首页 > 最新文献

Earth Surface Dynamics最新文献

英文 中文
Geomorphic indices for unveiling fault segmentation and tectono-geomorphic evolution with insights into the impact of inherited topography, Ulsan Fault Zone, Korea 揭示韩国蔚山断裂带断层分段和构造地貌演化的地貌指数以及对继承地形影响的见解
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-22 DOI: 10.5194/egusphere-2024-198
Cho-Hee Lee, Yeong Bae Seong, John Weber, Sangmin Ha, Dong-Eun Kim, Byung Yong Yu
Abstract. Quantifying present topography can provide insights into landscape evolution and its controls, as the present topography is a cumulative expression of the types, distributions, and intensities of past and present processes. The Ulsan Fault Zone (UFZ) is an active fault zone on the southeastern Korean Peninsula that has been reactivated as a reverse fault around 5 Ma. This NNW–SSE-trending fault zone exhibits a predominantly reverse sense of movement today and dips towards the east. This study investigates the history of tectonic activity along the UFZ and the landscape evolution of the hanging wall side of the UFZ, focusing on neotectonic perturbations using 10Be-derived catchment-wide denudation rate and bedrock incision rates, geomorphic indices, and a landscape evolution model. We evaluated the spatial variation in the relative tectonic intensity from the variation in geomorphic indices along the UFZ. Five geological segments were identified along the fault based on the relative tectonic intensity and fault geometry. We then simulated four cases of landscape evolution using modelling to investigate the geomorphic processes and topographic changes in the study area in response to fault slip. The model results reveal that the geomorphic processes and the patterns of geomorphic indices (e.g., χ anomalies) depend on the inherited topography (i.e., the topography that existed prior to reverse faulting on the UFZ). On the basis of this important finding, we interpret the tectono-geomorphic history of the study area as follows: (1) the northern part of the UFZ has been in a transient state and is in topographic and geometric disequilibrium, as this part underwent asymmetric uplift (westward tilting) prior to reverse faulting on the UFZ around 5 Ma; and (2) its southern part was negligibly influenced by the asymmetric uplift before reverse faulting. Our study demonstrates geomorphic indices as reliable criteria for dividing faults into segments and, together with landscape evolution modelling, to investigate the influence of inherited topography on present topography and to help determine tectono-geomorphic histories.
摘要由于现在的地形是过去和现在过程的类型、分布和强度的累积表现,因此量化现在的地形可以帮助人们深入了解地貌演变及其控制因素。蔚山断裂带(Ulsan Fault Zone,UFZ)是朝鲜半岛东南部的一个活动断裂带,在 5 Ma 前后作为逆断层重新活跃起来。如今,这条 NNW-SSE 走向的断层带主要呈现反向运动,并向东倾斜。本研究利用 10Be 导出的全流域剥蚀率和基岩切变率、地貌指数以及地貌演化模型,研究了 UFZ 沿线的构造活动历史以及 UFZ 悬壁一侧的地貌演化,重点关注新构造扰动。我们根据 UFZ 沿线地貌指数的变化评估了相对构造强度的空间变化。根据相对构造强度和断层几何形状,我们确定了断层沿线的五个地质段。然后,我们利用模型模拟了四种地貌演变情况,以研究断层滑动对研究区地貌过程和地形变化的影响。模型结果表明,地貌过程和地貌指数(如 χ 异常)的模式取决于继承地形(即 UFZ 逆断层之前的地形)。根据这一重要发现,我们对研究区的构造地貌历史进行了如下解释:(1) 联合区北部一直处于瞬变状态,处于地形和几何不平衡状态,因为在联合区发生逆断层之前,该地区在 5 Ma 左右经历了非对称隆升(向西倾斜);(2) 联合区南部在发生逆断层之前受非对称隆升的影响微乎其微。我们的研究表明,地貌指数是将断层划分为不同地段的可靠标准,与地貌演化模型一起,可用于研究继承地形对当前地形的影响,并帮助确定构造-地貌历史。
{"title":"Geomorphic indices for unveiling fault segmentation and tectono-geomorphic evolution with insights into the impact of inherited topography, Ulsan Fault Zone, Korea","authors":"Cho-Hee Lee, Yeong Bae Seong, John Weber, Sangmin Ha, Dong-Eun Kim, Byung Yong Yu","doi":"10.5194/egusphere-2024-198","DOIUrl":"https://doi.org/10.5194/egusphere-2024-198","url":null,"abstract":"<strong>Abstract.</strong> Quantifying present topography can provide insights into landscape evolution and its controls, as the present topography is a cumulative expression of the types, distributions, and intensities of past and present processes. The Ulsan Fault Zone (UFZ) is an active fault zone on the southeastern Korean Peninsula that has been reactivated as a reverse fault around 5 Ma. This NNW–SSE-trending fault zone exhibits a predominantly reverse sense of movement today and dips towards the east. This study investigates the history of tectonic activity along the UFZ and the landscape evolution of the hanging wall side of the UFZ, focusing on neotectonic perturbations using <sup>10</sup>Be-derived catchment-wide denudation rate and bedrock incision rates, geomorphic indices, and a landscape evolution model. We evaluated the spatial variation in the relative tectonic intensity from the variation in geomorphic indices along the UFZ. Five geological segments were identified along the fault based on the relative tectonic intensity and fault geometry. We then simulated four cases of landscape evolution using modelling to investigate the geomorphic processes and topographic changes in the study area in response to fault slip. The model results reveal that the geomorphic processes and the patterns of geomorphic indices (e.g., χ anomalies) depend on the inherited topography (i.e., the topography that existed prior to reverse faulting on the UFZ). On the basis of this important finding, we interpret the tectono-geomorphic history of the study area as follows: (1) the northern part of the UFZ has been in a transient state and is in topographic and geometric disequilibrium, as this part underwent asymmetric uplift (westward tilting) prior to reverse faulting on the UFZ around 5 Ma; and (2) its southern part was negligibly influenced by the asymmetric uplift before reverse faulting. Our study demonstrates geomorphic indices as reliable criteria for dividing faults into segments and, together with landscape evolution modelling, to investigate the influence of inherited topography on present topography and to help determine tectono-geomorphic histories.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139921565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Autogenic vs Subsidence Controls on Grain Size Fining through Multi-Channel Landscape Evolution Modelling 多通道地貌演化模型对粒度细化的自生与沉降控制作用
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-21 DOI: 10.5194/egusphere-2024-351
Amanda Lily Wild, Jean Braun, Alexander C. Whittaker, Sebastien Castelltort
Abstract. Within the stratigraphic record, changes in grain size are often interpreted as a signature of external forcing events. However, it is not yet well constrained how autogenic processes (such as channel mobility) influence grain size signatures within the fluvial system. Here, we combine a landscape evolution model based on the Stream Power Law but modified for sedimentation (Yuan et al., 2019) with an extension of the self-similar grain size model Fedele and Paola (2007) to multiple dimensions (i.e., along dynamically evolving river channels) to study the relative importance of autogenic processes in con- trolling grain size fining. We first show how our new model can reproduce the results obtained by classical analytical solutions assuming that fining is controlled by subsidence only, in a single or amalgamated channel. We then show that deviations from past (subsidence and single channel only) predictions arise when varying two main parameters: first the ratio between the incoming sediment flux and integrated subsidence rate (F ), which increases with the degree of bypass of the system; and second, the ratio of the discharge leaving the mountain to the discharge generated within the subsiding basin (β), which controls the shape of the topography of the basin. We demonstrate that there exists two regimes, one corresponding to low values of F or high values of β, where the grain size fining is controlled by subsidence, and one corresponding to high F and low β values, where grain size fining is controlled by autogenic processes under steep topographic slopes that propagate sedimentary waves through the basin. Coupling the LEM to a flexural model predicts that grain size fining evolves from subsidence to autogeniccontrol in basins characterized by a progressive increase of F (under-filled to over-filled foreland), as seen in the case example of the Alberta Foreland Basin. Our results indicate that grain size fining during low filling conditions (e.g. early stage as the basin is forming) can indicate the dominantly tectonic controlled parameter of the flux relative to underlying subsidence ratio (F ); whereas, any fining under high bypass conditions (e.g. late stage once the basin is overfilled) can indicate the climate controlled upstream vs downstream ratio (β).
