt generated within the mantle wedge environment in conjunction with arc magmatism. A full km thick section of felsic crust was generated along the batholithic belt above this mantle lithosphere section during the Cretaceous. It thus appears that the batholithic belt represents the products of complete lithosphere reconstitution above the subducting Farallon plate. The main residue assemblage created during felsic melt production in the batholith was rich in eclogitic assemblages, which when added to the hosting mantle wedge peridotites, rendered the sub-batholithic uppermost mantle gravitationally metastable. In the Late Cretaceous such mantle lithosphere was sheared off beneath the southernmost Sierra, Mojave/Salinia (restored) and San Gabriel Mountains (restored) regions by an anomalously low-dipping segment in the Farallon plate. During this regime of low-angle subduction the lower crust was reconstructed by the tectonic underplating of Franciscan-affinity subduction accretion assemblages. Xenolith data in the Mojave Desert region record further reconstitution of the mantle lithosphere by the subduction underplating of Farallon plate abyssal peridotites, and by the subsequent inflow of subcontinental asthenosphere. By use of relative plate motions, palinspastic restorations and structural chronology this low-angle subduction regime can be tracked eastward into the North American plate interior as the latest Cretaceous- Paleogene Laramide orogeny. The residual sub-batholithic mantle lithosphere segments that survived the Laramide regime remained metastable beneath the greater Sierra Nevada and northern Peninsular Ranges through much of the Cenozoic. However, they have been recently mobilized as critical elements of the Pliocene-Quaternary deformational regime of southern. As a result of Neogene slab window migration beneath the southern Sierra, and possibly high magnitude extension immediately to the east (Death Valley corridor), the Sierran residual mantle lithosphere was mobilized westward as a high-density drip structure. Replacement by buoyant asthenosphere has resulted in the current phase of accelerated Sierra Nevada uplift. As the Peninsular Ranges have moved northward along the San Andreas fault, and impinged on the western Mojave-southern Sierra region, its mantle lithosphere appears to have delaminated and descended northward deeper into the mantle as a second drip-like structure centered beneath the eastern Transverse Ranges. The question posed by these regional relations is: could the big bend in the San Andreas fault and the related Transverse Ranges convergence zone be the result of the plate juncture deforming in response to the impingement of these second order upper mantle (drip) structures. Speaker Biography: CalTech for over a decade, previously Professor at University of, Santa Barbara Page 2

3 Message from the President Please see AEG Inland Empire Chapter webpage at AEG Southern Section Web-site: Short Course Announcement Geology Continuing Education Series* GIS Applications in Geology and Groundwater Studies March 4, 2006, Saturday (9am to 5pm) UC Riverside Extension Center Riverside, CA Enrollment/Information Flyer (see web link) Register by Ph (951) (8am-7pm) Eight Speakers - focused topics Thanks to the 20 Professionals who participated in this meeting (see note, below), as follows: Jim Madden (Speaker), Leighton; Scott Mathis, Leighton; Pat McNamarra, Leighton; Richard Orr, Leighton; Warham Stringer; Leighton; Bob Riha, Leighton; Kristin Stout, Leighton; Kevin Clark, LGC-Inland; Dennis Bohme, AMEC; Gary Wallace, RMA Group; Justin Koralski, RMA Group, Dave Darrow, GEOCON; Jamie Nichols, GEOCON; Gene Lewis, GMU Geotechnical; Phuong Chau, Leighton; Dr. Kerry Cato, Cato Geosciences; Mike Cook, Kleinfelder; Bob Mutchnick, GMU Geotechnical; Dave Amlborn, EARTH TECH; Roderick Marcus, Leighton. (Note, those not signed-in could not be listed - I counted 22 and the server thought there were 23) $65 Members $65 Non-Members $10 Students (enroll / attend, refund of $10) - Lunch and Parking fee included Sponsored by Inland Geological Society and AEG Inland Empire Chapter in cooperation with Department of Earth Sciences, Univesrity of, Riverside. Presiding Instructor: Dr. Tien Lee, UCR Professor of Geophysics and Hydrogeology, Department of Earth Sciences. Thanks Nearly all the attendees were Members of AEG. What a reunion for an incredible turn out of Leighton Group employees, of Leighton Consulting and Leighton and Associates, Inc. Serving professionals in Ground-Water, Environmental and Engineering Geology Page 3

