Three stages in the Late Paleozoic to Triassic magmatism of southwestern Gondwana, and the relationships with the volcanogenic events in coeval basins
Three stages in the Late Paleozoic to Triassic magmatism of southwestern Gondwana, and the relationships with the volcanogenic events in coeval basins
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DOI：
10.1016/j.jsames.2015.07.005
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发表时间：
2015-11
影响因子：
1.8
通讯作者：
A. Sato;E. J. Llambías;M. Basei;Carlos E. Castro
中科院分区：
文献类型：
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作者：
A. Sato;E. J. Llambías;M. Basei;Carlos E. Castro
中酸性Choiyoi岩浆区是冈瓦纳西南部晚古生代大陆边缘最显著的特征，沿着分布，一般认为是与邻近冈瓦纳盆地沉积序列互层的火山灰堆积物的可能物源。Choiyoi岩浆活动在地质上限制在阿根廷额科迪勒拉、前科迪勒拉和圣拉斐尔地块地区的早二叠世圣拉斐尔造山阶段和三叠纪伸展瓦尔皮卡阶段之间。为了更好地评价阿根廷前科迪勒拉山脉的Choiyoi岩浆活动，我们获得了6个新的来自Colangüil火山岩和一个相关火山岩的278.8 ± 3.4 Ma和252.5 ± 1.9 Ma的LA-ICPMS U-Pb年龄。对智利和阿根廷晚古生代至三叠纪露头的年龄数据进行全球分析，可以确定岩浆活动的三个阶段：（1）前Choiyoi造山岩浆活动，（2）Choiyoi岩浆活动（286-247 Ma），（3）与伸展构造有关的后Choiyoi岩浆活动。在Choiyoi阶段，岩浆活动向东南方向东移和扩展，覆盖了一个广泛的区域，定义了Choiyoi岩浆区。通过与冈瓦纳古陆盆地火山成因年龄的对比，我们认为：（a）帕甘佐盆地Choiyoi前火山活动（320-296 Ma）可能除了有额部科迪勒拉地区的火山活动外，还有一个地方性的火山活动源。(b)在巴拉那盆地（304-275 Ma）发现的前Choiyoi和Choiyoi事件很可能起源于智利的Precordillera。(c)在酱料大盆地（284-281 Ma）发现的Choiyoi岩浆活动的早期阶段可能来自邻近的Las Matras至Chadileuvú地块。(d)卡鲁盆地的前Choiyoi和Choiyoi事件（302-253 Ma）包括最长的Choiyoi间隔，并作为一个整体承担沿智利和阿根廷额山脉沿着的年龄记录最相似。
The intermediate to acid Choiyoi Magmatic Province is the most conspicuous feature along the Late Paleozic continental margin of southwestern Gondwana, and is generally regarded as the possible source for the widespread ash fall deposits interlayered with sedimentary sequences in the adjacent Gondwana basins. The Choiyoi magmatism is geologically constrained between the early Permian San Rafael orogenic phase and the Triassic extensional Huarpica phase in the region of Argentine Frontal Cordillera, Precordillera and San Rafael Block. In order to better assess the Choiyoi magmatism in Argentine Frontal Cordillera, we obtained 6 new LA-ICPMS U–Pb ages between 278.8 ± 3.4 Ma and 252.5 ± 1.9 Ma from plutonic rocks of the Colangüil Batholith and an associated volcanic rock. The global analysis of age data compiled from Chilean and Argentine Late Paleozoic to Triassic outcrops allows us to identify three stages of magmatism: (1) pre-Choiyoi orogenic magmatism, (2) Choiyoi magmatism (286–247 Ma), and (3) post-Choiyoi magmatism related to extensional tectonics. In the Choiyoi stage is there an eastward shift and expansion of the magmatism to the southeast, covering an extensive region that defines the Choiyoi magmatic province. On the basis of comparison with the ages from volcanogenic levels identified in the coeval Gondwana basins, we propose: (a) The pre-Choiyoi volcanism from the Paganzo basin (320–296 Ma) probably has a local source in addition to the Frontal Cordillera region. (b) The pre-Choiyoi and Choiyoi events identified in the Paraná basin (304–275 Ma) are likely to have their source in the Chilean Precordillera. (c) The early stage of the Choiyoi magmatism found in the Sauce Grande basin (284–281 Ma) may have come from the adjacent Las Matras to Chadileuvú blocks. (d) The pre-Choiyoi and Choiyoi events in the Karoo basins (302–253 Ma) include the longest Choiyoi interval, and as a whole bear the best resemblance to the age records along the Chilean and Argentine Frontal Cordillera.