摘要在地层记录中,粒度变化通常被解释为外部作用事件的特征。然而,目前还不能很好地解释自生过程(如河道流动性)如何影响河道系统内的粒度特征。在此,我们将基于溪流幂律但针对沉积进行了修改的景观演化模型(Yuan 等,2019 年)与 Fedele 和 Paola(2007 年)的自相似粒度模型扩展到多个维度(即沿动态演化的河道)相结合,研究自生过程在控制粒度细化中的相对重要性。我们首先展示了我们的新模型是如何在单一或混合河道中重现经典分析方法得出的结果的,即假设细化仅由沉降控制。然后,我们展示了当改变以下两个主要参数时,过去(仅由沉降和单一河道控制)的预测结果会出现偏差:首先是进入的沉积通量与综合沉降速率(F)之间的比率,该比率会随着系统旁路程度的增加而增加;其次是离开山体的排水量与沉降盆地内产生的排水量之间的比率(β),该比率控制着盆地地形的形状。我们证明存在两种情况,一种是 F 值低或 β 值高,晶粒细化受沉降控制;另一种是 F 值高、β 值低,晶粒细化受陡峭地形斜坡下的自生过程控制,沉积波在盆地中传播。将 LEM 与挠曲模型耦合可预测,在以 F 值逐渐增加(前陆充填不足到前陆充填过度)为特征的盆地中,粒度细化会从沉降演变为自生控制,这在阿尔伯塔前陆盆地的案例中可以看到。我们的研究结果表明,在低充盈条件下(如盆地形成的早期阶段)的粒度细化可以表明通量相对于基本沉降比(F)的参数主要受构造控制;而在高旁通条件下(如盆地过度充盈的晚期阶段)的任何细化可以表明受气候控制的上游与下游比(β)。
{"title":"Autogenic vs Subsidence Controls on Grain Size Fining through Multi-Channel Landscape Evolution Modelling","authors":"Amanda Lily Wild, Jean Braun, Alexander C. Whittaker, Sebastien Castelltort","doi":"10.5194/egusphere-2024-351","DOIUrl":"https://doi.org/10.5194/egusphere-2024-351","url":null,"abstract":"<strong>Abstract.</strong> Within the stratigraphic record, changes in grain size are often interpreted as a signature of external forcing events. However, it is not yet well constrained how autogenic processes (such as channel mobility) influence grain size signatures within the fluvial system. Here, we combine a landscape evolution model based on the Stream Power Law but modified for sedimentation (Yuan et al., 2019) with an extension of the self-similar grain size model Fedele and Paola (2007) to multiple dimensions (i.e., along dynamically evolving river channels) to study the relative importance of autogenic processes in con- trolling grain size fining. We first show how our new model can reproduce the results obtained by classical analytical solutions assuming that fining is controlled by subsidence only, in a single or amalgamated channel. We then show that deviations from past (subsidence and single channel only) predictions arise when varying two main parameters: first the ratio between the incoming sediment flux and integrated subsidence rate (<em>F</em> ), which increases with the degree of bypass of the system; and second, the ratio of the discharge leaving the mountain to the discharge generated within the subsiding basin (<em>β</em>), which controls the shape of the topography of the basin. We demonstrate that there exists two regimes, one corresponding to low values of <em>F</em> or high values of <em>β</em>, where the grain size fining is controlled by subsidence, and one corresponding to high <em>F</em> and low <em>β</em> values, where grain size fining is controlled by autogenic processes under steep topographic slopes that propagate sedimentary waves through the basin. Coupling the LEM to a flexural model predicts that grain size fining evolves from subsidence to autogeniccontrol in basins characterized by a progressive increase of <em>F</em> (under-filled to over-filled foreland), as seen in the case example of the Alberta Foreland Basin. Our results indicate that grain size fining during low filling conditions (e.g. early stage as the basin is forming) can indicate the dominantly tectonic controlled parameter of the flux relative to underlying subsidence ratio (<em>F</em> ); whereas, any fining under high bypass conditions (e.g. late stage once the basin is overfilled) can indicate the climate controlled upstream vs downstream ratio (<em>β</em>).","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139921569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
How water, temperature and seismicity control the preparation of massive rock slope failure (Hochvogel, DE/AT) 水、温度和地震如何控制大规模岩坡崩塌的准备工作(Hochvogel,德国/奥地利)
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-16 DOI: 10.5194/egusphere-2024-231
Johannes Leinauer, Michael Dietze, Sibylle Knapp, Riccardo Scandroglio, Maximilian Jokel, Michael Krautblatter
Abstract. The increasing hazard of major rock slope failures, exacerbated by climate change, underscores the importance of anticipating pre-failure process dynamics. While standard triggers are recognized for small rockfalls, few comprehensive driver quantifications exist for massive pre-failure rock slopes. Here we exploit >4 years multi-method high-resolution monitoring data from a well-prepared high-magnitude rock slope instability. To quantify and understand the effect of possible drivers – water from rain and snowmelt, internal rock fracturing and earthquakes – we correlate slope displacements with environmental data, local seismic recordings and earthquake catalogues. During the snowmelt phase, displacements are controlled by meltwater infiltration with high correlation and a time lag of 4–9 days. During the snow-free summer, rainfall drives the system with a time lag of 1–16 h for up to several days without a minimum activation rain sum threshold. Detected rock fracturing, linked to temperature and freeze-thaw cycles, is predominantly surface-near and unrelated to displacement rates. A classic Newmark analysis of recent and historic earthquakes indicates a low potential for immediate triggering of a major failure at the case site, unless it is already very close to failure. Seismic topographic amplification of the peak ground velocity at the summit ranges from a factor of 2–11 and is spatially heterogeneous, indicating a high criticality of the slope. The presented methodological approach enables a comprehensive rockfall driver evaluation and indicates where future climatic changes, e.g. in precipitation intensity and frequency, may alter the preparation of major rock slope failures.
