湘西柳林汊金矿带钠长石的矿物学和地球化学研究

湘西雪峰山地区是湖南最重要的黄金产地，湖南省80%以上的金矿床均赋存在该区前寒武系的浅变质岩中。柳林汊金矿带位于湘西雪峰山中段的北部，尽管该金矿带发现较早，采矿历史很长，但地质工作程度较低。在系统野外调研的基础上，本课题组首次确认柳林汊一带金矿床为典型的钠长石-石英脉型金矿床，明显有别于雪峰山地区其它石英脉型金矿床。本学位论文以该区四个有典型代表性的钠长石-石英脉型金矿为研究对象，在系统野外地质考察和系统采样的基础上，利用矿物学、元素地球化学、同位素地球化学、流体地球化学等研究手段，对该区金矿床的载金矿物—钠长石进行了较详细的矿物学和地球化学研究。在此基础上初步探讨了柳林汊一带金矿床的成矿流体来源、成矿物质来源、成矿时代及矿床成因。本论文主要取得以下几点新认识： 1.柳林汊金矿带金矿床的矿脉中的这些长石呈肉红色，在镜下通常呈板条状、粒状，解理不发育，双晶以聚片双晶为主，负低突起，干涉色一级灰白到一级淡黄。本文首次确认了该区矿脉中的肉红色长石为低温、高有序度的钠长石，该区的金矿类型为典型的钠长石-石英脉型金矿。 2.该区钠长石具Ab含量高，An、Or含量极低等特征，接近纯钠长石。钠长石中Sr 含量相对较高而稀土含量普遍较低，通常为LREE富集型，无明显的Eu、Ce异常。 3.柳林汊一带金矿脉中钠长石的氧同位素组成为10.2‰～14.5‰，对应的成矿流体的δ18O‰为1.9‰～6.9‰。该区成矿流体可能主要来自经演化的大气降水。 4.与钠长石共生的石英中的包裹体主要以液体包裹体为主。其均一温度为140～300℃，盐度为1～8%NaCl，成矿流体的密度为0.60～0.99g/cm3。该区金矿床成矿流体具中低温、低盐度和中等密度等特征。 5.根据本区金矿床的地质特征，并结合前人对湘西地区金矿床的研究成果，提出该区金矿的成矿物质来源为元古宇板溪群，成矿时代为加里东期，矿床的成因类型为层控的热液改造型金矿床。 关键词：柳林汊金矿带 钠长石 矿物学 元素地球化学 流体包裹体 矿床成因

植物稳定同位素多尺度、高分辨率古气候信息综合辨识-以安图红松和红原泥炭为例

植物稳定同位素气候学因其具有坚实的理论基础，在古气候研究中倍受关注。同位素“语言”对气候变化的记录是一种“精确”记录。近30多年来，大量科学家不懈努力，提出并完善了植物C、H、O同位素分馏模型，为全球气候变化提供了理想的研究手段。古气候研究面临空前的机遇和挑战；不论是气候规律的发掘以及气候驱动机制的探讨，均需要大力加强。作者利用植物同位素气候学这一理想的研究“工具”，分别选取树轮和泥炭气候历史档案库作为信息载体，开展了中国全新世以来高分辨率、多时间尺度的气候信息综合辨识。我的工作表明：植物稳定同位素组成是理想的气候代用指标。树轮、泥炭档案库相结合，可以获得多尺度（年际、代际、百年以及千年时间尺度）、高分辨率气候信息，对于认识全球气候变化规律以及深入探讨全球气候动力学机制是十分重要的。1、安图红松树轮同位素气候代用记录研究（1）安图红松树轮同位素组成受多种气象因子的联合作用，因而单一地将某一同位素指标与某一气象因子做回归分析所得结果不甚理想。本论文构建了“温度一湿度”复合气候指标，取得了理想的结果。研究发现，不论是树轮δ13C还是δ18O，均与5-8月温湿复合指标显著相关。重建的气候变化与《安图县志》记录的气候变化事件大多吻合。证明这种新的研究方案是可行的，值得在以后的工作中进一步加强。（2）安图红松树轮δ13C灵敏地记录了该区过去200年来5-7月低云量变化。综合分析各种气象要素之间的相关关系以及气象要素与树轮δ13C之间的相关关系，作者认为，低云量对树轮δ13C的影响是一种间接影响。低云量非常显著地影响日照强度以及降雨量等气象因子，进而借助于日照强度及降雨量等气象因子在树轮δ13C中留下自身的变化“印记”。（3）功率谱分析证明，安图红松树轮δ13C、δ18O序列均包含了显著的准2年周期、准4年周期、准10-8年周期。分别是对东亚夏季风准两年振荡（QBO），ENSO准4年周期，太阳活动准11年周期的响应。（4）作者在传统树轮氢、氧同位素分馏模型基础上，同时引入“交换因子”和“蒸腾因子”两个新参数，改进了树轮氢、氧同位素分馏模型。改进的模型能利用树轮H、O同位素组成较准确模拟大气降水H、O同位素组成。改进的模型采用“自适应”方式，具有很大的灵活性，可望用于“用泥炭同位素组成模拟大气降水同位素组成”这项研究中。2、红原泥炭氧同位素气候代用记录研究（1）过去6000年来，红原温度变化趋势与金川、敦德温度变化趋势有很好的相似性，证明中国大多地区温度变化趋势是一致的。6000～4000aBP平均温度水平较低；4000-1500 aBP平均温度水平较高；1500aBP至今平均温度水平相对较低。4000aBP和1500aBP是近6000年温度变化序列中两个显著的转折点。（2）红原温度变化序列中记录到一系列低温突变，这些突变事件与金川、敦德、格陵兰、北大西洋，等等，广泛区域内温度突变事件具有很好的一致性。特别地，每当一次低温突变事件发生，通常有相应的社会结构重整、社会崩溃、古文明坍塌等重大历史事件与之对应。这进一步证实，气候变化（特别是气候突变）对整个社会经济和文明的冲击是十分明显的。（3）近6000年红原、金川温度变化趋势与大气14C变化趋势非常相似，暗示中国地区温度变化的主要驱动力来自太阳活动。功率谱分析进一步证实了这一结论。功率谱分析中最显著的周期信号是88-yr和123-127-yr年周期，体现了一种典型的世纪尺度温度变化特征。3、综合讨论（1）“红原-金川”平均温度变化趋势显示，近千年中国平均温度变化与经典的太阳活动极小期，如Darton极小、Maunder极小、sp6rer极小、oort极小，等等，表现一致。表明中国气温变化主要驱动力来自太阳活动。大约在1050-1250AD期间，中国温度水平较高。而同期大气14C，南极冰心10Be以及模拟的总太阳辐射等均表明太阳活动处于较高水平。大量树轮记录也表明近百年中国并无异常升温。这些资料表明，最近百年气温变化可能并未超出自然变率。（2）提出了“大洋温盐环流一季风”概念模型。这一模型能很好解释北大西洋温度突变与印度洋夏季风突变的一致性、中国东北和西南长期降雨趋势的反相性、北太平洋（温盐环流上翻区）温度记录与北大西洋温度记录的“跷跷板”效应（seesaw effect），等等。大洋温盐环流可能是主宰印度洋夏季风区、东亚夏季风区长期干湿变迁的主要因素。

