Geothermal gradient of the upper mantle beneath Jeju Island, Korea: Evidence from mantle xenoliths   总被引：2，自引：0，他引：2  

Seong Hee Choi  Yong-Joo Jwa  Han Yeang Lee 《Island Arc》2001,10(2):175-193

Abstract Ultramafic xenoliths found in alkali basalts from Jeju Island, Korea are mostly spinel lherzolites accompanied by subordinate amount of spinel harzburgites and pyroxenites. The combination of results from a two-pyroxene geothermometer and Ca-in-olivine geobarometer yields temperature–pressure (T–P) estimates for spinel peridotites that fall in experimentally determined spinel lherzolite field in CaO-Fe-MgO-Al₂O₃-SiO₂-Cr₂O₃ (CFMASCr) system. These T–P data sets have been used to construct the Quaternary Jeju Island geotherm, which defines a locus from about 13 kbar at 880°C to 26 kbar at 1040°C. The geothermal gradient of Jeju Island is greater than that of the conventional conductive models, and may be as a result of a thermal perturbation by the heat input into the lithospheric mantle via the passage and emplacement of magma. Spinel–lherzolite is the main constituent rock-type of the lithospheric mantle beneath Jeju Island. Pyroxenites may be intercalated in peridotites at similar depth and temperature as re-equilibrated veins or lenses.  相似文献   

The thermal state and composition of the lithospheric mantle beneath the Leizhou Peninsula, South China     

Jin-Hai Yu  Suzanne Y. O&#x;Reilly  W. L. Griffin  Xisheng Xu  Ming Zhang  Xinmin Zhou 《Journal of Volcanology and Geothermal Research》2003,122(3-4):165-189

Two localities on the Leizhou Peninsula, southern China (Yingfengling and Tianyang basaltic volcanoes) yield a wide variety of mantle-derived xenoliths including Cr-diopside series mantle wall rocks and two distinct types of Al-augite series pyroxenites. Metapyroxenites have re-equilibrated granoblastic microstructures whereas pyroxenites with igneous microstructures have not thermally equilibrated to the mantle conditions. An abundant suite of megacrysts and megacrystic aggregates (including garnet, plagioclase, clinopyroxene, ilmenite and apatite) is interpreted as the pegmatitic equivalents of the igneous pyroxenite suite. Layered spinel lherzolite/spinel websterite xenoliths were formed by metamorphic differentiation caused by mantle deformation, inferred to be related to lithospheric thinning. Some metapyroxenites have garnet websterite assemblages that allow calculation of their mantle equilibration temperatures and pressures and the construction of the first xenolith geotherm for the southernmost China lithosphere. Heat flow data measured at the surface in this region yield model conductive geotherms (using average crustal conductivity values) that are consistent with the xenolith geotherm for the mantle. The calculated mean surface heat flux is 110 mW/m². This high heat flux and the high geotherm are consistent with young lithospheric thinning in southern China, and with recent tomography results showing shallow low-velocity zones in this region. The xenolith geotherm allows the construction of a lithospheric rock type section for the Leizhou region; it shows that the crust–mantle boundary lies at about 30 km, consistent with seismic data, and that the lithosphere–asthenosphere boundary lies at about 100 km.  相似文献   

ZK03井水温异常与印尼8.7级地震的关系   总被引：4，自引：1，他引：3  

邱永平 《华北地震科学》2005,23(4):13-16

分析认为该井水温出现的中、短、临异常可能与印尼8.7级地震有关.年日均值图显示,中期异常出现在震前11个月左右,表现为脉冲式向上突跳及阶跃式上升,最大异常量为日均正常上升速率的84倍;中短期异常出现在震前4个月和1个月,最大异常量为正常日均波动值的274倍;临震异常出现在震前的第9天,震前25小时达到最高值,最大异常量为正常日均波动值的2.5倍.水温异常出现的原因可能是由于地震前的长周期波通过上地幔或软流层传播,间接地导致了地下流体温度发生了微小的变化.  相似文献   

辽宁大民屯凹陷地热资源形成条件分析     

张洪梅 《地质与资源》2013,22(1):25-29

大民屯凹陷是新生代陆相凹陷盆地,其地层、构造、岩浆岩等地质背景具备传导性地热的良好成矿条件,热源主要为幔源热,储热层为沙河街组砂砾岩层段层状热储,盖层为第四系、新近系馆陶组、明化镇组和部分古近系东营组泥岩段地层.凹陷内基底断层及多期次级断裂形成了地热田良好的导热和导水通道.新近系平均地温梯度2.9℃/100 m,古近系平均地温梯度3.18℃/100 m,一定深度下的地下热水可以达到理想温度,具备地热开发条件.  相似文献   

