RARE-EARTH ELEMENT PATTERNS AND CRUSTAL EVOLUTION .1. AUSTRALIAN POST-ARCHEAN SEDIMENTARY-ROCKS
RARE-EARTH ELEMENT PATTERNS AND CRUSTAL EVOLUTION .1. AUSTRALIAN POST-ARCHEAN SEDIMENTARY-ROCKS
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DOI：
10.1016/0016-7037(76)90093-4
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发表时间：
1976-01-01
影响因子：
5
通讯作者：
TAYLOR, SR
中科院分区：
文献类型：
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作者：
NANCE, WB;TAYLOR, SR
分析了从元古界到三叠纪的一套澳大利亚页岩、灰岩和亚灰岩的稀土元素(REE)，以发现稀土分布的长期变化。这些太古代以后的沉积物显示出非常相似的相对稀土模式。它们的特征是相对于球粒陨石具有几乎恒定的Eu负异常(平均Eu/Eu∗=0.6 7±0.0 5)和几乎恒定的轻、重稀土比值(平均∑LREE/∑HREE=9.7±1.8)。稀土元素丰度在较年轻的沉积物中普遍较高，表明碎屑沉积物中稀土的绝对丰度随着时间的推移而逐渐增加。由于在太古代以后的沉积物中没有检测到相对稀土分布的长期变化，因此至少在过去的1500万年里，地壳生长和演化的统一过程似乎一直在进行。澳大利亚岩的稀土分布与碎屑岩的平均分布非常相似。这表明玻璃陨石母质起源于上地壳。
A suite of Australian shales, greywackes and subgreywackes ranging in age from Proterozoic to Triassic were analyzed for the rare earth elements (REE) in order to detect any secular changes in rare earth distribution. These post-Archean sediments show remarkably similar relative rare earth patterns. They are characterized by negative Eu anomalies of almost constant magnitude (average Eu/Eu∗= 0.67±0.05) relative to chondrites and nearly constant ratios of light to heavy rare earths (average∑ LREE/∑ HREE= 9.7±1.8). The REE abundances are generally higher in the younger sediments which may suggest that the absolute abundances of the rare earths in clastic sediments have gradually increased with time. Since no secular change in relative rare earth distribution was detected in the post-Archean sediments, a uniform process of crustal growth and evolution seems to have operated over the past 1500 million years at least. Australites show rare earth distributions very similar to that of the average clastic sediment. This suggests that the tektite parent material originated in the upper crust.