Professor of Marine Geophysics Specialties: Tectonics, Geophysics, Paleomagnetic and Potential Field Methods brief Curriculum Vitae last update August 2010
	Bruce Luyendyk on stern of icebreaker N.B. Palmer in western Ross Sea. Ross Island in background.	Office: Webb 2036 Phone: (805) 893-3009 or 893-3471 E-mail: luyendyk@geol.ucsb.edu

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	Studies in the Ross Sea and Marie Byrd Land, West Antarctica.
	Geology of western Marie Byrd Land My Antarctic work started with a multifaceted project aimed at understanding the effects of mid-Cretaceous Gondwana rifting on western Marie Byrd Land in West Antarctica. This region borders the Ross Sea rift, one of the larger regions of extended crust on Earth. The study focused on a metamorphic culmination in the Fosdick Mountains of the northern Ford Ranges. Our studies included field mapping, isotopic age dating, on-ice gravity, and paleomagnetic studies. Gondwana rifting here included a massive thermal event and exhumation of the Fosdick Metamorphic complex to within a few kilometers of the surface between 105 and 94 Ma. The thermal event remagnetized virtually the entire upper crust. Gravity data suggest basin-and-range structure throughout western MBL. They also reveal troughs of possible glacial origin in the continental margin extending from onshore to beneath the bordering ice shelf. Air-ground study of tectonics at the boundary between the eastern Ross Embayment and western Marie Byrd Land This project was collaborative between myself, Doug Wilson of UCSB, and Christine Siddoway of Colorado College. We conducted a combined airborne and ground geological-geophysical study of the boundary between the Ross Sea Rift and western Marie Byrd Land (MBL). Our study used the SOAR facility aircraft (Support Office for Aerogeophysical Research). The SOAR system comprises carrier-phase differential GPS, 1.7 kW laser altimeter, 10 kW ice-penetrating radar, towed proton magnetometer, and a Bell BGM-3 gravimeter. We flew 37,000 km2 at a spacing of 5.3 km with 15.6 km tie lines, and 86,000 km2 with a 10.6 x 10.6 km spacing. Our study includes aerogeophysics combined with on-ground geology. Our rationale for a combined program is the complete coverage of crustal-scale structure from the airborne geophysics, and mountain-range and outcrop scales from the geologic field work. During the 1998/99 season the SOAR group finished flying the project area in western Marie Byrd Land (green boxes show our MBL survey, red and blue are other WANT surveys - image from M. Studinger). The survey area covers the Edward VII Peninsula, the Ford Ranges and a large portion of the West Antarctic Ice Sheet. Within this region are included 12 survey blocks about 112 km on a side. During December and January the SOAR Twin Otter aircraft acquired airborne magnetic, gravity, laser elevation, and radar ice thickness on flights over the survey area. Results of this survey are found in Luyendyk et al. (2003). Marine geology in the Ross Sea My Antarctic research group conducted a marine geology and geophysics study of the Ross Sea and Marie Byrd Land during 1996, 2003, and 2004 using the icebreaker Nathaniel B. Palmer. This project had as goals determining the glacial marine stratigraphy and mapping shallow structure which may have resulted from rifting episodes in the Ross Sea. We made the first geophysical exploration of the continental margin of western Marie Byrd Land. We found major extensional faults cutting the continental shelf that predate the Neogene glaciation here.  These form half-grabens that have subsequently routed the flow of glaciers across the shelf during the last glacial maximum. In 1996 we also conducted a site survey for the Cape Roberts Drilling Project offshore from the Transantarctic Mountains in southern Victoria Land. Our site survey was a critical component to siting the drill holes for this project. In addition, our data provided a meaningful context for the drilling results. By our interpretation we have identified a major fault zone along the Transantarctic Mountains front. And, we have shown structural evidence for the timing of uplift of these mountains during Oligocene time. In 2003 and 2004 we took the Palmer on a cruise to the far southeastern Ross Sea to investigate an area of sea floor recently exposed by the break-off of giant iceberg B-15 et al. This project is exploring the new ground in preparation for drilling into the sea floor at a future date with the ANDRILL project. GPS Measurement of Isostatic Rebound and Tectonic Deformation in Marie Byrd Land, West Antarctica In December of 1998 we installed an array of three continuously operating autonomous Global Positioning System (GPS) stations in Marie Byrd Land, West Antarctica to measure glacio-isostatic rebound and tectonic deformation. The autonomous systems were designed and constructed by the project collaborator Andrea Donnellan at the Jet Propulsion Lab and installed by her team. GPS measurements collected between 1999 and 2002 indicate no significant present motion between East and West Antarctica greater than 1–2 mm/year. Low strain rates imply that the Ross Sea rift is either inactive or active at a very low rate. This result indicates that the two subcontinents are likely joined as a single coherent lithospheric plate. They could have been joined since the end of Adare Trough spreading in Oligocene time. The volcanic activity in the Ross Sea sector at present such as at Mount Erebus is most likely related to mantle upwelling and not associated with continental rifting. GPS measurements of vertical rates indicate postglacial rebound of up to 12+/-4 mm/year in western Marie Byrd Land (wMBL). Errors are scaled 1sigma. The rock uplift rates are consistent with postglacial rebound models of significant ice thinning in the eastern Ross Ice Shelf in the late Holocene. The GPS stations (seen here in Rockefeller Mountains) gathered data for four years, and were installed in concert with a series of autonomous stations in the Transantarctic Mountains, resulting in an unprecedented long baseline array across the Ross Embayment. See Donnellan and Luyendyk (2004) for a review of the findings. All of the above projects are supported by the Office of Polar Programs, NSF.
