热液羽流的扩散过程常常记录于其下的热液沉积物中。研究热液羽流的沉积学记录有利于在现代洋底寻索所动热液喷口的位置,甚至还可为陆地类似成因矿床的发现提供有价值的线索。本文报道了来自Juan de Fuca洋脊(Jd FR)Endeavour段的8个按...热液羽流的扩散过程常常记录于其下的热液沉积物中。研究热液羽流的沉积学记录有利于在现代洋底寻索所动热液喷口的位置,甚至还可为陆地类似成因矿床的发现提供有价值的线索。本文报道了来自Juan de Fuca洋脊(Jd FR)Endeavour段的8个按规律采样的羽流末端沉积物样品的矿物学和地球化学分析结果。分步化学淋滤结果表明,热液来源物质直接对于该沉积物的贡献最少为23.03–33.展开更多
Although various types of geophones are applied in seismic exploration,there are only three common types of signals produced by geophones:displacement,velocity,and acceleration signals.Currently,our understanding of t...Although various types of geophones are applied in seismic exploration,there are only three common types of signals produced by geophones:displacement,velocity,and acceleration signals.Currently,our understanding of the signal characteristics,such as the generation mechanism,the geophysical properties,and the significance of the corresponding rock physics,remains unclear,which makes it difficult to both scientifically evaluate and take full advantage of the different types of geophones.In this paper,the mechanism by which seismic waves are generated is studied based on the spring–damped vibration theory.The physical characteristics of the three above-mentioned signal types and the relationships among the physical properties of the signals and medium are analyzed,as well as the signalto-noise ratio(SNR),resolution,and spectrum characteristics.Based on laboratory tests,field experiments,and applications,we obtained the following conclusions.The acceleration signal reflects the elastic characteristics of the medium and the change rules,and the signal strength is positively correlated with physical property changes.The acceleration signal has favorable attributes,such as small distortion,high fidelity,strong high-frequency amplitudes,and a wide frequency band.Therefore,the acceleration signal is more suitable for high-precision seismic exploration of complex media.In addition,the P-wave acceleration signal more accurately reflects the elastic Young modulus,shear modulus,and density changes than the velocity signal.However,the sensitivity decreases with increasing shear modulus and density.For the S-wave,the acceleration signal is more sensitive to the shear modulus and density than the velocity signal.展开更多
In marine seismic exploration,especially in deep-water and hard ocean-bottom cases,free-surface multiples are strongly developed.Compared with primary waves,the wider illumination aperture of the multiples is benefici...In marine seismic exploration,especially in deep-water and hard ocean-bottom cases,free-surface multiples are strongly developed.Compared with primary waves,the wider illumination aperture of the multiples is beneficial for high-resolution seismic imaging.In this study,by introducing a new compound source composed of primaries and free-surface multiples and by ignoring internal multiples,we derive a new linearized forward problem(free-surface-multiple prediction model)under a weak-scattering assumption(i.e.,first-order Born approximation).On the basis of the new linearized problem,we propose a joint inversion-imaging method by simultaneously using the primaries and free-surface multiples under the general framework of least square inversion.To eliminate the crosstalk artifacts introduced by the cross-correlation of multiples with different orders,we prove that the crosstalk artifacts can be gradually eliminated during the inversion if a proper step length is selected.Synthetic-andfield-data tests demonstrate the effectiveness of the proposed method.展开更多
文摘热液羽流的扩散过程常常记录于其下的热液沉积物中。研究热液羽流的沉积学记录有利于在现代洋底寻索所动热液喷口的位置,甚至还可为陆地类似成因矿床的发现提供有价值的线索。本文报道了来自Juan de Fuca洋脊(Jd FR)Endeavour段的8个按规律采样的羽流末端沉积物样品的矿物学和地球化学分析结果。分步化学淋滤结果表明,热液来源物质直接对于该沉积物的贡献最少为23.03–33.
基金supported by the National Major Science and Technology Project of“the 13th Five-year Plan”(No.2017ZX05005004003)。
文摘Although various types of geophones are applied in seismic exploration,there are only three common types of signals produced by geophones:displacement,velocity,and acceleration signals.Currently,our understanding of the signal characteristics,such as the generation mechanism,the geophysical properties,and the significance of the corresponding rock physics,remains unclear,which makes it difficult to both scientifically evaluate and take full advantage of the different types of geophones.In this paper,the mechanism by which seismic waves are generated is studied based on the spring–damped vibration theory.The physical characteristics of the three above-mentioned signal types and the relationships among the physical properties of the signals and medium are analyzed,as well as the signalto-noise ratio(SNR),resolution,and spectrum characteristics.Based on laboratory tests,field experiments,and applications,we obtained the following conclusions.The acceleration signal reflects the elastic characteristics of the medium and the change rules,and the signal strength is positively correlated with physical property changes.The acceleration signal has favorable attributes,such as small distortion,high fidelity,strong high-frequency amplitudes,and a wide frequency band.Therefore,the acceleration signal is more suitable for high-precision seismic exploration of complex media.In addition,the P-wave acceleration signal more accurately reflects the elastic Young modulus,shear modulus,and density changes than the velocity signal.However,the sensitivity decreases with increasing shear modulus and density.For the S-wave,the acceleration signal is more sensitive to the shear modulus and density than the velocity signal.
基金the sponsors of the WPI group for their financial supportfinancially supported by the National Key R&D Program of China (Grant Number: 2018YFA0702503, 2019YFC0312004)+2 种基金National Natural Science Foundation of China (Grant Number: 41774126)Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang) (ZJW-2019-04)National Science and Technology Major Project of China (Grant Number: 2016ZX05024-001, 2016ZX05006-002)。
文摘In marine seismic exploration,especially in deep-water and hard ocean-bottom cases,free-surface multiples are strongly developed.Compared with primary waves,the wider illumination aperture of the multiples is beneficial for high-resolution seismic imaging.In this study,by introducing a new compound source composed of primaries and free-surface multiples and by ignoring internal multiples,we derive a new linearized forward problem(free-surface-multiple prediction model)under a weak-scattering assumption(i.e.,first-order Born approximation).On the basis of the new linearized problem,we propose a joint inversion-imaging method by simultaneously using the primaries and free-surface multiples under the general framework of least square inversion.To eliminate the crosstalk artifacts introduced by the cross-correlation of multiples with different orders,we prove that the crosstalk artifacts can be gradually eliminated during the inversion if a proper step length is selected.Synthetic-andfield-data tests demonstrate the effectiveness of the proposed method.
