山东招-掖金矿带的西延去向探讨   总被引：3，自引：0，他引：3  

朱光 《地质与勘探》1999,35(2):6-9

山东招（远）－掖（县）金矿带所处的胶北隆起带与五河一蚌埠金矿带所处的淮河地块,在中生代以前为处于华北板块南缘的同一构造单元,郯庐断裂中生代大规模左行平移使两者错开,招－掖金矿带与五河－蚌埠金矿带具有类似的基底,矿源层,成矿期,矿床类型,成矿期岩浆活动,控矿构造等。因而,推测五河－蚌埠金矿带是招－掖金矿带在郯庐断裂带以西的延伸。由于淮河地块燕山期岩浆活动和郯庐断裂系的发育较弱于胶北隆起带,估计五河－  相似文献   

海洋腹毛目纤毛虫—束状全列虫的形态学以及与相近种的比较     

《中国海洋大学学报(自然科学版)》1999,(3)

报道了一种采自青岛沿岸养殖水体的自由生纤毛虫——束状全列虫。文中对其形态学作了重新描述,利用蛋白银技术研究了其纤毛图式,并与其它相近种作了比较。  相似文献   

南极威德尔海冰层下的砂壳纤毛虫   总被引：2，自引：0，他引：2       下载免费PDF全文

宋微波  徐奎栋 《极地研究》1999,11(1):37-41

本文依据壳体的形态特征,对采自南极威德尔海冰层下的１１种砂壳纤毛虫进行了分类学描述（包括一未定种拟波膜虫Ｐａｒｕｎｄｅｌａｓｐ．）,它们是柱状拟铃虫、船生孔环虫、亚圆原波纹虫、杯状波缘杯虫、梵氏波缘杯虫、简单原纹虫、短原纹虫、变形条纹虫、针状平顶虫和截短角口虫  相似文献   

渤、黄海大泷六线鱼耳石微化学特征与群体判别     

王英俊  孔晓  赵文溪  于超勇  王馨  唐学玺  刘洪军  宋爱环 《海洋科学》2023,47(1):54-65

为探究中国近海大泷六线鱼(Hexagrammosotakii)耳石微化学成分特征及群体分化状况,采集了连云港、青岛、威海、烟台、秦皇岛、大连、丹东7个野生群体和1个威海养殖群体的大泷六线鱼样本。利用LA-ICPMS技术测定耳石中的微量元素,以微量元素与钙的比值进行了分析,结果显示大泷六线鱼耳石中, Na/Ca、Sr/Ca、Fe/Ca、Mg/Ca较高,而Mn/Ca、Ba/Ca、Zn/Ca、Li/Ca较低。耳石1龄前元素比值的组间比较(S-N-K检验)结果显示:Na/Ca、Sr/Ca、Fe/Ca在群体间具显著性差异(P<0.05)。耳石边缘区元素与环境中元素比较发现,Li、Mn元素在耳石中富集程度较大,Sr在耳石的中元素含量远远大于水环境中的浓度,说明耳石中的元素沉积与海水中元素并不是简单的线性关系。判别分析结果显示:耳石1龄前元素指纹的判别分析结果表明,大泷六线鱼群体的判别成功率为63.0%,判别正确范围为30.0%～80.0%,耳石边缘区元素的判别正确率为57.1%,判别正确范围20.0%～80.0%,秦皇岛群体有高的判别成功率80.0%。耳石元素指纹可以用于不同大泷六线鱼群体的...  相似文献   

地震断层形态研究综述          下载免费PDF全文

徐龙军  彭龙强  谢礼立   《世界地震工程》2023,39(1):028-37

随着我国工程建设事业的不断发展,一大批土木工程基础设施正不断向地下深部、深海和中西部地区延伸转移,如地铁工程、跨海跨湾工程铁路和铁路工程(如川藏铁路)等都具有里程长、规模大的显著特点,在我国特殊的地震地质构造背景下,会不可避免地遇到地表或地下深部地震断层的作用。断层的作用方式与断层破裂的形态关系密切,研究不同场地的地表断层形态对工程结构抗断层错断设计有重要意义。本文归纳了不同场地条件下地震地表断层的形态和断层的空间展布特征,总结了地震断层形态的研究现状,分析了影响地震断层形态的因素,探讨了当前研究工作的不足与今后的研究方向,以期能为相关研究工作提供参考。  相似文献   

Measurements and estimation of flow velocity in mobile bed rills     

Yunyun Ban 《国际泥沙研究》2023,38(1):97-104

Rills are primary sediment sources and hillslope water/sediment runoff transport channels. Water flow velocities in rills are easily affected by bed condition over eroding and non-eroding slopes, which is an important hydrodynamic process in soil erosion research. This research is done to demonstrate the poorly understood “feedback mechanism” related to slope independence of flow velocity to slope gradient. A series of experiments were done on silt loam soil slopes to measure water flow velocity...  相似文献   

粉沙质海岸泥沙运动和淤积分析计算   总被引：15，自引：1，他引：14  

曹祖德焦桂英  赵冲久 《海洋工程》2004,22(1):59-65

介绍了粉沙质海岸的泥沙运动特点,通过理论分析和水槽试验揭示出粉沙质海岸的泥沙淤积物中悬移质和推移质的比例,并提出粉沙质海岸淤积计算的方法。  相似文献   

Mound development as an interaction of individual plants with soil,water erosion and sedimentation processes on slopes     

