三峡地区岩家河埃迪卡拉系-寒武系界线剖面碳同位素地层学研究

湖北宜昌三峡地区埃迪卡拉系一寒武系界线位置尚存争议,跨越这一界线的岩家河组地层的分段工作也缺乏统一的意见。对岩家河剖面开展岩相学和碳同位素地层学研究,揭示其碳同位素演化可与扬子板块内滇东北老林剖面和肖滩剖面对比,即自下而上在该界线附近存在一个大的δ13C负漂移、一个稍小的δ13C负漂移和一个大的δ13C正漂移。结合该剖...     

新疆北部青河县阿斯喀尔特铍矿区花岗质岩石年代学及地球化学特征

新疆北部青河县阿斯喀尔特铍矿床的形成与岩浆活动密切相关,是中国花岗岩型铍矿床的典型代表。对矿区斑状二云母二长花岗岩进行LA-ICP-MS锆石U-Pb年龄测试,获得其加权平均年龄为(216.7±2.8)Ma(MSWD=0.48),表明该岩体形成时代为晚三叠世,据此限定阿斯喀尔特铍矿床成矿时代略晚于216 Ma,为晚三叠世—早侏罗世。岩石具有高硅(w(Si O2)=70.86%~76.34%)、富碱(ALK=5.54~9.30)、富铝(w(Al_2O_3)=13.00%~14.74%,A/CNK=0.99~1.23)、低钛(w(Ti O2)=0.02%~0.18%)和镁(w(Mg O)=0.02%~1.21%)特征,为过铝质中钾-高钾岩石系列。稀土元素配分型式显示LREE的相对弱富集,HREE较平坦以及Eu弱-中等的负异常(δEu=0.37~0.90),呈略右倾型。微量元素Ba、Sr、Hf、Ti等具负异常,Rb、Th、K、Nb、Ta、La、Ce、Nd、Sm等具正异常,Rb/Sr比值较高(9.34~26.81),显示出S型花岗岩特征。结合区域资料,认为阿斯喀尔特铍矿矿区印支期花岗岩形成于后造山构造阶段,可能是上地壳含砂泥质岩石部分熔融的产物。     

Distribution,genesis, and pollution risk of ammonium nitrogen in groundwater in an arid loess plain,northwestern China

Nitrogenous pollutants from intense human activities have become serious environmental and health problems worldwide, particularly in groundwater source areas used for public water supply. To investigate the genesis and pollution risks associated with elevated concentrations of ammonium nitrogen in a groundwater source area, investigations were undertaken in the Jinji groundwater source area, located in an arid loess plain in northwestern China where 16 groundwater samples were collected from an aquifer used for water supply. The investigation indicated that high concentrations of ammonium nitrogen originated mainly from: infiltration of water from the Yellow River; livestock; and the discharge of industrial wastes. Measured parameters including pH, the permanganate index and the oxidation reduction potential could be used as important indicators of the genesis of ammonium nitrogen. A modified DRTCLN model was applied to the observed distribution of ammonium nitrogen to assess pollution risk of regional groundwater. The model was optimized by rebuilding the index system, and the analytic hierarchy process was used to calculate the rating scale of each index. A Monte Carlo simulation was performed to analyze the uncertainty of results of the risk assessment. The result showed that the risk value is relatively low in most areas of the groundwater source area. Only an industrial area in the southwestern part of the groundwater source area was classified as high risk; it should be the key factor of pollution control.     

松辽盆地增强型地热系统开发选区评价

干热岩是一种新型清洁能源,其开发利用区的确定十分重要。笔者首先通过对松辽盆地热源、资源量、导热、聚热、地震活动5个方面资料的收集,提出了松辽盆地增强型地热系统开发选区适宜性评价方法;然后选取8项评价因子,利用ArcGIS 10.2平台将松辽盆地划分为26个评价单元,根据打分法和层次分析法(AHP)求取每个因子的权重;最后,对26个选区进行综合评价,将其分成适宜、较适宜、一般适宜、较不适宜和不适宜5个等级。结果表明:松辽盆地干热岩开发适宜区和较适宜区主要集中在盆地中部的大安—大庆一带,确定的适宜选区范围对今后干热岩开发工作具有一定指导作用。     

Temporal and Spatial Distribution of the Late Devonian (Famennian) Strata in the Northwestern Border of the Junggar Basin, Xinjiang, Northwestern China

The base of the Saerba Member (Mbr) of the Hongguleleng Formation (Fm.) probably lies in the Famennian Palmatolepis crepida Zone; the Longkou Mbr is probably a sedimentary wedge that thins out northwards; the Duguer Mbr has an approximate age from the upper part of the Pa. marginifera Zone or the Lower Pa. rugosa trachytera Zone through the top of the Pa. perlobata postera Zone; the Wulan Mbr has an age approximately corresponding to the whole Pa. gracilis expansa Zone. In the Bulongguoer section, the Lower Mbr of the Hongguleleng Fm. corresponds to Famennian Pa. crepida Zone through Pa. marginifera Zone; the Middle Mbr probably ranges from the Pa. r. trachytera Zone through the Pa. g. expansa Zone. The basal Namu Mbr of the Heishantou Fm. is probably the product during and after the Hangenberg Event in the upper part of the Siphonodella praesulcata Zone, which is still within the Devonian. In this context, the underlying Chasi Mbr may approximately correspond to the lower part of the S. praesulcata Zone (before the Hangenberg Event). Lateral distribution of strata indicates that the Upper Devonian in the Gennaren and Saerba areas each constitutes a structure of syncline, which differs from the previous recognition of a monocline structure.     