贵州凉风洞石笋的古气侯记录与古生态环境意义

自20世纪60年代以来，探索全球性气候变化规律和环境变迁史的研究工作在世界各国广泛开展。大规模的深海岩芯的研究、中国北方黄土的系统研究、大型湖泊沉积岩芯的研究及对树木年轮、泥炭、珊瑚、冰芯等“自然环境历史档案”开展的研究工作，都为重建古气候和古生态环境提供了大量的资料。洞穴化学沉积物（石笋）由于其特有的微层结构及其内的稳定氧、碳同位素和微量元素所蕴含的古气候与古生态环境信息，并且具有分布广、时间长、信息保存完整等特点，因此，它是研究地球环境变化很好的自然环境历史档案。本论文通过对凉风洞洞穴体系的综合研究和对凉风洞石笋（微层）生长特征及石笋的碳、氧稳定同位素组成的研究，系统探讨了贵州凉风洞石笋的古气候记录和古生态环境意义，得出以下主要结论：1，地表植被的类型及生物量等信息可综合反映于洞穴体系的不同组．分（气样、土样、水样）中。而洞穴的水动力条件也能很好的被洞穴滴水中所含微量（常量）元素记录。根据分析，洞穴综合体系对外界气候与生态环境的响应关系存在一定规律性。通过对比说明，我们所选的凉风洞基岩的溶蚀和缓冲对水体中的信息影响不大，即洞穴滴水较好的继承了土壤水所携带的地表气候与生态环境信息，是理想的研究对象。2．凉风洞石笋具有多个沉积旋回，不同沉积旋回的纹层组合及纹层结构存在一定的差异，指示不同的沉积环境。根据年龄数据判断，旋回①至旋回⑧之间年龄跨度为1570-8000 aBP，以呈缓平顶（柱）对称叠复状的沉积形态组合为主，示洞顶滴水量较大，滴水点相对稳定，且均匀，与全新世较为稳定的气候与环境变化的主旋律相一致。旋回⑧以下至底部石葡萄状沉积物之上部分之间年龄跨度为8000-14220 aBP，期间经历末次冰期晚期向全新世大暖期过渡，受诸如新仙女木事件（Younger Dryas）等的影响，气候变化幅度大，且经历多次反复，石笋生长的沉积学特征表现为斜锥（柱）、尖顶锥不对称叠复纹层组合，示洞顶滴水水量较小但变化较大，且洞穴滴水不稳（固）定。与此时间段内不稳定的气候与环境变化的主旋律也相一致。3．凉风洞石笋上段微层具有典型南方石笋微层发育的特性：微层发育较差，层面多弯曲，层间界面模糊等。下段因为沉积间断较多、风化层面厚及受到若干时段内碳酸钙重结晶而导致晶体穿插层位生长的影响，尽管在某些层位有微层发育，但无法对石笋微层作连续观察记录。根据高精度的石笋TIMS、ICP-MS测年数据和在显微镜下所数石笋微层数量的对比，扣除若干个沉积间断及风化层导致的微层缺失，以及显微镜下肉眼对细小微层计数的误差，我们认为，凉风洞石笋微层是年生长层的可能性较大。4，由于部分测年数据仍在测试中，目前无法精确控制石笋中沉积间断的存在导致的信息缺失，因此，我们仅仅根据部分石笋测年数据，建立了凉风洞石笋在不同时段的生长速率。全新世以来石笋的生长速率在22μm／yr-51μm／yr之间，明显高于末次冰期晚期向全新世过渡这一时间段内的石笋生长速率（16μm／yr）。这些数据间接印证了石笋生长响应于外界气候，尤其是降雨的变化。5．通过对洞穴体系的综合分析对比，我们判断凉风洞洞穴综合体系相对完整，洞穴化学沉积物的6先值较为直接的响应了土壤c压的61t值变化，即反映了地表的植被（c3植物和c；植物）的组成状况。贵州地区降雨80％集中在5-10月份，在此期间，基本受西南季风和东亚季风所控制。西南季风盛行时贵州各地的降雨频繁，是一年中雨量最集中的时期，在东亚季风影响时期，贵州多晴少雨，往往形成干早的天气。又西南季风控制区大气降雨创的值的加权平均值明显低于东亚季风控制区大气降雨δ18O值的加权平均值。因此，贵州地区年均降雨量和年均降雨δ18O值主要取决于西南（印度洋）季风的强弱：西南季风加强，降雨量增加，年均降雨剐、值偏负；西南季风减弱，降雨量减少，年均降雨δ18O值偏正。洞穴滴水的6旧O值变化基本继承了大气降水的别勿值变化。