COASTAL GEOMORPHOLOGY OF THE MARTIAN NORTHERN PLAINS
COASTAL GEOMORPHOLOGY OF THE MARTIAN NORTHERN PLAINS
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DOI：
10.1029/93je00618
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发表时间：
1993-06-25
影响因子：
4.8
通讯作者：
SCHNEEBERGER, DM
中科院分区：
文献类型：
--
作者：
PARKER, TJ;GORSLINE, DS;SCHNEEBERGER, DM
北方低地平原约占火星表面积的三分之一。大多数外流渠道和许多山谷网络流入低地，但很少或根本没有形态学证据表明，通道切割继续深入平原，尽管继续basinward区域地形梯度。从这些渠道排出的水的直接命运取决于其就位时的主要古气候。尽管目前的火星古气候模型表明，在火星历史的大部分时间里，年平均温度可能低于冰点，但地貌证据表明，当时发生了规模与著名的陆地古湖泊相当的海岸侵蚀。这些地貌可以追溯到北方平原几乎完全封闭，似乎需要至少两个，也许是几个，温度高于冰点的海洋或海洋的高地，至少在地质学上短暂的时间。最新的高点可能是在亚马逊河早期。这些地形的海拔和面积范围提供了独立的火星水预算的估计，可以与流行的火星挥发性演化模型进行比较。北方平原周边主要河道系统排放的水和沉积物的估计量可与根据现有地形计算的流域体积进行比较。仅环Chryse流出通道的数值就足以在盆地内产生大量的静水。这些估计值可能与所确定的较年轻、范围最小的高位所含的盆地体积相当。较早的、更广泛的高位描绘了一个盆地，其隐含体积要大得多，这可能需要在主要通道事件之前，在北方平原存在半永久性的、可能被冰覆盖的海洋。现今的北方平原可能由水成沉积物组成，沉积物与来自主要火山中心的洪水熔岩互层至相当深的深度，沉积物构成了现今地表的大部分。
The northern lowland plains comprise approximately one third Mars' surface area. Most outflow channels and many valley networks debouch into the lowlands, yet there is little or no morphologic evidence to suggest that channel cutting continued far into the plains, despite a continued basinward regional topographic gradient. The immediate fate of the water discharged from these channels was dependent on the prevailing paleoclimate at the time of its emplacement. Though current models of the martian paleoclimate suggest that mean annual temperatures were likely below freezing throughout most of martian history, geomorphic evidence suggests that coastal erosion on a scale comparable to that of well-known terrestrial paleolakes occurred. These landforms can be traced to nearly complete closure of the northern plains and appear to require at least two, and perhaps several, highstands of a sea or ocean with temperatures above freezing at least for geologically brief periods of time. The latest highstand may have been as recent as Early Amazonian time. The elevations and areal extent of these landforms provide independent estimates of the martian water budget that can be compared to prevailing models of martian volatile evolution. Estimated volumes of water and sediment discharged by the major channel systems peripheral to the northern plains can be compared to the volume of the basin based on the available topography. Values for the circum-Chryse outflow channels alone are sufficient to have produced large bodies of standing water within the basin. These estimates may be comparable to the basin volume contained within the younger, least extensive highstand identified. The earlier, more extensive highstand delineates a basin with a much larger implied volume that may require the presence of a semi-permanent, possibly ice-covered ocean in the northern plains prior to major channeling events. The northern plains today probably consist of water-lain sediments interbedded to considerable depths with flood lavas from the major volcanic centers, with sediment comprising most of the present surface.