西藏拿顿铜(金)矿床岩矿相学、流体包裹体和地球化学特征与成矿作用研究

拿顿矿床位于多龙矿集区西南部,地处西藏成矿潜力巨大的班公湖-怒江成矿带上,目前该矿床的勘查研究程度非常低,仅在地表圈定出一个铜金矿体,具有很大的找矿前景。本文对拿顿矿床的岩矿相学、流体包裹体及地球化学特征进行了研究。矿床中主要蚀变矿物有高岭土、绢云母、绿帘石、方解石、白云石等,并存在银金矿、辰砂、方铅矿、闪锌矿等特征金属矿物组合。斑晶与胶结物中的流体包裹体均一温度集中在222~360℃之间,主要成分以H2O为主,含有少量CO_2,斑晶中包裹体的盐度为一组高盐度值(18.35%~26.7%NaCleqv.)和一组低盐度值(0.18%~12.85%NaCleqv.),胶结物中包裹体盐度值较低,主要分布在1.6%~12.5%NaCleqv.区间内,是在中低温、低盐度、氧化环境中形成,成矿流体受大气降水的影响较为明显。花岗闪长斑岩中SiO2含量为55.9%~65.67%,平均值为60.52%,Na_2O+K_2O含量为3.54%~5.563%,平均值为4.83%,属于高钾钙碱性系列至钾玄岩系列。A/CNK值为1.63~2.93,平均值为2.6,反映原岩为过铝质岩石。花岗闪长斑岩中稀土总量ΣREE变化范围为29.09×10~(-6)~98.73×10~(-6),整体上具轻微铕负异常(δEu=0.7~1.12),不具铈异常(δCe=0.84~0.99);岩石富集大离子亲石元素(LILE:Rb、K),亏损Nb、Ta、P、Ti等高场强元素(HFSE),具岛弧火山岩的典型特征。矿床脉状黄铁矿中Co/Ni比值为0.05~8.523,平均值为4.219,为热液成因,脉状黄铁矿多与石英脉共生,为后期热液作用阶段的产物。矿床中黄铁矿δ34S值的分布范围为-4.5‰~0.7‰,平均值为-1.95‰,黄铜矿的δ34S值为-7‰~-3.3‰,平均值为-5.43‰,硫同位素δ34S值偏小,且为负值,指示矿床中的硫受到了还原硫的影响。矿床中赋矿岩体为花岗闪长斑岩,发育银金矿、辰砂等特征矿物组合,流体包裹体具有斑岩型铜(金)矿床的中高温流体特征,据此判断矿床成因类型为低硫型浅成低温热液矿床叠加斑岩型铜(金)矿床。根据因子分析,矿床最早期的成岩作用形成早期的中酸性岩体;矿床的成矿作用主要为热液铜金矿化作用,随后发生铅锌矿化、磁铁矿化和钾化等作用,在成矿后期有含碳酸盐热液的侵入。     

Annual variations in the surface radiation budget and soil water and heat content in the Upper Yellow River area

Measurements taken between July 2006 to May 2007 at the Maqu station in the Upper Yellow River area were used to study the surface radiation budget and soil water and heat content in this area. These data revealed distinct seasonal variations in downward shortwave radiation, downward longwave radiation, upward longwave radiation and net radiation, with larger values in the summer than in winter because of solar altitudinal angle. The upward shortwave radiation factor is not obvious because of albedo (or snow). Surface albedo in the summer was lower than in the winter and was directly associated with soil moisture and solar altitudinal angle. The annual averaged albedo was 0.26. Soil heat flux, soil temperature and soil water content changed substantially with time and depth. The soil temperature gradient was positive from August to February and was related to the surface net radiation and the heat condition of the soil itself. There was a negative correlation between soil temperature gradient and net radiation, and the correlation coefficient achieved a significance level of 0.01. Because of frozen state of the soil, the maximum soil thermal conductivity value was 1.21 W m⁻¹°C⁻¹ in January 2007. In May 2007, soil thermal conductivity was 0.23 W m⁻¹°C⁻¹, which is the lowest value measured in the study, likely due to the fact that the soil was drier then than in other months. The soil thermal conductivity values for the four seasons were 0.27, 0.38, 0.55 and 0.83 W m⁻¹°C⁻¹, respectively.     

