绵阳地区白垩系岩石风化过程的生态效应

论述了四川绵阳地区白垩系七曲寺组砂岩、泥岩风化过程的信息动态及其对森林植被的生态效应，为长江上游水土保持防护林提供开发信息。     

Titanium Isotope Analysis of Igneous Reference Materials using a Double-spike MC-ICP-MS Method

Ti separation was achieved by ion-exchange chromatography using Bio-Rad AG 1-X8 anion-exchange and DGA resins. For high-Fe/Ti and high-Mg/Ti igneous samples, a three-column procedure was required, whereas a two-column procedure was used for low-Fe/Ti and low-Mg/Ti igneous samples. The Ti isotopes were analysed by MC-ICP-MS, and instrumental mass bias was corrected using a 47Ti-49Ti double-spike technique. The 47Ti-49Ti double-spike and SRM 3162a were calibrated using SRM 979-Cr, certificated value 53Cr/52Crtrue = 0.11339. Isobaric interference was evaluated by analysing Alfa-Ti doped with Na, Mg, Ca, and Mo, and results indicate that high concentrations of Na and Mg have no significant effect on Ti isotope analyses; however, Ca and Mo interferences lead to erroneous δ49/47Ti values when Ca/Ti and Mo/Ti ratios exceed 0.01 and 0.1, respectively. Titanium isotopic compositions were determined for 12 igneous reference materials, BCR-2, BHVO-2, GBW07105, AGV-1, AGV-2, W-2, GBW07123, GBW07126, GBW07127, GBW07101, JP-1, and DTS-2b. Samples yield δ49/47Ti (‰) of ?0.035 ± 0.022, ?0.038 ± 0.031, 0.031 ± 0.022, 0.059 ± 0.038, 0.044 ± 0.037, 0.000 ± 0.015, 0.154 ± 0.044, ?0.044 ± 0.018, 0.010 ± 0.022, 0.064 ± 0.043, 0.169 ± 0.034, and ?0.047 ± 0.025 (relative to OL-Ti, ±2SD), respectively; of which isotopic compositions of DTS-2b, JP-1, GBW07101, GBW07105, GBW07123, GBW07126, and GBW07127 are reported for the first time. Standard Alfa-Ti was analysed repeatedly over a ten-month period, indicating a reproducibility of ±0.047 (2SD) for δ49/47Ti, similar to the precisions obtained for geochemical reference materials.     

西藏申扎县索尔碎屑岩岩石学特征及其成因

索尔碎屑岩出露于西藏中部索尔—戈昂错一带,角度不整合覆盖于果芒错蛇绿混杂岩中的地幔橄榄岩之上,粗碎屑岩层和细碎屑岩层互层产出,并见有角砾状灰岩夹层。索尔碎屑岩中粗碎屑岩主要由灰黑色碎屑和土黄色基质所组成;细碎屑岩呈灰黑色,块状构造。碎屑的主体成分为蛇纹岩,并含有少量的尖晶石和斜长石,基质为泥晶结构碳酸盐。碎屑主要呈棱角状—次圆状,边界平直,可能是构造破碎后快速堆积而形成的。在蛇纹岩碎屑边部普遍可见垂直边界生长的板状或粒状方解石,部分碎屑之中方解石呈逐步向内部生长的趋势,而在少量的岩石中已形成了交代残余结构,反映索尔碎屑岩中的碎屑受到了碳酸盐不同程度的交代作用。通过与Gebel Mohagara蛇绿质碳酸盐岩和West Magnitogorsk古岛弧中出露的蛇绿质碳酸盐岩对比研究,初步认为索尔碎屑岩是地幔橄榄岩发生破碎后受到碳酸盐热液流体的交代所形成的。     

