论文中英文摘要.doc

论文中英文摘要

作者姓名：赵慈平
论文题目：腾冲火山区现代幔源氦释放特征及深部岩浆活动研究
作者简介：赵慈平，男，1966年2月出生，2003年9月师从于中国地震局地质研究所上官志冠教授，于2008年7月获博士学位。

中 文 摘 要

本论文以揭示现今腾冲火山区岩浆活动为目标，以温泉为研究对象，以化学地质温标、同位素示踪、同位素地质温标为手段，依托现代化学和同位素分析测试技术，通过对腾冲火山区温泉逸出气体的大规模采样及成份和同位素分析测试，来研究腾冲火山区现今幔源物质释放场、上地壳温度场和岩浆囊现今温度，并结合前人深部探测、活动监测及成因研究方面的成果，提出腾冲火山孕育喷发的成因机制模型。
本文主要进行了如下7个方面的内容研究：
1、研制防大气污染和具富集功能的野外气体取样器 为了保证所采集气体样品不被空气污染，提高观测结果的可信度。同时，为了克服野外采样中诸如温泉气体温度过高、采样空间狭小等原因难以近距离采样，排气规模太小以及CH4需要富集等等一系列问题，研制一套集排气装置、储气装置、微量组份富集装置、样品输出接口装置于一体的气体样品采集器具。
2、采集腾冲火山区温泉逸出气体，分析测试这些气体的常规组份和氦氖碳同位素组成 用本研究研制的防大气污染采样器采集腾冲火山区温泉逸出气样品，用于常规组分和碳同位素组成分析的气体样品用铝塑气体样品袋装样，用于氦同位素分析的样品用钢瓶或玻璃瓶装样。用气相色谱仪测试常规组分，质谱仪（VG5400）分析3He/4He、4He/20Ne。用本研究研制的防大气污染和具富集功能的采样器采集幔源物质释放强和相对地热梯度高的重叠异常区（岩浆活动区）上方温泉的CO2和CH4气体样品，对CH4碳同位素样品进行现场富集取样，外送分析这些样品的碳同位素组成。
3、腾冲火山区上地壳温度场的研究 利用前人的温泉水化学分析资料，选用统一地球化学温标，计算热储温度，假定各热储等深，则热储温度与泉口温度之差为相对地热梯度。计算腾冲火山区上地壳的相对地热梯度。通过克里金插值法获得整个腾冲火山区的相对地热梯度平面分布图。根据此空间分布图和数据，研究腾冲火山区上地壳温度场的空间分布特征，探讨与岩浆的存在及其活动性的关系
4、腾冲火山区幔源物质释放场研究 通过样品的4He/20Ne值对样品的大气污染进行3He/4He矫正，对样品氦同位素组成的源区百分比进行计算，最后对源区百分比进行校正计算。通过克里金插值法获得整个腾冲火山区的原始氦同位素组成3He/4He（Ra）、校正后的3He/4He校正（Ra）以及氦同位素组成地幔源贡献百分比M和校正后的氦同位素组成地幔源贡献百分比M校正的平面分布图。这种图件即能反映出腾冲火山区的幔源物质释放的空间强度水平，同一释放点的时间序列则能反映幔源物质释放的时间变化。结合具体的数据和这些图件，研究腾冲火山区幔源物质释放的时空分布特征，探讨与岩浆的存在及其活动性的关系。
5、腾冲火山区岩浆囊现今温度研究 对CO2-CH4碳同位素地质温度计的相关文献进行研究，选取最合理的已有平衡分馏方程，或利用最合理的平衡分馏系数数据拟合出最适用的平衡分馏方程，用本研究获得的CO2-CH4碳同位素分馏数据，计算腾冲火山区岩浆囊的的现今温度。
6、岩浆的存在及其活动性的综合分析研究 根据本论文的上述观测资料和研究成果，结合前人获得的大地电磁测深、人工地震测深等深部探测资料来佐证岩浆囊的存在，并研究这个或几个岩浆囊的规模；利用本研究和前人长期积累的幔源物质释放强度观测资料（20年），岩浆囊温度资料，结合前人获得的形变、地震等活动性监测资料研究这个或几个岩浆囊的现今活动性。
7、腾冲火山孕育喷发的成因机制模型研究 根据本研究得到的上地壳温度场、幔源物质释放场、岩浆囊温度结果、结合前人大地电磁测深、人工地震测深成果确定目前腾冲火山区现存岩浆囊的数量、空间分布、大小和埋深。然后结合前人通过岩石学和岩石地球化学研究得到的相关成因信息，提出腾冲火山孕育喷发的成因机制模型。
