Lineated valley fill (LVF), also called lineated floor deposit, is a feature of the floors of some channels on Mars, exhibiting ridges and grooves that seem to flow around obstacles. Shadow measurements show that at least some of the ridges are several metres high. LVF is believed to be ice-rich. Hundreds of metres of ice probably lie protected in LVF under a thin layer of debris. The debris consists of wind-borne dust, material from alcove walls, and lag material remaining after ice sublimated (changed from a solid directly to a gas) from a rock-ice mixture. Some glaciers on Earth show similar ridges. High-resolution pictures taken with HiRISE reveal that some of the surfaces of lineated valley fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terr
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| - Lineated valley fill (en)
- 线状谷底沉积 (zh)
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| - Lineated valley fill (LVF), also called lineated floor deposit, is a feature of the floors of some channels on Mars, exhibiting ridges and grooves that seem to flow around obstacles. Shadow measurements show that at least some of the ridges are several metres high. LVF is believed to be ice-rich. Hundreds of metres of ice probably lie protected in LVF under a thin layer of debris. The debris consists of wind-borne dust, material from alcove walls, and lag material remaining after ice sublimated (changed from a solid directly to a gas) from a rock-ice mixture. Some glaciers on Earth show similar ridges. High-resolution pictures taken with HiRISE reveal that some of the surfaces of lineated valley fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terr (en)
- 线状谷底沉积 (Lineated valley fill),简称“LVF”,又叫线状底表沉积(lineated floor deposit),是火星上某些谷道中的一种特征,显示为象被环流冲刷出道道沟脊的障碍物。阴影测量显示,至少部分沟脊有数米高。据认为,这些线状谷底沉积富含百米厚的水冰,并可能被保护在一层薄薄的岩壳下面。这层岩壳由风载尘埃、碎落岩壁以及冰岩混合物中冰蒸发(从固态直接变成气态)后的剩余物所构成。地球上一些冰川也显示了类似的脊状。高分辨率成像科学设备拍摄的高清照片显示,部分线状谷底沉积表面显示出一层奇特的图案,叫做细胞闭合型和细胞开放型脑纹地形。研究认为这种类似脑纹的地形,为堆积的尘埃和其他碎屑表面产生的裂纹以及部分表面冰升华所致,是重力和季节性冷热变化共同作用的结果。舌状岩屑坡和同心坑沉积也显示出这种相同的表面,因此,这三种结构的表面被认为有关联性。
* 背景相机拍摄的桌山宽景图所显示的线状谷底沉积和舌状岩屑坡(LDA),据信,二者都是被碎屑覆盖的冰川。图像位于伊斯墨诺斯湖区。
* 上一幅桌山图像中的舌状岩屑坡特写,显示了开放型脑纹地形和更常见的闭合型脑纹地形,细胞开放型脑纹地形被认为里面含有冰核。高分辨率成像科学设备拍摄。
* 高分辨率成像科学设备拍摄的闭合型脑纹地形,该类表面更常见于舌状岩屑坡、同心坑沉积和线状谷底沉积。
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| - Lineated valley fill (LVF), also called lineated floor deposit, is a feature of the floors of some channels on Mars, exhibiting ridges and grooves that seem to flow around obstacles. Shadow measurements show that at least some of the ridges are several metres high. LVF is believed to be ice-rich. Hundreds of metres of ice probably lie protected in LVF under a thin layer of debris. The debris consists of wind-borne dust, material from alcove walls, and lag material remaining after ice sublimated (changed from a solid directly to a gas) from a rock-ice mixture. Some glaciers on Earth show similar ridges. High-resolution pictures taken with HiRISE reveal that some of the surfaces of lineated valley fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terrain resembles a human brain. It is believed to be caused by cracks in the surface accumulating dust and other debris, together with ice sublimating from some of the surfaces. The cracks are the result stress from gravity and seasonal heating and cooling. This same type of surface is present on Lobate debris aprons and Concentric crater fill so all three are believed to be related.
* Wide CTX view of mesa showing lineated valley fill and lobate debris apron (LDA). Both are believed to be debris-covered glaciers. Location is Ismenius Lacus quadrangle.
* Close-up of lobate debris apron from the previous CTX image of a mesa. Image shows open-cell brain terrain and closed-cell brain terrain, which is more common. Open-cell brain terrain is thought to hold a core of ice. Image is from HiRISE under HiWish program.
* Closed-cell brain terrain, as seen by HiRISE under the HiWish program. This type of surface is common on lobate debris aprons, concentric crater fill, and lineated valley fill.
* Open- and closed-cell brain terrain, as seen by HiRISE, under HiWish program.
* Wide CTX view showing mesa and buttes with lobate debris aprons and lineated valley fill around them. Location is Ismenius Lacus quadrangle.
* Close-up of lineated valley fill (LVF), as seen by HiRISE under HiWish program. Note: this is an enlargement of the previous CTX image.
* Lineated valley fill, as seen by HiRISE under HiWish program.
* Close view of Lineated valley fill, as seen by HiRISE under HiWish program
* Close, color view of Lineated valley fill, as seen by HiRISE under HiWish program
* Valley showing Lineated valley fill, as seen by HiRISE under HiWish program Linear valley flow is caused by ice movements. Location is Casius quadrangle.
* Lineated valley fill in valley, as seen by HiRISE under HiWish program Linear valley flow is ice covered by debris. Location is Ismenius Lacus quadrangle.
