Age estimates of isochronous reflection horizons by combining ice core, survey, and synthetic radar data
Age estimates of isochronous reflection horizons by combining ice core, survey, and synthetic radar data
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DOI：
10.1029/2003jb002858
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发表时间：
2004-04
影响因子：
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通讯作者：
O. Eisen;U. Nixdorf;F. Wilhelms;H. Miller
中科院分区：
文献类型：
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作者：
O. Eisen;U. Nixdorf;F. Wilhelms;H. Miller
[1]冰芯记录和探冰雷达数据包含关于冰川地下结构和成分的补充信息，为解释过去和现在的环境条件提供了各种机会。为了充分利用各种可能的应用，需要对内部雷达反射层位进行精确定年，并了解其构成特征。三个冰芯记录的基础上，从德龙宁毛德地，南极洲，地面雷达剖面连接的钻探位置，我们调查的准确性，从冰芯获得的年龄-深度关系转移到连续的雷达反射。有两种方法用于测定五个内反射层位的日期：（1）通过将所跟踪的反射的传播时间转换为单个深度来执行常规的测年，然后将该单个深度与每个岩芯位置处的年龄相关联，以及（2）电磁波传播的正演建模基于冰芯的介电剖面并且被执行以识别所跟踪的反射起源的深度范围，从而得到每个钻探地点的年龄范围。所有年龄估计的统计分析结果在5-10年的年龄不确定性的常规测年和误差范围1-16年的正演模拟。对于我们的雷达业务在200和250兆赫的冰盖上100米，包括约1000-1500年的沉积历史，最终年龄的不确定性是8年，在有利的情况下，21年的可行性限制。大约三分之一的不确定性与最初的冰芯测年有关;其余部分与雷达数据质量和分析有关。
[1] Ice core records and ice-penetrating radar data contain complementary information on glacial subsurface structure and composition, providing various opportunities for interpreting past and present environmental conditions. To exploit the full range of possible applications, accurate dating of internal radar reflection horizons and knowledge about their constituting features is required. On the basis of three ice core records from Dronning Maud Land, Antarctica, and surface-based radar profiles connecting the drilling locations, we investigate the accuracies involved in transferring age-depth relationships obtained from the ice cores to continuous radar reflections. Two methods are used to date five internal reflection horizons: (1) conventional dating is carried out by converting the travel time of the tracked reflection to a single depth, which is then associated with an age at each core location, and (2) forward modeling of electromagnetic wave propagation is based on dielectric profiling of ice cores and performed to identify the depth ranges from which tracked reflections originate, yielding an age range at each drill site. Statistical analysis of all age estimates results in age uncertainties of 5–10 years for conventional dating and an error range of 1–16 years for forward modeling. For our radar operations at 200 and 250 MHz in the upper 100 m of the ice sheet, comprising some 1000–1500 years of deposition history, final age uncertainties are 8 years in favorable cases and 21 years at the limit of feasibility. About one third of the uncertainty is associated with the initial ice core dating; the remaining part is associated with radar data quality and analysis.