为了研究目标和上述研究内容的实现，本论文2003年7月开始实施野外观测，2008 年5月完成全部研究工作，历时5年。本论文在腾冲火山区及其外围共实施了3期（2003年、2004年、2006年各一期）温泉气体地球化学观测，先后使用车辆4辆，行程16200公里，在63公里半径，12350平方公里的范围内实地考察测量温泉159个次，测量温泉温度145个次，共采集气体样品254个，获得分析测试数据1229个。其中常规组份和CO2碳同位素样品117个，氦氖同位素样品88个，CH4碳同位素样品49个，获得常规气体组份数据724个（96个样品），富集CH4常规气体组份数据181个（21个富集样品），氦氖同位素数据264个（88个样品），CO2碳同位素数据36个（36个样品），CH4碳同位素数据24个（24个样品）。另外搜集与整理了研究区及外围304个温泉的前人温度和水化学成分数据。
通过以上数据的获取和以此为基础对腾冲火山区上地壳温度场、幔源物质释放场及岩浆囊现今温度的研究，结合深部探测、活动性监测和前人的成因研究结果的综合分析，本研究得到如下5点结论：
1、腾冲火山区地下现今可能存在3个岩浆囊，第1个岩浆囊位于腾冲县城和清水一带，第2个岩浆囊位于马站和曲石一带，第3个岩浆囊位于五合、龙江、团田和浦川一带。3个岩浆囊上方的上地壳相对地热梯度分别为140℃、120℃、130℃。3个岩浆囊释放挥发物质的幔源比例依次为70%、60%和30%。
2、3个岩浆囊的几何尺度（水平方向的直径）可能依次约是20km、19km和23 km（长45km）。3个岩浆囊的埋藏深度不同：第1个岩浆囊位于地下5-25km之间，第2个岩浆囊可能也位于地下10-25km之间，第3个岩浆囊位于地下7-14km之间。
3、3个岩浆囊的的现今温度分别为：第1个岩浆囊324-789℃间，平均555℃；第2个岩浆囊402-663℃间，平均532℃；第3个岩浆囊320-1194℃间，平均679℃。可以认为，腾冲火山区地下岩浆囊顶部气体富集区目前的温度变化范围为320-1200℃，岩浆囊的实际温度应高于平均值600℃。三大岩浆囊的边缘温度可能在300-600℃间，中心温度可能在700-1200℃间。
4、3个岩浆囊的活动性不同：第1个岩浆囊集相对地热梯度、幔源物质释放、形变和地震活动等异常于一身，岩浆囊正在接受幔源岩浆的补充，活动性最强，直接位于腾冲县城之下，喷发将造成最为严重的损失，需重点监视；第2个岩浆囊的幔源物质释放强度也引人注目，岩浆囊可能也正在接受幔源岩浆的补充，需加强监测；第3个岩浆囊规模大，埋深较浅，幔源物质释放较弱（30%），目前幔源岩浆的补充可能比较微弱，但岩浆囊温度依然较高，需引起注意。
5、腾冲火山的形成与现今的板块俯冲无关，是局部地幔上隆引起地壳拉张的结果。地幔上隆的原因可能和古怒江洋壳型岩石圈或/和古密支那洋壳型岩石圈的拆沉有关，但地幔上隆和腾冲火山的喷发远远晚于东西两个古洋壳型岩石圈的俯冲时限，因此可以认为已与严格意义上的板块俯冲作用无关了。腾冲火山区现今幔源物质释放强度的空间分布图象就是这一地幔隆升区空间尺度和隆升强度的最直接反映，上隆区的大小大致为南北长100km，东西宽50km。局部上隆的地幔既为腾冲火山的孕育提供了岩浆物质来源，其产生的地壳拉张也为岩浆的上侵提供了构造通道，这种拉张得到现今本地区地貌和形变观测的支持。
本论文对腾冲火山的现今活动性这一关键科学问题进行了比较明确的回答，并结合前人通过岩石学和岩石地球化学研究得到的相关成因信息，提出了腾冲火山孕育喷发的成因机制模型，产出了如下4个创新点：
