河北涞源白石山地质公园“1.5Ga前地裂缝”新解

梁定益等(2002)研究认为太行山北段河北省涞源县白石山地质公园内存在一条与中元古代雾迷山组沉积时代相当的地裂缝构造,且地裂缝内填充由地震触发,重力垮塌形成的震积岩(含软沉积变形)。近期实地考察后,笔者等得出与上述观点不同的认识,即先前认为的地裂缝实为一条断裂带:震积岩为断裂带构造岩;断层主滑移带内发育S—C面理构造;断层角砾复杂结构是构造变形和压溶作用的结果;断裂整体表现为含正断层分量的走滑断层。结合太行山北段区域构造演化历史,本文提出该断裂最早形成于燕山运动期间,此后在区域构造应力作用下可能多次活动。     

大凌河下游沿河水源工程对白石水库水源的吸夺率分析

通过理论公式、历史实测资料和断面测流法实验资料，分析计算了大凌河白石水库下游各河段抽水井对河水的吸夺量，进而定量地分析了白石水库下游沿河水源工程在河道干枯条件下对白石水库水源的吸夺率，为水库合理征收用水工程费提供了科学依据。     

四川龙门山中段早埃姆斯期生态地层及古环境新认识

本文讨论了龙门山中段白石 苟家大型飞来峰内早埃姆斯期的甘溪组分布及岩性特征。首次将甘溪组划分为两个生态地层单元 ,即Anetoceras Plectodonta群落及Dicoelostrophia Eosophragmophora群落 ;指定了群落的层型剖面 ,分析了各群落的生物组成、丰富度、生态特征及生态环境。认为区内早埃姆斯期属深水陆棚至深水盆地沉积环境 ,为龙门山区泥盆纪沉积盆地的性质和演化提供了新资料。     

ESTIMATION OF SOIL EROSION IN A RESERVOIR WATERSHED USING ^137CS FALLOUT RADIONUCLIDE

Sedimentation from soil erosion is a critical reservoir watershed management issue. Due to the difficulty of field investigations, empirical formulas are commonly used to estimate the soil erosion rate. However, these estimations are often far from accurate. An effective alternative to estimating soil erosion is to analyze the spatial variation of 137Cs inventory in the soil. 137Cs can be adsorbed by the soil and is widely assumed to change its distribution only when disturbed by rainfall and human activities. Thus, 137Cs distributed in soils can be a useful environmental tracer to estimate soil erosion. In this study, the net soil loss estimate is 108,346 t/yr and the gross erosion and net erosion rates are 10.1 and 9 t/ha yr respectively. The sediment delivery ratio is therefore estimated to be 0.9 based on the two erosion rates. Because of the steep hillsides in the watershed, only 10% of the sediment yield stayed in the deposition sites and 90% was transported to the river as the sediment output. Soil erosion estimates from spatial variations of the 137Cs activity in the Baishi river watershed showed satisfactory accuracy when compared to sediment yield data. Using soil 137Cs concentrations is therefore a feasible method for estimating soil loss or deposition in Taiwan. Data sampling, analysis and result of this approach are given in this paper.     

一种新的地质地貌景观类型—河北省白石山大理岩构造峰林特点及成因

河北省涞源县白石山,在构造上位于NNE向太行山深断裂带的西缘。白石山呈现“双层结构”,山体“底座”为燕山期花岗岩,“顶盖”为中元古界雾迷山组(Jxw)白云石大理岩,形成巨型“顶盘悬挂体”。这里实际上是燕山期以来构造活动带和强震带中的一块“安全岛”,既有产生构造峰林强大的构造应力,又能使峰林很好地保存下来。产状近于水平的白云石大理岩层,因受强大的燕山期主压应力作用,产生两组直立的、规模宏大的NNE和NNW向共轭剪切节理,形成“X型构造”。新生代以来,山体上升,在构造节理的主导下,配合物理风化及部分地表流水作用,逐步发展成为白云石大理岩构造峰林。这是中国地质地貌景观的一种新类型。     

河北省白石山中元古代地震遗迹的发现

在河北省涞源县白石山构造峰林游览路线上,中元古界雾迷山组(距今10～14亿年间)第二段地层下部,发现“震动坍塌巨角砾岩”(震积岩)。“巨角砾岩”受两条同沉积期正断层控制,是由两侧断崖上坍塌的岩块瞬时地在水下形成的。这是目前所知最早的震积岩(古地震遗迹)。根据震积岩的规模与两条正断层的断陷程度推测,白石山古地震的强度大体相当里氏6级以上,是华北中元古代地震灾变事件濒发期的具体表现。白石山距古太行山深断裂不足10km,白石山震积岩、同沉积期正断层与古太行山断裂带均呈NNE向延伸,推断当时白石山地区处在古太行山断裂带活动的影响范围内。