Geology and Regional Implications of Carbonatites in the Lemitar Mountains, Central New Mexico
Geology and Regional Implications of Carbonatites in the Lemitar Mountains, Central New Mexico
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新墨西哥州中部勒米塔山脉碳酸岩的地质和区域影响
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发表时间：
1987
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影响因子：
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通讯作者：
V. McLemore
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作者：
V. McLemore
在新墨西哥州的勒米塔尔山脉，有100多条碳酸岩岩脉和矿脉侵入复杂的前寒武纪地形。这些奥陶纪碳酸岩不与任何碱性岩石或金伯利岩有关，但它们具有碳酸岩的结构、矿物学、化学和蚀变特征。尽管在结构上的变化，Lemitar碳酸岩可以分组的矿物学，化学和结构的基础上，作为原始岩浆和替代硅碳酸岩和rodbergs。Lemitar硅碳酸岩由50%以上的碳酸盐矿物和不同量的副矿物组成，它们富含轻稀土元素。岩石中碳酸盐矿物含量超过50%，被赤铁矿染成红色，稀土元素模式平坦。在碳酸岩和围岩中发现了成因不明的碳酸盐脉和重晶石-萤石-方铅矿脉。在元古代、晚古生代和第三纪期间，新墨西哥州和科罗拉多南部发生了周期性的碱性岩浆活动。Lemitar碳酸岩是晚古生代期间影响新墨西哥州和科罗拉多南部的碱性和碳酸岩岩浆活动区域幕的一部分。大陆裂谷可能发生在前寒武纪和晚古生代在新墨西哥州中部，虽然确切的地理界限的古生物无法确定，因为重叠时期的构造作用可能影响该地区自古生代。
More than 100 carbonatite dikes and veins intrude a complex Precambrian terrain in the Lemitar Mountains, New Mexico. These Ordovician carbonatites are not associated with any alkalic rocks or kimberlites, but they exhibit textures, mineralogy, chemistry, and alteration characteristic of carbonatites. Despite variations in texture, the Lemitar carbonatites can be grouped on the basis of mineralogy, chemistry, and texture as primary-magmatic and replacement silicocarbonatites and rodbergs. The Lemitar silicocarbonatites consist of more than 50% carbonate minerals and varying amounts of accessory minerals, and they are enriched in LREE. The rodbergs consist of more than 50% carbonate minerals, are stained red by hematite, and exhibit flat REE patterns. Carbonate and barite-fluorite-galena veins of uncertain origin are found in the carbonatites and country rocks. Periodic episodes of alkalic magmatism occurred in New Mexico and southern Colorado during the Proterozoic, late Paleozoic, and Tertiary. The Lemitar carbonatites are part of a regional episode of alkalic and carbonatite magmatism which affected New Mexico and southern Colorado during the late Paleozoic. Continental rifting may have occurred during the Precambrian and late Paleozoic in central New Mexico, although exact geographical limits of paleorifts cannot be determined because overlapping periods of tectonism may have affected the area since Paleozoic times.