1、提出了相对地热梯度的新概念和计算方法，揭示了腾冲火山区上地壳的温度场特征 通过对前人温泉基本要素数据的深度挖掘，提出了相对地热梯度的新概念和计算方法。用该概念和方法揭示了腾冲火山区上地壳的温度场特征，发现腾冲火山区上地壳存在3个高于100℃的相对地热梯度异常区。相对地热梯度异常是其下方的岩浆囊的热扩散造成的，可以理解为岩浆囊的热晕（热帽），间接反映了岩浆囊的存在。
2、揭示了目前腾冲火山区的幔源物质释放强度的空间分布特征 应用氦同位素示踪技术，在东起怒江，西至中缅边境的涵盖整个腾冲火山区的范围内进行了幔源物质释放强度测量。幔源物质释放强度空间分布结果表明，腾冲火山区的幔源物质释放可分强度不同的三个区域。这三个幔源物质释放较强的区域与相对地热梯度研究得到的3个高地热梯度区符合很好，进一步说明腾冲火山区岩浆囊的存在。
3、发现目前腾冲火山区存在3个壳内岩浆囊，估计了它们的大小、埋深和现今温度等重要参数，评估了它们的活动性 通过对腾冲火山区上地壳温度场、幔源物质释放场的分析研究，结合前人的大地电磁、人工地震等测深结果，发现目前腾冲火山区存在3个壳内岩浆囊。3个壳内岩浆囊的发现为回答腾冲火山现今活动性这一关键科学问题确立了基础。估计了3个岩浆囊的空间尺度和埋深。应用同位素地质温标原理，估算了3个岩浆囊的现今温度。评估了3个岩浆囊的活动性。
4、提出了腾冲火山孕育喷发的成因机制模型 根据本研究发现的目前腾冲火山区存在3个壳内岩浆囊，结合前人通过岩石学和岩石地球化学研究得到的相关成因信息，提出了腾冲火山孕育喷发的成因机制模型，认为腾冲火山的形成与板块俯冲无关，是局部地幔上隆并引起地壳拉张的结果。腾冲火山区现今幔源物质释放强度的空间分布图象就是这一地幔隆升区空间尺度和隆升强度的最直接反映。局部上隆的地幔既为腾冲火山的孕育提供了岩浆物质来源，也为岩浆的上侵提供了构造通道。

关键词：腾冲火山、氦同位素、碳同位素、地质温度计、岩浆囊、模型、温泉

Mantle-derived Helium Release Characteristics and Deep Magma Charmber Activities of Present Day in the Tengchong Volcanicic Area
Zhao Ci Ping
ABSTRACT

This dissertation, taking revealing nowadays magmatic activities in the Tengchong volcanic area as a goal, the hot spring as the object of research, chemical geothermometer, isotopic tracer, isotopic geothermometer as the means, based upon the modern chemical and the isotopic analysis technology, adreesses three specific scientific questions: They are the present release field of mantle-derived volatiles, temperature field of the most upper crust and the temperature of nowadays magma chamber of the Tengchong volcanic area. In conjunction with the predecessor’s achievements of deep sounding, the activities monitoring and the origin research, this work proposes a machanism model for the Tengchong volcano generation and eruptions.
