中亚成矿域斑岩铜金成矿的地质环境问题

中亚成矿域在蒙古、乌兹别克斯坦、吉尔吉斯斯坦和哈萨克斯坦产有Oyu Tolgoi、Almalyk、Andash-Taldy Bulak、Aktogai、Kounrad等众多巨型和世界级斑岩铜金矿床,中国新疆北部斑岩铜金找矿持续重大突破令人期待。中亚成矿域大规模斑岩铜金成矿于什么地质环境?新疆北部、尤其天山斑岩铜金地质找矿持续突破的前景怎样?都是颇受关注的重大地质和找矿问题。通过广泛深入文献调研和重要矿集区实地调查研究表明,中亚构造成矿域在古亚洲洋壳俯冲增生、陆陆碰撞和后碰撞伸展等不同时期地质环境中,虽然均有斑岩铜金成矿作用发生,但古亚洲洋俯冲形成不同时期的增生岛弧是中亚斑岩铜金最为重要的成矿地质环境,大规模斑岩铜金成矿出现在洋盆演化末期、或即将关闭时的成熟岛弧环境。为什么中亚重要斑岩铜金矿床多形成于年长的成熟岛弧是值得探索的重要科学问题。新疆北部、尤其天山不同时期的岛弧发育完整,岛弧岩浆作用强烈而漫长,斑岩铜金成矿条件优越,大型-超大型铜金矿地质找矿潜力巨大,有望持续发现重要斑岩铜金矿床。     

老挝川圹省PhuKham铜金矿床地质特征及找矿方向

老挝Phu Kham铜金矿为大型斑岩-夕卡岩型铜金矿床,地处老挝川圹省西南部。通过野外地质调查和室内工作,研究了Phu Kham铜金矿床形成的地质背景、矿床地质特征、成矿时代、找矿模式及成因类型。结果表明:铜金矿容矿岩系为石炭-二叠系碳酸盐岩、火山碎屑岩、夕卡岩及斑岩脉;矿石矿物主要为黄铁矿、黄铜矿、蓝铜矿、斑铜矿及孔雀石等;矿床成因为斑岩-夕卡岩型,成矿时代为晚石炭世—早二叠世。预测在Phu Kham矿区及长山成矿带内具有寻找大型-超大型铜金铁锡矿床的潜力。     

西藏尕尔穷—嘎拉勒铜金矿集区成矿规律、矿床模型与找矿方向

尕尔穷—嘎拉勒铜金矿集区位于西藏班公湖—怒江成矿带西段南缘的北冈底斯北侧,矿体类型丰富(斑岩型、矽卡岩型及铁氧化物铜金建造型),金品位较高(最高可达205g/t),构造位置独特,研究意义重大。通过对矿集区成矿地质条件的系统总结及对前人研究资料的系统分析,查明了矿石特征,发现了大量自然金、金属互化物,总结了成矿规律,认为成矿主要与晚燕山期侵位的石英闪长岩及花岗闪长岩有关,成岩与成矿之间演化时间在1Ma左右,区内矿化具有上铜金下钼的垂向分带特征,矿床S、Pb同位素显示成矿物质具有壳幔混合的源区特征。在准铝质-微弱过铝质钙碱性-高钾钙碱性岩浆岩的侵位、分馏演化过程中,在岩体隆起部位及其与白垩纪碳酸盐的内外接触带形成斑岩-矽卡岩型铜金(钼)矿体,在岩体边缘构造破碎带(F1断层)内形成铁氧化物铜金建造型矿体,由此建立了岩浆岩-地层-构造控制的斑岩-矽卡岩-铁氧化物铜金建造"三位一体"矿床模型。结合以上研究,提出矿集区应予以重视的找矿方向。     