因此，对地处我国西南地区贵州南部的凉风洞，源于洞穴滴水的凉风洞石笋的别勺值变化直接响应了外界的大气降雨量的变化和西南季风与东亚季风相互的强弱交替。6．对凉风洞石笋碳、氧同位素组成的时间序列曲线作20点移动平均，发现，特别是进入全新世后，石笋的引3c值和扩、值几乎具有完全一致的同步变化，只是在变化幅度上在某些时段存在差异。说明在凉风洞石笋反映的14220-1570 aBP时间段内，尤其是10500-1570 aBP期间，本区域气候具有雨热（或干冷）同期的气候特征：在气温较高时间段，西南季风增强，气候湿润多雨，更有利于地表。植物的生长。气温降低时，随着东亚季风增强，西南季风减弱，气候干旱少雨，地表C；植物的生长占有一定的比例。据此重建和恢复了本地区14220-1570 aBP期间的古气候和古生态环境：（1）．14220-10500aBP，处于末次冰期晚期，气温较低。凉风洞石笋此时段的司、值都大于-9.8‰，最小值为-9.31‰，最大值达-7.290‰，平均值为-8.552‰。说明凉风洞洞穴地表的生长植被。植物占有一定的组分，石笋的δ18C值受C3植物和C4植物的共同影响。此时段内石笋6、值也存在一定的波动（-5.651‰－6.942‰），考虑到末次冰期晚期先全新世过渡期间气温变幅较大，O'Neil等（1969）所建立的氧同位素平衡分馏方程中的温度变化已不能忽略，并且大气降雨的温度效应作用也比较明显，因此我们对此时段的季风和大气降雨量的变化不作讨论。（2）. 10500-9300 aBP，新仙女木事件结束，进入全新世，气温逐渐回升。凉风洞石笋此时段的扩3c值大都小于-9.8‰，最小值为-10.377‰，最大值为-9.267‰，平均值为-9.910‰。凉风洞洞穴地表植被已逐渐由C3植物占主导。此时段石笋δ18C值明显卜降，最小值为-7.420‰，最大值为-6.077‰，平均值为-6.854‰。反映在全新世早期夏季风盛行，降雨量较大，西南季风对本地区全年降雨贡献率大。（3）．9300-8300 aBP，经历一段明显温度波动变化。仟3c值在-9.8‰上下波动，最小值为-10.155‰，最大值为-9.096‰，平均值为-9.712‰。凉风洞洞穴地表植被C4植物所占比例存在反复。此时段石笋岁a0值变化幅度不是很大，最小值为-6.796‰，最大值为-6.260‰，平均值为-6.490‰。受冬季风影响，夏季风有一定的减弱，总体降雨量一般，东亚季风对本地区全年降雨贡献率比全新世初期有所增大。（4）．8300-3l000BP，俗称全新世大暖期，此时段全球气温明显回升，石笋δ18C值总体逐渐降低，最小值为-n．926编，平均值为-10.496‰。凉风洞洞穴地表植被基本由C3植物所控制。但在扩飞值总体逐渐降低的趋势一F，也存在若干扩3c值明显增大时段，如7700-6700 aBP时段，61七值最大值达-8.110‰，地表C4植物所占比例已不能忽略。此时段石笋6150值变化幅度较大，最小值为-7.373‰，最大值为-5.047‰，平均值为-6.261‰。反映在全新世大暖期的大背景下西南季风和东亚季风的交替以及大气降雨量的变化存在较大的波动，说明了季风气候的不稳定性。（5）．3100-1570 aBP，在3100aBP前后，凉风洞石笋的δ18C值和δ18O值均急剧上升，标志进入晚全新世。此时段气温变幅很大，δ18C值总体虽然仍偏低，平均值为-10.275‰，但刻畜介于-6.495-12.097‰之间；δ18C值平均值为-6.184‰，变幅介于-4.677-8.65‰之间，均超过以往任何时段。此时段凉风洞洞穴地表植被基本上仍然由C。植物所控制，始于3100 aBP的急速降温事件使得在全新世晚期开始时段C4植物所占比例有一定的上升。此时段内西南季风和东亚季风反复多次交替，大气降雨量存在较大幅度的变化，说明了季风气候在此时段的很不稳定性。对于169于巧70 oBP百年时间段内石笋的δ18C值和司、值巨大幅度的急剧升高，有待进一步研究，也不排除石笋表层长期裸露受外界污染所致。

