Zircon U-Pb geochronology from the Paraná bimodal volcanic province support a brief eruptive cycle at ~135Ma
Zircon U-Pb geochronology from the Paraná bimodal volcanic province support a brief eruptive cycle at ~135Ma
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DOI：
10.1016/j.chemgeo.2010.11.031
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发表时间：
2011-02
期刊：
影响因子：
3.9
通讯作者：
V. Pinto;L. Hartmann;J. Santos;N. McNaughton;W. Wildner
中科院分区：
文献类型：
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作者：
V. Pinto;L. Hartmann;J. Santos;N. McNaughton;W. Wildner
本文报道了副<s:1>岩浆省1个高钛皮坦加型拉斑岩和3个低钛帕尔马斯型和高钛Chapecó型长英质火山岩锆石的离子探针U-Pb同位素数据。4种火山岩的火成岩锆石给出的火山作用年龄分别为134.4±1.1Ma（玄武岩）、134.6±1.4 ma（流纹石）、134.8±1.4 ma（石英白垩岩）和135.6±1.8Ma（石英白垩岩）。根据以往的Ar-Ar年代学，副<s:1>岩浆作用年龄有两个不同的范围：1)1 ~ 200万年，岩浆峰值在131 ~ 133ma， 2) ~ 10my以上。在137到127毫安之间。结果表明，本省的双峰火山（至少在Piquiri构造以南）在短时间内具有非常高的喷发速率，主脉冲为~135Ma，比建议1早约2%，更类似于短时间的岩浆活动。这些结果对认识这一大型板内岩浆省的时间关系具有重要意义。
Ion microprobe U–Pb isotopic data on zircons from the Paraná magmatic province are presented from one tholeiitic (high-Ti Pitanga type) and three felsic volcanic rocks from the low-Ti Palmas and high-Ti Chapecó types. Igneous zircons from the four volcanic rocks yield volcanism ages within error: i.e. 134.4±1.1Ma (basalt), 134.6±1.4Ma (rhyodacite), 134.8±1.4 (quartz latite) and 135.6±1.8Ma (quartz latite). The age of Paraná magmatism based on previous Ar–Ar geochronology has two divergent ranges: 1) 1 to 2million years with magmatic peak at 131–133Ma, and 2) over ~10m.y. between 137 and 127Ma. Our results show that the bimodal volcanics of the province, at least to the south of the Piquiri lineament, have very high effusion rates over a brief period with a main pulse at ~135Ma, about 2% older than proposal 1, more akin to a short period of magmatism. These results are most significant for the understanding of time relations in this large intraplate magmatic province.