• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Paleoenvironmental and paleolandscape reconstructions of Greenwich Bay region, RI.
【24h】

Paleoenvironmental and paleolandscape reconstructions of Greenwich Bay region, RI.

机译：罗德岛格林威治湾地区的古环境和古景观重建。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A paleoenvironmental and paleolandscape reconstruction of two separate sites in the Greenwich Bay region of RI was completed for use in the Paleocultural Landscapes Project. Investigations of a lacustrine sediment record in Warwick, RI were completed in order to develop a regional paleoenvironmental reference record. Investigations of the acoustic sub-bottom record in Greenwich Bay, RI were completed in order to develop paleolandscape reconstructions of the observed depositional environments for future use in an archaeological site prediction model.;For Chapter one, we took a single sediment core from Gorton Pond, Warwick, RI in the summer of 2013 for the purpose of developing a regional paleoenvironmental reference record. The core was dated using both AMS-radiocarbon dating of four terrestrial macrofossil samples, and correlations with a radiometric/pollen age model from a surface core taken from Gorton Pond for a previous study. The oldest terrestrial macrofossil was a spruce cone dated to ~12,100 calendar years BP, but an estimated 18,000 years of sediment is in the Gorton Pond record, based on bracketing ages from dated recessional moraines in the region. However, we only sampled an estimated 16,000 years, based on a Younger Dryas transition of 13,000 BP.;Physical, magnetic, and elemental/isotopic (C, N, S, D/H) proxy measurements were made, and six distinct environmental zones were interpreted. The Gorton Pond record indicates significant changes in lake productivity and temperature. The Late Pleistocene Deglacial Period (16.0-13.0 ky BP) is indicated by low OC%, high concentrations of magnetic material, and terrestrially-sourced organic matter. The Younger Dryas chronozone was observed (13.0-11.8 kyr BP) as large decreases in deltal13C, OC%, and deltaDBA, indicating cold conditions. A transition from the Late Pleistocene to Early Holocene (11.8-9.6 ky BP) was observed by rapid warming and increased aquatic productivity. The Middle Holocene (9.6-3.6 ky BP) was characterized by depleted deltaD BA of behenic acid ratios, which may suggest Gorton Pond is sensitive to changes in air mass/moisture sources, but other local effects are being investigated.;In chapter two, a geophysical survey was conducted using acoustic sub-bottom (CHIRP) seismic reflection techniques, and 24 lines covering 40 km were processed and interpreted. Four distinct seismic units were interpreted, spanning from the Pleistocene-aged deglacial sediments to modern day estuarine sediments. A basal till/bedrock surface marks the limit of seismic penetration, and overlying thick (up to 42 m) varved proglacial lake sediments suggest that the area was part of Glacial Lake Narragansett (GLN). Paleochannel stream cuts unconformably lie above the proglacial lake sediments, indicating a draining of GLN and a period of subaerial exposure in which an organized tributary system existed in Greenwich Bay. A GIS-based Local Polynomial Interpolation model was used to create a representative surface of the stream-dissected paleolandscape that existed prior to marine inundation. While useful, denser CHIRP coverage (100 m line spacing minimum) is recommended in order to take stress off of the interpolation. The proximity of channels to archaeological finds at Cedar Tree Beach would suggest that they might have been important resources for ancient inhabitants. Comparisons to the USGS East Greenwich Quadrangle Surficial Geology Map (Smith, 1955) shows significant kame terrace and other glacial meltwater deposits that may indicate a paleo-drainage of the modern day Pawtuxet river into the paleolandscape observed in the Greenwich Bay seismic record.
机译：在RI格林威治湾地区的两个不同地点的古环境和古景观重建工作已完成，可用于古文化景观项目。为了开发区域古环境参考记录，完成了对罗德岛州沃里克湖沉积物记录的调查。为了开发观察到的沉积环境的古地形重建，以供将来在考古现场预测模型中使用，完成了对RI格林威治湾地下声记录的调查。第一章，我们从Gorton Pond中提取了一个沉积岩心，于2013年夏季在罗德岛州的沃里克市进行，目的是开发区域古环境参考记录。使用四个陆地大型化石样品的AMS放射性碳测年法以及与取自Gorton Pond的地表岩心的辐射度/花粉年龄模型的相关性对日期进行了定年，该模型用于先前的研究。陆地上最古老的化石是云杉锥，约BP约12100历年，但根据该地区年代久远的凹纹岩层出的年龄，戈登池塘记录中估计有18000年的沉积物。但是，我们仅根据13,000 BP的年轻得里亚斯转变来估计了16,000年。;进行了物理，磁和元素/同位素（C，N，S，D / H）替代测量，并建立了六个不同的环境区被解释。戈顿池塘的记录显示了湖泊生产力和温度的重大变化。晚更新世冰期晚期（16.0-13.0 ky BP）表现为低OC％，高浓度磁性材料和地源有机物。由于deltal13C，OC％和deltaDBA的大幅降低，观察到了年轻的Dryas钻纹带（13.0-11.8 kyr BP），表明天气寒冷。通过快速变暖和增加的水生生产力，观测到了从更新世晚期到全新世（11.8-9.6 ky BP）的过渡。中全新世（9.6-3.6 ky BP）的特征在于山hen酸比率的deltaD BA减少，这可能表明Gorton Pond对空气质量/湿度源的变化敏感，但正在研究其他局部影响。利用声底（CHIRP）地震反射技术进行了地球物理勘测，处理并解释了覆盖40 km的24条线。解释了四个不同的地震单元，从更新世时代的冰期沉积物到现代河口沉积物。基层/基岩表面标志着地震渗透的极限，上覆的厚厚（高达42 m）的曲折性湖状湖泊沉积物表明该地区是纳拉甘塞特湖（GLN）的一部分。古河道截流不协调地位于湖滨湖泊沉积物上方，表明GLN排放和一段地下暴露期，格林威治湾中存在有组织的支流系统。使用基于GIS的局部多项式插值模型创建在海洋被淹之前存在的溪流剖析的古地貌的代表性表面。虽然有用，但建议使用更密集的CHIRP覆盖范围（最小100 m的行距），以减轻插值的压力。通道与雪松树海滩的考古发现相距很近，这表明它们可能是古代居民的重要资源。与美国地质调查局东格林威治四边形浅部地质图（史密斯，1955年）的比较显示，有大量的钾石阶地和其他冰川融水沉积物，这可能表明现代的帕wtuxet河被古排水到格林威治湾地震记录中观察到的古地貌中。

著录项

  • 作者

    Morissette, Cameron E.;

  • 作者单位

    University of Rhode Island.;

  • 授予单位 University of Rhode Island.;
  • 学科 Sedimentary Geology.;Paleoclimate Science.
  • 学位 M.S.
  • 年度 2014
  • 页码 151 p.
  • 总页数 151
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号