中元古代昆阳群Fe-Cu-REE矿床地球化学研究-以武定迤纳厂矿床为例

稀土元素成矿与地壳的构造运动密切相关，稀土在中元古代具有大规模暴发性成矿特征。云南武定迤纳厂稀土铁铜矿床为昆阳群因民组出现稀土富集成矿的典型代表。本论文选择迤纳厂矿床为主要研究对象，系统研究矿床不同类型岩（矿）石和矿物的稀土元素地球化学特征，探讨富稀土的成矿流体、成矿物质来源和稀土元素成矿时代，揭示昆阳裂谷初期因民组稀土元素富集的地球化学机制。主要认识如下：1、迤纳厂矿床产于昆阳裂谷初期形成的禄丰一武定火山断陷盆地中。早中元古界昆阳群分布于绿汁江岩石圈断裂和小江一易门断裂的夹持地带，呈狭长状展布。迤纳厂矿床赋矿地层为昆阳群因民组上段的硅质白云岩和碱性火山岩（粗面安山岩）。矿体产出形态和矿石的结构构造等均显示矿体与赋矿地层同沉积特征；出现独立矿物氟碳饰矿、独居石及褐帘石，磷灰石、萤石、菱铁矿等矿物中也含有一定量的稀土，沿矿体走向和垂向稀土元素变化不大。2、矿体顶、底板围岩（石榴石黑云母片岩、钠长黑云母片岩等）的原岩为碱性火山岩（粗面安山岩），相对富集大离子亲石元素Ba、Cs、Rb、K、LRE日及贫Zr、Sr、Ti、Hf、HEE，为早元古代末期一中元古代早期交代富集地慢低程度部分熔融所形成的碱性火山岩。矿石稀土总量高（645-4443）×10-6，强烈富集轻稀土（（La/Tb）N＝17.3-81.1），稀土元素分布特征明显不同于矿区正常沉积的硅质白云岩和后期侵入的钠长石英斑岩及火山角砾岩，而与矿体顶、底板碱性火山岩中稀土元素配分特征基本一致，暗示稀土成矿物质来源与碱性火山岩有密切的关系；3、矿石中微量元素组合及变化特征与现代海底正在喷出的热液和热液沉积物中元素组合有较大的可比性，明显不同与火成碳酸岩型稀土矿床中的特征元素组合；在微量元素判别图解（Al-Fe-Mn、Fe／Ti-Al／（Al+Fe＋Mn）、U-Th、Y-P2O5等）中，逸纳厂矿石均投影在热水沉积区，矿石的Y／Ho值与黑烟囱值接近，表明成矿流体为高温、还原性质，稀土成矿可能以热水沉积作用方式为主；4、对矿石中主要矿物萤石、菱铁矿、磁铁矿、石英、方解石的稀土元素特征研究表明，矿石沉积时不同矿物中稀土元素分布特征基本相同，主要受成矿流体中稀土分布特征制约。而后期变质作用形成的矿物，其稀土元素分布主要受矿物晶体结构控制。同期成矿流体从早期到晚期（块状矿石→条带状矿石），轻重稀土分异变小，稀土总量增加，条带状矿石中稀土含量最高；矿石黄铜矿6345值变化在一任3％0到2g％。范围，显示慢源硫特征；菱铁矿6r3C（8％-9.1%）、δ18O（-11.17%-15.37）‰指示成矿流体具岩浆来源和有机质的脱梭酸分解作用参与；成矿流体中稀土元素可能主要以（RE（CO3）3F）4-、（既（CO3）3F2）、（RE（F，Cl万等形式迁移，当温度降低时沉淀出氟碳饰矿等稀土矿物；5、矿石和萤石单矿物 Sm-Nd等时线年龄分别为1621士110Ma和15：38士43Ma，与矿区碱性火山岩错石的U-Pb年龄1676Ma、因民组顶部石英正长斑岩的错石U-P1。年龄1685Ma基本一致，也与因民组地层年龄1765M。较为接近，反映成矿时代为早元古代晚期和中元古代早期：这一时间也与一早元古代晚期一中元古代早期昆阳裂谷初始裂陷阶段，大量来自于地幔的碱性火山岩喷发事件相吻合。矿石。Nd（t）:-2.87-3.60，萤石单矿物εNd（t）：-3.93-5.90，变化范围较窄并全为负值，接近0，指示源区为富集地幔。同时结合矿床形成的构造一地质环境及矿体产出的地质形态，认为逛纳厂稀土铁铜矿床可能是在昆阳裂谷初期，在碱性火山岩浆喷发的间歇期，来自地幔富稀土、挥发份的成矿流体由火山喷流一同生沉积方式形成的矿床。6、昆阳群因民组地层中出现的稀土富集、成矿与我国的白云鄂博稀土REE-Fe-Nb超大型矿一床和澳大利亚的olympic Dam Cu-U-Au-Ag-REE超大型矿床，在成矿时代、产出大地构造背景、成矿物质来源等方面具有较大的相似性，均体现成矿受控于中元古代1.5Ga超大陆聚合前或随后裂解初始阶段伴随的非造山型碱性岩浆或热液作用，稀土来源于超大陆拼合前因板块俯冲交代而形成的富集地幔。

