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The role of the Polochic Fault as part of the North American and Caribbean Plate boundary: Insights from the infill of the Lake Izabal Basin
Basin Research ( IF 2.8 ) Pub Date : 2020-01-28 , DOI: 10.1111/bre.12431
Jonathan Obrist‐Farner 1 , Andreas Eckert 1 , Marek Locmelis 1 , James L. Crowley 2 , Byron Mota‐Vidaure 3 , Emanuele Lodolo 4 , Joshua Rosenfeld 5 , Edward Duarte 1
Affiliation  

[Abstract The Lake Izabal Basin in Guatemala is a major pull‐apart basin along the sinistral Polochic Fault, which is part of the North American and Caribbean plate boundary. The basin infill contains information about the tectonic and sedimentological processes that have imparted a significant control on its sedimentary section. The inception of the basin has been linked to the relative importance of the Polochic Fault in the tectonic history of the plate boundary; yet, its sedimentological record and its inception age have been poorly documented. This study integrates diverse datasets, including industry reports, well logs and reports, well cuttings, vintage seismic data, outcrop observations and geochronological data to constrain the initial infill and age of inception of the basin. The integrated data show that during the Oligocene–Miocene, a marine carbonate platform was established in the region which was later uplifted and eroded in the early Miocene. The fluvial–lacustrine deposits above this carbonate platform are part of the initial infill of the basin and are constrained with zircon weighted‐mean 206Pb/238U ages of 12.060 ± 0.008 from a volcanic tuff ~30 m above the unconformity. Sandstone, mudstone and coal dominate the interval from 12 to 4 Ma, with an increase in conglomerate correlating to the uplift of the Mico Mountains and San Gil Hill at 4 Ma. Fault switch activity between the Polochic and Motagua faults has been hypothesized to explain total offset along the Polochic Fault and the geologic and geodetic slip rates along the two faults. The 12 Ma age determined for the initial infill of the basin confirms this hypothesis. Consequently, our study confirms that at ~12 Ma the Polochic Fault served as the main fault of the plate boundary with inferred slip rates ranging from 13 to 21 mm/yr with a strong possibility that the Polochic Fault was, at some point between 15 Ma and 7 Ma, the only active fault of the plate boundary. The results of this study show that tectonic records preserved in sediments of strike‐slip basins improve the understanding of the relative significance of individual faults and the implications with respect to strain partitioning throughout its tectonic history., The Lake Izabal Basin initiated at 12 Ma. The Polochic Fault was the main plate boundary in the Miocene. Fault switch activity must have occurred along the plate boundary. ]

中文翻译:

波罗奇断层作为北美和加勒比板块边界一部分的作用:来自伊萨巴尔湖盆地填充物的见解

[摘要 危地马拉的伊萨巴尔湖盆地是沿左旋波罗奇断层的一个主要拉分盆地,该断层是北美和加勒比板块边界的一部分。盆地填充物包含有关构造和沉积学过程的信息,这些信息对其沉积剖面产生了显着的控制。盆地的开始与极地断层在板块边界构造历史中的相对重要性有关;然而,它的沉积学记录和它的形成年代却鲜有记载。该研究整合了多种数据集,包括行业报告、测井和报告、钻井切割、老式地震数据、露头观测和地质年代学数据,以限制盆地的初始填充和开始年龄。综合数据表明,在渐新世-中新世期间,该地区建立了一个海相碳酸盐台地,后来在中新世早期被抬升和侵蚀。该碳酸盐台地上方的河湖沉积物是盆地初始充填物的一部分,受不整合面上方约 30 m 火山凝灰岩的锆石加权平均 206Pb/238U 年龄为 12.060 ± 0.008 的限制。砂岩、泥岩和煤在 12 至 4 Ma 期间占主导地位,砾岩的增加与 4 Ma 时米科山脉和圣吉尔山的隆起有关。已假设 Polochic 断层和 Motagua 断层之间的断层转换活动来解释沿 Polochic 断层的总偏移以及沿两个断层的地质和大地滑移率。为盆地初始充填确定的 12 Ma 年龄证实了这一假设。最后,我们的研究证实,在约 12 Ma 时,极地断层作为板块边界的主要断层,推断的滑动速率范围为 13 至 21 毫米/年,极有可能在 15 至 7 Ma,板块边界唯一的活动断层。这项研究的结果表明,在走滑盆地沉积物中保存的构造记录提高了对单个断层的相对重要性的理解,以及对整个构造历史中应变分区的影响。伊萨巴尔湖盆地始于 12 Ma。Polochic断层是中新世的主要板块边界。故障切换活动一定是沿着板块边界发生的。] 这项研究的结果表明,在走滑盆地沉积物中保存的构造记录提高了对单个断层的相对重要性的理解,以及对整个构造历史中应变分区的影响。伊萨巴尔湖盆地始于 12 Ma。Polochic断层是中新世的主要板块边界。故障切换活动一定是沿着板块边界发生的。] 这项研究的结果表明,在走滑盆地沉积物中保存的构造记录提高了对单个断层的相对重要性的理解,以及对整个构造历史中应变分区的影响。伊萨巴尔湖盆地始于 12 Ma。Polochic断层是中新世的主要板块边界。故障切换活动一定是沿着板块边界发生的。]
更新日期:2020-01-28
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