A basic program for calculating subsurface water temperatures using chemical geothermometers-implication to geothermal reservoir estimation

GEOTHERM is a computer program written in BASIC language to estimate geothermal reservoir temperature using the well-known chemical gèothermometers. The empirical equations used in the program were obtained from the literature. Three different chemical geothermometers are included in the program: Na-K, Na-K-Ca, and silica geothermometers; this gives the user the opportunity not only to select the most reliable geothermometer in estimating subsurface temperature, but also to select the type of geothermometer according to available data. A sample input file of geothermal waters obtained from Iceland has been tested, so as to show the applicability and usefulness of the program.     

南秦岭汉阴北部金斗坡矿区S2面理和黑云母-石榴石变斑晶矿物温压条件与控矿关系

南秦岭汉阴北部金斗坡矿区志留系梅子垭组面理以S₂面理为主。大比例尺构造-岩相填图和剖面实测所获得的大量S₂面理产状数据显示,S₂面理倾向305°~355°,倾角为25°~50°,为稳定北倾的平直面理。通过S₂面理产状数据连图和综合分析,S₂面理与金矿化具有相同的展布特征及变化规律,对成矿具有制约作用。此外,选取梅子垭组含石榴石黑云母变斑晶绢云母石英片岩中的共生矿物石榴石-黑云母进行电子探针测试,运用Holdaway石榴石-黑云母地质温度计方法,估算出该区热蚀变温度为590 ℃~670 ℃。综合研究表明,印支晚期—燕山早期为金矿的成矿期,在此期间岩浆热液的强烈活动引起热蚀变作用的发生,生成石榴石与黑云母变斑晶;热变质作用促使Au元素发生活化,有利于后期Au元素富集成矿。     

Evolution of kaolinite subgroup minerals and mixed-layer illite/smectite in the Paleogene Damintun Depression in Liaohe Basin of China and its implication for paleotemperature

The oil-rich Damintun Depression is located in the Liaohe Basin, Northeast China, and was formed during the Paleogene. The major oil-producing strata in the depression are mudstone and shale. To explore the burial diagenetic history of the basin and the formation thresholds of hydrocarbons, the characters of the kaolinite subgroup minerals and mixed-layer illite/smectite in the mudstone and the shale are studied by using X-ray diffraction, electron probe, scanning electron microscope, and Fourier infrared s...     

东营凹陷中央隆起带地温场建立及地热系统发育模式

针对断陷盆地中央隆起带地热能开发地温场建立难度大的实际,采用井筒测温法、SiO2地热温标、钾镁地热温标、钠钾地热温标等建立地温场,研究地温场分布的控制因素,建立地温场发育模式。结果表明,东营凹陷中央隆起带沙二段—第四系可以划分为地表变温带、第一增温带、第一保温带、第二增温带、第二保温带、第三增温带和第三保温带共7个温度带。采用SiO2、钾镁、钠钾地热温标等方法求取了地温。综合研究区内地层对比、构造、储层、测井等地质研究成果,利用测温及化验资料,垂向上划分了6个砂组,建立了地温场的地质模型。地温梯度变化主要受中央隆起带底部塑性物质、主断裂分布、岩性、地层层位、砂地比控制。根据中央隆起带的地热成因及发育特征、温度及产水量,建立了该区的地热系统发育模式,划分为热扩张带、高温裂隙带、高温致密带、中温致密带、中温热水带、低温热水带和封盖带7层结构,从热源、盖层、热储层、热流通道、封闭性几方面分析了地热系统发育成因。     

西藏朗久地热田水文地球化学特征

朗久热田地下热水为中性－偏碱性低矿化水，富Ｌｉ，Ｂ，Ａｓ；Ｃｌ－ＨＣＯ３－（ＳＯ４）－Ｎａ水是主要水化学类型；Ｃａ２＋，Ｍｇ２＋是钙、镁在水溶液中的主要存在形式，其无机配合物居于次要地位；铀的主要存在形式是〔ＵＯ２（ＣＯ３）３〕４－和〔ＵＯ２（ＣＯ３）２２－〕，铀羟基配合物含量甚微；铀酰配合物计算及氢、氧稳定同位素测试结果表明，朗久地下热水主要是由大气降水起源的渗入水经深循环至还原环境形成，并有部分岩浆水混入；利用地化温标计算的地热系统浅部温度为１５０～２５０℃。     