In this paper, 7 aspects of research were conducted as follows:
1. Developing sample collecting tool for atmosphere-contaminating-prevention with enrichment function In order to guarantee that the gas sample collected is not contaminated by the atmosphere so as to improve the credibility of the observation result, and at the same time, to overcome a series of sampling problems in field such as that hot spring gas is of hyperpyrexia, that it is diffculty to collect sample over a short distance because operation space is too narrow, and that it takes a too long time because outgassing is too less, or that certain minor components need to concentrate by chemical reaction, and so on. This research has designed a set of gas sample collection installments which integrate atmosphere exhausting device, gas store device, enrichment device of trace component, the output interface of sample all in one.
2. Sample-collecting, analysis of conventional and isotopic composition This work collectes gas samples escaped from hot springs in the Tengchong volcanic area using the sample collecting instrument with atmosphere-contaminating-prevention and enrichment function. The gas samples which are used to analyze conventional component and carbon isotope composition are packed in aluminum-film-covered plastic bags, the ones for helium isotope compostion analysis are packed in the steel cylinder or glass bottle. With the gas chromatograph it analyzes conventional component, with the mass spectrometer (VG5400) it analyzes 3He/4He, 4He/20Ne. This work collectes CO2 and CH4 gas samples escaped from hot springs in overlaped abnormal areas (magmatically active region), where both the intensity of mantle-derived mass release and relative geothermal gradient are high, using the sample collecting instrument this research developed. This work carries on enrichment to CH4 of the CH4 carbon isotope sample at site, analyzes carbon isotope composition both CO2 and CH4 sample with the mass spectrometer (MAT251).
3. Analysis of temperature field in upper crust of the Tengchong volcanic area Using predecessor's hydrochemical data of hot springs, selecting unified geothermometer, this work calculates the temperature of thermal reservoirs. Assuming that the depth of these thermal reservoirs are same, then the temperature difference between hot springs and thermal reservoirs is defined as relative geothermal gradient. According to this definition, this work calculates the values of relative geothermal gradient in entire the Tengchong volcanic area.Using the values of relative geothermal gradient, the map of relative geothermal gradient in the entire Tengchong volcanic and adjacent areas is obtained with Kriging interpolation. According to this space distribution map and the data, this work studies spatial distribution characteristic of the temperature field of the most upper crust in the Tengchong volcano area, and discusses the relationship between the existence and the activity of magma chambers and the spatial distribution characteristic of the temperature field.
4. Analysis of spatial-temporal distribution of release of mantle-derived gas Atomsphere contamination correction is made for 3He/4He ratio through the 4He/20Ne value. Then this work calculates percentage proportion of atmosphere, crust and mantle of helium isotope compostion. Finally the correction for percentage proportion of different sources is performed.Using Kriging interpolation, the plane distribution maps of primitive helium isotopic compostion 3He/4He (Ra) ratio values, of corrected helium isotopic compostion 3He/4Hec (Ra) ratio values, of percentage M which express contribution of mantle reservoir to helium isotopic compostion, and of corrected percentage Mc in entire the Tengchong volcanic and adjacent areas are obtained. These maps can reflect the spatial intensity level of mantle-derived mass release in the entire Tengchong volcanic and adjacent areas, and time series of these values of helium isotopic compostion at the same localities can reflect time variations of mantle-derived mass release. Synthesising specific data and these maps, this work studies spacial and temporal distribution characteristics of intensity of mantle-derived mass release in the entire Tengchong volcanic and adjacent areas, discusses the relationship between the existence and activity of magma chambers and these spacial and temporal distribution characteristics.
5. Calculating of temperature of magma chambers To search, read and analyze literatures mainly about the thermodynamics principle of isotopic exchange reaction, data of equilibrium fractionation factor and equilibrium fractionation equation of carbon isotope exchange reaction between CO2 and CH4 and temperature range of their utilization, so that this work can select the most appropriate formula and the data explanation principle for this research. Choosing the most resonable equilibrium fractionation equation or formula regressed from carbon isotope equilibrium fractionation factors of CO2 and CH4 which were theoretically calculated or experimentally determined, this work finally calculates the temperature of gas source area (magma chambers).
