超然于时代的写作——论曹聚仁二十世纪五六十年代的随笔散文     

孙德喜 《吉林地质》2009,(4)

20世纪50年代和60年代是曹聚仁随笔散文写作的高峰期。这一时期,无论是内地还是港台,政治气氛都十分浓厚。而作为国共两党的联系人的曹聚仁疏离政治,可以自由地往来于大陆和港台之间,仍然保持与母体文化联系,从而使他在写作上保持一定的文化优势。曹聚仁在随笔写作中重在对所游之地、所读之书的文史挖掘,显示出深厚的文化底蕴。曹聚仁以随笔散文的方式传承着民族文化的血脉,独自守望着古老而深厚的民族文化,具有十分重要的意义。  相似文献   

Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates     

YU Zhiteng  LI Jiabiao  LIANG Yuyang  HAN Xiqiu  ZHANG Jie  ZHU Lei 《海洋学报(英文版)》2013,32(12):109-117

Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.  相似文献   

塔西南甫沙地区被动顶板双重构造和乌泊尔地区背驮盆地的数值模拟     

黄光明  李忠海  周永智 《地质学报》2017,91(8):1674-1693

塔里木盆地西南缘前陆褶皱冲断带发育被动顶板双重构造(甫沙地区)和背驮盆地(乌泊尔地区)两种明显不同的构造类型。为了探讨它们的不同成因,利用有限差分软件FLAC开展了一系列二维数值模拟研究。采用遵循平面应变的黏弹塑性本构模型,设置两个滑脱层和三个能干层。同时考虑基底沉降、同构造剥蚀和沉积,缩短速率为8mm/a,剥蚀速率为每年侵蚀基准面以上高程的3×10-7(相当于每1000m每年剥蚀0.3mm)。在基底水平的情况下,采用均一的沉降速率1.6mm/a并以填平补齐的方式进行沉积时,3.5 Ma后发育成与甫沙地区相似的被动顶板双重构造。而当模型采用中部小两端大的拱形沉降速度以及填平补齐的沉积时最终发育成背驮盆地,和乌泊尔地区地质原型接近。模拟结果表明,同构造沉积地层对褶皱冲断带的影响巨大,当沉积物大量堆积在褶皱冲断带前缘时有利于被动顶板双重构造的形成,而沉积物大量堆积在逆冲楔顶与斜坡时则更有利于背驮盆地的发生。模拟结果认为甫沙地区和乌泊尔地区都接受了填平补齐的沉积方式,但基底沉降差异造成了两者的构造样式明显不同。在小范围内(后陆至前陆小于80km),甫沙地区基底以水平方式发生沉降,褶皱冲断带前缘接受了大量沉积;而乌泊尔地区基底在挤压下发生弯曲,使得后陆发生了更大的沉降从而接受了更多的沉积。  相似文献   

琼东南盆地地壳伸展深度依赖性及其动力学意义   总被引：8，自引：2，他引：6       下载免费PDF全文

张中杰  刘一峰  张素芳  范蔚茗  陈林 《地球物理学报》2010,53(1):57-66

地壳或岩石圈尺度内伸展因子随深度变化特征对于理解岩石圈演化有重要的指示意义.我们利用南海北部大陆边缘琼东南盆地区深反射地震剖面的地壳分层模型,计算了沿剖面上地壳与全地壳的伸展因子.结果表明:琼东南盆地区具有明显的地壳尺度内伸展的深度相关性（上地壳尺度伸展因子变化范围为1.0~2.0,全地壳尺度的伸展因子变化范围为1.2~2.5）;琼东南盆地各构造单元内的上地壳与全地壳伸展具有明显的非均一性(长昌凹陷上地壳尺度伸展最大,乐东—陵水凹陷其次,松南—宝岛凹陷最小;长昌凹陷和松南—宝岛凹陷的地壳尺度伸展因子较乐东—陵水凹陷大) 与各向异性(南东—北西剖面较之北东—南西向剖面地壳伸展因子大).这些结果预示着琼东南盆地区地壳伸展优势方向为北西向,盆地区东西部的伸展过程或伸展机制可能差异较大拟或存在太平洋岩石圈俯冲角空间差异或地幔岩浆产出时空差异.结合研究区相关研究成果,推断地壳伸展因子的深度相关性可能是共轭大陆边缘低角度拆离控制的简单剪切系统内伴随地幔挤出的动力学现象.  相似文献   

