HR: 0800h
AN: V11A-1404    [Abstracts]
TI: Tomography in CCSD area of Jiangsu Donghai
AU: * Jiang, M
EM: jiangmei@geochina.cn
AF: Institute of Geology, CAGS, 26 Baiwanzhuang Street, Beijing, 100037 China
AU: Qian, H
EM: qianhui@ccsd.org.cn
AF: Institute of Geology, CAGS, 26 Baiwanzhuang Street, Beijing, 100037 China
AU: Su, H
EM: suheping@ccsd.org.cn
AF: Institute of Geology, CAGS, 26 Baiwanzhuang Street, Beijing, 100037 China
AB: Sulu-Dabie Orogeny is typical UHP zone containing wide-spreading eclogite. CCSD choose largely covered eclogite area­ŠJiangsu Donghai as first site to commence deep drilling because this will disclose the geodynamic processes of orogeny and deformation and diapiring afterwards. Less of geostatistic data and documentation for deep geology of this area makes tomography one of the most important methods for velocity perturbation analysis of deep material. And this can be the preceding procedure for deep drilling and deep survey, as we deployed a crossing profile centered at the drilling address with NS azimuth of 340. Approximate 5000 events were acquired between May and October of 2000 from IRIS, among which P wave coverage events has 3500 pieces and PKP 870 pieces. After carefully arrival time picking , 355 utilizable P events were collected in which 27 events has magnitude bigger than 6. Using 41 stations tomography inversed 917 model blockstransversed by 1185 rays. Then traval time residue less than 1s were selected to revise the model, through which data residue reduced from 0.64 to 0.3 and the diagonal elements sum of resolution matrix reachs 2000. Observed from time travel time residue data, southern stations have bigger residue due to southward events and get smallest at the center part of model,then become bigger again to the north. But this rule is not effect for the E-W profile. This kind of distribution illustrate the tectonic strike may go through EW direction and the center part has the highest velocity and southern part have more low velocity material than the north part. Applying tomography inversion, we get the image of velocity at different depth. The 3rd layer is consistent with Bouger gravity anormality , where high velocity perturbation and high gravity both appear at the center, and Tanlu, Jiashan-Xiangshui Fault both serve as boundary of high and low velocity and gravity. NS section perpendicular to tectonic strike can be divided into three parts which represent Yangtze, Sulu and North China respectively. The fault normal in south part is dipper with a dipping high velocity body of indistinct discontinuity, but faults in the north part have coherently northward inclination controlled by Tanlu Fault. Upper the depth of 200km, there are three horizontal changing zone at 30km,80km and 130km, which is about the depth of Moho, lithosphere and asthenosphere. This scheme illustrates the feature of lithosphere activity of Sulu area controlled by deep faults.
DE: 8180 Tomography
DE: 8010 Fractures and faults
DE: 8123 Dynamics, seismotectonics
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting