【作者】 王玉娟；

【导师】 尹观；

【作者基本信息】 成都理工大学 ， 地球化学， 2008， 硕士

【摘要】 论文依托于国家自然科学基金《川南主要含卤地层卤水的氘过量参数演化机理》（40643015）项目的研究,通过项目前阶段的工作,发现盆地卤水的同位素组成及氘过量参数,在宏观上具有明显规律性:（1）海相沉积含卤层卤水,同位素相对集中于δD-δ¹⁸O图右方,氢同位素组成均低于海水,而氧同位素则高于海水。卤水（主体）源于海水,不同时期海水的蒸发程度有所差异。由震旦含卤层卤水分布区向上,经寒武、二叠茅口至三叠系嘉陵江、雷口坡组,卤水的δD值随时代变新而相对富重同位素;（2）陆相沉积含卤层卤水,源于大气降水,同位素组成落在大气降水线附近:（3）海、陆过渡相含卤层（上三叠系须家河组）卤水,同位素组成落在海相沉积含卤层卤水与大气降水端员之间,系大气降水和蒸发海水的混合;（4）盆地内不同时代的含卤层,卤水的氘过量参数（d值）有明显随含卤层时代变老逐步降低的趋势。三叠雷口坡-嘉陵江组、二叠茅口组、寒武及震旦系含卤层均系碳酸盐地层,反映出水/岩作用十分强烈,同时显示出卤水的氘过量参数的变化是时间的函数;（5）所有含卤层,凡是分布于盆地周边或处在断裂构造发育或经过长期开采卤资源的卤井,明显受到大气降水渗漏补给的影响,它们的氘过量参数（d）都有不同程度的升高,升高的程度取决于现代大气降水混入的数量;（6）三叠系不同组含卤层的卤水,卤水d值的变化与平面分布和含卤层的埋深有一定的关联,含卤层埋深愈深,卤水的氘过量参数（d）值就愈低。在这诸多的规律中,卤水的氘过量参数（d）演化与水/岩反应的关系,特别令人瞩目。为了查明卤水储层水/岩相互作用的条件及其主要的影响因素,深入了解卤水的氘过量参数（d）演化机理,卤水的水/岩反应模拟实验被提上研究日程。水/岩反应系液相与固相之间的氧同位素交换。本文依据J.R.O’Neil的溶解-再沉淀的机理,着手探索影响水/岩反应的主要因素,设计出卤水/碳酸盐氧同位素交换的模拟实验研究方案。以碳酸盐矿物和不同浓度的卤化物溶液为研究对象,分析温度效应,CaCl₂溶液中的同离子效应,以及KCl、NaCl溶液中的盐效应等对氧同位素交换的影响。通过方解石与卤化物（NaCl、KCl、CaCl₂）溶液及纯水的水/岩反应后的系统模拟实验研究,初步获得了以下几点认识:（1）在浓度为10 g/L的KCl溶液实验研究中,当温度为40℃,80℃和120℃时,溶液的δ¹⁸O值分别为-12.0‰,-11.5‰和-11.3‰,温度对氧同位素交换有着强烈的影响,各种溶液δ¹⁸O值均随温度的升高而升高;（2）KCl、NaCl溶液对氧同位素交换有明显的促进作用,当溶液浓度小于25g/L时,在设定的温度（40℃,80℃和120℃）条件下,NaCl溶液δ¹⁸O值变化明显大于KCl溶液。当溶液浓度达到25g/L时,在上述温度条件下,KCl溶液的δ¹⁸O值变化又明显大于NaCl溶液;（3）CaCl₂溶液中Ca²⁺的存在对氧同位素交换有抑制作用,在上述各种温度条件下,同离子效应都很明显,但随着温度的升高,CaCl₂溶液中的同离子效应影响越来越弱,到120℃时,同离子效应对氧同位素交换的抑制作用影响甚微,此时,温度和盐效应又占主导作用;（4）综上所述,温度效应为影响碳酸盐矿物水—岩反应的第一要素,而浓度效应、同离子效应、盐效应相对弱于温度效应,浓度效应的影响是小。更多还原