4 Directions to Meeting The meeting location is in Ontario,, just north of the Ontario Airport, and south of the I-10 just east of Vineyard Avenue in Ontario,. Marie Calenders, Ontario 2149 Convention Center Way Ontario, CA (909) If proceeding west on I-10 towards Ontario, proceed west past I-215 and then I-15, and begin looking for Haven Avenue and then Archibald Avenue. Take Ontario Airport exit which is Holt Avenue Exit, and follow to eventually cross westerly and southerly under I-10 and proceed to either Guasti Road (or E. Convention Center Drive) to turn right, or proceed further to Vineyard Avenue and turn right. If turning right on Convention Center (Gusti) proceed northwesterly to around E. D. Street to prepare to enter Marie Calender parking area. If proceeding north on Vineyard, turn right (east) on Convention Center Drive and proceed past Dearborn Court, and prepare to turn into Marie Calender parking area by E. D. Street. If proceeding south on I-15 check you map to take I-210 west to Vineyard to go south to the I-10, and proceed past I-10 and immediately turn left (east) on Convention Center Drive to Marie Calenders (see instructions above). Or taking I-15 south, proceed to I-10, and converge to I-10 west, and follow directions described above. If proceeding east on I-10 or I-210, continue into Ontario looking for Ontario airport and Vineyard Avenue, and turn (south) on Vineyard, to cross under I-10 to turn immediateyy left (east) on Convention Center Drive to tun into Marie Calender parking area (see directions above). If proceeding from U.S. Hywy 91 north (east),when in Corona take I-15 north to I-10 (west) and proceed west and follow directions above. (There other ways to do this, at tour skill or risk. If proceeding east on U.S Hywy 60, when in Ontario take Grove Steer Exit, and turn left (north), proceed north to E. Holt Boulevard (before reaching I-10) and turn right (east) on Holt to eaither Vineyard or (E. Guasti Road/ Convention Center Drive)(see directions above). If proceeding west on U.S. Hywy 60 proceed west from Riverside, or west from I-15 and take I-15 (north) and follow directions above; or, continue west past I-15 and exit at Haven Avenue. Proceed north to Guasti (before getting to I-10) to turn left (west) and proceed to either Convention Center Drive of Vineyard Avenue (see directions above). If proceeding north on I-215, follow the directions immediately above. If proceeding north on I-15 towards Corona, continue past Corona and take heading approaching the Ontario area (several avenues of approach indicated above based on other major freeways. RSVP Please: RSVP by THURSDAY, February 23, 2006: send RSVP to Rick Gundry at COB 23- FEB-06, or call RSVP (951) to leave message. IMPORTANT! This meeting may fill-up fast and to the brim. Late RSVP is your risk, but if there is room available, we will honor late RSVP (but we need to get the bulk of numbers to restaurant for their ordering and prep-work Thanks. Page 4

5 Next Meetings APR Wednesday APR 19, 2006 Temecula - Marie Calenders/ Grill(?) Artificial recharge through a thick, heterogeneous unsaturated zone along Oro Grande Wash, western Mojave Desert, Dr. John A. Izbicki, U.S. Geological Survey, Water Resources Division, San Diego, MAY Wednesday MAY 17, 2006 Colton - Pinnacle Peak BBQ Steakhouse Dealing with uncertainty regarding the chemistry of drinking water wells an example from the City of Riverside Dr. Matt Werner, Sr. Project Director, Earth Tech, Long Beach, (part of focus is perchlorate anion) Rick Gundry Treasurer rick.gundry@verizon.net (951) ,x257 Mike Cook Secretary MCook@kleinfelder.com (909) Connecting Professionals, Practice and the Public JUNE Thursday JUN 22, 2006 Temecula - (location to be decided) Stringfellow (West Riverside) (subject) Jo Aldern, Kleinfelder and Associates, Inc. THIS IS CANCELLED BUT WE WILL MEET WITH A DIFFERENT SPEAKER AND TOPIC Note: Speaker suggestions? contact R. Gundry Contact Information, AEG Inland Empire Chapter Gary Wallace, President Gary@rmap.com (909) Scott Mathis VicePresident, So. Sector SMathis@leightongeo.com (951) Doug Cook VicePresident, No. Sector DCook@sladdenengineering.com (760) The Association of Environmental and Engineering Geologists (AEG) contributes to its members Professional success and the public welfare by providing leadership, advocacy and applied research in environmental and engineering geology. Page 5

6 Corporate and Individual Petras Sponsor PETRAS Sponsors for Inaugural Year "Petras" is a Latin term for a large rock edifice, monolith or massif of strength (eg., Rock of Gibralter), as different to "petros", a term for a rock or stone, something one can pick up. It can mean something like a cornerstone, such as one set for the foundation of a building something strong and set first from which a foundation is built for a larger structure needing the strength. GOLD PETRAS SPONSOR John Gregg, Gregg Drilling and Testing, Inc, Gregg In Situ, Inc, Signal Hill, SILVER PETRAS SPONSOR Roy J. Shlemon, Ph.D., Newport Beach, Arlan Ruen, Ruen Drilling International, Inc., Ruen Driling, Inc, Clark Fork, Idaho and Modesto, Antony Martin, GEOVision Geophysical Services Services, Inc, Corona, Richard R. Gundry, Agency Water Rights Hydrologist, Southern Agency, U.S. Bureau of Indian Affairs, Riverside, Joe Aldearn, Regional Manager, Kleinfelder Inland Empire, Redlands, PETRAS SPONSOR Richard L. Orr, Leighton Group Of Companies, Leighton and Associates, Inc. Rancho Cucamonga, N. Thomas Sheahan, Vice President, Geomatrix Consultants Inc., Inland Empire Office, Corona, Steven C. Suitt, Principal, Steven C. Suite and Associates, Canyon Lake, Kerry Cato, Ph. D., President, Cato Geosciences, Inc., Temecula, Jeffrey R. Keaton, Ph. D., Senior Principal Engineering Geologist, MACTEC Engineering and Consulting, Inc., Los Angeles, Robert Riha, Manager, Leighton Consulting, Temecula, We are continuing to seek sponsors in our inaugural year, as we only were a fiment of imagination late last March The distinguishing point is donations that recognize interest and generosity building Page 6

7 foundational financial support to the Inland Empire Chapter in this inaugural year. And, ones that certainly take an immediate, bold and positive step. A solid contribution or donation if $50.00 or more is Petras Sponsor. Other, smaller donations are requested, and are as important. All donors will be recognized. New categories of Sponsors are Silver Petras Sponsor ($250 or more); Gold Petras Sponsor ($500 or more); and Platinum Petras Sponsor ($1,000 or more). If you would like to make a foundational donation, please send them to the address listed in this Newsletter *Geology Continuing Education Series University of, Riverside - UC Extension Center Quarterly One-Day Short Courses are focused to geologically-related subjects of interest to the southern community. Some will be centered on particular geologic issues, and some will be aligned with specific geologic applications to a variety of earth sciences issues and problems. Speakers are comprised primarily of experts from professional services industries and government, and from academic institutions. Courses presided by a coordinating instructor. We are continuing to provide these courses for communication and dialogue among students, teachers, educators and professionals alike in discussions and learning about various geologic problems and issues in southern. In the same venue will be a forum for exchange of information and cross-fertilization between professionals, educators, teachers and students. The cost structure employed is structured at a low cost to all, and also to provide qualified students an opportunity for free short courses upon enrollment, attendance, and successful completion. We are seeking your input (suggestions/ideas) for future topics and any suggested speakers for those topics. We would like to hear your suggestions/ideas concerning topics/problems involving geologic hazards issues; engineering geology and geotechnical issues; economic/mining geology and mineral resources issues; environmental and contaminant hydrogeology issues; groundwater and water rights issues; flood and debris issues; hill-side development and alluvium fan development issues; and land-planning and land use issues in the context of earth-science issues and problems. Please feel free to add to the list and let us know (as indicated below). Inland Geological Society and AEG Inland Empire Chapter in cooperation with the Department of Earth Sciences, University of, Riverside, are Co-sponsoring the ongoing short course series quarterly over the next few years. Our collective interest is to provide an opportunity for certain specialized and focused education, and generate interest and participation in learning and discussion and communication participation by students, consultants, business, industry, government, individuals, and academic institutions and researchers. If you have questions, comments, suggestions or ideas, please contact Phuong Chau or Rick Gundry, Program Chairpersons: (PChau@LeightonGeo.com or Rick.Gundry@verizon.net). Watch for information for the upcoming 20-May 2006 topic: Regulatory Issues Page 7