塞尔维亚蒂莫克铜金矿集区典型矿床地质特征

特提斯成矿带是全球三大成矿带之一,阿普塞尼（Apuseni）-巴纳特（Banat）-蒂莫克（Timok）-斯雷德诺戈里斯基（Srednogorie）岩浆成矿带（ABTS多金属成矿带）位于特提斯成矿带西缘,由阿普塞尼–巴纳特铁铜铅锌矿集区、蒂莫克铜金矿集区和斯雷德诺戈里斯基铜金矿集区组成,成矿作用主要与晚白垩世钙碱性岩浆活动有关。塞尔维亚蒂莫克铜金矿集区作为ABTS多金属成矿带经济意义巨大的矿集区之一,总结该地区矿床地质特征及成矿规律对下一步的找矿勘查具有重要指导意义。综述了蒂莫克铜金矿集区及其典型矿床的地质特征,总结了矿集区成矿规律与动力学背景。蒂莫克铜金矿集区典型矿床形成时代集中在88～78 Ma之间,成矿作用历时10 Ma左右,矿集区内成矿作用时代呈现出由东向西逐渐年轻的趋势。矿集区中典型矿床类型主要为斑岩型（如马伊丹佩克矿床、克里韦利矿床和瓦利亚斯特尔茨矿床）和高硫化浅成低温热液-斑岩型（如博尔矿床和丘卡卢佩吉矿床）,这些矿床以铜金矿化为主。矿床类型、矿化特征及矿体埋深存在的差异可能与区域上新生代右旋构造在矿集区形成的逆冲推覆构造及成矿后不均匀剥蚀有关。根据矿集区典型矿床的矿化类...     

藏北多龙斑岩铜金矿集区综合信息找矿模型研究

藏北多龙矿集区产出环境和成矿动力学背景在青藏高原斑岩铜矿中独具特色,目前已经发现了多龙、多不杂、拿若、荣那等超大型—大型斑岩铜(金)矿,其有效找矿模式亟待研究总结。典型矿床的综合信息找矿模型研究对于进一步开展矿体定位预测具有重要意义。研究认为多龙矿集区铜金矿体产于花岗闪长斑岩体内及岩体边部的黄铁绢英岩化和青磐岩化变质(长石)石英砂岩及火山岩中。自含矿斑岩体中心向外存在中心对称分布的3个蚀变带,依次为弱钾化带、绢英岩化带和黄铁矿化-角岩化带。根据地、物、化、遥异常套合特征,划分出"三带五田"。"三带"为呈北西向雁列状排列的拿若—色那—尕尔勤铜金矿带、多不杂—波龙—铁格隆南铜金钼矿带和地堡那木岗铜金矿带;"五田"为拿若—赛角—荣那矿田、尕尔勤矿田、地堡那木岗矿田、波龙—多不杂矿田和铁格隆南矿田,并分别厘定了各矿田的基本组成与矿床地质特征。通过地、物、化综合异常分析,建立了"四位一体"找矿模式。指出铁帽、孔雀石化和蚀变花岗闪长斑岩体为地表寻找斑岩铜矿的直接标志;低磁异常间接反映遭受蚀变的花岗闪长斑岩体成矿母岩;激电高极化异常直接反映斑岩型铜矿体两翼的黄铁矿化带,间接反映硫化物带包裹着铜矿体;Cu、Au元素高异常反映成矿元素的区域富集。以此为基础,对拿若、荣那矿区掩埋矿体运用了"四位一体"找矿模式,发现隐伏斑岩型铜矿床。     

综合物探方法在西藏冈底斯成矿带西段鲁尔玛斑岩型铜(金)矿的找矿应用

鲁尔玛斑岩型铜(金)矿区位于冈底斯成矿带西段,是南拉萨微陆块中新发现的铜(金)矿,具有钾硅酸盐化、绢英岩化、青磐岩化等明显的斑岩型矿床蚀变特征,含矿斑岩为晚三叠世石英二长斑岩。通过1∶50000矿产地质专项填图、磁法扫描和水系沉积物测量发现了鲁尔玛地区铜金矿化线索,为进一步查明异常源属性和铜矿地质特征,在综合研究基础上实施大比例尺磁法、电法测量等物探工作,同时利用钻探和槽探施工进行异常查证,进而发现了铜(金)矿体。大比例尺激电、磁测和测深结果显示,发现矿化区域的北东部和深部存在低磁、低阻、高极化等有利异常,认为该异常区具有较大的找矿潜力,通过地质勘查工作可望提高铜金的资源量,扩大矿床规模。同时,对矿床发现和评价过程中找矿技术手段选择的实践表明,在高海拔地区采用高精度磁法和激电测量是快速圈定斑岩型铜矿靶区的有效勘查手段。     