扬子地块周边C、P硅岩建造中硒的富集机理对比研究-以渔塘坝、紫阳富硒区为例

在自然界中存在一套由硅质岩、泥质岩／页岩或板岩、碳酸盐岩和粉砂岩组成的沉积建造，并以富含有机质和菌藻微生物等为特征，沉积厚度较大，岩石类型以硅岩为主，称之为“硅岩建造”。硅岩建造中的硅质岩不仅是许多重要矿种（如金、硒、铀、钒、磷、锰、铂族元素、重晶石和黄铁矿等）的赋存层和含矿岩系的重要岩类，而且由于它形成于特定的地球化学条件下，能够反映出某些沉积相带特殊的地质背景，另外，硅质岩本身就是一种生物岩，对探讨生物成岩、成矿作用有重要意义。所以对硅岩建造及其内硅质岩研究具有十分重要的理论意义和实用价值。因此，本论文选择扬子地块周边寒武系（南秦岭紫阳硒富集区）、二叠系（湖北恩施双河渔塘坝硒矿床）富硒硅岩建造为研究对象。通过岩石地球化学、同位素地球化学、矿物学以及流体包裹体等方法从含硒规律、岩石成因、沉积环境、成矿流体性质等方面，分别对对两个不同时代或不同层位的富硒硅岩建造开展了系统的地球化学对比研究；并从矿物学、包裹体成分及物理化学条件等方面对渔塘坝硒矿床的成因作了探讨。通过研究，取得了以下主要认识：1渔塘坝硒矿区和紫阳硒富集区富硒硅岩建造岩石以硅质岩为主，硅质岩中5102含量范围分别为64.2％-95.84％和63.62％-95.24％。同时包括部分碳质硅质岩丫碳质页岩 和碳、硅板岩及含腐泥层的石煤；渔塘坝硒矿床硅质岩中Se含量大于80ug/g的样品均采自下二叠统茅口组的硅质岩段内，紫阳下寒武统硒富集体中硅质岩中硒的含量最高（可达278ppm）。2微量元素研究表明，两地区富硒硅质岩中均含有较高的Cu，Ni、V、As、Sb、Cr，且U／Th＞1。在U-Th、Zr-Cr和P2O5-Y相关图以及Fe-Mn-（Cu+Co+Ni）三角图上，两研究区内硅质岩样品点均落于热水沉积区。渔塘坝硒矿区硅质岩的REE总量较低，平均为38.9×10-6，紫阳硒富集区硅质岩REE总量除个别较高（达110×10-6以上）外，总体也较低（12.0-37.6）×l0-6；另外，从稀土元素配分模式看，两地区硅质岩均有较明显的Ce负异常，且Eu从无明显Eu异常到出现正Eu异常。都反映出热水沉积硅质岩的特征。从si和O同位素组成来看，两个地区硅质岩的δ3051和δ18O值也总体位于热水成因硅质岩区域内。根据隧石一水的氧同位素分馏方程计算得知，两研究区硅质岩的形成温度分别为46℃-72℃和78.6℃-126.20℃。地球化学特征表明，两地区富硒硅质岩均来自热水沉积作用。另外，渔塘坝硒矿区硅质岩中Cr含量较高，且存在腕足类生物化石；紫阳硒富集区硅质岩中Ba及有机质含量较高，且存在叶琳生物标志化合物。结合两地区碳同位素组成特征（渔塘坝地区δ13c为正值，可能和上扬子区早、晚二叠世之间多期次喷发的火山活动，造成地球史上二叠纪生物大灭绝有关；紫阳地区δ13C为负值，说明碳同位素来源于沉积有机物质），暗示两地区硅质岩的成因可能与火山沉积作用有关，且在成岩过程中有部分生物的参与。3渔塘坝赋矿硅质岩硫同位素组成具有较高的负值，表明矿床形成于缺氧的海盆内：紫阳硒富集区形成黄铁矿的硫主要来自海水硫酸盐。4系统研究了渔塘坝硒矿区硒的矿物学，显示硒以自然硒、独立矿物、类质同像及有机吸附四种形式赋存于矿床中。废弃石煤堆中的自然硒矿物，是自然因素和人为活动共同干预的结果，并非石煤的缓慢自燃的结果。5对研究区成矿流体中包裹体均一温度、盐度和密度进行了系统研究，结果显示：两地区的流体包裹体以原生包裹体为主，数量较多且形态复杂；研究区（渔塘坝硒矿和紫阳硒富集区）成矿流体处于中一低温（ 190-250）℃和（120-155）℃条件。渔塘坝硒矿区石英和方解石包裹体内的流体盐度分别为（5.9-10.l）B％和（3.9-4.5）WB％，紫阳硒富集区流体盐度为（1.2-2.8）WB％，后者流体盐度明显低于前者。流体密度经计算分别为0.79-0.79／cm3和0.69-0.969／cm3。重点对渔塘坝硒矿区的石英和方解石包裹体进行了拉曼光谱成分测试，结果显示：包裹体成分以H2O和N2为主，含少量 CH4、C2H4、C2H6、C3H5、C4H6、C4H4和C6H6等成分，说明成矿溶液介质主要为具有还原性质的水溶液，其成矿条件具还原性的特点。6渔塘坝硒矿区成矿物理化学条件的研究表明，即富硒成矿流体为中低温（190-250）℃、压力平均为60Mpa。成矿早期02、eZ相对较低，乃较高，且fS2/fSe2＞l，有利于硫化物沉淀在成矿主阶段，随着硫化物的沉淀，fS2和fSe2相应增大，且fO2较高。高的fO2阻止了硒进入硫化物，而有利于硒化物的形成。 7系统研究了富硒硅岩建造的沉积环境和构造环境特征，认为渔塘坝硒矿床中富硒硅质岩主要形成于浅海滞留的盆地沉积环境，紫阳下寒武统硅质岩沉积环境属于深水滞留沉积环境；渔塘坝硒矿床主要形成于拉张的断陷盆地中，紫阳硒富集体则形成于拉张的裂谷环境。

