Recent ice ages on Mars
Recent ice ages on Mars
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DOI：
10.1038/nature02114
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发表时间：
2003-12-18
期刊：
影响因子：
64.8
通讯作者：
Marchant, DR
中科院分区：
文献类型：
--
作者：
Head, JW;Mustard, JF;Marchant, DR
地球冰河时代的一个关键起搏器是由于行星轨道参数变化引起的气候强迫。最近的火星探索揭示了尘土飞扬、富含水冰的地幔沉积物，这些沉积物呈层状，厚数米，且与纬度有关，分布在从中纬度到两极的两个半球。在这里，我们展示的证据表明，这些沉积物是在地质上最近的冰河时期形成的，该冰河时期发生在大约 2.1 至 0.4 Myr 之前。这些沉积物对称地分布在大约 30 度的纬度，相当于地球上的沙特阿拉伯和美国南部，这是为了响应倾斜角（火星自转极点与黄道面之间的角度）达到 30 - 35 度时水冰和尘埃稳定性的变化。火星目前正处于“间冰期”，富含冰的沉积物正在经历改造、退化和退缩，以应对当前近地表冰的不稳定。与地球不同，火星冰河时代的特点是极地气候变暖，大气中水和尘埃向赤道的输送增强，从而在中纬度地区产生广泛的光滑沉积物。
A key pacemaker of ice ages on the Earth is climatic forcing due to variations in planetary orbital parameters. Recent Mars exploration has revealed dusty, water-ice-rich mantling deposits that are layered, metres thick and latitude dependent, occurring in both hemispheres from mid-latitudes to the poles. Here we show evidence that these deposits formed during a geologically recent ice age that occurred from about 2.1 to 0.4 Myr ago. The deposits were emplaced symmetrically down to latitudes of similar to30degrees equivalent to Saudi Arabia and the southern United States on the Earth - in response to the changing stability of water ice and dust during variations in obliquity ( the angle between Mars' pole of rotation and the ecliptic plane) reaching 30 - 35degrees. Mars is at present in an 'interglacial' period, and the ice-rich deposits are undergoing reworking, degradation and retreat in response to the current instability of near-surface ice. Unlike the Earth, martian ice ages are characterized by warmer polar climates and enhanced equatorward transport of atmospheric water and dust to produce widespread smooth deposits down to mid-latitudes.