西藏尕尔穷铜金矿床S、Pb同位素地球化学特征——成矿物质来源示踪

尕尔穷铜金矿为近几年在班公湖-怒江成矿带西段取得找矿新突破的与斑岩有关的矽卡岩型铜金-破碎带型铜金(铁)矿床。通过对矽卡岩型矿石中主要的金属矿物黄铁矿、黄铜矿的S、Pb同位素特征进行研究,进一步确定矿床成矿物质来源,并结合区域矿产特征对区域成矿规律给出指示。结果显示,两种金属矿物中的δ34S主要分布于-2.9‰～0.5‰之间,平均值为-1.1‰,其频率直方图具有塔式分布特征,具幔源硫特征;矿石的208Pb/204Pb主要分布于38.384～39.134之间,207Pb/204Pb主要分布于15.577～15.725之间,206Pb/204Pb主要分布于18.112～18.615之间,μ值在9.44～9.69之间,其具有上地壳与地幔混合的造山带铅特征。矿床成矿物质主要来自具幔源特征物质和念青唐古拉基底片麻岩。在班怒带西段伴随着晚白垩世南羌塘-三江复合板片与冈底斯-念青唐古拉板片之间弧-陆碰撞,在措勤-申扎火山岩浆弧内形成了与上地幔或初生下地壳重熔并受上地壳物质混染的斑岩-矽卡岩铜金矿成矿系列。     

青藏高原两个斑岩-浅成低温热液矿床成矿亚系列及其"缺位找矿"之实践

斑岩_浅成低温热液型铜金矿床是西藏最新发现的组合矿床类型,其具有巨大的找矿潜力。笔者在西藏多龙矿集区铁格隆南铜金矿床、雄村矿集区主要矿体系统地质编录、综合研究的基础上,对其矿床地质背景、矿体形态产状、矿物组合、蚀变特征、成岩成矿年龄等进行了系统的总结,在前人研究的基础上,提出班怒成矿带与早白垩世岛弧型中_酸性火山岩_浅成岩组合有关的铜、金、银、铅锌矿床成矿亚系列,以及冈底斯成矿带与早侏罗世—晚侏罗世岛弧型中_酸性火山岩_浅成岩组合有关的铜、金、银、铅锌矿床成矿亚系列,是西藏最重要的寻找斑岩型_浅成低温热液型铜金矿的矿床成矿系列。依据"缺位找矿"理论,预测多龙矿集区尕尔勤、地堡那木岗、铁格隆山是浅成低温热液型铜金矿床的进一步勘查评价区,色那、拿顿角砾岩筒是寻找独立高硫化型浅成低温热液金矿床的重要靶区。铁格隆南浅成低温热液矿体叠加在斑岩型矿体之上,高硫化型浅成低温热液矿床浅部发育多孔状硅帽和明矾石_地开石_高岭石蚀变组合,金属矿物以硫砷铜矿_铜蓝_蓝辉铜矿_黝铜矿_黄铜矿_斑铜矿_黄铁矿等铜硫二元体系矿物组合为主,其中黄铁矿_黄铜矿_斑铜矿形成较早,矿床规模可突破1200万吨。雄村铜金矿集区发育低硫化型浅成低温热液多金属金矿体,矿体呈脉状,或在火山机构边缘构造中独立产出,或叠加于斑岩型铜金矿体之上产出,以绢云母化、叶蜡石化、伊利石化发育,闪锌矿、黝铜矿、磁黄铁矿_黄铁矿为主要金属矿物组合为特征,洞嘎、普钦木_哑达是低硫化型浅成低温热液矿床的勘查评价区,深部有找到斑岩型铜金矿的可能。上述2套矿床成矿系列亚系列都与燕山期斑岩铜金矿床的流体演化有关,具有特殊的蚀变矿物、金属矿物组合,寻找独立的浅成低温热液型金矿是下一步需要重视的找矿方向。     

江苏南京西横山地区铜金矿找矿潜力

通过对江苏南京西横山地区地质背景、地球物理场、地球化学元素综合异常特征的综合研究,认为西横山地区既有寻找接触交代型金铜矿、热液充填型铜金矿和斑岩型铜金矿的成矿地质背景条件,又有良好的重、磁、电和地球化学元素综合异常反映。结合沿江Ⅳ级成矿带找矿模式和獾子洞铜金矿、上湾塘金矿典型矿床重磁场特征分析,对江苏南京西横山地区铜金矿找矿潜力进行了探讨。     

西藏谢通门县吉拉铜金矿矿床地质特征及找矿前景分析

吉拉铜金矿位于冈底斯成矿带中段南缘,谢通门铜金富铁矿集区,与著名的雄村特大型铜金矿毗邻,成矿条件优越,化探异常显示Cu、Au、Pb、Zn、Ag元素标准差、变化系数大,富集能力强,元素套叠好,异常浓集中心突出,浓集中心与矿化（体）相对应,属典型的致矿异常,矿（化）体分布与大理岩和闪长岩接触带上。建议应以冈底斯成矿带铜多金属矿成矿找矿模式及雄村矿床的发现经验来指导找矿,继续加强勘查和研究工作,将有望实现斑岩型、矽卡岩型铜多金属矿,韧性剪切带型、蚀变岩性金铜矿的重大找矿突破。     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours.     