连续与断裂:重新认识下川遗址在中国旧石器文化研究上的意义

2014~2017年,北京师范大学历史学院和山西省考古研究院组织联合考古队,对下川遗址富益河圪梁地点、小白桦圪梁地点、牛路地点、水井背地点、流水腰地点进行了考古发掘。确认下川遗址包含了旧石器中期简单石核-石片文化（大约相当于MIS5）、旧石器晚期早段简单石核-石片文化（4.4~3.0万年）、旧石器晚期中段石叶-细石叶文化（2.7~2.5万年）和旧石器晚期晚段石叶-细石叶文化（1.7~1.6万年）共4个文化发展阶段。经历了3次文化转变,即从旧石器中期向晚期的转变;简单的石核-石片技术向石叶-细石叶技术的转变以及末次冰盛期前后石叶-细石叶技术的变化;在这些转变过程中,并没有表现出完全、持续的连续性;无论在时间上还是技术上,都存在明显的断裂现象;深入研究这些现象,将为中国北方现代人出现和演化提供新的解释。

     

基于地质建造的西南山区成土母质分类方案——以大凉山区为例

为适应生态地质调查和评价工作对成土母质研究的要求,以四川大凉山区为例,提出基于地质建造的成土母质分类方案,即以地质构造演化和地质建造环境为依据,结合残坡积物的成因类型对成土母质进行分类。大凉山区的成土母质可划分为第四纪冲洪积物、新近纪—第四纪砂泥岩类残坡积物、侏罗纪—白垩纪泥质岩类残坡积物、三叠纪砂泥岩类残坡积物、中生代中酸性岩类残坡积物、二叠纪基性—超基性岩类残坡积物、震旦纪—三叠纪砂泥岩类残坡积物、震旦纪—三叠纪碳酸盐岩类残坡积物、元古宙中酸性岩类残坡积物、元古宙火山碎屑岩类残坡积物、元古宙基性—超基性岩类残坡积物、元古宙变质岩类残坡积物等12类。研究表明,大凉山区成土母质和土壤存在差异性,但同一成土母质上的不同土壤类型具有一定相似的地球化学特征,不同成土母质形成的同一种土壤类型存在较大的地球化学差异。因此,基于地质建造的成土母质分类方案既能有效反映不同构造背景和成岩环境下的成土母质差异,又能有效表征成土母质与其上土壤的内在联系。     

Water-rock-tailings interactions and sources of sulfur and metals in the subtropical mining region of Taxco,Guerrero (southern Mexico): A multi-isotopic approach

Multi-isotope (H, O, S, Sr, Pb) systems coupled with conventional (major and trace element) hydrogeochemical analysis were applied to determine the origin of water, to model water-rock-tailings interactions and for source apportionment of sulfur and associated toxic metals in the mining region of Taxco, Guerrero in southern Mexico. Oxygen and H isotopes indicate that meteoric water in the zone is rainwater undergoing varying degrees of isotopic fractionation by atmospheric evaporation whereas Sr isotopes trace the interaction of pristine water from volcanics of the regional recharge zone and subsequently flowing through sandstone and shale to spring points. Leachates form from two distinctive sources (spring water and surface water) having differential interactions with bedrocks prior to entering the tailings. Compared to pristine water, leachates are enriched in sulfate, metals (e.g. Fe, Mn, Pb and Zn) and metalloids (e.g. As). The sulfur isotopic composition of ore-sulfides, leachates, secondary precipitates, regional surface water and hypogenic sulfates is described in terms of a two-component mixing model with shale of Mexcala and limestone of Morelos formations representing the light and heavy end-members, respectively, whereas Sr isotopic composition is bracketed combining three lithogenic (Mexcala/Morelos, Tilzapotla and Taxco Schist) sources. Finally, leachates have a mixture of lead from ore-sulfides and Taxco Schist Formation (Family I) or from ore-sulfides alone (Family II). The application of multiple environmental isotopic techniques is an outstanding tool for elucidating complex interactions of water with bedrocks and tailings and for determining the source of sulfur and toxic metal from mining and other metal polluted environments.     