摘要重大岩石边坡崩塌的危害日益严重,气候变化更是雪上加霜,这凸显了预测崩塌前过程动态的重要性。虽然人们已经认识到小型落石的标准触发因素,但对于大规模崩塌前岩石边坡来说,很少有全面的驱动因素量化。在这里,我们利用了一个准备充分的高震级岩石边坡失稳的 4 年多方法高分辨率监测数据。为了量化和了解可能的驱动因素(雨雪融水、岩石内部断裂和地震)的影响,我们将边坡位移与环境数据、当地地震记录和地震目录相关联。在融雪阶段,位移受融水渗透控制,相关性很高,时滞为 4-9 天。在无雪的夏季,降雨驱动系统,时滞为 1-16 小时,持续时间长达数天,没有最小激活雨量总和阈值。检测到的岩石断裂与温度和冻融循环有关,主要是地表附近的断裂,与位移率无关。对近期和历史地震进行的经典纽马克分析表明,在案例地点立即引发重大破坏的可能性很低,除非已经非常接近破坏。山顶峰值地面速度的地震地形放大系数为 2-11 倍,并且在空间上具有异质性,这表明斜坡具有高度临界性。所提出的方法能够对岩石崩落的驱动因素进行全面评估,并指出未来气候的变化(如降水强度和频率)可能会改变主要岩石边坡崩塌的准备情况。
{"title":"How water, temperature and seismicity control the preparation of massive rock slope failure (Hochvogel, DE/AT)","authors":"Johannes Leinauer, Michael Dietze, Sibylle Knapp, Riccardo Scandroglio, Maximilian Jokel, Michael Krautblatter","doi":"10.5194/egusphere-2024-231","DOIUrl":"https://doi.org/10.5194/egusphere-2024-231","url":null,"abstract":"<strong>Abstract.</strong> The increasing hazard of major rock slope failures, exacerbated by climate change, underscores the importance of anticipating pre-failure process dynamics. While standard triggers are recognized for small rockfalls, few comprehensive driver quantifications exist for massive pre-failure rock slopes. Here we exploit &gt;4 years multi-method high-resolution monitoring data from a well-prepared high-magnitude rock slope instability. To quantify and understand the effect of possible drivers – water from rain and snowmelt, internal rock fracturing and earthquakes – we correlate slope displacements with environmental data, local seismic recordings and earthquake catalogues. During the snowmelt phase, displacements are controlled by meltwater infiltration with high correlation and a time lag of 4–9 days. During the snow-free summer, rainfall drives the system with a time lag of 1–16 h for up to several days without a minimum activation rain sum threshold. Detected rock fracturing, linked to temperature and freeze-thaw cycles, is predominantly surface-near and unrelated to displacement rates. A classic Newmark analysis of recent and historic earthquakes indicates a low potential for immediate triggering of a major failure at the case site, unless it is already very close to failure. Seismic topographic amplification of the peak ground velocity at the summit ranges from a factor of 2–11 and is spatially heterogeneous, indicating a high criticality of the slope. The presented methodological approach enables a comprehensive rockfall driver evaluation and indicates where future climatic changes, e.g. in precipitation intensity and frequency, may alter the preparation of major rock slope failures.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Channel cross-section heterogeneity of particulate organic carbon transport in the Huanghe 黄河颗粒有机碳迁移的河道断面异质性
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-15 DOI: 10.5194/esurf-12-347-2024
Yutian Ke, Damien Calmels, Julien Bouchez, Marc Massault, Benjamin Chetelat, Aurélie Noret, Hongming Cai, Jiubin Chen, Jérôme Gaillardet, Cécile Quantin
Abstract. The Huanghe (Yellow River), one of the largest turbid river systems in the world, has long been recognized as a major contributor of suspended particulate matter (SPM) to the ocean. However, over the last few decades, the SPM export flux of the Huanghe has decreased over 90 % due to the high management, impacting the global export of particulate organic carbon (POC). To better constrain sources and modes of transport of POC beyond the previously investigated transportation of POC near the channel surface, SPM samples were for the first time collected over a whole channel cross-section in the lower Huanghe. Riverine SPM samples were analyzed for particle size and major element contents, as well as for POC content and dual carbon isotopes (13C and 14C). Clear vertical and lateral heterogeneities of the physical and chemical properties of SPM are observed within the river cross-section. For instance, finer SPM carry more POC in general with higher 14C activity near the surface of the right bank. Notably, we discuss how bank erosion in the alluvial plain is likely to generate lateral heterogeneity in POC composition. The Huanghe POC is millennial-aged (4020 ± 500 radiocarbon years) and dominated by organic carbon (OC) from the biosphere, while the lithospheric fraction is ca. 12 %. The mobilization of aged and refractory OC, including radiocarbon-dead biospheric OC, from deeper soil horizons of the loess–paleosol sequence through erosion in the Chinese Loess Plateau is an important mechanism contributing to fluvial POC in the Huanghe drainage basin. Altogether, anthropogenic activities can drastically change the compositions and transport dynamics of fluvial POC, consequentially altering the feedback of the source-to-sink trajectory of a river system to regional and global carbon cycles.
摘要黄河是世界上最大的浑浊河流之一,长期以来一直被认为是向海洋排放悬浮颗粒物(SPM)的主要来源。然而,在过去的几十年里,由于管理水平较高,黄河的 SPM 出口通量下降了 90% 以上,影响了全球颗粒有机碳 (POC) 的出口。为了更好地确定 POC 的来源和传输模式,除了之前调查的河道表面附近的 POC 传输外,还首次在黄河下游整个河道断面采集了 SPM 样品。对河道 SPM 样品进行了粒度、主要元素含量、POC 含量和双碳同位素(13C 和 14C)分析。在河道断面内,SPM 的物理和化学性质存在明显的纵向和横向异质性。例如,较细的 SPM 一般携带更多的 POC,右岸表面附近的 14C 活性较高。值得注意的是,我们讨论了冲积平原的河岸侵蚀如何可能导致 POC 成分的横向异质性。黄河 POC 的年龄为千年(4020 ± 500 放射性碳年),主要由来自生物圈的有机碳(OC)构成,而岩石圈部分约占 12%。通过中国黄土高原的侵蚀作用,从黄土-古土壤层序的深层土壤地层中移动了老化的难溶性有机碳,包括放射性碳死亡的生物圈有机碳,这是黄河流域河流有机碳的一个重要机制。总之,人类活动可以极大地改变河流 POC 的组成和迁移动力学,从而改变河流系统从源到汇的轨迹对区域和全球碳循环的反馈。
{"title":"Channel cross-section heterogeneity of particulate organic carbon transport in the Huanghe","authors":"Yutian Ke, Damien Calmels, Julien Bouchez, Marc Massault, Benjamin Chetelat, Aurélie Noret, Hongming Cai, Jiubin Chen, Jérôme Gaillardet, Cécile Quantin","doi":"10.5194/esurf-12-347-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-347-2024","url":null,"abstract":"Abstract. The Huanghe (Yellow River), one of the largest turbid river systems in the world, has long been recognized as a major contributor of suspended particulate matter (SPM) to the ocean. However, over the last few decades, the SPM export flux of the Huanghe has decreased over 90 % due to the high management, impacting the global export of particulate organic carbon (POC). To better constrain sources and modes of transport of POC beyond the previously investigated transportation of POC near the channel surface, SPM samples were for the first time collected over a whole channel cross-section in the lower Huanghe. Riverine SPM samples were analyzed for particle size and major element contents, as well as for POC content and dual carbon isotopes (13C and 14C). Clear vertical and lateral heterogeneities of the physical and chemical properties of SPM are observed within the river cross-section. For instance, finer SPM carry more POC in general with higher 14C activity near the surface of the right bank. Notably, we discuss how bank erosion in the alluvial plain is likely to generate lateral heterogeneity in POC composition. The Huanghe POC is millennial-aged (4020 ± 500 radiocarbon years) and dominated by organic carbon (OC) from the biosphere, while the lithospheric fraction is ca. 12 %. The mobilization of aged and refractory OC, including radiocarbon-dead biospheric OC, from deeper soil horizons of the loess–paleosol sequence through erosion in the Chinese Loess Plateau is an important mechanism contributing to fluvial POC in the Huanghe drainage basin. Altogether, anthropogenic activities can drastically change the compositions and transport dynamics of fluvial POC, consequentially altering the feedback of the source-to-sink trajectory of a river system to regional and global carbon cycles.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Dimensionless argument: a narrow grain size range near 2 mm plays a special role in river sediment transport and morphodynamics 无量纲论证:2 毫米附近的窄粒径范围在河流泥沙输运和形态动力学中发挥着特殊作用
