依据236口井共2706组的静温数据以及25口井的系统测温数据，分析计算了渤海盆地地温梯度及大地热流；建立地壳分层结构模型，利用回剥法计算现今地幔热流、深部温度以及岩石圈厚度；在此基础上，利用地球动力学方法恢复本区热流演化史...依据236口井共2706组的静温数据以及25口井的系统测温数据，分析计算了渤海盆地地温梯度及大地热流；建立地壳分层结构模型，利用回剥法计算现今地幔热流、深部温度以及岩石圈厚度；在此基础上，利用地球动力学方法恢复本区热流演化史。结果表明：渤海盆地背景地温梯度为32.2℃/km，热流值为64.8 mW/m2；盆地现今热岩石圈厚度在61～69 km 之间，地幔热流占地表热流的比例在60％左右，属于“热幔冷壳”型岩石圈热结构，盆地地壳底部或莫霍面温度变动在548～749℃之间；热流演化的特征与盆地的构造演化背景吻合，新生代以来盆地经历了3期岩石圈减薄并加热的过程，在东营组沉积末期热流达到最高（70～83 mW/m2），这期间盆地内产出多期碱性玄武岩，表明盆地经历了波及地幔的裂谷过程，随后进入热沉降期，热流逐渐降低，盆地向坳陷型转变。展开更多
Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equa...Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514°C to 603°C and the thermal lithosphere where the heat conduction dominates is 138–182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however, the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers, which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northern flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest. The total lithospheric strength of this region is4.77×1012–5.03×1013 N/m under extension, and 6.5×1012–9.4×1013 N/m under compression. The lithospheric brittleductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the Tarim lithosphere makes it little deform interior, 展开更多
Xenoliths of garnet and spinel-garnet 1herzolite from Mingxi, Eastern China have been studied in terms of comprehensive methods of mineralogy, petrology, fabrics, mierostructures and infrared spectrum. The temperature...Xenoliths of garnet and spinel-garnet 1herzolite from Mingxi, Eastern China have been studied in terms of comprehensive methods of mineralogy, petrology, fabrics, mierostructures and infrared spectrum. The temperature and pressure equilibration of the xenolith have been calculated using the TEMPEST program with the two-pyroxene geothermometer of Bertrand and Mercier (1985) combined with the geobarometer of Nickel and Green (1985). The temperature and pressure of xenoliths range from^1300 K at 1. 9 GPa (60 km) to ~1500 K at 2. 6 GPa (80 km). The geotherm inferred from xenolith is excellently consistent with the measured surface heat flow (70 mW/m2) in Mingxi. A character of geothermal curve and conductive type suggest that these xenoliths are from the lithosphere, not from the asthenosphere. The geotherm and mierostructures and preferred orientations of minerals in the xenolith are consistent with tecon-ic thinning of the lithosphere in the present-day extensional back-arc environment.展开更多
文摘依据236口井共2706组的静温数据以及25口井的系统测温数据，分析计算了渤海盆地地温梯度及大地热流；建立地壳分层结构模型，利用回剥法计算现今地幔热流、深部温度以及岩石圈厚度；在此基础上，利用地球动力学方法恢复本区热流演化史。结果表明：渤海盆地背景地温梯度为32.2℃/km，热流值为64.8 mW/m2；盆地现今热岩石圈厚度在61～69 km 之间，地幔热流占地表热流的比例在60％左右，属于“热幔冷壳”型岩石圈热结构，盆地地壳底部或莫霍面温度变动在548～749℃之间；热流演化的特征与盆地的构造演化背景吻合，新生代以来盆地经历了3期岩石圈减薄并加热的过程，在东营组沉积末期热流达到最高（70～83 mW/m2），这期间盆地内产出多期碱性玄武岩，表明盆地经历了波及地幔的裂谷过程，随后进入热沉降期，热流逐渐降低，盆地向坳陷型转变。
基金This work was jointly supported by the National Natural Science Foundation of China (Grant No. 49832040) the State Key Program for Basic Sciences of China (Grant No. 1999043302)the National 9th Five-Year Plan Special Research Programs of China (Grant No. 99-111).
文摘Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514°C to 603°C and the thermal lithosphere where the heat conduction dominates is 138–182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however, the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers, which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northern flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest. The total lithospheric strength of this region is4.77×1012–5.03×1013 N/m under extension, and 6.5×1012–9.4×1013 N/m under compression. The lithospheric brittleductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the Tarim lithosphere makes it little deform interior,
文摘Xenoliths of garnet and spinel-garnet 1herzolite from Mingxi, Eastern China have been studied in terms of comprehensive methods of mineralogy, petrology, fabrics, mierostructures and infrared spectrum. The temperature and pressure equilibration of the xenolith have been calculated using the TEMPEST program with the two-pyroxene geothermometer of Bertrand and Mercier (1985) combined with the geobarometer of Nickel and Green (1985). The temperature and pressure of xenoliths range from^1300 K at 1. 9 GPa (60 km) to ~1500 K at 2. 6 GPa (80 km). The geotherm inferred from xenolith is excellently consistent with the measured surface heat flow (70 mW/m2) in Mingxi. A character of geothermal curve and conductive type suggest that these xenoliths are from the lithosphere, not from the asthenosphere. The geotherm and mierostructures and preferred orientations of minerals in the xenolith are consistent with tecon-ic thinning of the lithosphere in the present-day extensional back-arc environment.