喀斯特城市地下水C、N同位素地球化学——污染物迁移和转化研究

中国西南喀斯特地区有突出的地球化学敏感性和生态环境脆弱性等特征，其中水环境污染是喀斯特地区所面临的极其严重的生态与环境问题。水环境生源物质循环过程对于人类生存环境质量的保护和提高有着直接的联系，由于环境体系受多种控制因素影响，利用多同位素方法讨论单一环境体系中物质循环过程和生态环境效应已成为同位素地球化学发展的一个重要趋势。碳、氮同位素已被广泛用于探讨和解决当前的一些重大环境问题，如生源要素生物地球化学对人为污染物的响应、温室气体的来源、湖泊富营养化、地下水硝酸盐污染等。为此本论文利用稳定同位素技术（13C、I5N、18O），以喀斯特城市地下水为主要研究对象，对贵阳雨水中的C、N沉降过程、贵阳／遵义地下水C、N同位素地球化学进行了初步研究。通过以上研究，得到以下的主要认识。1．探讨了贵阳雨水中碳沉降的年变化特征，结果表明贵阳雨水DOC平均值为3.76mg／L，POc平均值为0.54mg/L，含量季节间变化不显著。雨水中DOc与PH呈负相关关系，表明有机碳中酸性成份对酸雨有一定贡献。δ13C-POC取值范围在（-27.0，-24.0‰）之间，季节间差异不大，结合已有研究结果表明雨水中颗粒有机碳主要来源于雨水所冲刷的本地大气颗粒物。2．探讨了贵阳雨水无机氮沉降的年变化特征，结果表明贵阳城区雨水中的NH4＋、NO3-、δ15N-NH4+，δ15N-NO3-，δ18O-NO3-，季节性差别都不大。NH4＋主要来源于土壤中NH3挥发以及大气颗粒物中按的洗脱，而硝酸盐可能主要来源于燃煤和机动车的排放等，同时气候是影响同位素组成差异性表现的一个重要影响因素。3．初步分析了贵阳与遵义地下水／地表水主要水化学成分，结果证实水体水化学组成主要受研究区水文地质背景控制，即阳离子主要以Ca2+，Mg2+为主，而阴离子以HCO3-，SO42-离子为主。但是有部分水样有较高的人为输入物质K+，Na+，Cl-和NO3-，表明人为活动在研究区内已对地表水／地下水产生一定影响。4．利用碳同位素较好地示踪了地下水溶解无机碳季节变化的主要规律，地下水夏季的DIC含量明显低于冬季DIC含量，这是由于大量降水的稀释作用引起的。地下水DIC夏季一般比冬季更富集12C，表明夏季地下水中生物成因无机碳贡献增加。经计算表明贵阳／遵义地下水来源于碳酸盐风化的无机碳比重大多数大于50％，表明硫酸可能参与风化过程。5．较为系统地探讨了地下水／地表水中有机碳的冬季／夏季演化规律以及受影响因素，地下水大多数样品DOC和POC含量不高，个别受污染样品明显具有较高有机碳含量。大部分夏季地下水δ13C-POC明显大于冬季，表明夏季地下水颗粒有机碳受外源（C4植物碎屑）输入影响。地表水TOC（DOC+POC）与人为输入离子［K+Na++Cl-］呈一定的正相关关系，表明有机碳主要受人为污染影响。6．以贵阳为例，根据δ13CDIC等势图、结合主要水化学特征在空间上的分布可知，贵阳市区中部，东北部及西郊农业区地下水受污染较为严重。表明一定条件下，碳同位素组成可以用来指示区域地下水受人为活动影响范围。7．通过对地下水三氮分析初步掌握了地下水氮污染的基本特征，地下水中NO3-是最主要的无机氮形态，NH4+和NO2-含量大多较低，地下水中具有高NO2-与NH4+的水样比较分散，表明点源污染是主要的。8．利用氮氧同位素示踪了贵阳地下水硝酸盐污染来源的季节变化，同时证实了部分地下水发生反硝化。冬季硝酸盐相对夏季含量较低，并且目SN与夕80的平均值都相对较高，表明夏季受外源氮污染明显，郊区地下水硝酸盐主要受硝态氮肥污染影响，城区地下水硝酸盐污染严重，城市生活排泄物是主要的氮污染源；硝酸盐氮氧同位素联同按氮同位素等可以得知部分地下水中存在明显的反硝化作用。9．利用氮同位素取值分布和季节间频度分布变化初步讨论了遵义地下水硝酸盐污染来源的季节变化。遵义含NO3-较高的地下水主要分布在市区、茅草铺（市东北郊）和新店子一忠庄一带（市东南郊）。夏季地下水硝酸盐δ15N的平均值明显低于冬季，一表明夏季地下水受农业化肥等低δ15N值氮污染源污染。10．两城区地下水受点源污染为主，在局部区域有向含水层面源污染转化的趋势。喀斯特城区地下水中C、N物质的循环对环境变化响应较快，同时受不同区域降雨过程和土壤营养物质过程影响而表现出一定的差异性。

The life history and ecology of black scabbardfish (Aphanopus carbo Lowe 1839) in the north-east Atlantic

The black scabbardfish is a deep water species that supports commercial fisheries across a large area of the NE Atlantic shelf. The life history of black scabbardfish is poorly understood and a major unresolved issue is population structure. In this study it was used a combination of methodologies to get further knowledge in the life history and population structure of A. carbo over its wide distribution range in the Northeast Atlantic. The new knowledge acquired during this study, will increase our ability to better manage this species in the NE Atlantic. It has been postulated that fish caught to the west of the British Isles are pre-adults that migrate further south (to Madeira) for spawning, implying a single panmictic population. In this study, specimens of Aphanopus carbo were sampled between September 2008 and May 2010 from two different areas: NW Scotland (French trawlers and deep water surveys) and Madeira Islands (longliners commercial landings). Geographical differences in reproductive state of scabbardfish were evident, supportive of a north-south migration theory. In the northern area, all specimens found were immature, while in Madeira all maturity stages were observed. In Madeira, spawning occurred during the fourth quarter, with peak maturity in October (males) and in November (females). The age of this species has proven difficult and has led to different and contradictory age and growth estimates. For this study, we used two reading interpretations to determine age and estimate the growth parameters. To the west of the British Isles, specimens reached a lower maximum age and had a higher growth rate than those caught off Madeira. These differences are consistent with the theory of a single population of black scabbardfish in the NE Atlantic, highly segregate, with smaller, immature and younger fish caught to the west of the British Isles and bigger and mature caught in Madeira Islands. The feeding ecology showed strong evidence that the diet of black scabbardfish is associated with the spawning migration of blue whiting, which may support a northerly feeding migration theory for black scabbardfish. The stable isotope analyses in the muscle of black scabbardfish identified that black scabbardfish feeds on species with epipelagic and benthopelagic affinities. Comparison with stable isotope analysis in Madeira samples indicated that black scabbardfish feed at a similar trophic level and has the same trophic niche width in both areas, assuming similar baseline isotope compositions. Otolith stable isotopes (oxygen - δ18O and nitrogen - δ15N) analyses were used as a tool to clarify migratory behaviour. Otolith isotope ratios can provide insight into whether adults caught around Madeira fed in an isotopically depleted northerly ecosystem (NW Scotland) during their pre-adult period and then migrate towards south to spawn. Overall, the results support a south-north migration of pre adult fish from spawning areas around Madeira and a north-south migration from the west of Scotland to the spawning areas. Given its life cycle there is an urgent need that the management process recognizes the existence of a continuous widely distributed stock of black scabbardfish between the west of the British Isles and Madeira. The results highlight large scale dispersal in this species which needs to be treated as a highly migratory species and be managed as a single population.