中晚全新世湘西莲花洞石笋旋回沉积速率变化及其古气候意义

石笋旋回沉积速率是按照石笋沉积旋回测年得到的沉积速率,是石笋沉积过程的重要参数和反演古气候变化的有效代用指标。旋回沉积速率的波动可能反应了地表温度和降雨量的变化,与夏季风强度存在关联。文章以湖南湘西莲花洞LH2石笋为材料,利用42个230Th年龄获得的石笋旋回沉积速率序列重建了8.6 ka BP以来湖南湘西地区温度和降雨雨量的变化历史: 8.6-4.2 ka BP期间,气候以高温多雨为特征,夏季风强,石笋生长率高,但气候并不稳定,存在一系列千年-百年尺度的波动;4.2-0.05 ka BP期间,气候整体偏冷干,旋回沉积速率偏低。总体上,在轨道尺度上,LH2石笋的旋回沉积速率与该石笋的δ18O值之间存在负相关关系。旋回沉积速率的重复性检验证明了旋回沉积速率古气候记录的有效性。石笋旋回沉积速率变化主要受北半球夏季太阳辐射量的控制和ITCZ的直接影响,在百年尺度上,旋回沉积速率的波动可能与中晚全新世的弱季风事件存在关联。      

下扬子皖南地区上二叠统(泾页1井)发现海陆过渡相页岩气

<正>1研究目的(Objective)中国下扬子地区上二叠统广泛发育大隆组—龙潭组暗色页岩,但勘查程度较低,一直未获页岩气调查突破。通过前期综合研究,在下扬子皖南坳陷孤峰向斜西翼部署实施了泾页1井,在上二叠统见良好页岩气显示。开展了系统分析测试工作,评价了区域页岩气资源潜力,分析了页岩气成藏条件与富集规律,为页岩气资源评价和进一步调查部署提供了依据。     

相山铀矿田矿石有用共生组分研究

相山铀矿田是我国目前规模最大的火山岩型热液铀矿田,其发育碱交代型铀矿化和酸交代型铀矿化两种矿床类型。笔者通过对该矿田主要酸交代型铀矿床的物质组分研究,发现其矿石中富含Th、Mo、HREE、Y等多种有用组分,且含量普遍可达综合利用品位;有用组分主要以独立矿物、类质同像形式存在,主要赋存于铀矿体的矿化中心带富矿石中,与铀为同空间富集。因此认为,相山铀矿田酸交代型矿床的矿石中,Th、Mo、HREE、Y与铀密切相关,矿物具有共生关系;应重视Th、Mo、HREE、Y等有用组分的综合利用评价。     

滇西腾冲更新世粗面安山岩Ar-Ar年代学、地球化学特征及其构造意义

腾冲芒棒地区广泛发育新近纪以来的火山岩,本文首次对该区粗面安山岩进行的高精度40Ar/39Ar同位素定年,其坪年龄分别为2.1±0.1Ma和2.0±0.1Ma,代表其喷溢时代为早更新世。岩石地球化学特征研究显示,粗面安山岩属高钾钙碱性系列,富集大离子亲石元素、亏损高场强元素,具有弧火山岩与大陆板内火山岩的双重属性,推测其形成于后造山环境。综合研究表明,腾冲地块更新世火山岩的形成与印度-欧亚板块俯冲-碰撞造山隆升后的伸展垮塌、富集地幔部分熔融作用密切相关,而印支陆块向东南逃逸以及腾冲弧形走滑断裂带(龙川江断裂带、大盈江断裂带)的活化促使了该期火山岩的喷发与侵位。     

通化盆地下白垩统烃源岩石油地质特征及生烃潜力研究

通化盆地是松辽盆地东部外围的油气远景区之一,烃源岩发育特征和生烃潜力等问题未知,制约着盆地基础油气资源研究和后续油气资源勘探部署工作。为揭示通化盆地下白垩统烃源岩生烃潜力和页岩油气的赋存状态,在盆地内部署通地1井,对岩芯样品进行系统取样,完成了暗色泥岩有机质丰度、类型和成熟度的测试工作。实验结果表明,通化盆地下白垩统亨通山组暗色泥岩有机质丰度较高,有机质类型以Ⅰ-Ⅱ1型为主,局部含有Ⅲ型,镜质组反射率分布范围为0.972%~1.127%,已进入大量生烃的成熟阶段;下桦皮甸子组暗色泥岩有机质丰度较高,有机质类型以Ⅰ型为主,局部含有Ⅱ和Ⅲ型,镜质组反射率在0.986%~1.399%之间,已进入大量生烃的成熟阶段。其地球化学特征和世界上许多页岩油气田的烃源岩有相似之处,综合研究表明通化盆地下白垩统具有较好的常规油气和页岩气生成潜力。