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本文报道唐古拉山北坡开心岭地区的晚石炭-早二叠世地层的古地磁学研究结果.岩石磁学实验研究表明扎日根组灰岩样品中的磁性矿物以磁铁矿为主,诺日巴尕日保组砂岩样品中的磁性矿物以赤铁矿为主或磁铁矿与赤铁矿共存.采用系统热退磁方法对样品进行磁清洗,大部分样品的退磁曲线呈双分量特征,高温分量明显.高温特征分量成功通过了砾石可靠性检验,代表了地层岩石的原生剩磁信息.获得羌北地块晚石炭-早二叠世地层(16个采点127块样品)的原生剩磁分量的平均方向为Ds=30.2°,Is=-40.9°,ks=269.0,a95=2.3°;其对应的古地磁极位置为λ=25.7°N,φ=241.5°E,dp/dm=2.8/1.7,相应的古纬度为23.4°S.表明晚石炭-早二叠世时期羌北地块位于南纬低纬度地区,可能属于冈瓦纳大陆的北缘.结合前人古地磁学研究结果,该地块在其后快速北移,可能与早二叠世-晚三叠世古特提斯洋快速消亡以及新特提斯洋北支班公湖-怒江洋快速扩张相关.
This paper reports the Paleomagnetism of Late Carboniferous-Early Permian strata in Kaixinling area on the northern slope of Tanggula Mountain.The results of rock magnetism experiments show that magnetite is the main magnetite in the Zhaurigen limestone samples, The magnetic minerals in the sandstone sample of Nipponbashi Formation in Japan and Japan are mainly hematite or magnetite and hematite coexist.The samples were magnetically cleaned by system thermal demagnetization method.The demagnetization curve of most samples showed double component characteristics, The high-temperature component is obvious.The high-temperature characteristic component successfully passed the gravel reliability test and represents the primary residual magnetism information of the stratigraphic rocks.On the primary residual of Late Carboniferous-Early Permian strata (127 samples of 16 mining sites) in Qiangbei block The average direction of the magnetic component is Ds = 30.2 °, Is = -40.9 °, ks = 269.0, a95 = 2.3 °. The corresponding paleomagnetic pole position is λ = 25.7 ° N, φ = 241.5 ° E, dp / dm = 2.8 / 1.7, corresponding to an ancient latitude of 23.4 ° S. It is suggested that the Qiangbei block in Late Carboniferous-Early Permian may be located in the northern latitude of the southern Gondwanaland, As a result, the site moved northward fast thereafter, possibly with the Early Permian-Late Triassic Gutierrez Oceanic And the north branch of the Neo-Tethys Bangong - Nujiang ocean rapid expansion related.