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-15 DOI: 10.5194/esurf-12-367-2024
Gary Parker, Chenge An, Michael P. Lamb, Marcelo H. Garcia, Elizabeth H. Dingle, Jeremy G. Venditti
Abstract. The grain size 2 mm is the conventional border between sand and gravel. This size is used extensively, and generally without much physical justification, to discriminate between such features as sedimentary deposit type (clast-supported versus matrix-supported), river type (gravel bed versus sand bed), and sediment transport relation (gravel versus sand). Here we inquire as to whether this 2 mm boundary is simply a social construct upon which the research community has decided to agree or whether there is some underlying physics. We use dimensionless arguments to show the following for typical conditions on Earth, i.e., natural clasts (e.g., granitic or limestone) in 20 ∘C water. As grain size ranges from 1 to 5 mm (a narrow band including 2 mm), sediment suspension becomes vanishingly small at normal flood conditions in alluvial rivers. We refer to this range as pea gravel. We further show that bedload movement of a clast in the pea gravel range with, for example, a size of 4 mm moving over a bed of 0.4 mm particles has an enhanced relative mobility compared to a clast with a size of 40 mm moving over a bed of the same 4 mm particles. With this in mind, we use 2 mm here as shorthand for the narrow pea gravel range of 1–5 mm over which transport behavior is distinct from both coarser and finer material. The use of viscosity allows the delineation of a generalized dimensionless bed grain size discriminator between “sand-like” and “gravel-like” rivers. The discriminator is applicable to sediment transport on Titan (ice clasts in flowing methane/ethane liquid at reduced gravity) and Mars (mafic clasts in flowing water at reduced gravity), as well as Earth.
摘要粒径 2 毫米是砂和砾石之间的常规边界。这一粒度被广泛用于区分沉积沉积类型(碎屑支撑与基质支撑)、河流类型(砾石河床与砂石河床)以及沉积运移关系(砾石与砂石)等特征,但通常没有太多的物理依据。在此,我们要探究的是,2 毫米的边界究竟是研究界达成共识的一种社会建构,还是其中蕴含着某种潜在的物理学原理。我们使用无量纲参数来说明地球上的典型条件,即 20 ℃ 水中的天然碎屑(如花岗岩或石灰石)。由于粒径范围从 1 毫米到 5 毫米(包括 2 毫米在内的窄带),在冲积河流的正常洪水条件下,泥沙悬浮物变得非常小。我们将这一范围称为豌豆砾石。我们进一步表明,与粒径为 40 毫米的泥块在粒径为 4 毫米的泥床上移动相比,粒径为 4 毫米的泥块在粒径为 0.4 毫米的泥床上移动时,其相对移动性会增强,例如,粒径为 4 毫米的泥块在粒径为 0.4 毫米的泥床上移动时,其相对移动性会增强。有鉴于此,我们在此使用 2 毫米作为 1-5 毫米这一狭窄的豌豆砾石范围的简称,在这一范围内,豌豆砾石的迁移行为与更粗和更细的材料都截然不同。使用粘度可以在 "类沙 "和 "类砾 "河流之间划分出一个通用的无量纲河床粒径判别器。该判别器适用于土卫六(在重力减小的情况下甲烷/乙烷液体中流动的冰碎屑)和火星(在重力减小的情况下流动的水中的岩浆碎屑)以及地球上的沉积物迁移。
{"title":"Dimensionless argument: a narrow grain size range near 2 mm plays a special role in river sediment transport and morphodynamics","authors":"Gary Parker, Chenge An, Michael P. Lamb, Marcelo H. Garcia, Elizabeth H. Dingle, Jeremy G. Venditti","doi":"10.5194/esurf-12-367-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-367-2024","url":null,"abstract":"Abstract. The grain size 2 mm is the conventional border between sand and gravel. This size is used extensively, and generally without much physical justification, to discriminate between such features as sedimentary deposit type (clast-supported versus matrix-supported), river type (gravel bed versus sand bed), and sediment transport relation (gravel versus sand). Here we inquire as to whether this 2 mm boundary is simply a social construct upon which the research community has decided to agree or whether there is some underlying physics. We use dimensionless arguments to show the following for typical conditions on Earth, i.e., natural clasts (e.g., granitic or limestone) in 20 ∘C water. As grain size ranges from 1 to 5 mm (a narrow band including 2 mm), sediment suspension becomes vanishingly small at normal flood conditions in alluvial rivers. We refer to this range as pea gravel. We further show that bedload movement of a clast in the pea gravel range with, for example, a size of 4 mm moving over a bed of 0.4 mm particles has an enhanced relative mobility compared to a clast with a size of 40 mm moving over a bed of the same 4 mm particles. With this in mind, we use 2 mm here as shorthand for the narrow pea gravel range of 1–5 mm over which transport behavior is distinct from both coarser and finer material. The use of viscosity allows the delineation of a generalized dimensionless bed grain size discriminator between “sand-like” and “gravel-like” rivers. The discriminator is applicable to sediment transport on Titan (ice clasts in flowing methane/ethane liquid at reduced gravity) and Mars (mafic clasts in flowing water at reduced gravity), as well as Earth.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Cirque-like alcoves in the northern mid-latitudes of Mars as evidence of glacial erosion 作为冰川侵蚀证据的火星北部中纬度地区漩涡状凹地
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-13 DOI: 10.5194/egusphere-2023-2568
An Li, Michelle Koutnik, Stephen Brough, Matteo Spagnolo, Iestyn Barr
Abstract. While glacial remnants in the form of viscous flow features in the mid-latitudes of Mars are considered to be cold-based in the present-day, an increasing amount of geomorphic evidence suggests that at least some flow features were previously wet-based or had a mixed thermal state (polythermal) at during their evolution. Many of the viscous flow features known as glacier-like forms have been observed to emerge from alcoves that appear similar to cirques on Earth. Terrestrial cirques are typically characterized by a concave basin connected to a steep backwall. Cirques are expected to form from depressions in mountainsides that fill with snow/ice and over time support active glaciers that deepen the depressions by wet-based glacial erosion. To assess which alcoves on Mars are most “cirque-like”, we mapped a population of ~2000 alcoves in Deuteronilus Mensae, a region in the mid-latitudes of Mars characterized by mesas encompassed by glacial remnants. Based on visual characteristics and morphometrics, we refined our dataset to 386 “cirque-like alcoves”, which is five times the amount of glacier-like forms in the region, and used this to assess the past extent and style of glaciation on Mars. Using high resolution imagery, we find geomorphic evidence for glacial occupation associated with the cirque-like alcoves, including crevasse-like features, surface lineations, polygonal terrain, and moraine-like ridges. We propose that the cirque-like alcoves with icy remnants similar to rock glaciers on Earth represent a late stage of glacier-like form evolution. We also outline stages of cirque-like alcove evolution, linking a potential early stage of cirque-like alcoves to gully activity. On a population-wide scale, the cirque-like alcoves have a south to southeastward aspect bias, which may indicate a requirement for increased insolation for melting to occur and a connection to gullies on Mars. While the alcoves also have similarities to other features such as landslide scarps and amphitheater-headed valleys, the cirque-like alcoves have unique morphologies and morphometrics that differentiate their origin. Assuming warm-based erosion rates, the cirque-like alcoves have timescales consistent with both glacier-like forms and other viscous flow features like lobate debris aprons, whereas cold-based erosion rates would only allow the older timescales of lobate debris aprons. We propose that based on the geomorphic features and southward aspect, cirque-like alcove formation is more consistent with warm-based glaciation.
摘要。虽然火星中纬度地区以粘流地貌形式存在的冰川遗迹被认为是以冷为基础的,但越来越多的地貌证据表明,至少有些粘流地貌以前是以湿为基础的,或者在其演化过程中具有混合热状态(多热)。据观察,许多被称为冰川状的粘性流地貌都是从凹洞中出现的,这些凹洞看起来与地球上的盘旋地貌相似。陆地上的凹涡通常具有凹陷的盆地和陡峭的后壁相连的特征。预计凹地是由山坡上的凹陷形成的,这些凹陷充满了冰雪,随着时间的推移,活跃的冰川通过湿基冰川侵蚀作用加深了凹陷。为了评估火星上哪些凹地最 "像凹地",我们在火星中纬度地区的Deuteronilus Mensae绘制了约2000个凹地。根据视觉特征和形态计量学,我们将数据集细化为 386 个 "盘旋状凹地",是该地区冰川状凹地数量的五倍,并以此评估火星过去冰川作用的范围和类型。通过使用高分辨率图像,我们发现了与 "类盘旋凹地 "相关的冰川侵蚀地貌证据,包括裂缝地貌、地表线形、多边形地形和冰碛脊。我们认为,具有类似于地球上岩石冰川的冰雪残留物的盘旋凹地代表了冰川形态演化的晚期阶段。我们还概括了盘旋凹地的演化阶段,将盘旋凹地的早期阶段与沟谷活动联系起来。在整个群体范围内,盘旋状凹地的地势倾向于南向和东南向,这可能表明融化的发生需要更多的日照,并与火星上的沟壑有关。虽然凹地与其他地貌(如滑坡疤痕和露天剧场式山谷)也有相似之处,但盘旋状凹地具有独特的形态和形态计量学特征,可以区分其起源。假设以暖流为基础的侵蚀速率为依据,盘旋状凹地的时间尺度与类似冰川的形态和其他粘性流地貌(如裂片状碎屑围岩)一致,而以冷流为基础的侵蚀速率则只能使裂片状碎屑围岩的时间尺度更长。我们认为,根据地貌特征和南向剖面来看,圈状凹槽的形成更符合暖基性冰川作用。
{"title":"Cirque-like alcoves in the northern mid-latitudes of Mars as evidence of glacial erosion","authors":"An Li, Michelle Koutnik, Stephen Brough, Matteo Spagnolo, Iestyn Barr","doi":"10.5194/egusphere-2023-2568","DOIUrl":"https://doi.org/10.5194/egusphere-2023-2568","url":null,"abstract":"<strong>Abstract.</strong> While glacial remnants in the form of viscous flow features in the mid-latitudes of Mars are considered to be cold-based in the present-day, an increasing amount of geomorphic evidence suggests that at least some flow features were previously wet-based or had a mixed thermal state (polythermal) at during their evolution. Many of the viscous flow features known as glacier-like forms have been observed to emerge from alcoves that appear similar to cirques on Earth. Terrestrial cirques are typically characterized by a concave basin connected to a steep backwall. Cirques are expected to form from depressions in mountainsides that fill with snow/ice and over time support active glaciers that deepen the depressions by wet-based glacial erosion. To assess which alcoves on Mars are most “cirque-like”, we mapped a population of ~2000 alcoves in Deuteronilus Mensae, a region in the mid-latitudes of Mars characterized by mesas encompassed by glacial remnants. Based on visual characteristics and morphometrics, we refined our dataset to 386 “cirque-like alcoves”, which is five times the amount of glacier-like forms in the region, and used this to assess the past extent and style of glaciation on Mars. Using high resolution imagery, we find geomorphic evidence for glacial occupation associated with the cirque-like alcoves, including crevasse-like features, surface lineations, polygonal terrain, and moraine-like ridges. We propose that the cirque-like alcoves with icy remnants similar to rock glaciers on Earth represent a late stage of glacier-like form evolution. We also outline stages of cirque-like alcove evolution, linking a potential early stage of cirque-like alcoves to gully activity. On a population-wide scale, the cirque-like alcoves have a south to southeastward aspect bias, which may indicate a requirement for increased insolation for melting to occur and a connection to gullies on Mars. While the alcoves also have similarities to other features such as landslide scarps and amphitheater-headed valleys, the cirque-like alcoves have unique morphologies and morphometrics that differentiate their origin. Assuming warm-based erosion rates, the cirque-like alcoves have timescales consistent with both glacier-like forms and other viscous flow features like lobate debris aprons, whereas cold-based erosion rates would only allow the older timescales of lobate debris aprons. We propose that based on the geomorphic features and southward aspect, cirque-like alcove formation is more consistent with warm-based glaciation.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Path length and sediment transport estimation from DEMs of difference: a signal processing approach 从差分 DEM 估算路径长度和沉积物运移:一种信号处理方法
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-09 DOI: 10.5194/esurf-12-321-2024
Lindsay Marie Capito, Enrico Pandrin, Walter Bertoldi, Nicola Surian, Simone Bizzi
Abstract. The difficulties of measuring bedload transport in gravel-bed rivers have given rise to the morphological method wherein sediment transport can be inferred from changes in riverbed elevation and estimates of the distance traveled by sediment: its path length. Because current methods for estimating path length are time- and labor-intensive, we present a method to estimate a characteristic path length from repeat digital elevation models (DEMs of difference, i.e., DoDs). We propose an automated method to extract the spacing between erosional and depositional sites on the DoD by the application of variational mode decomposition (VMD), a signal processing method, to quantify the spacing as a proxy for path length. We developed this method using flume experiments where bed topography and sediment flux were measured and then applied it to published field data with physical path length measured from tracer measurements. Our sediment transport estimates were not significantly different than the measured sediment flux at lower discharges in the lab. However, we observed an underestimation of sediment flux at the higher discharges in the flume study. We interpret this as a limit of the method in confined settings, where sediment transport becomes decoupled from morphological changes. We also explore how the time between survey acquisitions, the morphological active width relative to the channel width, and DoD thresholding techniques affect the proposed method and the potential issues they pose for the morphological method in general.