The effect of a hydrous phase on P‐wave velocity anisotropy within a detachment shear zone in the slow‐spreading oceanic crust: A case study from the Godzilla Megamullion,Philippine Sea          下载免费PDF全文

Katsuyoshi Michibayashi  Tohru Watanabe  Yumiko Harigane  Yasuhiko Ohara 《Island Arc》2016,25(3):209-219

We studied the contributions of plagioclase, clinopyroxene, and amphibole to the P‐wave velocity properties of gabbroic mylonites of the Godzilla Megamullion (site KH07‐02‐D18) in the Parece Vela Rift of the central Parece Vela Basin, Philippine Sea, based on their crystal‐preferred orientations (CPOs), mineral modes, and elastic constants and densities of single crystals. The gabbroic mylonites have been classified into three types based on their microstructures and temperature conditions: HT1, HT2 and medium‐temperature (MT) mylonites. The P‐wave velocity properties of the HT1 mylonite are dominantly influenced by plagioclase CPOs. Secondary amphibole occurred after deformation in the HT1 mylonite, so that its effect on P‐wave velocity anisotropy is minimal due to weak CPOs. Although the HT2 mylonite developed deformation microstructures in the three minerals, the P‐wave velocity properties of the HT2 mylonite are essentially isotropic, resulting from the destructive interference of different P‐wave velocity anisotropy patterns produced by the distinct CPOs of the three constituent minerals (i.e., plagioclase, clinopyroxene, and amphibole). The P‐wave velocity properties of the MT mylonite are influenced mainly by amphibole CPOs, whereas the effect of plagioclase CPOs on P‐wave velocity anisotropy becomes very small with a decrease in the intensity of plagioclase CPOs. As a result, the gabbroic mylonites tend to have weak P‐wave velocity anisotropy in seismic velocity, although their constituent minerals show distinct CPOs. Such weakness in the whole‐rock P‐wave velocity anisotropy could result from the destructive contributions of the different mineral CPOs with respect to the structural framework (foliation and lineation). These results show that amphibole has a high potential for P‐wave velocity anisotropy by aligning both crystallographically and dimensionally during deformation in the hydrous oceanic crust. The results also suggest that the effect of a hydrous phase on P‐wave velocity anisotropy within the detachment shear zone in a slow‐spreading oceanic crust varies depending on the degree of deformation and on the timing of hydrothermal activity.  相似文献   

Magnetotelluric study of the Xuefeng mountain area,Hu’nan Province,China          下载免费PDF全文

Musen Chen  Lingxiang Xue  Yousheng Wang  Shengjun Zhu 《地震科学（英文版）》2016,29(2):127-137

A magnetotelluric study was carried out in the Xuefeng mountain uplift belt and its western margins. A detailed investigation was made of the resistivity of the formations, and reliable data were obtained. The sedimentary cover and basement structure of the Xuefeng mountain area and the deep geological structure were analyzed in detail using magnetotelluric data from the two-dimensional inversion of the resistivity profile data in combination with regional gravity and magnetic data. It was concluded that the tectonic movements were characterized by basement detachment, and north-south ramp. The study area can be divided into a southern uplift zone, a southern thrust-faulted zone, a central uplift zone, and a northern depression zone. This work has provided geophysical evidence that can be used in future studies of the tectonics and petroleum geology of this region.  相似文献   

Effects of plant roots on the soil erosion rate under simulated rainfall with high kinetic energy     

Yoshinori Shinohara  Sohei Otani  Tetsuya Kubota  Kyoichi Otsuki  Kazuki Nanko 《水文科学杂志》2013,58(13):2435-2442

ABSTRACT

This study examined the effects of herbaceous plant roots on interrill erosion using two herbaceous species: clover (Trifolium repens) and oats (Avena sativa). We developed a simple rainfall simulator with relatively high normalized kinetic energy (KE; 23.2 J m^?2 mm^?1). Under simulated rainfall, we measured eroded soil for 42 boxes with various amounts of aboveground and belowground biomass. Aboveground vegetation had a significant effect on the soil erosion rate (SER). We found a clear negative relationship between the percent vegetation cover (c) and the SER. In contrast, plant roots showed no effects on the SER. The SER was not significantly different between the boxes with and without plant roots under similar c conditions. Thus, plant roots could have less of an effect on the SER under higher KE conditions.