【作者】 张文治； 李普；

【Author】 Zhang Wenzhi (Tianjin Institute of Geology and Mineral Resources) Li pu (The Institute of Geomechanics)

【机构】 天津地质矿产研究所； 地质力学研究所；

【摘要】 在蓟县震旦亚界整个剖面的58个采样点上,采取了158块岩石标本,切制了486个样品。经峰值20—40毫特斯拉的交变磁场检验,测量剩余磁性,求得采样点的古地磁极位置及各岩组的古地磁极平均位置。退磁实验得知,砂岩的剩余磁性很不均匀,交变磁场退磁对它没有作用。紫色微晶白云岩、红色及蛋青色微晶灰岩的剩余磁性较强,且稳定,认为与颜色有关的剩余磁性是原始磁化的结果。测量结果表明:(1)蓟县震旦亚界沉积时期曾出现一次极性倒转,它发生在蓟县系洪水庄组和铁岭组的沉积时期(约11亿年),我们称它为铁岭反极性期。据此,可能与国外前寒武系进行对比;(2)蓟县沉积地层多处于30°S—30°N的低古地理纬度区,为蓟县地区形成大量碳酸盐岩提供了古地理依据。初步建立了蓟县震旦亚代的视古地磁极迁移轨迹。古地磁极从350°E,70°N(19.5亿年)向南、向东移动,在杨庄组(60°E,19°N)返向西。文中也列出了其他作者得到的中国长江峡东地区震旦系的某些结果。可以看出,峡东震旦系的古地磁极恰在蓟县震旦亚代视古地磁极迁移轨迹的向西延长部位,这提供了中国南北方震旦亚界可以上下衔接的旁证。更多还原

【Abstract】 The Sinian Suberathem in Jixian is one of the stratotype section in China, whose continuous sedimentary age ranges from 1950m.y.to 850m.y.There 158 rock samples(cut into 486 specimens) were sampled from 58 sites of whole section.The alternating field treatments(20—40 mT peak value) were performed and the remnant magnetization was measured on all specimens.The palaeomagnetic poles of each site and the mean palaeomagnetic poles of each formation were estimated. From the demagnetization experiments of the sandstone,the remnant magnetization is not uniform and the alternating field demagnetization is not effective for it.The remains of the purple microlitic dolomite,red and light bluish microlitic limestone are at the same time stronger and more stable.It is considered that the remains which are in connection with the colours are as a result of the initial magnetization. The results of observation show that(1) One pole reversal had taken place in the Sinian Subera of Jixian during the period between Hongshuizhuang and Tieling Formations(about 1100 m.y.).It is called"Tieling reverse polar epoch",probably correlating wih the upper Precambrian in the other regions of The world.(2) most of the sediments of Jixian existed in the lower geographical palaeolatitude range——30°S—30°N. The apparent polar-wander path at Sinian Subera of Jixian has been established preliminarily.The pole moved from 350°E,70°N(1950m.y.) to south or to east,at the time of Yangzhuang Formatin(60°E,19°N),it trended reversely to west.更多还原