摘要由于难以测量砾石床河流中的床面负荷迁移量,因此产生了一种形态学方法,即通过河床高程的变化和沉积物移动距离的估算(即路径长度)来推断沉积物的迁移量。由于目前估算路径长度的方法耗时耗力,我们提出了一种从重复数字高程模型(DEMs of difference,即 DoDs)中估算特征路径长度的方法。我们提出了一种自动方法,通过应用信号处理方法变异模态分解(VMD)来提取差异数字高程模型上侵蚀点和沉积点之间的间距,从而量化间距作为路径长度的替代值。我们利用测量床面地形和沉积通量的水槽实验开发了这一方法,然后将其应用于通过示踪测量测量物理路径长度的已公布实地数据。我们的沉积物输运估算值与实验室测量的较低排水量下的沉积物通量没有明显差异。不过,在水槽研究中,我们观察到较高排水量下的沉积物通量被低估了。我们将此解释为该方法在封闭环境中的局限性,在这种环境中,沉积物运移与形态变化脱钩。我们还探讨了勘测采集之间的时间间隔、形态活动宽度与河道宽度的相对关系以及 DoD 临界值技术对拟议方法的影响,以及它们对一般形态学方法造成的潜在问题。
{"title":"Path length and sediment transport estimation from DEMs of difference: a signal processing approach","authors":"Lindsay Marie Capito, Enrico Pandrin, Walter Bertoldi, Nicola Surian, Simone Bizzi","doi":"10.5194/esurf-12-321-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-321-2024","url":null,"abstract":"Abstract. The difficulties of measuring bedload transport in gravel-bed rivers have given rise to the morphological method wherein sediment transport can be inferred from changes in riverbed elevation and estimates of the distance traveled by sediment: its path length. Because current methods for estimating path length are time- and labor-intensive, we present a method to estimate a characteristic path length from repeat digital elevation models (DEMs of difference, i.e., DoDs). We propose an automated method to extract the spacing between erosional and depositional sites on the DoD by the application of variational mode decomposition (VMD), a signal processing method, to quantify the spacing as a proxy for path length. We developed this method using flume experiments where bed topography and sediment flux were measured and then applied it to published field data with physical path length measured from tracer measurements. Our sediment transport estimates were not significantly different than the measured sediment flux at lower discharges in the lab. However, we observed an underestimation of sediment flux at the higher discharges in the flume study. We interpret this as a limit of the method in confined settings, where sediment transport becomes decoupled from morphological changes. We also explore how the time between survey acquisitions, the morphological active width relative to the channel width, and DoD thresholding techniques affect the proposed method and the potential issues they pose for the morphological method in general.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The impact of bedrock meander cutoffs on 50 ka-year-scale incision rates, San Juan River, Utah 犹他州圣胡安河基岩蜿蜒断面对 50 ka 年尺度侵蚀率的影响
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-07 DOI: 10.5194/egusphere-2024-71
Aaron T. Steelquist, Gustav B. Seixas, Mary L. Gillam, Sourav Saha, Seulgi Moon, George E. Hilley
Abstract. Incision rates of major rivers may reflect the effects of drainage reorganization, hillslope processes, tectonic uplift, climate, the properties of rocks into which rivers incise, and other autogenic processes. On the Colorado Plateau, incision rates along the Colorado River have been interpreted as resulting from abrupt base-level changes produced by the integration of the Colorado River system. Specifically, the integration of the Colorado River in the location of Grand Canyon is thought to have created a knickpoint, enhanced by lithologic contrasts, which is retreating upstream. While evidence exists for a <1 Ma acceleration of incision on parts of the Colorado River, uncertainty about the processes reflected in shorter-term incision rates muddies comparison with longer-term averages. In this work, we combine a cosmogenic radionuclide depth profile exposure age and post-Infrared Infrared Stimulated Luminescence (p-IR IRSL) to date fluvial deposits adjacent to the San Juan River, a major tributary of the Colorado River, near Mexican Hat, Utah. The deposits, resting on a 32 m strath surface, are constrained to be ∼28–40 ka, suggesting an incision rate of 804–1151 m Myr-1, nearly an order of magnitude higher than the long-term rate of ∼140 m Myr-1 over the past ∼1.2 Ma. We observe fluvial deposits that were abandoned due to a bedrock meander cutoff, which partially explains our accelerated incision rate. We use a simple geometric model, informed by our field data, to demonstrate how planform river evolution may, in some circumstances, increase short-term incision rates, relative to long-term incision rates. These short-term rates may also reflect a combination of autocyclic and climatic processes, which limits their ability to resolve longer-term changes in incision rate that may be related to changes in base-level or tectonics.