西藏班戈县江错铁矿正长斑岩锆石LA-MC-ICP-MS U-Pb定年及意义

在班戈县东偏北约100km的江错铁矿采集正长斑岩样品,进行系统的岩相学、地球化学及锆石LAMC-ICP-MS U-Pb定年。结果显示正长斑岩的SiO_2含量变化为59.55%～62.61%,平均值61.52%,Na_2O含量变化为9.31%～10.01%,平均值9.74%;K_2O含量变化为0.107%～0.12%,平均值0.113%,里特曼指数变化范围为5.16～5.36,属于钠质碱性岩系列,是班公湖-怒江缝合带中段班戈地区首次发现的碱性岩。锆石U-Pb年龄为170±2.4Ma,表明其为中侏罗世的产物。综合对比区域地质资料,认为这套正长斑岩应该是班公湖-怒江洋盆开始俯冲早期的不成熟岛弧阶段的产物。     

共存镉/铜对沉积物(生物膜)中主要组分吸附阿特拉津的影响

采用选择性萃取分离技术对沉积物(生物膜)中非残渣态组分(铁、锰氧化物和有机质)进行分离,研究阿特拉津(atrazine,AT)-Cd-Cu系中共存重金属对选择性萃取前后沉积物(生物膜)吸附AT的影响.研究结果表明:共存体系中,沉积物(生物膜)中铁氧化物对AT的吸附贡献最大,其次是有机质,而锰氧化物则抑制AT的吸附;共存镉促进了AT在沉积物(生物膜)原样及各非残渣态组分上的吸附,镉质量浓度为0.2 mg/L时,促进作用最显著,各组分对阿特拉津的吸附贡献增加了3.20%～32.31%(沉积物)和1.61%～17.10%(生物膜),但随镉质量浓度的增加,其促进作用减弱;共存铜抑制沉积物(生物膜)原样及铁氧化物、有机质对AT的吸附,铜质量浓度为75.0 mg/L时,其抑制作用最强,铁氧化物和有机质对阿特拉津的吸附贡献分别降低了29.21%、22.36%(沉积物)和9.46%、77.27%(生物膜),但同时减弱了锰氧化物对AT吸附的抑制作用,其吸附贡献分别提高了28.98%(沉积物)和17.46%(生物膜).     

The effects of slope shape and polyacrylamide application on runoff,erosion and nutrient loss from hillslopes under simulated rainfall

Natural hillslopes are mostly composed of complex slope shapes, which significantly affect soil erosion. However, existing studies have mainly focused on uniform slopes to simplify complex hillslopes, and the mechanisms responsible for the influence of slope shape on soil and nutrient losses are still not well understood, especially in the application of soil improvers to reduce soil loss. To investigate the effects of slope shape and polyacrylamide (PAM) application on runoff, soil erosion and nutrient loss, this study conducted artificial field rainfall experiments involving two PAM application rates and nine slope shapes. The results indicate that the average amount of soil loss from convex slopes was 1.5 and 1.3 times greater than that from concave and uniform slopes, respectively, and the average amount of ammonia nitrogen loss and phosphate loss increased by 24.0%–58.6%. Soil and nutrient losses increased as the convexity of the convex slopes increased. For runoff, there was little difference between concave and convex slopes, but the runoff amount for both slopes was greater than that for uniform slopes. After PAM application, the soil loss decreased by more than 90%, and the nutrient loss decreased by 28.2%–68.1%. The application of PAM was most effective in reducing soil erosion and nutrient loss from convex slopes, and it is recommended to appropriately increase the PAM application rate for convex slopes. A strong linear relationship between ammonia nitrogen and phosphate concentrations and sediment concentrations was found in the runoff on slopes with no PAM application. However, this linear relationship weakened for slopes with PAM application. The findings of this study may be valuable for optimizing nonpoint source pollution management in basins.     