Denitrification and inference of nitrogen sources in the karstic Floridan Aquifer

Aquifer denitrification is among the most poorly constrained fluxes in global and regional nitrogen budgets. The few direct measurements of denitrification in groundwaters provide limited information about its spatial and temporal variability, particularly at the scale of whole aquifers. Uncertainty in estimates of denitrification may also lead to underestimates of its effect on isotopic signatures of inorganic N, and thereby confound the inference of N source from these data. In this study, our objectives are to quantify the magnitude and variability of denitrification in the Upper Floridan Aquifer (UFA) and evaluate its effect on N isotopic signatures at the regional scale. Using dual noble gas tracers (Ne, Ar) to generate physical predictions of N2 gas concentrations for 112 observations from 61 UFA springs, we show that excess (i.e. denitrification-derived) N2 is highly variable in space and inversely correlated with dissolved oxygen (O2). Negative relationships between O2 and δ15N NO3 across a larger dataset of 113 springs, well-constrained isotopic fractionation coefficients, and strong 15N:18O covariation further support inferences of denitrification in this uniquely organic-matter-poor system. Despite relatively low average rates, denitrification accounted for 32 % of estimated aquifer N inputs across all sampled UFA springs. Back-calculations of source δ15N NO3 based on denitrification progression suggest that isotopically-enriched nitrate (NO3-) in many springs of the UFA reflects groundwater denitrification rather than urban- or animal-derived inputs. © Author(s) 2012.

Environmental Isotopes as Indicators for Ground Water Recharge to Fractured Granite

To assess the contribution of accumulated winter precipitation and glacial meltwater to the recharge of deep ground water flow systems in fracture crystalline rocks, measurements of environmental isotope ratios, hydrochemical composition, and in situ parameters of ground water were performed in a deep tunnel. The measurements demonstrate the significance of these ground water recharge components for deep ground water flow systems in fractured granites of a high alpine catchment in the Central Alps, Switzerland. Hydrochemical and in situ parameters, as well as d18O in ground water samples collected in the tunnel, show only small temporal variations. The precipitation record of d18O shows seasonal variations of ~14‰ and a decrease of 0.23‰ ± 0.03‰ per 100 m elevation gain. d2H and d18O in precipitation are well correlated and plot close to the meteoric water line, as well as d2H and d18O in ground water samples, reflecting the meteoric origin of the latter. The depletion of 18O in ground water compared to 18O content in precipitation during the ground water recharge period indicates significant contributions from accumulated depleted winter precipitation to ground water recharge. The hydrochemical composition of the encountered ground water, Na-Ca-HCO3-SO4(-F), reflects an evolution of the ground water along the flowpath through the granite body. Observed tritium concentrations in ground water range from 2.6 to 16.6 TU, with the lowest values associated with a local negative temperature anomaly and anomalous depleted 18O in ground water. This demonstrates the effect of local ground water recharge from meltwater of submodern glacial ice. Such localized recharge from glaciated areas occurs along preferential flowpaths within the granite body that are mainly controlled by observed hydraulic active shear fractures and cataclastic faults.

Isotopic composition of tropospheric and soil N2O from successive depths of agricultural plots with contrasting crops and nitrogen amendments

Agricultural soils are the dominant contributor to increases in atmospheric nitrous oxide (N2O). Few studies have investigated the natural N and O isotopic composition of soil N2O. We collected soil gas samples using horizontal sampling tubes installed at successive depths under five contrasting agricultural crops (e.g., unamended alfalfa, fertilized cereal), and tropospheric air samples. Mean d 15N and d 18O values of soil N2O ranged from -28.0 to +8.9‰, and from +29.0 to +53.6‰. The mean d 15N and d 18O values of tropospheric N2O were +4.6 ± 0.7‰ and +48.3 ± 0.2‰, respectively. In general, d values were lowest at depth, they were negatively correlated to soil [N2O], and d 15N was positively correlated to d 18O for every treatment on all sampling dates. N2O from the different agricultural treatments had distinct d 15N and d 18O values that varied among sampling dates. Fertilized treatments had soil N2O with low d values, but the unamended alfalfa yielded N2O with the lowest d values. Diffusion was not the predominant process controlling N2O concentration profiles. Based on isotopic and concentration data, it appears that soil N2O was consumed, as it moved from deeper to shallower soil layers. To better assess the main process(es) controlling N2O within a soil profile, we propose a conceptual model that integrates data on net N2O production or consumption and isotopic data. The direct local impact of agricultural N2O on the isotopic composition of tropospheric N2O was recorded by a shift toward lower d values of locally measured tropospheric N2O on a day with very high soil N2O emissions.

