High resolution 40AR/39AR chronostratigraphy of the Late Cretaceous El Gallo Formation, Baja California del Norte, Mexico
High resolution 40AR/39AR chronostratigraphy of the Late Cretaceous El Gallo Formation, Baja California del Norte, Mexico
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墨西哥北下加利福尼亚州晚白垩世埃尔加洛组的高分辨率 40AR/39AR 年代地层学
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发表时间：
1991
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影响因子：
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通讯作者：
C. Busby
中科院分区：
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作者：
P. Renne;M. Fulford;C. Busby
激光探针40 Ar/39 Ar分析的4个凝灰岩的个体透长石颗粒在冲积的晚白垩世（Campanian）El Gallo组产生统计上不同的平均年龄范围为74.87±0.05 Ma至73.59±0.09 Ma。这些日期的特殊精度允许计算的统计上显着的沉积物积累率，远远高于被动沉积物加载会导致，这意味着快速的构造引起的沉降。这些日期与先前报道的埃尔加洛组重要恐龙和哺乳动物群的年龄紧密相关。这些数据支持的年龄小于73马的坎帕尼亚/马斯特里赫特阶的阶段边界，年轻的几个目前使用的时间尺度。单颗粒~（40）Ar/~（39）Ar技术的进一步应用，可望对中生代沉积盆地的地层学研究和生物地层学、磁性地层学时间尺度的标定起到重要作用。
Laser probe 40Ar/39Ar analyses of individual sanidine grains from four tuffs in the alluvial Late Cretaceous (Campanian) El Gallo Formation yield statistically distinct mean dates ranging from 74.87±0.05 Ma to 73.59±0.09 Ma. The exceptional precision of these dates permits calculation of statistically significant sediment accumulation rates that are much higher than passive sediment loading would cause, implying rapid tectonically induced subsidence. The dates bracket tightly the age of important dinosaur and mammalian faunas previously reported from the El Gallo Formation. The dates support an age less than 73 Ma for the Campanian/Maastrichtian stage boundary, younger than indicated by several currently used time scales. Further application of the single grain 40Ar/39Ar technique may be expected to greatly benefit stratigraphic studies of Mesozoic sedimentary basins and contribute to calibration of biostratigraphic and magnetostratigraphic time scales.