A new improved Na/K geothermometer by artificial neural networks

A new Na/K geothermometer equation has been developed. The temperature function is:Concentrations are in mg/kg. The new improved geothermometer equation was developed by artificial neural networks. The normalized mean square error (NMSE) used in the new improved Na/K equation for temperatures ranging from 94 to 345 °C is 0.179, which is lower than the corresponding NMSE 0.226, 0.598, 0.656, 0.268, 0.328 and 0.225 for the equations of Arnorsson et al. (1983; Geochim. Cosmochim. Acta 47, 567–577), Truesdell (1975; Proc. 2nd UN Symposium), Tonani (1980; Proc. Adv. Eur. Geoth. Research, 2nd Symposium), Fournier (1979a; J. Volcanol. Geotherm. Res. 5, 1–16), Nieva and Nieva (1987; Heat Recovery Systems and CHP 7, 243–258) and Giggenbach (1988; Geochim. Cosmochim. Acta 52, 2749–2765), respectively. It is therefore strongly recommended to use this new improved Na/K geothermometer equation for geothermal exploration. Since the proposed Na/K geothermometer was developed on a purely empirical basis, it should not be applied outside the T-P-X range of calibration.     

地热温标在地热系统中的应用研究

在地热系统中,地热温标通常被用来评价地下热储温度,但是如果作为地热温标的化学组分在热储内部没有达到平衡,则估算出的热储温度往往与实际温度相差很远。本文以平顶山八矿地下热水为例,通过Na—K—Mg三角图及以WATCH程序等建立起来的多矿物平衡图在地热系统中的运用,对地热系统中矿物和流体的化学平衡做出了定量和定性的判断,从而为地热温标的选取提供依据。     

西藏邦铺斑岩钼(铜)多金属矿床侵入岩锆石微量元素特征及其地质意义

西藏邦铺斑岩钼(铜)多金属矿床位于冈底斯成矿带东段,矿区侵入岩期次和类型多样,主要包括成矿前期黑云母二长花岗岩、成矿期闪长玢岩和二长花岗斑岩及成矿后期石英二长斑岩和辉绿玢岩等5种。在系统总结前人研究成果基础上,利用LA-ICP-MS技术获得了矿区闪长玢岩岩体锆石微量元素特征。结果表明:邦铺矿区侵入岩锆石类型主要包括岩浆锆石和热液锆石;5种侵入岩球粒陨石标准化稀土元素配分模式显示具相似的特征,曲线左倾,整体较陡,表现为明显的Ce正异常和Eu负异常,轻稀土元素亏损,重稀土元素富集。通过锆石Ti含量地质温度计计算出侵入岩锆石结晶温度,显示出成矿期和成矿后期侵入岩体岩浆来源于在水近饱和条件下发生的部分熔融。根据锆石中特定微量元素和稀土元素特征变化,各侵入岩锆石均是从陆壳岩浆中结晶分异形成的,与锆石相对应的寄主岩石均形成于陆壳环境。     

广西河三铅锌（银）矿床的成矿物理化学条件

矿物包裹体和方铅矿－闪锌矿对地温计研究表明，河三矿床形成于中－高温（２０３～４２０℃）和中低压的成矿条件下．随着成矿作用的进行，成矿温度、压力降低，成矿热液的密度增加，盐度中等（变化为５．７～１１．５％ＮａＣｌ）．在主要成矿阶段，成矿热液可能发生沸腾，挥发性组分大量逸出，矿质浓集成矿。这可能是河三铅锌矿床富大集中，但围岩蚀变及脉石矿物不发育的主要原因。     

Geochemistry of thermal springs around Lake Abhe,Western Djibouti

The Republic of Djibouti, occupying an area of 23,180 km², falls within the arid zone of East Africa and is located above the ‘Horn of Africa’, adjacent to the Red Sea. This country has several thermal springs and fumaroles distributed over three regions – Lake Assal, Lake Hanle and Lake Abhe. The most characteristic feature of Lake Abhe is the presence of several linear chains of travertine chimneys. The thermal waters are typical of the Na-Cl type near neutral waters rich in CO₂. These waters show an oxygen shift, indicating reservoir temperatures>200°C. The chemical signature of the thermal springs and the geology of the Lake Abhe region are very similar to the Tendaho geothermal area of Ethiopia. The geology, temperature gradient and its proximity to Damah Ale volcano make the Lake Abhe region a potential site for geothermal power development.