地质灯笼 (Ge o’ the Lantern)

本文发表于《大众科学》的前博客网络，反映了作者的观点，不一定代表《大众科学》的观点 (This article was published in 大众科学’s former blog network and reflects the views of the author, not necessarily those of 大众科学)

(万圣节快乐！这篇文章最初发表于 En Tequila Es Verdad 博客，于 2011 年，我认为大家可能会喜欢在这里重刊。正常发帖将很快恢复，现在服装狂潮已经结束，只剩下庆功派对了。很快再见！)

也被称为地质灯笼，是普通南瓜灯笼的一个亚种。(Otherwise known as a geolantern, subspecies of the common jack o’ lantern.)

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是的，我给这个该死的东西上了色。相信我，你不会想让我拿着刀靠近南瓜的。结果可能会让你想起开膛手杰克犯罪现场的照片。(And yes, I painted the damned thing. Trust me, you don’t want to let me near a pumpkin with a knife. The results could put you in mind of Jack the Ripper crime scene photos.)

这一切都源于一系列有趣的事件的巧合。正如我所说，我非常不擅长雕刻南瓜，所以我本来打算放弃 Michael Klaas 的 “增生楔” 主题。没有时间，工具，也没有南瓜，对吧？即使如此，还在忙着写 NaNoWriMo。但是，在星期天，在去车里取汽水的路上，我看到了这个完美的、原始的南瓜，真是太美了，孤零零地坐在垃圾箱旁边。所以我把它捡起来搬上楼。我对被遗弃的葫芦科植物成员有种特别的喜爱。(This all came about through an interesting confluence of events. As I said, I am teh suck at pumpkin carving, so I was going to give Michael Klaas’s Accretionary Wedge topic a miss. Didn’t have time, tools, or a pumpkin, right? Busy doing NaNo, even so. But then, on Sunday, on the way out to the car to retrieve soda, I saw this beauty of a pristine pumpkin sitting forlornly by the dumpster. So I fetched it up the stairs. I have a soft spot in my heart for orphaned members of the squash family.)

嗯，我想。我可以把它变成一块混合岩。(Hmm, I thought. I could turn it into a migmatite.)

然后 Volcanoclast 发布了这张漂亮的台面照片 (And then Volcanoclast posted this beaut of a countertop)

灵感就此而来。(And there it was. Inspiration.)

糟糕的是，我在绘画方面几乎和雕刻一样糟糕，但尽管如此，结果还算不错。(It’s too bad I suck almost as much at painting as I do carving, but it didn’t turn out too badly for all that.)

那张照片让我着迷，并在 Twitter 上引发了一场对话。这是那种可能被当作花岗岩出售的东西，但这里面包含的内容远不止这些。你有浅色的基质岩石，然后是这些颜色较深的包体。看起来像是长英质物质吞噬了镁铁质物质。这种情况有时会发生，当侵入的岩浆团抓住其他物质的碎片并将它们融入其中时。融入的碎片有时会融化，但并非总是如此。(That photo fascinated me and started a conversation on Twitter. It’s one of those things that probably got sold as granite, but there’s so much more going on here. You’ve got a pale host rock, and then these darker inclusions. It looks like something felsic gobbled up something mafic. That happens sometimes, where a mass of intruding magma grabs up bits of something else and incorporates them. The incorporated bits sometimes melt, but not always.)

然后 Lockwood 提到了反应边。我认为这才是真正吸引我注意力的东西，因为我以前从未听说过这些。(And then Lockwood mentioned reaction rinds. I think that’s what really grabbed my attention, because I hadn’t heard of those before.)

看到那些围绕着蓝灰色内部的较深岩石晕圈了吗？那就是他所说的。从 Twitter 语翻译成英语，以下是他所说的：“当捕虏岩/包体在岩浆环境中不稳定时，它会与岩浆发生反应，形成新的矿物。这些可以保护包体，和/或减缓反应速度，直到熔体在所有物质都反应完之前冷却。这留下了一个几乎原始的包体，周围环绕着 ‘反应边’。”(See those halos of darker rock around the blueish-gray interior? That’s what he was talking about. Translating from Twitterese to English, here’s what he said: “When a xenolith/inclusion isn’t stable in a magmatic environment, it reacts with the magma to form new minerals. These can protect the inclusion, and/or slow the reaction to the point where the melt cools before it all reacts. This leaves a mostly pristine inclusion surrounded by a ‘reaction rind.’”)

有问题的包体可能是钙长石，根据 Ron 的说法，是辉长岩的一种变种。深色包体中可爱的、略带蓝色的颜色可能来自 拉长石 矿物。如果你还没有机会欣赏它，去你当地的岩石商店买一些。转动它。观察它在壮丽的彩虹色中闪烁和发光。它太美了。(The inclusion in question is probably anorthosite, a variety of gabbro, according to Ron. The lovely sort-of blue in the dark inclusions probably results from the mineral labradorite. If you haven’t yet had the opportunity to enjoy some, get thee to your local rock shop and pick some up. Turn it round. Watch it shimmer and shine in a magnificent sort of iridescence. It’s gorgeous.)

Ron 不确定是什么导致了反应边中深沉而浓郁的棕色（或者如果你想要一个不那么像葫芦的同义词来形容这种现象，也可以称之为晕圈，尽管 “边” 非常符合这个增生楔主题的精神，你不觉得吗？）。可能是 角闪石。可能是 黑云母。通过台面的照片来确定这些事情并不总是可能的，无论照片多么棒。我们可以拿一个手标本并确定地找出答案，但台面所有者可能不太愿意允许这样做，即使是为了科学。(Ron’s not sure what’s causing the deep, rich brown color in the reaction rinds (or coronas, if you’d like a less gourd-like synonym for the phenomenon, though rind fits rather well with the spirit of this Accretionary Wedge theme, don’t you think?). Could be hornblende. Could be biotite. It’s not always possible to determine such things through a photograph of a countertop, no matter how awesome. We could grab a hand sample and find out for sure, but the countertop owner may not be entirely willing to allow that, even if it’s for science.)

所以，这就是启发了一篇增生楔文章的照片，并开启了一个全新的主题。未来请关注台面地质学！并关注 Volcanoclast 的博客。那里有很多好东西，外加一个引人入胜的神秘台面即将到来！(So, that’s the photo that inspired an Accretionary Wedge post and launched a whole new topic. Watch for countertop geology in the future! And watch Volcanoclast’s blog. Great stuff there, plus an intriguing mystery countertop to come!)

与此同时，我将留给你们一张猫与地质灯笼的凶残照片，法语：chat meurtrier avec la geolanterne。(In the meantime, I’ll leave you with a photo of chat meurtrier avec la geolanterne.)

感谢 Volcanoclast、Lockwood DeWitt 和 Ron Schott 提供的灵感和帮助。(With gratitude to Volcanoclast, Lockwood DeWitt, and Ron Schott for their inspiration and assistance.)