摘要主要河流的切入率可能反映了排水系统重组、山坡过程、构造隆起、气候、河流切入岩石的特性以及其他自生过程的影响。在科罗拉多高原,科罗拉多河沿岸的切入率被解释为科罗拉多河水系整合所产生的突然基底变化所致。具体来说,科罗拉多河在大峡谷位置的汇合被认为形成了一个因岩性对比而增强的节理点,该节理点正在向上游后退。虽然有证据表明科罗拉多河的部分河段在 1 亿年前加速了侵蚀,但短期侵蚀速率所反映的过程的不确定性使得与长期平均侵蚀速率的比较变得模糊不清。在这项研究中,我们结合了宇宙放射性核素深度剖面暴露年龄和后红外激发发光法(p-IR IRSL),对犹他州墨西哥帽附近科罗拉多河主要支流圣胡安河附近的河流沉积物进行了年代测定。这些沉积物位于 32 米长的地层表面,年代为 28-40 ka,表明侵蚀速率为 804-1151 m Myr-1,比过去 1.2 Ma 的长期侵蚀速率 140 m Myr-1 高出近一个数量级。我们观察到由于基岩河曲断裂而被遗弃的河道沉积,这部分解释了我们的加速侵蚀速率。我们利用一个简单的几何模型,并结合我们的实地数据,证明了在某些情况下,相对于长期侵蚀速率,平面河流的演化可能会增加短期侵蚀速率。这些短期速率也可能反映了自循环和气候过程的综合作用,这限制了它们解决可能与基底或构造变化有关的长期侵蚀速率变化的能力。
{"title":"The impact of bedrock meander cutoffs on 50 ka-year-scale incision rates, San Juan River, Utah","authors":"Aaron T. Steelquist, Gustav B. Seixas, Mary L. Gillam, Sourav Saha, Seulgi Moon, George E. Hilley","doi":"10.5194/egusphere-2024-71","DOIUrl":"https://doi.org/10.5194/egusphere-2024-71","url":null,"abstract":"<strong>Abstract.</strong> Incision rates of major rivers may reflect the effects of drainage reorganization, hillslope processes, tectonic uplift, climate, the properties of rocks into which rivers incise, and other autogenic processes. On the Colorado Plateau, incision rates along the Colorado River have been interpreted as resulting from abrupt base-level changes produced by the integration of the Colorado River system. Specifically, the integration of the Colorado River in the location of Grand Canyon is thought to have created a knickpoint, enhanced by lithologic contrasts, which is retreating upstream. While evidence exists for a &lt;1 Ma acceleration of incision on parts of the Colorado River, uncertainty about the processes reflected in shorter-term incision rates muddies comparison with longer-term averages. In this work, we combine a cosmogenic radionuclide depth profile exposure age and post-Infrared Infrared Stimulated Luminescence (p-IR IRSL) to date fluvial deposits adjacent to the San Juan River, a major tributary of the Colorado River, near Mexican Hat, Utah. The deposits, resting on a 32 m strath surface, are constrained to be ∼28–40 ka, suggesting an incision rate of 804–1151 m Myr<sup>-1</sup>, nearly an order of magnitude higher than the long-term rate of ∼140 m Myr<sup>-1</sup> over the past ∼1.2 Ma. We observe fluvial deposits that were abandoned due to a bedrock meander cutoff, which partially explains our accelerated incision rate. We use a simple geometric model, informed by our field data, to demonstrate how planform river evolution may, in some circumstances, increase short-term incision rates, relative to long-term incision rates. These short-term rates may also reflect a combination of autocyclic and climatic processes, which limits their ability to resolve longer-term changes in incision rate that may be related to changes in base-level or tectonics.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A numerical model for duricrust formation by water table fluctuations 地下水位波动形成硬壳的数值模型
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-06 DOI: 10.5194/egusphere-2024-160
Caroline Fenske, Jean Braun, François Guillocheau, Cécile Robin
Abstract. Duricrusts are hard elemental layers forming in climatically contrasted environments. Ferricretes (or iron duricrusts) are a type of duricrust, made of indurated iron layers. They form in tropical to semi-arid environments, but can be currently observed all around the world, in areas such as Africa, South America, India, and Australia. In most cases, they cap hills and appear to protect softer layers beneath. Two hypotheses have been proposed for the formation of duricrusts, i.e., the hydrological or horizontal model where the enrichment in the hardening element (iron for ferricretes) is the product of leaching and precipitation through the beating of the water table during contrasted seasonal cycles, and the laterisation or vertical model, where the formation of iron duricrusts is the final stage of laterisation. In this article, we present the first numerical model for the formation of iron duricrusts based on the hydrological hypothesis. The model is an extension to an existing regolith formation model where the position of the water table is used to predict the formation of a hardened layer at a rate set by a characteristic time scale τ and over a depth set by the beating range of the water table, λ. Hardening causes a decrease in surface erodibility, which we introduce in the model as a dimensionless factor κ that multiplies the surface transport coefficient of the model. Using the model we show under which circumstances duricrusts form by introducing two dimensionless numbers that combine the model parameters (λ and τ) as well as parameters representing external forcing like precipitation rate and uplift rate. We demonstrate that by using model parameter values obtained by independent constraints from field observations, hydrology and geochronology, the model predictions reproduce the observed conditions for duricrust formation. We also show that there exists a strong feedback from duricrust formation on the shape of the regolith and the position of the water table. Finally we demonstrate that the commonly accepted view that, because they are commonly found at the top of hills, duricrusts protect elements of the landscape is most likely an over-interpretation and that caution must be taken before using duricrusts as markers of uplift and/or base level falls.
摘要硬壳是在气候反差较大的环境中形成的坚硬元素层。铁锈岩(或铁硬壳岩)是硬壳岩的一种,由硬化的铁层组成。它们形成于热带至半干旱环境中,但目前在世界各地,如非洲、南美洲、印度和澳大利亚都能观察到。在大多数情况下,它们覆盖在山丘上,似乎保护着下面较软的地层。关于坚硬岩壳的形成有两种假说,一种是水文或水平模式,即硬化元素(铁锈岩中的铁)的富集是在对比强烈的季节周期中通过地下水位的跳动浸出和沉淀的产物;另一种是后期化或垂直模式,即铁质坚硬岩壳的形成是后期化的最后阶段。在本文中,我们首次提出了基于水文假设的铁质硬壳形成数值模型。该模型是对现有岩石形成模型的扩展,利用地下水位的位置来预测硬化层的形成,其速率由特征时间尺度 τ 设定,深度由地下水位的跳动范围 λ 设定。硬化会导致地表侵蚀性降低,我们在模型中引入了一个无量纲因子 κ,该因子与模型的地表传输系数相乘。我们在模型中引入了两个无量纲数字,将模型参数(λ 和 τ)以及降水率和隆起率等代表外部作用力的参数结合在一起,从而说明在什么情况下会形成硬壳。我们证明,通过使用从实地观测、水文和地质年代学中获得的独立约束条件所得到的模型参数值,模型预测结果再现了所观测到的硬壳形成条件。我们还证明,硬壳的形成对碎屑岩的形状和地下水位的位置有很强的反馈作用。最后,我们证明了人们普遍接受的观点,即由于它们通常出现在山顶,所以硬壳岩保护了地貌要素,这很可能是一种过度解读,在使用硬壳岩作为隆起和/或基底下降的标志之前必须谨慎。
{"title":"A numerical model for duricrust formation by water table fluctuations","authors":"Caroline Fenske, Jean Braun, François Guillocheau, Cécile Robin","doi":"10.5194/egusphere-2024-160","DOIUrl":"https://doi.org/10.5194/egusphere-2024-160","url":null,"abstract":"<strong>Abstract.</strong> Duricrusts are hard elemental layers forming in climatically contrasted environments. Ferricretes (or iron duricrusts) are a type of duricrust, made of indurated iron layers. They form in tropical to semi-arid environments, but can be currently observed all around the world, in areas such as Africa, South America, India, and Australia. In most cases, they cap hills and appear to protect softer layers beneath. Two hypotheses have been proposed for the formation of duricrusts, i.e., the hydrological or horizontal model where the enrichment in the hardening element (iron for ferricretes) is the product of leaching and precipitation through the beating of the water table during contrasted seasonal cycles, and the laterisation or vertical model, where the formation of iron duricrusts is the final stage of laterisation. In this article, we present the first numerical model for the formation of iron duricrusts based on the hydrological hypothesis. The model is an extension to an existing regolith formation model where the position of the water table is used to predict the formation of a hardened layer at a rate set by a characteristic time scale τ and over a depth set by the beating range of the water table, λ. Hardening causes a decrease in surface erodibility, which we introduce in the model as a dimensionless factor κ that multiplies the surface transport coefficient of the model. Using the model we show under which circumstances duricrusts form by introducing two dimensionless numbers that combine the model parameters (λ and τ) as well as parameters representing external forcing like precipitation rate and uplift rate. We demonstrate that by using model parameter values obtained by independent constraints from field observations, hydrology and geochronology, the model predictions reproduce the observed conditions for duricrust formation. We also show that there exists a strong feedback from duricrust formation on the shape of the regolith and the position of the water table. Finally we demonstrate that the commonly accepted view that, because they are commonly found at the top of hills, duricrusts protect elements of the landscape is most likely an over-interpretation and that caution must be taken before using duricrusts as markers of uplift and/or base level falls.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139759568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Flexural isostatic response of continental-scale deltas to climatically driven sea level changes 大陆尺度三角洲对气候驱动的海平面变化的挠曲等静力响应
IF 3.4 2区 地球科学 Q1 Earth and Planetary Sciences Pub Date : 2024-02-01 DOI: 10.5194/esurf-12-301-2024
Sara Polanco, Mike Blum, Tristan Salles, Bruce C. Frederick, Rebecca Farrington, Xuesong Ding, Ben Mather, Claire Mallard, Louis Moresi
Abstract. The interplay between climate-forced sea level change, erosional and depositional processes, and flexural isostasy in deep time on passive margin deltas remains poorly understood. We performed a series of conceptual simulations to investigate flexural isostatic responses to high-frequency fluctuations in water and sediment load associated with climatically driven sea level changes. We model a large drainage basin that discharges to a continental margin and produces a large deltaic depocenter, then prescribe synthetic and climatic-driven sea level curves of different frequencies to assess flexural response. Results show that flexural isostatic responses are bidirectional over 100–1000 kyr timescales and are in sync with the magnitude, frequency, and direction of sea level fluctuations and that isostatic adjustments play an important role in driving along-strike and cross-shelf river mouth migration and sediment accumulation. Our findings demonstrate that climate-forced sea level changes produce a feedback mechanism that results in self-sustaining creation of accommodation into which sediment is deposited and plays a major role in delta morphology and stratigraphic architecture.
