摘要
利用氧化缀饰法研究了云南马关新生代地幔尖晶石二辉橄榄岩包体中橄榄石的位错构造。其位错构造种类多样、形态各异,主要包括(100)和(001)位错壁、亚颗粒构造、位错网格、{100}滑动条带构造等,表明该区上地幔岩具高温高应变和低温高应变特征。包体形成的温度T为1016—1098℃,压力P为18.3×108—20.6×108Pa。马关上地幔温压状态具有大洋地幔地温特征,热流值达85mW·m-2。上地幔的流动应力σ为27.9—59.7MPa,流动速率ε为1.37×10-18—2.17×10-16s-1,等效粘滞度η为9.18×1022—6.92×1024Pa·s。该区上地幔的高流动应力、高热状态和裂谷带型的流动速率、等效粘滞度特征,可能与16MaB.P.以来区域性东西向伸展作用有关。
Dislocation configurations in olivine from Cenozoic mantle-derived spinel lherzolite xenoliths beneath Maguan,Yunnan Province were analyzed by oxidation decorating technique. The observed dislocation substructures are various and different, and include (100) and (001) dislocation walls, subgrain, disclocation net, {100} slip band superimposed on all other features, which reflect that olivine had mainly experienced high-temperature and high-stress as well as low-temperature and high-stress deformations. The temperature of spinel lherzolite xenoliths ranges from 1 016 to 1 098 ℃, and pressure from 18.3×10^(8) to 20.6×10^(8 )Pa. The geotherm of the upper mantle in Maguan is similar to the oceanic geotherm and the value of heat flow is 85mW·m^(-2). The value of flow stress of the upper mantle ranges from 27.9 to 59.7MPa, flow rate from 1.37×10^(-18) to 2.17×10^(-16)s^(-1), and equivalent viscosity from 9.18×10^(22) to 6.92×10^(24)Pa·s. The state of high flow stress and high heat, and the flow rate and equivalent viscosity with characteristics of the type of continental rift of the upper mantal beneath Maguan, Yunnan Province, may be contributed to the east-west extension of eastern Asia during the period of 16—0 Ma B.P.
出处
《热带海洋学报》
CAS
CSCD
北大核心
2004年第1期34-43,共10页
Journal of Tropical Oceanography
基金
中国科学院知识创新工程项目(KZCX2 209
KZCX2 SW 117)
中国科学院南海海洋研究所边缘海地质与古环境开放实验室基金项目(BYH01A09)
关键词
橄榄石
位错构造
地幔包体
上地幔物理状态
云南马关
olivine
dislocation substructure
mantle-derived xenloith
physical state of upper mantle
Maguan,Yunnan Province