Origin of a complex and spatially diverse dune-field pattern, Algodones, southeastern California
Origin of a complex and spatially diverse dune-field pattern, Algodones, southeastern California
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DOI：
10.1016/j.geomorph.2007.10.016
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发表时间：
2008-07-01
期刊：
影响因子：
3.9
通讯作者：
Briistow, Charlie
中科院分区：
文献类型：
--
作者：
Derickson, Dana;Kocurek, Gary;Briistow, Charlie
加州东南部的阿尔戈多内斯沙丘区显示出一种复杂的、空间多样的沙丘区格局，这种格局叠加在一系列地形线理之上。沙丘场格局参数（沙丘顶长度，波峰方向，沙丘间距和缺陷密度）来自航空图像的分析表明，沙丘场格局代表两个建设代。突出的复合新月形沙丘形成于第一代建设。年轻的一代由各种简单的新月形沙丘，线性沙丘和zibars。通过考虑沙丘格局演变的边界条件，解决了第二代沙丘群之间格局参数的统计差异，并解释了：（1）沙丘类型的多样性，（2）隐含的建造时间范围，（3）波峰方向范围，（4）线性沙丘种群的异常性质。改变格局发展的边界条件包括地形效应、粒度、植被、面积范围和先行条件。阿尔戈多内斯的地形线理范围从定义田野边缘的西部斜坡到被沙丘图案掩盖的微妙特征。使用探地雷达对西部斜坡进行的成像显示，高角度交叉地层垂直于线理趋势迁移。对于线理的起源，最合理的假设是沙丘脊从邻近的卡惠拉湖连续脱落，卡惠拉湖是阿尔戈多内斯沙子的来源。Algodones的整体地貌复杂性源于Cahuilla湖阶段沙丘脊的就位，两代沙丘场的建设，以及边界条件的控制。(c)2007年爱思唯尔B.V.保留所有战斗。
The Algodones Dune Field of southeastern California shows a complex and spatially diverse dune-field pattern that is superimposed upon a series of topographic lineations. Analysis of dune-field pattern parameters (dune crest length, crest orientation, dune spacing and defect density) derived from aerial images indicates that the dune-field pattern represents two constructional generations. Prominent compound crescentic dunes formed during the first constructional generation. A younger generation consists of a variety of simple crescentic dunes, linear dunes and zibars. Statistical differences in the pattern parameters between the dune groups within the second generation are resolved through consideration of the boundary conditions under which the dune pattern evolved, and provide explanations for: (1) diversity of dune types, (2) range in implied constructional times, (3) range in crest orientations, and (4) the anomalous nature of the population of linear dunes. The boundary conditions that have modified pattern development include orographic effects, grain size, vegetation, areal extent and antecedent conditions. Topographic lineations in the Algodones range from the Western Ramp, which defines the field margin, to subtle features masked by the pattern of dunes. Imaging of the Western Ramp using Ground Penetrating Radar shows high-angle cross-strata migrating perpendicular to the lineation trend. The most plausible hypothesis for the origin of the lineations is as dune ridges sequentially shed from adjacent Lake Cahuilla, which is the source of Algodones sands. The overall geomorphic complexity of the Algodones originates from the emplacement of the dune ridges during stages of Lake Cahuilla, the two generations of dune-field construction, and the controls exerted by boundary conditions. (c) 2007 Elsevier B.V. All fights reserved.