【Abstract】 Relied on the study of "Deuterium Excess Evolvement of Brines in Brine-bearing Strata in South Sichuan Basin",the project of National Fund of Natural Science,the former work revealed that the isotopic compositions and Deuterium Excess of brines in this basin have evident regularity:（1）On theδD-δ¹⁸O plot,the oxygen and hydrogen isotope compositions of brines sampled in marine sedimentary brine-bearing strata fall in the right part of the plot,and the hydrogen isotope compositions are lower than SMOW,while oxygen isotope compositions are higher than SMOW.From Sinian stratum,along Cambrian and Permian Maokou Formation up to Triassic Jialingjiang Formation,theδD value of brines gets relatively positive with strata turn to younger.（2）Brines of terrestrial deposit are derived from precipitation,the isotope compositions falling in the neighborhood of the globle meteoric water line（GMWL）.（3）Brines of transition between marine and terrestrial deposit（Upper Triassic Xujiahe Formation）haveδD andδ¹⁸O values falling between the two end members of marine deposit brines and precipitation.（4）In the basin,water samples of the brine-bearing strata of different ages,have various deuterium excess（d）which evidently decrease with strata getting older.The brine-bearing strata of Triassic Leikoupo-Jialingjiang Formation,Permian Maokou Formation,Cambrian and Sinian are all carbonate rocks.Having same lithology,the strata present brines whose deuterium excess essentially change with time.All brine-bearing strata surrounding the basin or locating at the fault structures,as well as brine well long-term exploited for resources,have been visibly influenced by precipitation supply.（5）Therefore,the deuterium excesses of their brines have increased to different extents,depending on the amount of mixing precipitation. （6）Brines from different strata of Triassic have d values whose change and distribution are correlative to depth of the stratum to a certain extent.The more depth of stratum is,lower deuterium excesses of its brine is presented.In above,the relationship between deuterium excesses evolvement of brines and water-rock interaction is specially attention-getting.In order to find out the conditons of water-rock interaction in brine-bearing strata and the main influencing factors,for deeply probe the evolving mechanism of deuterium excesses,the simulating experiment of brine’s water-rock interaction has been put on the study schedule.The water-rock interaction goes in water-rock system,the oxgen isotope has exchanged between walter and rock.According to dissolution-redeposition mechanism of J.R.O’Neil,this paper embarked upon analyzing the possible factors from microcosmic aspects,and designed the simulating experiment research of oxgen isotopic exchange in water and rock interaction.Take the carbonate and the different concentration halogenide solution as the object of study,the influence of temperature,homoion effect of CaCl₂,salting effect of KCl and NaCl upon oxgen isotope exchange was disccused.After simulating experiment of water-rock interaction in calcite-halide（NaCl,KCl,CaCl₂）solution and calcite-water solution,the results were obtained as follows:（1）Taking example forδ¹⁸O value in KCl solution of 10g/L,when 40℃for -12.04,when 80℃for-11.51,when 120℃for-11.30,it can be summarized that the influence of temperature on the oxygen isotopic exchange is intense.Along with temperature elevation,theδ¹⁸O value in KCl solution,NaCl solution and CaCl2 solution has the tendency of increasing gradually,this had fully proven the temperature is an important factor affecting the oxygen isotopic exchange.（2）KCl,NaCl solution has the obvious promotion to the oxygen isotopic exchange.When solution concentration is smaller than 25g/L,under the given three temperatures,the influence of NaCl solution uponδ¹⁸O value is obviously strong compared to KCl solution.But when the solution concentration achieves 25g/L,under the given three temperatures,the influence of KCl solution uponδ¹⁸O value is obviously strong compared to NaCl solution.（3）In the CaCl₂ solution,the CaCl₂ has the inhibitory action to the oxygen isotopic exchange.When the CaCl₂ solution concentration is low,regardless of any temperature,the homoion effect is obvious.But along with the temperature elevation, the influence of homoion effect of CaCl₂ gets more and more weak;when up to 120℃, the homoion effect on inhibitory action to the oxygen isotopic exchange in water-rock interaction cannot appear nearly.Here,the temperature and the salting effect are the main controlling factors.Comprehensively considered the effect of temperature,concentration,and homoion effect,salting effect,the author proposed that temperature effect mainly controlls the oxygen isotopic exchange in carbonate water-rock interaction;while the influences of concentration effect,homoion effect and salting effect are obviously weaker than that of temperature effect,and the influence of concentration effect is the weakest among them.更多还原