6. Integrated analysis of existence and activities of magams According to observed data and the research results of this dissertation mentioned above, unifing deep sounding data that the predecessors obtained by magnetotelluric sounding(MTS) and deep seismic sounding(DSS), it demonstrates the existence of magma chambers, and measures the size and depth of this one or these several magma chambers. It discusses the nowadays activity of this one or these several magma chambers using observed long-term data of intensity of mantle-derived mass release, which this thesis researches and the predecessors have accumulated for more than 2 decades, the data of temperature of magma chambers, to unify the data of Tenchong volcanic activity from crust deformation measurements and earthquake monitoring.
7. Research on model of mechanism of Tengchong volcano According to results on temperature field in upper crust, mantle-derived mass release field, temperature of magma chambers of the Tengchong volcanic area, unifing data of magnetotelluric sounding(MTS) and deep seismic sounding(DSS), this work determines the number, spatial distribution, size and depth of magma chambers which exist present day in the Tengchong volcanic area. Finally, in conjunction with the related information of petrology and the rock geochemistry research, this work proposes a model of Tengchong volcano origin.
In order to achieve the above research aim and to complete above contents, it taken 5 years for this dissertation to complete the field sample-collecting, analysizing and synthetic research work, from July, 2003 to May, 2008. Field sample-collecting, analysizing for hot spring gas is implemented altogether 3 times in 2003, 2004, 2006, respectively, in the Tengchong volcanic area and the periphery. Employing 4 vehicles successively, traveling 16200 kilometers, The author have surveyed 159 hot springs, measured temperature 145 times, altogether gathered 254 gas samples, obtaining 1229 data of chemical and isotopic composition of them in the range of 12350 square kilometers with the radius of 63 kilometers. Among these samples, 117 are for the conventional component and carbon isotope composition of CO2, 88 for isotope composition of Helium and Neon, 49 for carbon isotope composition of CH4. The author have obtained 724 conventional gas component data (of 96 samples), 181 conventional gas component data(of 21 CH4-enriching samples), 264 isotope composition data of Helium and Neon(88 samples), 36 carbon isotope composition data of CO2 (36 samples), 24 carbon isotope composition data of CH4 (24 samples). Moreover we have collected and compiled the numerous data of the temperatures and hydrochemistry ingredient of 304 hot springs in research area and the periphery which analyzed and measured by former investigators.
Based on the above data, by resolving theses 3 issues such as temperature field in most upper crust, mantle-derived mass release field, and temperature of magma chamber, and combining achievements in deep sounding, activity monitory and origin research that the former investigators obtained, this research obtains the following 5 conclusions:
1. There exist 3 magma chambers in crust present day in the Tengchong volcano area. The 1st one is located Tengchong county-Heshun township-Rehai resort area where is in middle of the Tengchong volcano area. The 2nd one is located Qushi-Mazhan where is in northern of the Tengchong volcano area. The 3rd one, lies in Wuhe-Puchuan-Xinhua area where is in southern of the Tengchong volcano area. The relative geothermal gradients of most upper crust above 3 magma chambers are 140℃, 120℃, 130℃, respectively. The mantle-derived proportions of volatile mass release of 3 magma chambers are 70%, 60% and 30%, respectively.
2. The sizes (the horizontal diameter) of 3 magma chambers are approximately 20km, 19km and 23 km (long 45km), respectively, the depths of them are different: the 1st at 5-25km, the 2nd is 10-25km, and the 3rd is 7-14km.
3. The temperature of the 1st magma chamber is within 324-789℃, with average 555℃. That of the 2nd, within 402-663℃, with average 532℃, That of the 3rd is within 320-1194℃, with average 679℃. It is believed that variation range of the present temperature of the gas enrichment region which is crown of magma chamber below the Tengchong volcano area is 320-1200℃, the actual temperature of magma chamber should be higher than the mean value 600℃. The temperatures of edge area of these 3 magma chambers possibly are in 300-600℃, the central temperature possibly in 700-1200℃. The nowadays temperatures of these 3 magma chamber’s center has achieved the formation temperature of Rhyolite magma (600-900℃), the Andesite magma (800-1100℃) and basalt magma (1000-1250℃), further suggesting the objective existence of th