Pliocene lacustrine system in the Nellis basin, southern Nevada: implications for the Colorado River drainage system

IF 2 4区 地球科学 Q1 GEOLOGY
B. Mclaurin, Dirk Goossens, Brenda J. Buck, Wanda Taylor
{"title":"Pliocene lacustrine system in the Nellis basin, southern Nevada: implications for the Colorado River drainage system","authors":"B. Mclaurin, Dirk Goossens, Brenda J. Buck, Wanda Taylor","doi":"10.2110/jsr.2022.116","DOIUrl":null,"url":null,"abstract":"Lacustrine basins and the sediments within them provide a critical component of regional tectonic development and climate history. Each sub-basin in the landscape records the interplay between active tectonism and shifting climate. Many of the basins in southern Nevada that contain deposits of the Muddy Creek Formation were closed fluvio-lacustrine systems during the latest Miocene and into the Pliocene. They were subsequently integrated into the regional Colorado River system. Lacustrine deposits of the Muddy Creek Formation are exposed along the trace of the Las Vegas Valley shear zone in the Nellis Dunes Recreation Area (NDRA), northeast of Las Vegas, NV. The Muddy Creek Formation in NDRA consists of approximately 130 m of mixed carbonates and clastics, and new tephrochronology suggests an early to late Pliocene age (about 4.7 to about 2.6 Ma) for the lowermost lacustrine deposits and an unknown, but younger age for the uppermost spring-fed lacustrine deposit. These sediments were deposited in an arid to semi-arid lake (Lake Nellis) and alluvial floodplain system based on the interpretation of lithologies and facies associations. The stratigraphic succession coarsens upward and reflects establishment of a lacustrine carbonate system overlain by a clastic succession of peripheral lake sediments of alluvial and floodplain origin. The peripheral lake deposits consist of spring-fed and fluvial wetland mudflats of brown claystone and siltstone. This brown claystone is capped by a succession of yellow and red sandstones deposited by fluvial and minor eolian processes. The second, and youngest freshwater limestone, likely disconformably, overlies the yellow and r ed sandstones, and is thought to be temporally and depositionally distinct from the underlying Muddy Creek deposits. The transition from the lower lacustrine carbonates to clastic fluvial channel and flood plain deposits indicates desiccation of Lake Nellis and possibly occurs soon after about 2.7 to about 2.6 Ma based on the ages of tuffs occurring within the uppermost limestone and marl beds. This is consistent with an interpreted increase in regional aridity after approximately 2.8 Ma (Smith et al. 1993). The second limestone deposit at the top of the section represents an even younger spring/lacustrine deposit of unknown age. Throughout the lower carbonate section, three tuffs were identified, and geochemically correlated, using a discriminant function analysis, to the tuff of Napa (≤ 4.70 ± 0.03 Ma), the Putah Tuff (about 3.3 Ma) and the lower tuffs of the Badlands ( about 2.7 – about 2.6 Ma). The timing of deposition of Lake Nellis sediments post-dates the integration of the three major lake syste ms in this region (Lake Grand Wash, Lake Hualapai, and Lake Las Vegas) into the Colorado River drainage (5.6 – 4.9 Ma), and also postdates the full integration of the river to sea level (4.8 - 4.63 Ma) (Howard et al. 2015; Crow et al. 2021). Lake Nellis represents an isolated lake basin that was one, and maybe the last, lacustrine system to be fully integrated into the Colorado River drainage in this region.","PeriodicalId":17044,"journal":{"name":"Journal of Sedimentary Research","volume":"58 7 1","pages":""},"PeriodicalIF":2.0000,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Sedimentary Research","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.2110/jsr.2022.116","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0