硅酸盐类样品中硅、铁、铝、钛、锰、钙、镁、钾、钠和磷的x射线荧光光谱测定

本文拟定了一种以熔融法制备样片,用X射线荧光光谱测定硅酸盐类样品中Si、Fe、Al、Tj、Mn、Ca、Mg、K、Na、P等元素的分析方法。在对不同靶材X光管和分光晶体实验对比的基础上,选择了最佳的测量条件。该法具有快速、准确,测量范围广,检测限低,价格便宜等优点。经过近百个各种类型标样或管理样品的分析对比表明,本法不仅适用于硅酸盐类岩石样品的分析,还适用于铁矿、铝土矿、碳酸盐类岩矿样品以及水泥、耐火材料等样品的分析。     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

This paper reports the first results of a study of 11 isotope systems (³He/⁴He, ⁴⁰Ar/³⁶Ar, ³⁴S/³²S, ⁶⁵Cu/⁶³Cu, ⁶²Ni/⁶⁰Ni, ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ^206–208Pb/²⁰⁴Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.     

Viscous, cohesive, non-Newtonian, depositing, radial slurry flow

Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance.     

硅酸盐中铁、锰、钛、钙、钾、磷、硅、铝、镁、钠、锶、铷、钡的X-射线荧光光谱定量测定

本文介绍样品经四硼酸锂熔融制成玻璃小饼。采用Lachance模式和理论a系数来校正元素间的效应,由3080E型X-射线荧光谱仪和DF-350B数据处理系统完成硅酸盐中十三个项目的测定。     

岩石密度和超高压岩石折返速率

在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。     

Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA

The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources.     

滇东南花岗岩与锡、银、铜、铅、锌多金属矿床的成因关系

滇东南锡、银、铅、锌多金属矿床主要分布在个旧、白牛厂、都龙3个矿区,而滇东南较大的3个花岗岩体又分别出露在3个矿区或附近.花岗岩体均形成于燕山晚期,岩石化学、矿物成分相似,富含锡、银、铅、锌、钨、铜等成矿元素.矿床主金属元素组合与岩体之间的距离由远而近出现由锡、钨、(铍、铌、钽)→锡、钨、(铁)、铜、铟→锡、铅、锌、银、铟、(锑)有规律的变化.花岗岩浆是成矿物质来源和成矿热源.岩浆侵入初期使上覆地层隆起产生背斜(凹陷部位成向斜);同时使地层产生一系列裂隙、压性断层或层间断裂;岩浆侵入晚期,这些断层再次活动,表现为张性,岩浆产生的含矿热液沿由其活动所造成的断裂迁移、充填、交代、沉淀而形成矿床.     

Bellechester,Minnesota, USA,lagoon collapses

Bellechester, Minnesota, is a small community of approximately 155 residents located on the county line between Goodhue and Wabasha counties in southeast Minnesota's karst region. Bellechester is served by a 21-year-old wastewater treatment facility (WWTF) consisting of three waste-stabilization ponds. On 28 April 1992 six sinkholes were discovered to have drained cell 2 of the WWTF resulting in the loss of approximately 8.7×10⁶ 1 of partially treated effluent and about 600 m³ of soil into previously undetected subsurface voids of unknown dimensions. In the week following the collapse, approximately 200 water wells located within a 5-km radius of the WWTF were sampled in an after-the-fact, emergency sampling program. Twelve samples with elevated fecal coliform levels, 18 samples with nitrate-nitrogen greater than the 10 mg/1 standard, and no samples with elevated chlorides were found. However, the elevated levels could not be unambiguously attributed to the WWTF collapse. This is the third WWTF to fail by sinkhole collapse in southeast Minnesota since 1974. All three collapsed lagoons have been located in similar geomorphic and stratigraphic settings. However, at least two lagoons have collapsed in the adjacent area in northeast Iowa, and these lagoons are located at different stratigraphic positions. Twenty-two WWTFs constructed in southeast Minnesota's karst region in the last 25 years have been identified as subject to potential sinkhole collapse. An unknown but significant number of manure storage lagoons, flood control structures, etc., have also been constructed in the karst region and are at risk. Public agencies are beginning to develop plans to deal with the risk associated with existing and future waste lagoons in this environment. The critical hydrogeologic parameters that can be used to prioritize the risk of collapse at existing facilities include: (1) the lithology of the first bedrock beneath each lagoon, (2) the thickness of surficial materials between the lagoon and the bedrock surface, (3) the presence and construction of liners (seepage rate), and (4) the proximity to existing sinkholes.