XIXI ZHAO Research Geophysicist, Earth & Planetary Sciences Paleomagnetism and Regional Tectonics
		Office: EMS C320 Phone: 831-459-5827 Fax: 831-459-3074 E-mail: xzhao@es.ucsc.edu Lab: Paleomag. Lab x9-4847		For more information: • Website

Education and Training

B.S., M.A. University of Science and Technology of China
Ph.D., University of California, Santa Cruz

Research Interests

Xixi Zhao's research interests encompass a wide variety of problems related to the Earth history. He is a geophysicist and applies paleomagnetism to tectonics, paleogeography, stratigraphy, and paleoclimatology.

Tectonics

Xixi Zhao's interests continue to focus on understanding the tectonics and paleogeography of eastern Asia, particular on China and Siberia. Because of their central positions and their myriad crustal sutures, China and Siberia hold keys to the past configuration of eastern Asia. During the past 18 years, he and his colleagues have been working on the problems of the amalgamation of major Chinese block (i.e., north and south China, and Tarim) and their accretion to Siberia. Field work and sample collections have ranged over almost all of east Asia: from South Korea in the east to Kazakhstan in the west, and from southern Siberia in the north to Tibet in the south. His current projects on tectonic studies include integrated paleomagnetic and isotopic study of Siberian Traps in Siberian platform and its western margin (to examine the Siberian superplume vs continental rifting hypotheses), a tectonic study of Mesozoic volcanic and sedimentary strata in the Transbaikalia region, SE Siberia (to study the closing history of Mongol-Okhotsk Ocean and intraplate tectonic movements in Siberian block), and an ntegrated paleomagnetic study along the Trans-Mexican Volcanic Belt in Mexico (to test the hypothesis and assess the timing of large-scale left-lateral displacement along the belt).

Magnetostratigraphy

The reversals of the Earth's magnetic field and the record of alternating polarity in rocks have allowed the establishment of synchronous time horizons of very high resolution on a world-wide base. In the lab, Xixi Zhao and his colleagues carry out magnetostratigraphic studies on samples from marine cores and from land outcrops. They have studied the Cenozoic magnetostratigraphy of the North Aoba Basin in Fuji and the Iberia Abyssal Plain off the coast of Portugal. His newest magnetostratigraphic project involves basin evolution of the Hoh Xil basin in northeastern Tibet to further our understanding about the extent of India-Asia collision and other fine level of neotectonic features that are characteristic of the tectonic evolution of this part of Asia. He also served as shipboard scientist on six Ocean Drilling Program cruises that focused on problems in marine geology, plate tectonics, and paleoclimatology.

Paleointensity

Measurements of the intensity of the earth's magnetic field in the geologic past (paleointensity) are important for understanding the processes in the core but also in the mantle and lithosphere, namely, plumes and the formation of large igneous provinces (LIPs). A new effort that Zhao and his colleagues are engaging is to determine the Earth's field intensity during late Paleozoic and Mesozoic using dated basalt units from Siberia, China, and Ontong Java Plateau. The ultimate goals of these projects are to understand how and why the time-averaged intensity of the earthís field has varied over geologic time and to contribute to our basic understanding of the geodynamo during late Paleozoic and Mesozoic and its relation to tectonics.