E. Bochet  J. Poesen  J. L. Rubio 《地球表面变化过程与地形》2000,25(8):847-867

In the Mediterranean region, semi‐natural shrubland communities (named ‘matorral’) often present a discontinuous cover, where isolated perennial plants alternate with bare inter‐plant areas. In such ecosystems, the patchy distribution of the vegetation is usually associated with microtopographic sequences of mounds that develop under isolated plants and break the overall slope continuity. In this study, the influence of three representative species of the Mediterranean matorral (Rosmarinus officinalis, Stipa tenacissima and Anthyllis cytisoides) on slope microtopography is determined and the processes that take part in the development of microtopographic structures beneath the plant canopy are identified. The influence of slope gradient, plant species and plant parameters on the shape and height of microtopographic structures is also studied. The shape of the microtopographic structures is described by using a two‐dimensional microprofilemeter and mound height is determined by measuring in the field a ‘mound height index’ defined as the distance from the top to the bottom of the mound. The results obtained show that plant species play a major role in the shape and height of the microtopographic structures. Whereas terrace‐type structures generally develop under Anthyllis shrubs, microtopographic forms associated with Rosmarinus and Stipa plants vary with slope gradient. The almost symmetric mound‐type structures that develop under these two species on gentle slopes change into terrace‐type structures as slope gradient increases. Moreover, statistically significant differences exist between the three species with regard to mound height. Mean values of mound height are 19·4, 14·6 and 4·3 cm under the canopy of Stipa, Rosmarinus and Anthyllis respectively. Plant parameters, essentially roughness, and slope gradient have a significant influence on mound height index. Four main processes were identified as affecting mound development in the studied field site: sedimentation, differential interrill erosion, differential splash erosion and bioturbation. Plant species interact in different ways with these processes according to their morphologies. Since Stipa and Rosmarinus plants are more efficient than Anthyllis shrubs in controlling water erosion, in retaining sediments and in modifying soil properties under their respective canopies, they give rise to higher microtopographic structures that facilitate water and nutrient storage by plants on slopes. Copyright © 2000 John Wiley & Sons, Ltd  相似文献   

Exploring landscape and geologic controls on spatial patterning of streambank groundwater discharge in a mixed land use watershed     

Kevin E. Jackson  Eric M. Moore  Ashley M. Helton  Adam B. Haynes  Janet R. Barclay  Martin A. Briggs 《水文研究》2024,38(3):e15112

Preferential groundwater discharge features along stream corridors are ecologically important at local and stream network scales, yet we lack quantification of the multiscale controls on the spatial patterning of groundwater discharge. Here we identify physical attributes that best explain variation in the presence and lateral extent of preferential groundwater discharges along two 5th order streams, the Housatonic and Farmington Rivers, and 32 1st to 4th order reaches across the Farmington River network. We mapped locations of preferential groundwater discharge exposed along streambanks using handheld thermal infrared cameras paired with high-resolution topographic and land use land cover datasets, surficial soil characteristic maps, and depth-to-bedrock geophysical measurements. The unconfined Housatonic River, MA, USA (12 km) had fewer discharge locations and less lateral extent (41 discharge locations with 38 m of active discharge/km of river) compared to the partially confined Farmington River, CT, USA (26 km; 169 discharge locations with 129 m of active discharge/km of river). Using a moving window analysis, we found along both rivers that discharge was more likely to occur where bank slopes were steeper, floodplain extent was narrower, and degree of confinement was higher. Along the Farmington River, groundwater discharge was more likely to occur where saturated hydraulic conductivity was higher and depth-to-bedrock was shallower. Among the 32 stream reaches surveyed (33.2 km of total stream length) within the Farmington River watershed, preferential discharge was observed in all but two stream reaches, varied from 0 to 25% of lateral extent along stream banks (mean = 6%), and was more likely to occur where stream reach slopes were steep, saturated hydraulic conductivity was high, and watershed urbanization was low. Our results show that, though both surface (e.g., topographic, land use land cover) and subsurface (e.g., soil characteristics, bedrock depth) factors control the prevalence of streambank preferential groundwater discharge, the dominant controls vary across valley settings and stream sizes.  相似文献   

红树林植株形态及种植密度对消波能力影响的数值模拟研究          下载免费PDF全文

朱俊宁  宋德海  陈光程  武文  鲍献文 《应用海洋学学报》2023,42(2):264-276

本研究利用非结构网格有限体积海洋模型FVCOM(Finite-Volume Coastal Ocean Model)、MDO(Mellor-Donelan-Oey)波浪模型以及可分层的植被波耗散参数化方案,通过对比有无红树林工况评估红树林的波浪衰减能力,研究了不同形态的红树林在高水位与低水位情况下的消波能力,分析了植株密度对红树林消波能力的影响。结果表明,红树林的消波系数与林带宽度呈非线性正相关,与水深的关系则与红树结构有关。以白骨壤(Avicennia marina)为代表的A型植株形态在低水位下的消波系数极大值为67.9%,高水位下则能够达到94.4%;以红海榄(Rhizophora stylosa)为代表的B型植株形态的消波系数在低水位和高水位的极大值分别为90.6%、89.4%;以角果木(Ceriops tagal)为代表的C型植株形态的消波能力在高低水位区别不大。植株密度的增加能提高红树林消波系数上限,还能使得红树林消波系数对林带宽度的变化更为敏感,减小达到消波系数极大值所需要的林带宽度。在保护现有的红树林生态系统或建立新的红树林综合减灾防护系统时,应注意不同植株结构红树林的...  相似文献