摘要人们对被动边缘三角洲的气候驱动海平面变化、侵蚀和沉积过程以及深时挠曲等静力之间的相互作用仍然知之甚少。我们进行了一系列概念模拟,以研究挠曲等静压对与气候驱动的海平面变化相关的水和沉积物负荷高频波动的响应。我们模拟了一个向大陆边缘排水并产生大型三角洲沉积中心的大型排水流域,然后设定了不同频率的合成海平面曲线和气候驱动的海平面曲线,以评估挠曲响应。结果表明,在 100-1000 千年的时间尺度上,挠曲等静力响应是双向的,与海平面波动的幅度、频率和方向是同步的,等静力调整在驱动沿岸和跨大陆架河口迁移和沉积物堆积方面发挥了重要作用。我们的研究结果表明,由气候引起的海平面变化产生了一种反馈机制,导致沉积物沉积的自持性容积的形成,并在三角洲形态和地层结构中发挥了重要作用。
{"title":"Flexural isostatic response of continental-scale deltas to climatically driven sea level changes","authors":"Sara Polanco, Mike Blum, Tristan Salles, Bruce C. Frederick, Rebecca Farrington, Xuesong Ding, Ben Mather, Claire Mallard, Louis Moresi","doi":"10.5194/esurf-12-301-2024","DOIUrl":"https://doi.org/10.5194/esurf-12-301-2024","url":null,"abstract":"Abstract. The interplay between climate-forced sea level change, erosional and depositional processes, and flexural isostasy in deep time on passive margin deltas remains poorly understood. We performed a series of conceptual simulations to investigate flexural isostatic responses to high-frequency fluctuations in water and sediment load associated with climatically driven sea level changes. We model a large drainage basin that discharges to a continental margin and produces a large deltaic depocenter, then prescribe synthetic and climatic-driven sea level curves of different frequencies to assess flexural response. Results show that flexural isostatic responses are bidirectional over 100–1000 kyr timescales and are in sync with the magnitude, frequency, and direction of sea level fluctuations and that isostatic adjustments play an important role in driving along-strike and cross-shelf river mouth migration and sediment accumulation. Our findings demonstrate that climate-forced sea level changes produce a feedback mechanism that results in self-sustaining creation of accommodation into which sediment is deposited and plays a major role in delta morphology and stratigraphic architecture.","PeriodicalId":48749,"journal":{"name":"Earth Surface Dynamics","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139661571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
期刊
Earth Surface Dynamics
全部 Acc. Chem. Res. ACS Applied Bio Materials ACS Appl. Electron. Mater. ACS Appl. Energy Mater. ACS Appl. Mater. Interfaces ACS Appl. Nano Mater. ACS Appl. Polym. Mater. ACS BIOMATER-SCI ENG ACS Catal. ACS Cent. Sci. ACS Chem. Biol. ACS Chemical Health & Safety ACS Chem. Neurosci. ACS Comb. Sci. ACS Earth Space Chem. ACS Energy Lett. ACS Infect. Dis. ACS Macro Lett. ACS Mater. Lett. ACS Med. Chem. Lett. ACS Nano ACS Omega ACS Photonics ACS Sens. ACS Sustainable Chem. Eng. ACS Synth. Biol. Anal. Chem. BIOCHEMISTRY-US Bioconjugate Chem. BIOMACROMOLECULES Chem. Res. Toxicol. Chem. Rev. Chem. Mater. CRYST GROWTH DES ENERG FUEL Environ. Sci. Technol. Environ. Sci. Technol. Lett. Eur. J. Inorg. Chem. IND ENG CHEM RES Inorg. Chem. J. Agric. Food. Chem. J. Chem. Eng. Data J. Chem. Educ. J. Chem. Inf. Model. J. Chem. Theory Comput. J. Med. Chem. J. Nat. Prod. J PROTEOME RES J. Am. Chem. Soc. LANGMUIR MACROMOLECULES Mol. Pharmaceutics Nano Lett. Org. Lett. ORG PROCESS RES DEV ORGANOMETALLICS J. Org. Chem. J. Phys. Chem. J. Phys. Chem. A J. Phys. Chem. B J. Phys. Chem. C J. Phys. Chem. Lett. Analyst Anal. Methods Biomater. Sci. Catal. Sci. Technol. Chem. Commun. Chem. Soc. Rev. CHEM EDUC RES PRACT CRYSTENGCOMM Dalton Trans. Energy Environ. Sci. ENVIRON SCI-NANO ENVIRON SCI-PROC IMP ENVIRON SCI-WAT RES Faraday Discuss. Food Funct. Green Chem. Inorg. Chem. Front. Integr. Biol. J. Anal. At. Spectrom. J. Mater. Chem. A J. Mater. Chem. B J. Mater. Chem. C Lab Chip Mater. Chem. Front. Mater. Horiz. MEDCHEMCOMM Metallomics Mol. Biosyst. Mol. Syst. Des. Eng. Nanoscale Nanoscale Horiz. Nat. Prod. Rep. New J. Chem. Org. Biomol. Chem. Org. Chem. Front. PHOTOCH PHOTOBIO SCI PCCP Polym. Chem.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
×
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
现在去查看 取消
×
提示
确定
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 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 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1