山东昌乐地区王家大山玄武岩流变性质研究  

High temperature deformation of natural basalt samples from Wangjiadashan,Shandong Province

作　　者：王晓宁 姜哲轩 郑小东 张洪通 李建峰[2,4] 吴东伟 宋茂双[2,4] WANG XiaoNing;JIANG ZheXuan;ZHENG XiaoDong;ZHANG HongTong;LI JianFeng;WU DongWei;SONG MaoShuang(College of Mining Engineering,Heilongjiang University of Science and Technology,Harbin 150022,China;State Key Laboratory of Deep Earth Processes and Resources,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,China;Tianjin Design Institute of China Petroleum Beijing Project Management Company,Tianjin 300457,China)

机构地区：[1]黑龙江科技大学矿业工程学院,哈尔滨150022 [2]中国科学院广州地球化学研究所,深地过程与战略矿产资源全国重点实验室,广州510640 [3]中国科学院大学,北京100049 [4]中国科学院深地科学卓越创新中心,广州510640 [5]中国石油北京项目管理公司天津设计院,天津300457

出　　处：《岩石学报》2025年第4期1454-1465,共12页Acta Petrologica Sinica

基　　金：广东省基础与应用基础研究基金项目(2022A1515011000);黑龙江科技大学引进高层次人才科研启动基金项目(HKD202202);国家自然科学基金项目(42172243、42374122)联合资助.

摘　　要：本文选用采自山东昌乐地区王家大山的玄武岩作为初始样品,利用Paterson气体介质高温高压流变仪在围压~300MPa、温度973~1173K、应变速率5×10^(-6) s^(-1)~4×10^(-5) s^(-1)的实验条件下开展了轴向压缩变形实验(应变量≤15%),以探究玄武岩的高温流变行为。傅里叶变换红外光谱仪分析测得变形前后样品都是含水的,说明玄武岩在实验过程中发生含水条件下的变形。应力-应变曲线表明玄武岩发生宏观塑形变形;样品稳态(或接近稳态)流变差应力介于41~427MPa之间,且随应变速率降低和温度升高而减小,遵守幂律流变方程。当温度≥1073K时,应力指数(n)=3.6±0.3,活化能(Q)=340±34kJ/mol;当温度≤1023K时,n=5.9±0.8,Q=259±23kJ/mol。显微结构观察发现:变形后样品以基质斜长石普遍发育形状优选定向(SPO)为最显著特征,可识别出基质斜长石发育波状消光和膝折等晶内变形显微证据;低温(≤1023K)高应力(>300MPa)样品中基质斜长石、单斜辉石发育微裂隙,并可见沿微裂隙的滑移错动,表明脆性破裂承担了部分应变量;温度≥1023K的样品中发生脱水引起部分熔融,在淬火熔体中可见细粒的重结晶角闪石生成,但由于熔体含量较低似乎对玄武岩的流变行为影响不明显。本文报道的含水条件下的玄武岩流变数据与前人报道的辉绿岩数据一起,可以为构建不同水含量的大陆下地壳(大洋洋壳)流变强度剖面提供支持,也可以为理解洋壳变形、下地壳流动和拆沉等重要构造过程提供流变学证据。Cylindrical specimens,core-drilled from a relative fresh basaltic block collected from Wangjiadashan,Changle County,Shandong Province,were tri-axially deformed at a confining system with pressure/temperature of~300MPa/973~1173K,and strain rates from 5×10^(-6) s^(-1) to 4×10^(-5) s^(-1),to explore the rheological behaviors of the basalts.Undeformed and deformed samples were both hydrous when measured by a Fourier transform infrared spectrometer,and thus the deformation was performed under hydrous conditions.Curves of loading differential stress versus strain described macroscopic plastic deformation,with steady flow stresses from 41MPa to 427MPa and decreasing as strain rate decreasing or temperature increasing.The deformation behaviors obeyed a power flow law with a stress exponent(n)of 3.6±0.3 and an activation energy(Q)of 340±34kJ/mol at temperatures≥1073K,while with n=5.9±0.8 and Q=259±23kJ/mol at temperatures≤1023K.All deformed samples were characterized by extensively developed shape preferred orientation(SPO)of matrix plagioclase,whose undulatory extinctions and kinks could be recognized.Besides,in samples deformed at low temperatures(≤1023K)and high stress(>300MPa),micro-fractures and slips along these micro-fractures developed in the mineral grains in matrix,implying brittle cracks accommodate some strain;while in samples deformed at high temperatures(≥1023K),melts and recrystallized amphibolite grains were recognized which demonstrated that partial melting of plagioclase and recrystallization took place.Together with previously reported mechanical data of dry diabase,rheological data of hydrous basalt in this study can be used to construct a lithospheric strength profile for a better understanding of many tectonic processes including deformation behaviors of the oceanic crust,flow and delamination of the lower continental crust.

关 键 词：玄武岩 流变 位错蠕变 矿物反应 

分 类 号：P588.145[天文地球—岩石学] P589.1[天文地球—地质学]