Palaeomagnetism of Permian red beds from south Kazakhstan: DRM inclination error or CRM shallowed directions?
Palaeomagnetism of Permian red beds from south Kazakhstan: DRM inclination error or CRM shallowed directions?
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哈萨克斯坦南部二叠纪红层的古地磁：DRM 倾角误差或 CRM 浅化方向？
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
V. Tselmovich
中科院分区：
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作者：
M. Bazhenov;Valerian L. Klishevich;V. Tselmovich
摘要
哈萨克斯坦南部上二叠统红层中的古地磁样品的热退磁作用产生了几乎没有噪音的数据。在7个向原点呈直线衰减的样品中，特征分量的倾斜校正平均方向为D=217d，I=-44d(K=81，α95=6.7d)。然而，大多数样品都显示出弯曲的退磁路径和立体网上矢量端点的稳定移动。对于后一类样品，NRM由倾角相似但倾角不同的两个分量解释。第一个紧密组合的分量是叠印，其平均倾角接近稳定欧洲的参考方向和具有直线退磁曲线的样品的参考方向。第二个高温组分比第一个组分更分散，大约浅15d。各向异性椭球的最大Kmax轴和中间Kint轴向立体网赤道倾斜，而许多Kmin轴是垂直的。岩石磁学研究表明，赤铁矿是这些岩石中唯一的剩磁载体。我们认为，高温分量的浅倾斜不是该地区水平输送的结果，而是NRM获取过程的结果。一种可能性是假设碎屑成因的最热稳定成分具有倾角误差，并被化学成因的成分叠印。我们还讨论了时间分布的CRM采集模型，并将倾角变浅归因于成岩压实作用。
SUMMARY
Thermal demagnetization of palaeomagnetic samples from Upper Permian red beds from south Kazakhstan yielded almost noiseless data. In seven samples that show rectilinear decay to the origin, the tilt-corrected mean direction of the characteristic component is D= 217d, I= -44d (K= 81, α95= 6.7d). Most samples, however, reveal curved demagnetization paths and steady shift of vector endpoints on stereonet. For the latter samples, the NRM is accounted for by two components with similar declinations and different inclinations. The first tightly grouped component is an overprint and its mean inclination is close to the reference direction for stable Europe and to that for samples with rectilinear demagnetization plots. The second high-temperture component is more dispersed and about 15d shallower than the first one. Maximal Kmax and intermediate Kint axes of anisotropy ellipsoids gravitate to the stereonet equator, whereas many Kmin axes are vertical. Rock magnetic studies revealed haematite as the only remanence carrier in these rocks. We argue that the shallow inclination of the high-temperature component has not resulted from horizontal transport of the area, but is due to NRM acquisition process. One possibility is to assume that the most thermally stable component of detrital origin has inclination error and is overprinted by a component of chemical origin. Also, we discuss a model of time-distributed CRM acquisition and attribute the inclination shallowing to diagenetic compaction.