{"title":"Delta size variability at Lake General Carrera, Patagonia","authors":"Rebecca M. E. Williams, B. Hynek","doi":"10.5027/andgeov49n2-3397","DOIUrl":null,"url":null,"abstract":"Punctuated lake level drops at Lake General Carrera, Chile, over the last ~13 ka are recorded in multiple stacked deltas that differ in scale. Fifteen delta terrace suites are studied to examine the factors that influence deposit morphology. Surprisingly, the pronounced longitudinal precipitation gradient is inversely correlated with the observed variations in delta size. We find the drainage basins with long-term water storage in glaciers are associated with larger deltas. In these cases, the added contribution of rare, high-magnitude ice meltwater release events (> 600 m3/s) is suggested as the differential driver to enhance delta growth. The overall progradation rate is modest (0.2 - 1 m/yr), and appears to have slowed over time. For the youngest deltas, we estimate the range in the intermittency factor, a dimensionless measure of the frequency of floods, is 1 x 10-2 to 4 x10-5. Our results illustrate the natural variability of delta growth in a small region (","PeriodicalId":49108,"journal":{"name":"Andean Geology","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2022-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Andean Geology","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5027/andgeov49n2-3397","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Punctuated lake level drops at Lake General Carrera, Chile, over the last ~13 ka are recorded in multiple stacked deltas that differ in scale. Fifteen delta terrace suites are studied to examine the factors that influence deposit morphology. Surprisingly, the pronounced longitudinal precipitation gradient is inversely correlated with the observed variations in delta size. We find the drainage basins with long-term water storage in glaciers are associated with larger deltas. In these cases, the added contribution of rare, high-magnitude ice meltwater release events (> 600 m3/s) is suggested as the differential driver to enhance delta growth. The overall progradation rate is modest (0.2 - 1 m/yr), and appears to have slowed over time. For the youngest deltas, we estimate the range in the intermittency factor, a dimensionless measure of the frequency of floods, is 1 x 10-2 to 4 x10-5. Our results illustrate the natural variability of delta growth in a small region (
智利卡雷拉将军湖在过去约13卡的时间里，记录到多个规模不同的堆叠三角洲出现了点状湖面下降。研究了15个三角洲阶地套房，以考察影响矿床形态的因素。令人惊讶的是，明显的纵向降水梯度与观测到的三角洲大小变化呈负相关。我们发现，冰川中长期蓄水的流域与更大的三角洲有关。在这些情况下，罕见的高强度冰融水释放事件（>600 m3/s）的额外贡献被认为是促进三角洲增长的差异驱动因素。总体进积速率适中（0.2-1米/年），并且随着时间的推移似乎有所减缓。对于最年轻的三角洲，我们估计间歇性因子（洪水频率的无量纲度量）的范围为1 x 10-2至4 x10-5。我们的结果说明了小区域三角洲增长的自然变异性(
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This journal publishes original and review articles on geology and related sciences, in Spanish or English, in three issues a year (January, May and September). Articles or notes on major topics of broad interest in Earth Sciences dealing with the geology of South and Central America and Antarctica, and particularly of the Andes, are welcomed.
The journal is interested in publishing thematic sets of papers and accepts articles dealing with systematic Paleontology only if their main focus is the chronostratigraphical, paleoecological and/or paleogeographical importance of the taxa described therein.
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