1990年6月14日苏联斋桑湖7.3级地震和两次强余震前富蕴地震窗的异常及其预报

近年来,地震窗预报方法已在国内广为应用。富蕴地震窗系笔者在王泽皋、姜秀娥等人工作的基础上^[1-3],于1984年在全国地震预报清理攻关中建立,在1987-1988年全国地震预报实用化攻关中又得以进一步深化和完善^[4]。     

Simulating the role of gravel in freeze–thaw process on the Qinghai–Tibet Plateau

Soils containing gravel (particle size ≥2 mm) are widely distributed over the Qinghai–Tibet Plateau (QTP). Soil mixed with gravel has different thermal and hydrological properties compared with fine soil (particle size <2 mm) and thus has marked impacts on soil water and heat transfer. However, the most commonly used land models do not consider the effects of gravel. This paper reports the development of a new scheme that simulates the thermal and hydrological processes in soil containing gravel and its application in the QTP. The new scheme was implemented in version 4 of the Community Land Model, and experiments were conducted for two typical sites in the QTP. The results showed that (1) soil with gravel tends to reduce the water holding capacity and enhance the hydraulic conductivity and drainage; (2) the thermal conductivity increases with soil gravel content, and the response of the temperature of soil mixed with gravel to air temperature change is rapid; (3) the new scheme performs well in simulating the soil temperature and moisture—the mean biases of soil moisture between the simulation and observation reduced by 25–48 %, and the mean biases of soil temperature reduced by 9–25 %. Therefore, this scheme can successfully simulate the thermal and hydrological processes in soil with different levels of gravel content and is potentially applicable in land surface models.

     

遥感构造蚀变生态景观研究及在陕西金矿找矿中的应用

本文针对秦岭成矿带中部金矿遥感地质特征,特别是主导控矿因素特点,在详细分析区内地物反射光谱特征曲线的基础上,提出“遥感构造蚀变生态景观”新方法,制定合理的计算机图像处理方案,提取构造蚀变和植被毒化等对金矿预测有贡献的有效信息,然后进行金矿成矿远景预测,取得了成功的尝试。     

东昆仑东段三叠纪岩浆混合作用:以香加南山花岗岩基为例

香加南山花岗岩基位于东昆仑造山带东段,岩基主要岩石类型为花岗闪长岩。千瓦大桥-加鲁河一带花岗岩体为香加南山岩基的重要组成部分。香加南山花岗岩基含大量暗色微粒包体,包体中捕掳晶丰富。千瓦大桥-加鲁河一带花岗岩体寄主岩中斜长石和暗色微粒包体中捕掳晶斜长石具正常环带,An值震荡变化,角闪石和黑云母Mg O含量和Mg#值较低,具壳源特征;暗色微粒包体中基质斜长石具核边结构,核部和边部An值存在间断,角闪石和黑云母Mg O含量和Mg#值较高,具幔源特征。LA-ICP-MS锆石U-Pb同位素定年结果显示千瓦大桥花岗闪长岩、暗色微粒包体和加鲁河辉长岩的结晶年龄分别为251.0±1.9Ma、252.8±3.0Ma和221.4±3.3Ma。千瓦大桥花岗闪长岩和加鲁河花岗闪长岩富集轻稀土元素(LREE)和大离子亲石元素(LILE),亏损高场强元素(HFSE),具较低的Mg#和Nb/Ta比值;从千瓦大桥到加鲁河花岗闪长岩呈现出由准铝质中钾钙碱性系列向准铝-弱过铝质中钾-高钾钙碱性系列演化;暗色微粒包体和加鲁河辉长岩轻重稀土元素分异程度相对较低,具较高的Mg#和Nb/Ta比值。千瓦大桥花岗闪长岩和加鲁河花岗闪长岩分别为古特提斯演化俯冲阶段和后碰撞阶段幔源岩浆底侵新生地壳使其部分熔融产物。镁铁质岩浆注入长英质岩浆的混合作用形成了暗色微粒包体。岩浆混合过程中,如果岩浆不完全混合,混合岩浆中混入物质除了长英质岩浆的残留岩浆和捕掳晶,还应该有镁铁质岩浆与长英质岩浆之间的元素梯度差导致的物质扩散;如果岩浆为近完全混合,混合岩浆近似为镁铁质岩浆和长英质岩浆以一定比例二元混合。东昆仑东段晚古生代-早中生代幔源岩浆对花岗质岩浆的影响是一个持续的过程,从俯冲阶段早期流体交代地幔熔融,到俯冲阶段后期板片断离,然后同碰撞阶段板片断离的持续影响,再到后碰撞阶段加厚地壳的拆沉作用,由于地球动力学体制不同,导致幔源岩浆影响的大小和特征不同。