Seismic Neighboring Traces Attenuation Tomography in Time Domain

Until 2009, 176 meteorite impact craters have been found in the world. Since the 80's of 20th century, Chinese scholars have confirmed, from the geological, geochemical and drilling data, that a circular structure was formed by meteorite impacting in Xiuyan County, Liaoning Province. But the deep structures and the overall characteristics of the crater need still to be confirmed by using the geophysical methods. In this paper, threedimensional Q structure has been obtained for the first time by using seismic refraction data in order to have a total understanding of the crater. Q value structure is of great significance for understanding the non-elastic and nonuniform nature of the crust. Using three-dimensional Q tomography method based on absorption characteristic time t * , the amplitude spectra have been obtained and by fitting the amplitude spectrum, t * values have been obtained, which reflect seismic wave attenuation. The three-dimensional Q value structure has been obtained by using t * values through three-dimensional Q tomography method. The results showed that the Q-value layer from the surface to the depth of 100 m within the crater corresponds to the upper 107 m thick lake sediments, the Q-value layer from the depth of 100 m to 300 m corresponds to the lower 188 m thick breccia accumulation lens. The Q-value layer from the depth of 300 m to 700 m corresponds to the broken Lower Proterozoic metamorphic rock layer with less impacting. The wave impedance interface about 250 m deep corresponds to the meteorite impact interface confirmed by geological drilling at the 260 m depth.

Section: Fig 2 Station and Shot Point Locationsmentioning

confidence: 99%

Three‐Dimensional Q Value Tomography for Xiuyan Meteorite Impact Crater

Fan¹,

Liu²,

Zhao³

et al. 2010

“…We use the wave equation method for viscoelatic media to calculate synthetic seismograms based on given models, and pick travel times and peak amplitudes of the first arrival from the horizontal components, which we take as the observations for our numerical experiment. After rebuilding the velocity image, we correct the receive direction of the original data and the geometrical attenuation, then implement the attenuation imaging [3,5] . Comparing the computed velocity and attenuation images with the given model images, we can evaluate the numerical result.…”

Section: Experiments Designmentioning

confidence: 99%

“…Amplitude Correction and Frequency Estimation [3,5] Based on the velocity image V P , the elastic wave equation modeling is implemented for eliminating the attenuation effect of the velocity structure with V S = 1/2V P . The calculated first arrival peak amplitude is expressed by A 0M .…”

Section: 4mentioning

confidence: 99%

Seismic Attenuation Tomography Using the Successive Linearization Method

Zhao¹,

Wang²,

Yao³

2004

Based on the attenuation tomographical method in time domain, we propose a successive linearation method which is similar to the current travel‐time tomographical methods. We deduce a series of successive linearization formulae and obtain the iterative arithmetic and the executable technique of the seismic attenuation tomography using the successive linearization method. The method feasibility is validated by numerical experiments. As a supplement, multi‐parameters tomography is realized. We have applied the successive linearization method to engineering reconnaissance practice and gained preferable results.

Distribution Characteristics of the Geotemperature Field in the Jiyan Gdepression, Shandong Province, North China

Gong

Wang

Liu

et al. 2003

Based on the analysis of geotemperature data derived from 703 exploration wells in the Jiyang depression of the Shengli oilfield, Shandong, North China, in conjunction with corresponding geothermal calculation results, we present the geothermal field distribution characteristics of this region, which include the plane contour plots of geothermal gradient present day, geotemperature at 3km, 4km and 5km depth, respectively, as well as the one at the top surface of lower Tertiary Es4 formation of the Jiyang depression. The average geothermal present day gradient of the whole Jiyang depression is about 35.5• C/km, the corresponding gradients of its four main sags, i.e. Zhanhua, Dongying, Chezhen and Huimin are 36.1• C/km, and 34.6• C/km, respectively. While for the Weibei sag, on the outer flank of the Jiyang depression, it is 35.5• C/km. The distribution of geothermal gradient and geotemperature in the Jiyang depression is mainly governed by its tectonic framework of alternating uplifts and depressions areas. This distribution is also related with the basement depth, characterizing by higher temperature in uplifts and lower one in depressions. In addition, those regions of relatively high geothermal gradient are consistent with areas of Cenozoic volcanic rock distribution. The pattern of basement depth of the Jiyang depression, which also represents the distribution of uplifts and depressions, is controlled by the lithospheric stretching during basin formation. This geodynamic process also accounts for the distribution of volcanic rocks in this region. Consequently, the geothermal field characteristics of the Jiyang depression arc resulted from its tectonic evolution process. In addition, our results also indicate that most of the Es4 formation in the Jiyang depression is still within liquid window of oil and gas.