2-D velocity structure and tectonics of the crust and upper mantle is revealed by inversion of seismic refraction and wide-angle reflection traveltimes acquired along the profile L1 in the Changbaishan-Tianchi volcani...2-D velocity structure and tectonics of the crust and upper mantle is revealed by inversion of seismic refraction and wide-angle reflection traveltimes acquired along the profile L1 in the Changbaishan-Tianchi volcanic region. It is used in this study that seismic traveltime inversion for simultaneous determination of 2-D velocity and interface structure of the crust and upper mantle. The result shows that, under Changbaishan-Tianchi crater, there exists a low-velocity body in the shape of an inverted triangle, and the crustal reflecting boundaries and Moho all become lower by a varying margin of 2-6 km, forming a crustal root which is assumed to be the Changbaishan-Tianchi volcanic system. Finally, we make a comparison between our 2-D velocity model and the result from the studies by using trial-and-error forward modeling with SEIS83.展开更多
2-D resistivity method is an indirect method to the shallow subsurface survey for maintaining the geo-environment. It is used to measure the apparent resistivity of subsurface. EHR technique was developed in order to ...2-D resistivity method is an indirect method to the shallow subsurface survey for maintaining the geo-environment. It is used to measure the apparent resistivity of subsurface. EHR technique was developed in order to get detail and deeper penetration for shallow subsurface study. In this study, 2-D resistivity with Enhancing Horizontal Resolution (EHR) technique is adopted to map and characterize the shallow subsurface (mineral exploration, geology, engineering and environment) using Pole-dipole array. The locations are Pagoh, Johor;Nusajaya, Johor and Puchong, Selangor (Malaysia). The study associated with mineral exploration is Pagoh, Johor while for Nusajaya, Johor is associated with geology and Puchong, Selangor is associated with engineering and environment. The 2-D resistivity and Induced polarization (IP) were employed at Pagoh, Johor to study and detect the subsurface variation of resistivity and chargeability of iron ore in the area. Result of the 2-D resistivity as well as the Induced Polarization (IP) shows that the area is underlain by a thick alluvium with resistivity value of 10 - 800 ohm-m iron which has chargeability rate of 0.1 - 3 msec. A sedimentary case study was executed at Nusajaya, Johor shows sandstone contains iron mineral (30 - 250 ohm-m) and weathered sandstone (500 -1000 ohm-m). Interpretation of 2-D resistivity data at Puchong, Selangor showed a low resistivity value (< 40 ohm-m), which appears to be a zone that is fully saturated with sandy silt and this could be an influence factor the increasing water level because sandy silt is highly permeable in nature. The borehole, support the results of 2-D resistivity method relating a saturated zone in the survey area. There is a good correlation between the 2-D resistivity investigations and the results of borehole records. The stratigraphy and structure of the three case studies (mineral exploration, geology, engineering and environment) can be mapped effectively using 2-D resistivity with EHR technique.展开更多
基金Key Project (95-11-02-01) from China Seismological Bureau.Contribution No. RCEG200129, Research Center of Exploration Geophysi
文摘2-D velocity structure and tectonics of the crust and upper mantle is revealed by inversion of seismic refraction and wide-angle reflection traveltimes acquired along the profile L1 in the Changbaishan-Tianchi volcanic region. It is used in this study that seismic traveltime inversion for simultaneous determination of 2-D velocity and interface structure of the crust and upper mantle. The result shows that, under Changbaishan-Tianchi crater, there exists a low-velocity body in the shape of an inverted triangle, and the crustal reflecting boundaries and Moho all become lower by a varying margin of 2-6 km, forming a crustal root which is assumed to be the Changbaishan-Tianchi volcanic system. Finally, we make a comparison between our 2-D velocity model and the result from the studies by using trial-and-error forward modeling with SEIS83.
文摘2-D resistivity method is an indirect method to the shallow subsurface survey for maintaining the geo-environment. It is used to measure the apparent resistivity of subsurface. EHR technique was developed in order to get detail and deeper penetration for shallow subsurface study. In this study, 2-D resistivity with Enhancing Horizontal Resolution (EHR) technique is adopted to map and characterize the shallow subsurface (mineral exploration, geology, engineering and environment) using Pole-dipole array. The locations are Pagoh, Johor;Nusajaya, Johor and Puchong, Selangor (Malaysia). The study associated with mineral exploration is Pagoh, Johor while for Nusajaya, Johor is associated with geology and Puchong, Selangor is associated with engineering and environment. The 2-D resistivity and Induced polarization (IP) were employed at Pagoh, Johor to study and detect the subsurface variation of resistivity and chargeability of iron ore in the area. Result of the 2-D resistivity as well as the Induced Polarization (IP) shows that the area is underlain by a thick alluvium with resistivity value of 10 - 800 ohm-m iron which has chargeability rate of 0.1 - 3 msec. A sedimentary case study was executed at Nusajaya, Johor shows sandstone contains iron mineral (30 - 250 ohm-m) and weathered sandstone (500 -1000 ohm-m). Interpretation of 2-D resistivity data at Puchong, Selangor showed a low resistivity value (< 40 ohm-m), which appears to be a zone that is fully saturated with sandy silt and this could be an influence factor the increasing water level because sandy silt is highly permeable in nature. The borehole, support the results of 2-D resistivity method relating a saturated zone in the survey area. There is a good correlation between the 2-D resistivity investigations and the results of borehole records. The stratigraphy and structure of the three case studies (mineral exploration, geology, engineering and environment) can be mapped effectively using 2-D resistivity with EHR technique.
