Cenozoic magmatism and extension in western Mexico: Linking the Sierra Madre Occidental silicic large igneous province and the Comondú Group with the Gulf of California rift
Cenozoic magmatism and extension in western Mexico: Linking the Sierra Madre Occidental silicic large igneous province and the Comondú Group with the Gulf of California rift
复制标题
DOI：
10.1016/j.earscirev.2017.04.006
复制
发表时间：
2017-05
影响因子：
12.1
通讯作者：
L. Ferrari;T. Orozco-Esquivel;S. Bryan;M. López‐Martínez;Argelia Silva-Fragoso
中科院分区：
文献类型：
--
作者：
L. Ferrari;T. Orozco-Esquivel;S. Bryan;M. López‐Martínez;Argelia Silva-Fragoso
过去十年来，关于马德雷山脉西方硅质大型火成岩省、下加利福尼亚州科蒙德群和加利福尼亚州海湾裂谷的成因及其之间的联系的新观点正在出现。支撑这一点的是来自加利福尼亚州海湾两侧边缘的大量新数据，包括近海采样和海洋地球物理数据，部分是由美国国家科学基金会的边缘项目提供的，其中加利福尼亚州海湾是主要的焦点地点。以前，马德雷山脉西部硅质大火成岩省和科蒙德群被广泛认为是超俯冲火山作用，特别是科蒙德群确定了早中新世超俯冲带火山弧的位置，因此成为加利福尼亚州湾裂谷何时开始的空间和时间障碍。更广泛地说，这种大陆岩浆作用发生在始新世晚期至中新世中期法拉隆板块俯冲的最后阶段，与活动板块边界几乎没有岩石成因联系，而与上板块的逐渐变薄和墨西哥西部下面浅层软流圈地幔的建立有更强的联系。为这项研究开发的数据库显示，从100 Ma到5 Ma，墨西哥西部有一个重要的过渡期，在50 Ma到40 Ma之间有一个重要的过渡期，在那里建立了相对较小的岩浆作用，覆盖了宽达800公里的大范围和延伸到1000公里的古海沟板块。自40 Ma以来，这条宽阔地带的岩浆通量大大增加，组成最初以硅质为主，但到约30 Ma时迅速成为双峰型。地壳伸展的时空格局被限定在39个地区，可以根据地质关系或热年代学来确定伸展的大致年龄。大陆伸展的开始受到始新世的限制，当时伸展盆地横跨中央高原和马德雷山脉最东端，位于古板块边界内侧约500公里处。到渐新世结束时，地壳伸展影响了从马德雷山脉东部到未来加利福尼亚州海湾(宽裂谷模式)的大范围区域(250公里宽)。与这一扩张相伴的是：(1)具有岩石圈特征的镁铁质岩浆[南科迪勒拉造山玄武岩(SCORBA)套]广泛侵入中上地壳，较少喷发大量未受污染的软流圈派生于板内的熔岩；(2)地壳熔融产生大量具有铁质(干燥)和过渡板内特征的硅质褐闪岩喷发脉冲(SMO滑移)。大约19 Ma，垂直伸展成为SMO西侧和下加利福尼亚州东部之间一条约80-100公里宽的带的焦点。这种向窄裂谷模式转变的后果是，在宽裂谷地带的大部分地区普遍放弃了火山活动，火山活动变得更加热力和中等组成(科蒙杜群)，集中在加利福尼亚州海湾未来遗址沿线迅速延伸但狭窄的构造凹陷中。到了公元12年左右，沿海湾轴线的地壳已经减薄到原来厚度的一半。自中新世晚期以来，与太平洋板块拖曳下加利福尼亚有关的右旋张张变形能够迅速完成岩石圈破裂，形成现代加利福尼亚州海湾。墨西哥西部的构造-岩浆演化，进而延伸到…
A new view on the genesis of, and links between, the Sierra Madre Occidental silicic large igneous province, the Comondú Group of Baja California, and the Gulf of California rift has been emerging over the past decade. Underpinning this has been a wealth of new data from both margins of the Gulf of California including offshore sampling and marine geophysical data, in part seeded by the NSF Margins program where the Gulf of California was a principal focus site. Previously, the Sierra Madre Occidental silicic large igneous province and Comondú Group had been widely regarded as supra-subduction volcanism, with the Comondú Group in particular defining the location of the early to mid-Miocene supra-subduction zone volcanic arc and therefore acting as both a spatial and temporal barrier to when the rifting of the Gulf of California could begin. More broadly, this continental magmatism occurring during the last phase of subduction of the Farallon Plate between the late Eocene and the middle Miocene shows little to no petrogenetic connection to the active plate boundary and is more strongly linked to the progressive thinning of the upper plate and establishment of a shallow asthenospheric mantle beneath western Mexico.A database developed for this study of 4255 ages and chemical analyses for igneous rocks from 100 to 5 Ma from across western Mexico reveals a significant transition period between 50 and 40 Ma where relatively low-volume magmatism was established across a broad area up to 800 km wide and extended up to 1000 km in the board of the paleotrench. Since 40 Ma, magma fluxes greatly increased across this broad belt, and compositions were initially silicic-dominated but quickly became bimodal by ~ 30 Ma. The space–time pattern of crustal extension is constrained in 39 areas, for which the approximate age of extension can be established on the basis of geologic relations or thermochronology. The onset of continental extension is constrained to the Eocene when extensional basins developed across the Central Plateau and the easternmost part of the Sierra Madre Occidental, approximately 500 km inboard of the paleo-plate boundary. By the end of Oligocene, crustal extension had affected a wide region (250 km width) from the eastern Sierra Madre Occidental to the site of the future Gulf of California (wide rift mode). Concomitant with this extension was (1) a widespread invasion of the mid- to upper crust by mafic magmas with lithospheric signatures [the Southern Cordillera Orogenic Basaltic Andesite (SCORBA) suite] and lesser erupted volumes of uncontaminated asthenosphere-derived within-plate lavas and (2) crustal melting producing voluminous pulses of silicic ignimbrite eruptions (the SMO SLIP) with a ferroan (dry) and transitional within-plate signature. At ~ 19 Ma, orthogonal extension became focused between the western side of the SMO and eastern Baja California in a ~ 80–100-km-wide belt. Consequences of this switch to a narrow rift mode were a general abandonment of volcanism across much of the wide rift zone and volcanism becoming more effusive and intermediate in composition (the Comondú Group), being concentrated within rapidly extending but narrow tectonic depressions along the future site of the Gulf of California. By ~ 12 Ma, the crust had thinned to half its original thickness along the axis of the Gulf. Since the late Miocene, right-lateral transtensional deformation associated with the dragging of Baja California by the Pacific Plate was then able to quickly complete lithospheric rupture to form the modern Gulf of California.The tectono-magmatic evolution of western Mexico and, by extension …