Geochronology and geothermometry of the Laramide metamorphism in the Cambrian metabasalts from the Cerro Rajón Formation, Caborca region, northwest Mexico
Geochronology and geothermometry of the Laramide metamorphism in the Cambrian metabasalts from the Cerro Rajón Formation, Caborca region, northwest Mexico
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墨西哥西北部卡博尔卡地区拉贡山地层寒武纪变玄岩中拉拉米德变质作用的年代学和地温测量
DOI：
10.1016/j.jsames.2019.01.005
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发表时间：
2019
影响因子：
1.8
通讯作者：
I. Alexander
中科院分区：
文献类型：
--
作者：
Barrón;Paz;Miggins Daniel P;I. Alexander
墨西哥索诺拉州西北部Caborca地区暴露出以Cerro Rajón组玄武岩组成的火山碎屑和熔岩流为特征的早寒武世火山岩。这些岩石经历了绿片岩相变质作用，以放线石、榍石、绿泥石、绿帘石和方解石的变质共生为特征，并伴有少量间隙钠长石。这种矿物组合通过电子探针分析进行了表征。经角闪斜长石测温计算，变质温度最高可达548 ± 40℃。对可能引起变质作用的岩体进行单键dpb年代学，得出其年龄为71.1 ± 0.4 Ma，平均温度为664 ± 40 °C。该侵入岩的初始压力平均为3.08 ± 1.5 kbar。用40ar /39Ar年代学确定了两个变质事件。变玄武岩样品从研究西部地区产生了年龄从55.89 ±0.6 马 60.26±0.33 妈,而时代81.37 ±0.81 马是来自东部的样本收集。综合研究结果表明，Laramide侵入岩对Caborca地区新元古代和寒武纪岩石均有变质作用。
Early Cambrian volcanic rocks characterized by pyroclastic and lava flows of basaltic composition form the Cerro Rajón Formation are exposed in the Caborca region, northwest Sonora, Mexico. These rocks underwent greenschist facies metamorphism characterized by a metamorphic paragenesis of actinolite, sphene, chlorite, epidote and calcite with minor interstitial albite. This mineralogical association was characterized by electron microprobe analysis. Metamorphic temperatures were calculated by amphibole-plagioclase geothermometry, which indicates temperatures as high as 548 ± 40 °C. Usingle bondPb geochronology of the pluton that may cause the metamorphism yielded an age of 71.1 ± 0.4 Ma, and an average estimated temperature of 664 ± 40 °C. Preliminary pressures in this intrusive show an average of 3.08 ± 1.5 kbar. Two metamorphic events where identified by40Ar/39Ar geochronology. Metabasalt samples from the western part of the study area yielded ages from 55.89 ± 0.6 Ma to 60.26 ± 0.33 Ma, while an age of 81.37 ± 0.81 Ma was obtained from a sample collected in the eastern part. Combined results suggest that Laramide intrusives metamorphosed the Neoproterozoic and Cambrian rocks in the Caborca region.