Nitrogen-15 and Oxygen-18 Natural Abundance of Potassium Chloride Extractable Soil Nitrate Using the Denitrifier Method

In agroecosystems, most isotopic investigations of NO3- involve the use of tracers that are artificially enriched in 15N. Although the dual isotope composition of NO3-— d15N and d18O is especially beneficial for understanding the origin and fate of NO3-, its use for KCl-extractable soil NO3- has been hampered by the lack of a suitable analytical technique. Our objective was to test whether the denitrifier method, whereby NO3- is reduced to N2O before mass spectrometric analysis, can be used to determine the N and O isotopic composition of NO3- from 2 M KCl soil extracts. Several internationally accepted NO3- standards were dissolved in 2 M KCl, the conventional extractant for soil inorganic N, and inoculated with the bacterial strain Pseudomonas aureofaciens (ATCC no. 13985). The standard deviation of the NO3- standards analyzed did not exceed 0.2‰ for d15N and 0.3‰ for d18O values. After appropriate corrections, differences between our measured and consensus d15N and d18O values of standard NO3- generally were within the standard deviations given for the consensus values. Both d15N and d18O values were reproducible among separate analytical runs. The method was also tested on genuine 2 M KCl extracts from unfertilized and fertilized soils. Depending on N fertilization, the soils had distinct d15N and d18O values, which were attributed to amendment with NH4NO3 fertilizer. Hence, our data indicate that the denitrifier method provides a fast, reliable, precise, and accurate way of simultaneously analyzing the natural abundances of 15N and 18O in KCl-extractable soil NO3-.

Identifying the influence of geology, land use, and anthropogenic activities on riverine sulfate on a watershed scale by combining hydrometric, chemical and isotopic approaches

Throughout the last few decades, sulfate concentrations in streamwater have received considerable attention due to their dominant role in anthropogenic acidification of surface waters. The objectives of this study conducted in the Oldman River Basin in Alberta (Canada) were to determine the influence of geology, land use and anthropogenic activities on sources, concentrations and fluxes of riverine sulfate on a watershed scale. This was achieved by combining hydrological, chemical and isotopic techniques. Surface water samples were collected from the main stem and tributaries of the Oldman River on a monthly basis between December 2000 and March 2003 and analyzed for chemical and isotopic compositions. At a given sampling site, sulfate sources were primarily dependent on geology and did not vary with time or flow condition. With increasing flow distance a gradual shift from ?34S values > 10 ‰ and ?18O values > 0 ‰ of riverine sulfate indicating evaporite dissolution and soil-derived sulfate in the predominantly forested headwaters, to negative ?34S and ?18O values suggested that sulfide oxidation was the predominant sulfate source in the agriculturally used downstream part of the watershed. Significant increases in sulfate concentrations and fluxes with downstream distance were observed, and were attributed to anthropogenically enhanced sulfide oxidation due to the presence of an extensive irrigation drainage network with seasonally varying water levels. Sulfate-S exports in an artificially drained subbasin (64 kg S/ha/yr) were found to exceed those in a naturally drained subbasin (4 kg S/ha/yr) by an order of magnitude. Our dataset suggests that the naturally occurring process of sulfide oxidation has been enhanced in the Oldman River Basin by the presence of an extensive network of drainage and irrigation canals.

Spectral gamma-ray logs and palaeoclimate change? Permian – Triassic, Persian Gulf

Spectral gamma ray (SGR) logs are used as stratigraphic tools in correlation, sequence stratigraphy and most recently, in clastic successions as a proxy for changes in hinterland palaeoweathering. In this study we analyse the spectral gamma ray signal recorded in two boreholes that penetrated the carbonate and evaporate-dominated Permian–Triassic boundary (PTB) in the South Pars Gasfield (offshore Iran, Persian Gulf) in an attempt to analyse palaeoenvironmental changes from the upper Permian (Upper Dalan Formation) and lower Triassic (Lower Kangan Formation). The results are compared to lithological changes, total organic carbon (TOC) contents and published stable isotope (δ18O, δ13C) results. This work is the first to consider palaeoclimatic effects on SGR logs from a carbonate/evaporate succession. While Th/U ratios compare well to isotope data (and thus a change to less arid hinterland climates from the Late Permian to the Early Triassic), Th/K ratios do not, suggesting a control not related to hinterland weathering. Furthermore, elevated Th/U ratios in the Early Triassic could reflect a global drawdown in U, rather than a more humid episode in the sediment hinterlands, with coincident changes in TOC. Previous work that used spectral gamma ray data in siliciclastic successions as a palaeoclimate proxy may not apply in carbonate/evaporate sedimentary rocks.

Late Quaternary climatic record from ODP Site 705 in the Northern Indian Ocean

The uppermost 500cm sedimentary core from ODP site located at the Eastern flank of Najareth bank in the Northern Indian Ocean has yielded altogether twenty four species of planktonic foraminifera. Among all these species, Globorotalia menardii has been found to be consistently dominant in the faunal assemblages from most of the samples. The 18O measured on the tests of Globorotalia menardii from all levels help in precisely working out the sediment accumulation rates at different isotopic stages, and deciphering the change in climate in the Late Quaternary as well.

North Atlantic surface ocean 14C variability between 30 – 40 kyr. BP

The Faroe-Shetland channel is situated in the main path of the inflow of warm North Atlantic surface water to the Nordic seas and further provides an escape route for the cold Norwegian Sea Deep Water. AMS 14C dates of planktonic foraminifera covering Marine Isotope Stage 3 from two cores in the Faroe-Shetland channel will be used to trace past variability of the Atlantic Meridional Overturning Circulation (AMOC). The reservoir age R shows considerable variability ranging between 50 to 2750 14C years. In particular high R values are observed during Heinrich event 4 (H4) with values around 1550 14C years and during the Laschamp magnetic excursion with R values as high as 2700 14C years. The period between Greenland interstadial 8 (GI8) and GI5 show highly variable R values with interstadial R values around 500 – 650 14C years, i.e. slightly higher than ‘normal’, whereas stadials show either significantly higher or lower R values. From GI5 towards the Last Glacial Maximum R values are generally around 1000 14C years or higher. Using magnetic susceptibility, IRD and δ13C and δ18O values measured on the planktic foraminifera species Neogloboquadrina pachyderma, we compare the observed R variability with reconstructed changes in the Atlantic Meridional Overturning Circulation (AMOC). Furthermore a climate model of intermediate complexity (GENIE) including 14C is used as conceptual tool for identifying oceanographic configuration explaining the observed R variability.