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重构南极区域的古水深和历史地质格局,首先需要对研究区域进行板块重构,即在特定的时间点将洋壳和陆壳恢复到他们原来的地理位置上。本文采用Greiner阐述的欧拉旋转法进行板块重构。欧拉极参数主要参考Muller等基于大西洋-印度洋热点参考系的有限欧拉极,并将部分参数进行了必要的转换和统一。对于指定的重构年代,地壳年龄比重建年代年轻的区域需被移除。本文借助于Matlab等编程工具,恢复了南极及周边区域自130 Ma以来15个特定时间段的位置。综合多种数据,将现代水深根据热驱动地壳沉降、沉积作用和均衡作用的影响进行调整,对30°S以南区域的古水深进行重构,绘制了研究区域不同年代的古水深图,分析了南大洋自130 Ma以来的形成演化过程。 相似文献
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东海莫霍面起伏与地壳减薄特征初步分析 总被引：3，自引：0，他引：3
收集、整理大量由地震剖面提供的沉积层厚度资料,得到东海沉积层等厚图。对完全布格重力异常进行沉积层重力效应改正后,得到剩余重力异常,利用地震资料揭示的莫霍面深度值来约束界面反演得到东海莫霍面埋深。结果表明,东海陆架盆地莫霍面深度在25～28 km之间平缓变化,地壳厚度为14～26 km,西厚东薄;冲绳海槽盆地莫霍面深度为16～26 km,地壳厚度为12～22 km,北厚南薄。东海陆架盆地东部与冲绳海槽盆地南部地壳减薄明显,拉张因子分别达到2.6和3。初步分析认为冲绳海槽地壳以过渡壳为主,并未形成洋壳。 相似文献
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北冰洋Gakkel洋中脊的地幔熔融控制因素及非岩浆地壳增生 总被引：3，自引：0，他引：3
Spreading rate is a primary factor of mantle melting and tectonic behavior of the global mid-ocean ridges. The spreading rate of the Gakkel ridge decreases gradually from west to east. However, the Gakkel ridge can be divided into four thick-and-thin zones with varying crustal thicknesses along ridge axis. This phenomenon indicates that mantle melting of the Gakkel ridge is not a simple function of spreading rate. Mantle temperature, water content,mantle composition, and other factors are important in crustal accretion processes. Based on gravity-derived crustal thickness and wet melting model, we estimate that the mantle potential temperatures of the four zones are1 270, 1 220, 1 280, and 1 280°C(assuming that mantle water content equals to global average value), with corresponding mantle water contents of 210, 0, 340, and 280 mg/kg(assuming that mantle potential temperature is 1 260°C), respectivly. The western thinned crust zone is best modeled with low mantle temperature, whereas the other zones are mainly controlled by the enhanced conduction caused by the slower spreading rate. Along the Gakkel ridge, the crustal thickness is consistent with rock samples types. Predominated serpentinized peridotite and basalt are found in the area with crustal thickness 1.5 km and 2.5 km, respectively. The rock samples are including from basalt to peridotite in the area with crustal thickness between 1.5 and 2.5 km. Based on this consistency, the traditional magmatic accretion zone accounted for only 44% and amagmatic accretion accounted for 29% of the Gakkel ridge. The amagmatic accretion is a significant characteristic of the ultra-slow spreading ridge. 相似文献
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利用2015—2016年福州城区内涝和地面气象观测资料,分析内涝成因、最大降雨量与积水深度的关系,建立城市内涝积水深度拟合方程,并对拟合效果进行了检验。结果表明:1)导致福州城市内涝的突发性原因占26%,是城市管网等数据更新困难的主因,非突发性原因占74%;2)在3次不同天气系统的降雨量拟合结果中,雨季降水过程拟合平均绝对误差最小,午后雷雨天气降雨过程拟合平均绝对误差最大;3)对内涝积水深度负拟合值进行归零处理和阈值限定后,其结果均与实况相符;4)基于最新数据资料所得拟合值的误差更小。 相似文献
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