* Close, color view of lineated valley fill, as seen by HiRISE under HiWish program
* Lineated valley fill, as seen by HiRISE under HiWish program Image located in Hellas quadrangle. Lineated floor deposits began as lobate debris aprons (LDAs), which form as material leaves narrow mountain valleys and spreads out as an apron. By tracing the paths of the ridges on LDAs, researchers have come to believe that the curved ridges characteristic of lobate debris aprons straighten out to form the more or less straight ridges of LVF. In the regions where LVF and LDAs occur, many craters have concentric crater fill: large ridges and other surfaces nicknamed brain terrain, after the surface corrugations of the human brain. The study of lineated valley fill and other features related to debris-covered ice has been greatly aided by the abundance of data received from Mars orbiting instruments. Excellent images have been obtained from THEMIS, MOC, CTX, and HiRISE. Detailed altimetry was collected by MOLA. The Mars Reconnaissance Orbiter's Shallow Radar gave a strong reflection from the top and base of LDAs, meaning that pure water ice made up the bulk of the formation (between the two reflections), strong evidence that the LDAs in Hellas Planitia are glaciers covered with a thin layer of rocks. Since lineated valley terrain is derived from lobate debris aprons, it probably contains buried ice—at least in places. (en)
- 线状谷底沉积 (Lineated valley fill),简称“LVF”,又叫线状底表沉积(lineated floor deposit),是火星上某些谷道中的一种特征,显示为象被环流冲刷出道道沟脊的障碍物。阴影测量显示,至少部分沟脊有数米高。据认为,这些线状谷底沉积富含百米厚的水冰,并可能被保护在一层薄薄的岩壳下面。这层岩壳由风载尘埃、碎落岩壁以及冰岩混合物中冰蒸发(从固态直接变成气态)后的剩余物所构成。地球上一些冰川也显示了类似的脊状。高分辨率成像科学设备拍摄的高清照片显示,部分线状谷底沉积表面显示出一层奇特的图案,叫做细胞闭合型和细胞开放型脑纹地形。研究认为这种类似脑纹的地形,为堆积的尘埃和其他碎屑表面产生的裂纹以及部分表面冰升华所致,是重力和季节性冷热变化共同作用的结果。舌状岩屑坡和同心坑沉积也显示出这种相同的表面,因此,这三种结构的表面被认为有关联性。
* 背景相机拍摄的桌山宽景图所显示的线状谷底沉积和舌状岩屑坡(LDA),据信,二者都是被碎屑覆盖的冰川。图像位于伊斯墨诺斯湖区。
* 上一幅桌山图像中的舌状岩屑坡特写,显示了开放型脑纹地形和更常见的闭合型脑纹地形,细胞开放型脑纹地形被认为里面含有冰核。高分辨率成像科学设备拍摄。
* 高分辨率成像科学设备拍摄的闭合型脑纹地形,该类表面更常见于舌状岩屑坡、同心坑沉积和线状谷底沉积。
* 开放和闭合型脑纹地形,高分辨率成像科学设备拍摄。
* 宽景背景相机视图中显示的被舌状岩屑坡和线状谷底沉积环绕的桌山和小丘群,图像位于伊斯墨诺斯湖区。
* 高分辨率成像科学设备拍摄的线状谷底沉积 (LVF)特写,是放大的前一幅背景相机图像。
* 高分辨率成像科学设备拍摄的线状谷底沉积。
* 高分辨率成像科学设备拍摄的线状谷底沉积近照。
* 高分辨率成像科学设备拍摄的线状谷底沉积彩色近照。
* 高分辨率成像科学设备在卡西乌斯区拍摄的有线状谷底沉积的峡谷,冰移动导致的线状谷底流。
* 峡谷中的线状谷底沉积,高分辨率成像科学设备拍摄于伊斯墨诺斯湖区。线状谷底流是被碎屑覆盖的冰。
* 高分辨率成像科学设备拍摄的更靠近的线状谷底沉积彩照。
* 高分辨率成像科学设备拍摄于赫拉斯区的线状谷底沉积。 线状底表沉积起始于舌状岩屑坡(LDAs),当这些碎屑泻入峡谷后就留在了狭窄的谷底,并摊开成一层覆盖层。通过追踪舌状岩屑坡的脊线路径,研究人员逐渐相信舌状岩屑坡弯曲的脊线会慢慢伸直,多少会变成较笔直的线状谷底沉积脊线。在发生线状谷底沉积和舌状岩屑坡的区域,许多撞击坑具有同心坑沉积:巨大的垄脊和类似人脑纹的“脑纹地形”表面。 西弥斯卫星、火星轨道相机、火星勘测轨道飞行器背景相机和高解析度成像科学设备获得的许多火星表面高品质图像以及详细的测高数据。这些大量的数据为研究线状谷底沉积及其它特征提供了极大的帮助。 火星勘测轨道器浅表层雷达接收到了分别来自舌状岩屑坡顶部和底部发出的强烈反射信号,这意味着它的里面大部分为纯净的水冰(在两个反射信号之间),有力地证明了赫拉斯平原的舌状岩屑坡为覆盖着一层薄岩壳的冰川。由于线状谷底地形来自于舌状岩屑坡,因此,可能至少在某些地方含有被埋藏的冰。 (zh)
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