Abstract

Lacustrine basins and the sediments within them provide a critical component of regional tectonic development and climate history. Each sub-basin in the landscape records the interplay between active tectonism and shifting climate. Many of the basins in southern Nevada that contain deposits of the Muddy Creek Formation were closed fluvio-lacustrine systems during the latest Miocene and into the Pliocene. They were subsequently integrated into the regional Colorado River system. Lacustrine deposits of the Muddy Creek Formation are exposed along the trace of the Las Vegas Valley shear zone in the Nellis Dunes Recreation Area (NDRA), northeast of Las Vegas, NV. The Muddy Creek Formation in NDRA consists of approximately 130 m of mixed carbonates and clastics, and new tephrochronology suggests an early to late Pliocene age (about 4.7 to about 2.6 Ma) for the lowermost lacustrine deposits and an unknown, but younger age for the uppermost spring-fed lacustrine deposit. These sediments were deposited in an arid to semi-arid lake (Lake Nellis) and alluvial floodplain system based on the interpretation of lithologies and facies associations. The stratigraphic succession coarsens upward and reflects establishment of a lacustrine carbonate system overlain by a clastic succession of peripheral lake sediments of alluvial and floodplain origin. The peripheral lake deposits consist of spring-fed and fluvial wetland mudflats of brown claystone and siltstone. This brown claystone is capped by a succession of yellow and red sandstones deposited by fluvial and minor eolian processes. The second, and youngest freshwater limestone, likely disconformably, overlies the yellow and r ed sandstones, and is thought to be temporally and depositionally distinct from the underlying Muddy Creek deposits. The transition from the lower lacustrine carbonates to clastic fluvial channel and flood plain deposits indicates desiccation of Lake Nellis and possibly occurs soon after about 2.7 to about 2.6 Ma based on the ages of tuffs occurring within the uppermost limestone and marl beds. This is consistent with an interpreted increase in regional aridity after approximately 2.8 Ma (Smith et al. 1993). The second limestone deposit at the top of the section represents an even younger spring/lacustrine deposit of unknown age. Throughout the lower carbonate section, three tuffs were identified, and geochemically correlated, using a discriminant function analysis, to the tuff of Napa (≤ 4.70 ± 0.03 Ma), the Putah Tuff (about 3.3 Ma) and the lower tuffs of the Badlands ( about 2.7 – about 2.6 Ma). The timing of deposition of Lake Nellis sediments post-dates the integration of the three major lake syste ms in this region (Lake Grand Wash, Lake Hualapai, and Lake Las Vegas) into the Colorado River drainage (5.6 – 4.9 Ma), and also postdates the full integration of the river to sea level (4.8 - 4.63 Ma) (Howard et al. 2015; Crow et al. 2021). Lake Nellis represents an isolated lake basin that was one, and maybe the last, lacustrine system to be fully integrated into the Colorado River drainage in this region.
内华达州南部内利斯盆地的上新世湖沼系统:对科罗拉多河排水系统的影响
湖沼盆地及其中的沉积物是区域构造发展和气候历史的重要组成部分。地貌中的每个子盆地都记录了活跃的构造运动与气候变迁之间的相互作用。在内华达州南部,许多含有泥溪地层沉积物的盆地在中新世晚期至上新世期间都是封闭的流积-湖积系统。它们后来融入了地区性的科罗拉多河水系。在内利斯沙丘休闲区(NDRA),内华达州拉斯维加斯东北部的拉斯维加斯谷剪切带沿线出露了泥溪地层的湖沼沉积物。NDRA 中的泥泞溪地层由大约 130 米长的混合碳酸盐岩和碎屑岩组成,新的热年代学研究表明,最下部的湖泊沉积物的年代为早至晚上新世(约 4.7 至约 2.6Ma),最上部的泉水湖泊沉积物的年代不明,但更年轻。这些沉积物沉积于干旱至半干旱的湖泊(内利斯湖)和冲积洪泛平原系统中,根据岩性和岩相关联的解释,这些沉积物沉积于干旱至半干旱的湖泊(内利斯湖)和冲积洪泛平原系统中。地层演替向上变粗,反映了湖泊碳酸盐系统的形成,其上覆盖着冲积和洪泛平原的外围湖泊沉积物碎屑演替。外围湖泊沉积物由褐粘土岩和粉砂质泥岩构成的泉水冲积层和河流湿地泥滩组成。在棕色粘土岩的顶部,是由河道和少量风化过程沉积而成的黄色和红色砂岩。第二层,也是最年轻的淡水灰岩,很可能是在黄色和红色砂岩的上覆层,被认为在时间和沉积上有别于下层的泥溪沉积。从下部湖相碳酸盐岩向碎屑河道和冲积平原沉积的过渡表明内利斯湖已经干涸,根据最上层石灰岩和泥灰岩床中凝灰岩的年龄,这一过渡可能发生在大约 2.7 Ma 到大约 2.6 Ma 之后不久。这与大约 2.8 Ma 之后区域干旱程度的增加相吻合(Smith 等人,1993 年)。位于该剖面顶部的第二个石灰岩沉积层是一个更年轻的泉水/湖沼沉积层,年代不详。在整个碳酸盐岩下段,发现了三块凝灰岩,并通过判别函数分析,将其与纳帕凝灰岩(≤ 4.70 ± 0.03 Ma)、普塔凝灰岩(约 3.3 Ma)和荒原下部凝灰岩(约 2.7 - 约 2.6 Ma)进行了地球化学关联。内利斯湖沉积物的沉积时间晚于该地区三大湖泊系统(大冲洗湖、华拉派湖和拉斯维加斯湖)融入科罗拉多河流域的时间(5.6 - 4.9 Ma),也晚于河流完全融入海平面的时间(4.8 - 4.63 Ma)(Howard 等,2015 年;Crow 等,2021 年)。内利斯湖代表了一个孤立的湖盆,它是该地区完全融入科罗拉多河流域的湖泊系统之一,也可能是最后一个湖泊系统。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
CiteScore
3.80
自引率
5.00%
发文量
50
审稿时长
3 months
期刊介绍: The journal is broad and international in scope and welcomes contributions that further the fundamental understanding of sedimentary processes, the origin of sedimentary deposits, the workings of sedimentary systems, and the records of earth history contained within sedimentary rocks.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信