The age of the Steens reversal and the Columbia River Basalt Group
The age of the Steens reversal and the Columbia River Basalt Group
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斯廷斯逆转的时代和哥伦比亚河玄武岩群
DOI：
10.1016/j.chemgeo.2010.04.001
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发表时间：
2010
期刊：
影响因子：
3.9
通讯作者：
J. Glen
中科院分区：
文献类型：
--
作者：
N. Jarboe;R. Coe;P. Renne;J. Glen
哥伦比亚河玄武岩群(CRBG)喷发具有明确的相对磁性地层学，但尚未与地磁极性时间尺度明确关联。40Ar/39Ar年龄来自于CRBG的R0至N1磁带和R0与N0之间的过渡时期喷发的熔岩。来自斯蒂恩斯山、卡特洛峰顶和扑克吉姆山脊的过渡磁化熔岩流的4个年龄的加权平均年龄为16.58±0.10 Ma，而卡特洛峰顶正常磁化的俄勒冈峡谷凝灰岩的加权平均年龄为16.654±0.025 Ma，表明CRBG最古老的磁臭氧(R0)与C5Cr时间相关。将贝叶斯统计分析应用于卡特洛峰的四个流量的数据(使用斯蒂恩斯反转的平均年龄)，得出斯蒂恩斯反转的最佳和优选年龄为16.73±0.13/−0.08 Ma(95%置信度)。根据地磁极性时间尺度模型，从N0到R2(CRBG侵位的中部和主体为0.34-0.45 Ma)的喷发速率平均为0.30-0.41km~3/a，并在R2期间达到峰值，速率是R2的1.1/2到4.5倍。
The Columbia River Basalt Group (CRBG) eruptions have a well-defined relative magnetostratigraphy but have not been definitively correlated to the geomagnetic polarity time scale.40Ar/39Ar ages are presented from lavas erupted in the R0through N1magnetozones of the CRBG and in the transition between R0and N0. Four ages from transitionally magnetized lava flows at Steens Mountain, Catlow Peak, and Poker Jim Ridge with a weighted mean age 16.58±0.10Ma1and the more precise age 16.654±0.025Ma of the normally magnetized Oregon Canyon tuff at the top of the Catlow Peak section show that the oldest CRBG magnetozone (R0) correlates with the C5Cr chron. Bayesian statistical analysis applied to data from four flows at Catlow Peak (using the mean age of the Steens reversal) gives a best and preferred age of the Steens reversal of 16.73+0.13/−0.08Ma (95% confidence). Depending on the geomagnetic polarity time scale model, the eruption rate from N0through R2(0.34–0.45Ma in the middle and the bulk of the CRBG emplacement) averaged 0.30–0.41km3/a and peaked at a rate 1 1/2 to 4 1/2 times higher during R2.