摘要
In order to explore the ability of airgun sources in imaging the crustal structure,we conducted an experiment along the Yangzte River at the section from Ma 'anshan to Anqing using an offshore airgun source( referred as the Anhui Airgun Experiment).During the experiment,the airgun source was fired 2973 times at 20 multiple shot points,while 109 permanent stations and 700 temporary stations( 11 profiles) were used to record the signal. For 20 multiple shot points,we picked up 335 P-wave arrivals at 52 permanent stations. Then we obtained the P-wave velocity structure of the crust beneath the southern tip of the Tancheng-Lujiang( Tan-Lu) fault. The preliminary result of P-wave velocity structure confirms the possibility of 3D body wave imaging using large volume airgun sources. The imaged velocity heterogeneity at a depth of 15 km is correlated to the geological settings. High velocity anomaly beneath the Qinling-Dabie orogenic belt could be explained by the ultrahigh-pressure metamorphic rocks in the deep region,while the low velocity anomaly at the Yangtze River region may correspond to the special background of mineralization.
In order to explore the ability of airgun sources in imaging the crustal structure, we conducted an experiment along the Yangzte River at the section from Ma＇anshan to Anqing using an offshore airgun source （referred as the Anhui Airgun Experiment）. During the experiment, the airgun source was fired 2973 times at 20 multiple shot points, while 109 permanent stations and 700 temporary stations （11 profiles ） were used to record the signal. For 20 multiple shot points, we picked up 335 P-wave arrivals at 52 permanent stations. Then we obtained the P-wave velocity structure of the crust beneath the southern tip of the Tancheng-Lujiang （Tan-Lu） fault. The preliminary result of P-wave velocity structure confirms the possibility of 3D body wave imaging using large volume airgun sources. The imaged velocity heterogeneity at a depth of 15km is correlated to the geological settings. High velocity anomaly beneath the Qinling-Dabie orogenic belt could be explained by the ultrahigh-pressure metamorphic rocks in the deep region, while the low velocity anomaly at the Yangtze River region may correspond to the special background of mineralization.
基金
jointly sponsored by the National Natural Science Foundation of China(41374070,41574052)
Academician Chen Yong Wonkstation Project of Yunnan Province(2014IC007)