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	Marine hydrocarbon seeps off Coal Oil Point, Santa Barbara.
	(to see a copy of Luyendyk letter to the Santa Barbara County Board of Supervisors on the relationship between oil production (drilling) and decreasing seepage; click HERE). (To visit our Seeps Project page click HERE). Our project is studying the natural marine hydrocarbon seeps offshore from UCSB. We are employing a multidisciplinary approach including marine geophysics, marine chemistry, ocean engineering, and physical oceanography. Prolific natural hydrocarbon seepage occurs offshore from Coal Oil Point. Most of the seepage occurs in the form of gas bubble plumes which rise through the water column and vent into the atmosphere. The gas bubbles at the ocean surface contain 60% methane, 10% non-methane hydrocarbons, and 30% air. During gas bubble rise, the hydrocarbons partially dissolve in sea water while air is absorbed. Oil contained in the rising bubbles is left on the sea surface as slicks. The oil slicks gradually lose volatiles and become tar balls, eventually washing onto southern California beaches. The locations of the seeps are determined using sonar surveys controlled by differential GPS. In situ gas chromatograph observations are used to map the dissolved hydrocarbon plume which extends several km down-current from the vents. Oceanographic conditions are determined from high resolution CTD surveys, and moored vector-measuring and acoustic Doppler current meters. Preliminary analysis indicates that 1) the dissolved hydrocarbon concentration in the ocean is proportional to the gas seepage rate and inversely proportional to current velocity, 2) the seep gas flux has decreased ca. 50% over 22 years within one km of oil platform Holly, possibly correlating with a decrease in subsurface reservoir pressure due to oil production, and, 3) aqueous CO2 and H2 anomalies 2x and 100x above background, respectively, are associated with the dissolved hydrocarbon plumes and are interpreted to be due to oxidation of hydrocarbons by bacteria in the ocean. Our current research focuses on advanced sonar methods of mapping seep gas plumes, determining sub-seafloor structure of the seep fields, estimating seepage rates, monitoring time variations, determining the evolution of the oil slicks on the surface and hydrocarbon plumes in the water column, and analyzing the amounts and variation of beach tar accumulation from seeps. We are establishing a baseline for long-term studies of variations in seep chemistry, intensity, and location. Research supported by the UC Energy Institute, Petroleum Research Foundation, California State Lands Commission, National Science Foundation, NASA, and the US Minerals Management Service.
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	Paleomagnetism and Tectonics of southern California and Mojave Desert.
	This research is concerned with the rotation of large regions of crust in southern California during the last 20 million years. It has been ongoing since 1975. During the last few years I have been concentrating on two aspects: 1) crustal rotations in the Mojave Desert; and 2) a synthesis of data and their evaluation (Luyendyk, 2001). In the Mojave my students and I discovered a crustal rotation event which had occurred between 22 and 18 million years ago. This is much earlier than the rotation event we had been studying in the Transverse Ranges and elsewhere in southern California. We completed a study of the tectonics in the northern Mojave Desert that found significant clockwise block rotations since 11 Ma (Schermer et al., 1996). Research also has been aimed at determining an accurate geochronology for volcanism and rotation events in southern California. Phil Gans, Marc Kamerling, and I conducted a project to date our extensive collection of southern California Neogene volcanic rocks by the 40Ar/39Ar method. This project has made a major impact on the volcanic stratigraphy of southern California and its connection with plate tectonic history, particularly the transition from subduction to transform margin (Luyendyk et al. 1998 in CV). Research supported by Earth Sciences Division, NSF, and the UCSB Academic Senate.
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	Tectonics of the South Pacific Ocean - Manihiki Plateau and Tongareva Triple Junction
	The Manihiki Plateau is a submerged volcanic feature covering an immense area about the size of Texas in the southwest Pacific, east of the Samoa Islands (161 W, 10-23 S). Investigations so far indicate it originated in Early Cretaceous time (ca. 124 million years ago) from the rapid outpouring of lavas onto the sea floor. It shares characteristics of other volcanic plateaus in the southwest Pacific including the Ontong-Java and Hikurangi Plateau. The latter submerged plateau, located adjacent to New Zealand, has been proposed to be a matching part of the Manihiki Plateau that rifted away from it via plate tectonics soon after formation. Other hypotheses state the plateaus evolved separately and were never connected. The project described here was conducted by me and a group of seven undergraduates from the department of Geological Sciences, along with Rob Clayton, Joann Stock, and graduate students from Caltech. We used the R/V Roger Revelle of the Scripps Inst. of Oceanography to make a geophysical survey of the Plateau to determine how it fits into the Mesozoic history of the southwest Pacific. Techniques we used include multibeam sonar echo sounding, seismic reflection, and magnetics and gravity field measurement. We combined our data with that from researchers at Rhode Island to complete an analysis of triple junction tectonics during the mid-Mesozoic (Larson et al. 2002). Recently we published an account of the subsidence history of the Manihiki Plateau based on seismic stratigraphy (Huirong et al. 2008).