冀北地区脉金矿床铅同位素地球化学特征

本文从冀北地区脉状金矿床地质背景出发,系统研究了太古宇及与金矿化有关的岩体铅同位素特征,认为本区脉状金矿床成矿物质来自古老地壳及地幔。文中强调无论是产于变质岩中的金矿,还是产于花岗岩、碱性岩、超基性岩中的金矿,均受深大断裂及古隆起活化带控制。文中还分析了冀东、冀西北金矿床铅同位素区域性差异及产生原因。     

夏杖子金矿床同位素组成及其地质意义

夏杖子金矿床中矿物包裹体水的氢、氧同位素分别为：δD=-91.7‰——73.1‰,δ¹⁸O_H2o=5.68‰-6.23‰,说明读矿床的成矿溶液是来源于岩浆水和大气降水;矿物的硫同位素组成基本上全是负值,且变化范田较小,同位素平衡温度平均为208-240℃,成矿溶液总硫平均同位素组成-19.70‰——20.64‰,证明成矿热液中H₂S原子团占优势,其硫源可能为本区结晶基底;石英中流体包裹体Rb-Sr同位素等时年龄为105±7.2Ma,说明其成矿时代为燕山晚期。综合分析认为,该矿床为与岩浆热液有关的中-低温热液脉型金矿床。     

河北牛圈热泉型银(金)矿床成因

牛圈银(金)矿床是冀北地区近几年来新发现的重要银矿床之一.本文从硅质角砾岩成因、成矿的阶段划分、成矿物理化学条件、矿物包裹体等方面入手探讨了该矿床成因并提出了成矿模式.该矿床成矿温度稍高(220-350℃),成矿压力很低(小于260×10⁵Pa),形成深度为0.42-0.86km的亚地表环境,成矿流体以低盐度(小于3.35wt%NaCl),富K⁺、Cl^-、F^-、SO₄^2-,贫Na⁺、Ca²⁺,以大气水为主为特征,属典型的热泉型矿床.     

陕西省榆林地区延安组湖滨下三角洲平原沉积中的决口扇三角洲沉积及其意义

陕西榆林延安组湖滨下三角洲平原沉积中决口扇三角洲具如下特点:（1）发育在湖滨下三角洲平原的分流间地区;（2）平面上垂直主分流河道向外呈扇形或朵叶状;（3）剖面上呈透镜状夹在两个煤分层之间;（4）前三角洲沉积的厚度小,前缘中植物碎屑含量高;（5）发育时间短,一般不超过1万年。决口扇三角洲沉积体间的排列关系受控于压实沉降作用,不同的排列形式导致煤层出现叠瓦状分叉和环状分叉。     

Features and values of geological heritage resources in Shunping County,Hebei Province

Hebei Province is rich in geological heritage resources due to its diverse landforms and unique natural conditions. However,detailed investigation and study of the resources are still limited,and a systematic survey conducted on a small scale has not been fully implemented. In this paper,the resource types and characteristics of the geological heritage in Shunping County are systematically discussed,on the basis of field investigation and scientific evaluation. With reference to the existing criteria for geological heritage resources survey,the heritage values and corresponding levels were assessed by using multi-factor quantitative evaluation approach. The results show that there are 33 geological heritage sites in Shunping County,which fall into 3 categories,10 classes and 17 subcategories. Among them,2 heritage sites are above the provincial level,14 heritage sites are at the provincial level and 17 ones are below the level. These heritage sites are not only natural resources with great tourism potential,but also valuable asset in geological research,human history,ecological conservation,scientific education and some other aspects. It is hence of great significance to conduct the scientific and reasonable appraisal for having a better understanding,good protection and development of the geological heritage resources in Hebei Province.     

“上山”找金铜, “下山”找钨锡及其理由

金铜和钨锡是两种不同类型的矿产资源, 金铜经常伴生, 钨锡经常伴生, 金铜和钨锡通常不在一起.研究表明, 金铜主要与埃达克岩和喜马拉雅型花岗岩有关, 产于加厚的地壳底部, 地表相应的出现高原或山脉; 钨锡主要与南岭型花岗岩有关, 代表减薄的陆壳, 产于平原区, 地势较低.因此, 从找矿的角度来说, 应当“上山”找金铜, “下山”找钨锡.文中识别出中国三叠纪以来可能存在过的7个山脉(华北北部山脉、西秦岭-东昆仑山脉、额尔古纳山脉、松潘-中甸山脉、湘赣山脉、浙闽山脉和哀牢山-羌塘山脉) 和2个高原(中国东部高原和湖南山地) 以及现存的青藏高原, 建议在上述高原和山脉上去找金铜矿, 指出喜马拉雅型花岗岩与金矿的密切关系, 是今后找金矿的一个重要目标.认为钨锡成矿目前仍然以华南为最佳, 但应注意在其他地块寻找钨锡的问题.      