红层软岩边坡生态防护技术探讨

红层软岩边坡,土质贫瘠,浅层稳定性差,生态防护失效的现象比较突出。为提高西部红层软岩边坡生态防护的可靠性,在对西部红层软岩地区铁路、公路边坡生态防护状况进行调研和分析的基础上,总结红层软岩边坡生态防护失败的原因,吸取经验教训,提出适于红层软岩边坡的生态防护方法和适合该区栽植的草木品种及配置方法。     

造山型金矿容矿建造分类、成矿模式及找矿勘查

造山型金矿床指造山过程中形成的后生脉状金矿床,受构造、建造双重控制,是全球最重要的金矿勘查类型。按容矿岩石建造的不同,造山型金矿可分为绿岩带型（包括绿片岩型、BIF型和花岗- 片麻岩型3个亚类型）、浊积岩型、碳酸盐岩型和浅成侵入岩型,构成了造山型金矿床完整的成矿谱系。不同类型之间具有紧密的时空和成因联系,可互为找矿标志。绿岩组合和浊积岩系具有高的金丰度,既是容矿岩系,也是重要的矿源层,多类型造山作用驱动大规模区域性流体活动,造就了造山型金矿省/巨型成矿带,岩浆流体叠加和“热机效应”是形成超大型金矿床的重要因素。构建了多源区域性流体+岩浆流体叠加的地壳连续成矿模型和造山型金矿区域成矿模式,强调了多旋回造山作用对造山型金矿的成矿意义。“富金矿源层+剪切变形带+浅成侵入岩”组合是大型金矿系统的勘查选区标志,靶区优选的目标是获取找矿潜力大的优质矿权;矿权区勘查的优先目标是发现可规模化露天开采的矿床（体）,通过化探异常评价和浅钻追索次生富集带,可快速发现主矿体;矿区深部找矿（深度>300 m）潜力巨大,主攻目标是资源量大、品位高的热液通道相的厚板状或筒状矿体。     

东昆仑造山带海德乌拉铀矿床成矿流体特征研究

东昆仑造山带海德乌拉铀矿床是近些年西北地区最新探明的与火山岩有关的独立铀矿床,该矿床的发现为东昆仑造山带探寻热液型铀矿床提供了指示意义。本文选择与海德乌拉铀矿成矿期相关的透明矿物（粉红色方解石、紫黑色萤石及石英）作为研究对象,系统地开展C- H- O同位素和流体包裹体研究,查明该矿床成矿流体的来源与性质,并探讨矿床成因。研究结果表明,海德乌拉铀矿床成矿期石英中主要为H2O气液两相包裹体,少见CO2- H2O两相包裹体;在粉红色方解石脉、紫黑色萤石脉中流体包裹体均含H2O气液两相包裹体,在粉红色方解石脉中偶见纯液相包裹体,均未见到纯气相及含固相包裹体。成矿期粉红色方解石、紫黑色萤石及石英中包裹体均一温度范围分别为133~187℃（均值163℃）、127~204℃（均值169℃）、183~287℃（均值219℃）,盐度范围分别为1. 40%~7. 02%NaCleq（均值3. 65%NaCleq）、0. 53%~3. 06%NaCleq（均值1. 26%NaCleq）、7. 17%~17. 26%NaCleq（均值为11. 46%NaCleq）。流体包裹体气相成分以H2O为主,另含少量CO2等。C- H- O同位素实验数据表明,流体中δ13CFluid- V- PDB、δDFluid- V- SMOW、δ18OFluid- V- SMOW值的变化范围分别为1. 59‰~1. 00‰、71‰~63‰、0. 03‰~3. 72‰,表明成矿流体并非单一来源,可能为大气降水与岩浆水混合来源。此外,沥青铀矿的沉淀主要是由于流体与围岩的相互反应所引起的物理化学条件变化加上流体沸腾/CO2去气,最终导致了沥青铀矿等成矿物质发生大规模的卸载与沉淀。