10.8线下小狗（第一次放狗能记住的不多

努力杀鸡的99

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billyisfragile!

Long Channels (Canali)

Most landforms of the volcanic plains and rises are reasonably ascribed to basaltic lavas. However, in several places the basaltic plains are incised by long meandering channels, designated canali—the fluid that cut the canali is not known. Canali are long channels, from 500 to 6800 km in length, sinuous and meandering, incised into volcanic plains (and rarely tesserae). Their widths are typically 3 km, ranging up to 10 km, and are constant over the lengths of each canale. Shorter channels are comparable to the lunar sinuous rilles, and can reasonably be ascribed to the flow of basaltic lava. But the longer canali, with their constant widths, are enigmatic.

The challenge presented by canali is to understand what sort of fluid could flow, at Venus’ surface, for the distance and time needed to produce channels 500 to 6800 kilometers long. Baker et al. [1992] showed that the canali required a low-viscosity fluid that was either very hot or had a melting temperature close to that of the Venus surface. Basaltic and komatiitic lavas seem to be precluded by their rapid cooling rates on Venus. The rapid cooling could be reduced by formation of an insulating cover, partially as a roof (although the channels are too wide to be spanned to form a lava tube), and partially by solid plates floating on and carried by the flow. On the other hand subsurface flows of basaltic lava could conceivably produce long channels, but it is not clear if sub-surface flows could produce the observed meanders of the canali.

然后k又出现什么问题说明k也不可能造成s这种情况（因为k的某些特性决定的，好像是温度）
因此，s跟r不可能是同一种东西，那么造成s 的物质是什么呢，是c这种熔浆，这种熔浆只在地球上被观察存在，它有比较少的物质a所以不容易凝固，又有区别于k熔浆的什么特性，导致它能冲刷出出前文所提到的那些s具有但是r不具有的特性。

所以又有一种解释是说lava只是warmer, 并且low viscocity。之后比较了lava里面含的硅，没有某种在地球的lava上有物质。这些原因导致slow cooler（这里有高亮题），使得慢慢凝固并出现结晶的沉淀。

Possible liquids other than basalts include liquid sulfur, carbonate-rich lavas (carbonatites), and even water if the channels formed when Venus’ surface were considerably cooler than at present. Liquid sulfur is a plausible product of reaction between oxidized atmospheric sulfur and reducing silicate rocks, but its low vapor pressure in the Venus atmosphere may imply that it would evaporate too rapidly to produce long channels [Komatsu et al., 1992]. Carbonate-rich and carbonate-sulfate lavas were considered by Kargel et al. [1994], and shown to have appropriately low viscosities, erosive potentials, and melting temperatures. They also showed that carbonate-sulfate liquids could plausibly form in the shallow crust by burial of basalt rock that was weathered at the surface.

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akkksd

数学第二题答案错了吧