青海共和盆地干热岩地热储层水力压裂物理模拟和裂缝起裂与扩展形态研究     

周舟  金衍  曾义金  张旭东  周健  汪文智  孟翰 《吉林大学学报(地球科学版)》2019,49(5):1425-1430

水力压裂是青海共和盆地干热岩地热资源开发的难点技术问题之一。本文基于升级改造的大尺寸真三轴水力压裂物理模拟实验系统模拟干热岩储层高温高压环境,利用青海共和盆地露头岩心进行水力压裂物理模拟实验,揭示干热岩储层水力裂缝的起裂和扩展规律。通过物理模拟实验发现：干热岩储层裂缝起裂可以通过文中提出的起裂模型判断起裂方式和预测起裂压力;水力裂缝在岩石基质中的扩展形态简单,仅沿最大主应力方向延伸;但是水力裂缝会受到岩石中弱面的影响,发生转向沿弱面延伸,形成较复杂的裂缝形态。因此,建议在干热岩储层实际施工中,在天然裂缝发育较丰富的层段开展水力压裂,以实现复杂裂缝网络提取地热能。  相似文献   

TM多波段影像资料应用于地热资源调查研究的一例     

彭东  陈尚品  吴树通  曹俊  郭建强 《四川地质学报》2005,25(1):41-43

采用TM多波段图像，通过与九寨沟流域的对比，建立解译标志，研究了松潘漳腊以北的一处影像异常。工作成果表明在一定条件下，应用TM影像开展地热调查是可行的。  相似文献   

MT法在河北献县地区地热勘查中的应用     

宋洪伟  夏凡  尚铭森 《地质与资源》2018,27(3):284-287

河北献县地热资源埋藏浅、温度高、储量大、开发潜力大,合理选择物探方法可以很好地确定靶区,圈定储热构造,减少因钻探位置不当带来的额外开发成本.本次勘查工作利用EH4连续电导率成像系统,采取单点进行大地电磁测深（MT）的数据采集方式,能够极大地降低地形因素的影响,由此保证了测量的精度.由于MT法探测深度的优势,其反演电阻率电性特征图能够很清晰地反映出地热田导水导热断裂构造的分布、产状.MT法在本次地下热源勘查工作中取得了很好的测量结果,成功圈定了地下热源的范围,为下一步的钻探工作提供了有力的技术支持.  相似文献   

青海德尔尼铜(钴)矿床矿石矿物特征及其地质意义   总被引：1，自引：0，他引：1  

段俊  钱壮志  黄喜峰  董富权  赵晓健  鲁浩 《地球科学与环境学报》2014,(1):201-209

青海德尔尼铜(钴)矿床赋存于东昆仑阿尼玛卿蛇绿岩套中部,岩石类型主要有蛇纹石化的方辉橄榄岩、纯橄榄岩和二辉橄榄岩,矿石类型主要为块状、条带状含铜黄铁矿矿石,矿床成因存在多种认识。通过野外详细观察、室内显微镜下矿石矿物特征鉴定以及电子探针分析,确定德尔尼铜(钴)矿床的矿石矿物主要为黄铁矿,其次为磁铁矿、磁黄铁矿、黄铜矿、闪锌矿和方铅矿等,矿石结构以半自形粒状结构为主;钴元素在早期黄铁矿中比较富集,晚期黄铁矿中较贫,w(Co)/w(Ni)值指示黄铁矿与巴西Sossego铁氧化物-铜-金矿一致;早期黄铁矿、黄铜矿、闪锌矿的微量元素质量比值指示矿床成矿温度为200℃~300℃,属于中温环境,进一步证明了该矿床不是岩浆型矿床,属于海底喷流-沉积成因。矿床成矿过程可划分为4个阶段:海底喷流-沉积阶段、构造变形阶段、热液阶段和表生氧化阶段,其中前两个阶段为铜、钴、锌的主要成矿期。  相似文献   

敦密断裂带(辉南段)结构及其赋存地热资源可能性     

丁兆芹  许志河  苏永飞  关淑艳  陈强 《吉林地质》2014,(2):98-102

本文通过对敦密断裂带上可控源音频大地电磁测深剖面分析,总结了敦密断裂带结构及其深部低阻异常特征,对其局部含热的可能性进行了探讨。  相似文献