Magnetostratigraphy, isotopic age calibration and intercontinental correlation of the Red Bird section of the Pierre Shale, Niobrara County, Wyoming, USA
Magnetostratigraphy, isotopic age calibration and intercontinental correlation of the Red Bird section of the Pierre Shale, Niobrara County, Wyoming, USA
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美国怀俄明州尼奥布拉拉县皮埃尔页岩红鸟剖面的磁性地层学、同位素年龄校准和洲际对比
DOI：
10.1006/cres.1998.0133
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发表时间：
1999
影响因子：
2.1
通讯作者：
L. Tauxe
中科院分区：
文献类型：
--
作者：
J. Hicks;J. Obradovich;L. Tauxe
怀俄明州东部皮埃尔页岩的红鸟剖面包含一个相对完整的细粒海洋碎屑序列，这些碎屑沉积于8100万至6900万年前的美国西部内陆晚白垩世陆表海航道。这些单位不仅包含一个良好的研究，高分辨率的菊石生物地层序列，通过该序列，在该地区的海道沉积物的广泛暴露相关，但它们也是同位素测年，由于存在许多透长石轴承火山灰层。红鸟剖面的磁性地层学由三个地磁反转组成，它们可以由7个40 Ar/39 Ar同位素年龄独立标定，时间跨度为1200万年的坎帕尼亚和马斯特里赫特阶段。磁性地层剖面与地磁极性时标（GPTS）中从C33 n亚时底到C31 n亚时底的部分可以进行可靠的对比。根据同位素年龄的线性内插和外推，给出了这些反转边界的年龄估计：C32 n/C31 r，70.44± 0.7Ma; C31 r/C31 n，69.01± 0.5Ma。C33 n/C32 r反转边界不能完全确定，但它肯定比C33 n顶部发现的反转年龄（74.62±1.2 Ma）年轻。这些年龄估计为白垩纪GPTS的校准做出了重大贡献，该校准以前严重依赖于三个或更少的校准点之间的插值，这些校准点在年龄上间隔很大。此外，通过C31在这一节中的年代C33的识别，使我们能够相关的高分辨率菊石分带的美国西部内陆直接的时间等效的欧洲远洋微体化石分带的基础上，在古比奥在中北部的意大利的磁性地层参考部分。
The Red Bird section of the Pierre Shale in eastern Wyoming contains a relatively complete sequence of fine-grained marine clastics that were deposited between 81 and 69 million years ago in the Late Cretaceous epicontinental seaway of the US Western Interior. These units not only contain a well-studied, high-resolution ammonite biostratigraphic sequence, by which the far-flung exposures of the seaway sediments are correlated across this region, but they are also isotopically well-dated due to the presence of numerous sanidine-bearing volcanic ash layers. The magnetostratigraphy of the Red Bird section consists of three geomagnetic reversals which can be independently calibrated by seven40Ar/39Ar isotopic ages in an interval that spans 12 million years of the Campanian and Maastrichtian stages. The magnetostratigraphic section can be confidently correlated to that part of the geomagnetic polarity time scale (GPTS) that ranges from the base of subchron C33n to the base of C31n. Linear interpolation and extrapolation from the isotopic ages gives the following age estimates for these reversal boundaries: C32n/C31r, 70.44±0.7 Ma; C31r/C31n, 69.01±0.5 Ma. The C33n/C32r reversal boundary cannot be identified with complete confidence but it is certainly younger than the 74.62±1.2 Ma age interpolated for the reversal found at the top of C33n. These age estimates make a significant contribution to the calibration of the GPTS for the Cretaceous Period, which has previously relied heavily on interpolation between three or fewer calibration points that are widely spaced in age. In addition, the recognition of the chrons C33 through C31 in this section enables us to correlate the high resolution ammonite zonation of the US Western Interior directly to the time-equivalent European pelagic microfossil zonation based on the magnetostratigraphic reference section at Gubbio in north-central Italy.
DOI：
10.1098/rspa.1953.0064
发表时间：
1953-01-01
影响因子：
--
作者：
FISHER, R
通讯作者：
FISHER, R