德州市深层地下水水质演化研究

德州市属于典型的黄河下游冲积平原孔隙水水文地质区,这一地区地下淡水的天然水环境条件非常敏感和脆弱。由于持续开采地下水,使该区域地下水的水动力场和水化学场发生了较大变化。根据德州市地下水水质监测数据,本文论述了深层地下水的水质特征,分析研究了深层地下水的水质演化。结果表明:在开采条件和自然条件的共同作用下,HCO3-和Na+浓度呈现出持续升高趋势,矿化度、总硬度及其它主要水质指标的浓度变化较小。深层地下水水质演化的特点表现为水化学动态并不随季节变化,而是在开采条件下,随着深层地下水系统压力、氧化?还原环境条件的改变有所变化。地下水水质指标浓度的历年变化主要受到水文地球化学环境的影响。针对研究区地下水水质的演化趋势,提出了应进行深层地下水人工回灌和降氟改水的水质改善措施。     

河北宽城崖门子中元古界高于庄组地球化学特征及其沉积环境意义

河北宽城崖门子剖面的高于庄组属于中元古界长城系,下伏长城系大红峪组,上覆中元古界蓟县系杨庄组,沉积年限200 Ma（1800~1600 Ma）,共划分为4个亚组,自下而上为官地亚组、桑树鞍亚组、张家峪亚组和环秀寺亚组,为一套厚940 m的碳酸盐岩沉积地层.从常量元素和微量元素2个方面探讨了高于庄组的地球化学特征.通过对岩石样品测试结果的分析,各种元素含量在岩石地层界线附近变化较明显,说明地球化学特征可以辅助划分沉积地层或对已划分的地层界线进行优化.另外,据CaO/MgO、Ca/（Ca+Fe）和Sr/Ba比值及V、Ti元素特征分析,该研究区高于庄组为较干热气候下的海洋环境沉积.     

Forest blowdown impacts of Hurricane Rita on fluvial systems

Hurricane Rita, a category three hurricane which struck the US Gulf Coast near the Louisiana/Texas border in 2005, did not cause extensive river flooding. However, the storm did result in extensive forest damage and tree blowdown. High‐resolution post‐storm aerial photography allowed an inventory of river bank trees blown into the channel along the lower Neches and Sabine Rivers of southeast Texas and southwest Louisiana. Blowdowns directly into the channel averaged 9·3 per kilometer in the lower Neches and 13·4 in the lower Sabine River, but individual reaches 10 to 20 km in length had rates of 20 to 44 blowdowns per kilometer. Though large woody debris (LWD) from Hurricane Rita was widely perceived to reduce the capacity of channels to convey flow, no strong evidence exists of increased flooding or significant reductions in channel conveyance capacity due to LWD from the storm. The Rita blowdown inventory also allowed an assessment of whether similar blowdown events could account for major logjams and rafts on Red, Atchafalaya, and Colorado Rivers on the Gulf Coast, which blocked navigation from tens to hundreds of kilometers in the 1800s. Results from Hurricane Rita suggest that blowdown into channels alone – not withstanding blowdown elsewhere in the river valleys or along tributaries which could deliver LWD to the river – is sufficient to completely block channels, thus providing a plausible mechanism for initiating such (pre)historic log rafts. Copyright © 2009 John Wiley & Sons, Ltd.     

松嫩平原生态脆弱区生态系统服务功能价值变化

在遥感和地理信息系统技术支持下,以1986～2000年的1∶100000LandsatTM图像解译数据为基础,全面分析了1986～2000年该区土地利用/覆被的动态变化特征,运用Costanza等人对全球生态系统服务价值的计算方法,对松嫩平原西部生态脆弱区土地利用/土地覆被变化(LUCC)引起的生态环境质量变化进行了评估。计算结果表明:在1986～2000年间,由于土地利用面积的变化而使该地区的生态系统的生态价值减少,松嫩平原西部耕地和城乡建设用地有所增加,其他林地、草地、水域和未利用地的面积均减少。耕地面积增加的比例为9.80%、城乡建设用地增加0.66%;林地、草地、水域和未利用地面积减少的比例分别为1.10%、6.80%、1.20%和1.20%,15年的时间里松嫩平原西部生态脆弱区生态系统总价值减少7000.15×104美元,使生态系统服务价值损失9.74%。