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关于一个构造问题与欧洲顶级大学教授的对话实录

已有 10732 次阅读 2013-3-21 17:18 |系统分类:科普集锦| 大学, 教授

 

      前天,偶然看到一位欧洲顶级大学教授编著的构造地质学方面新教材,其中图件很漂亮,论述也比较系统,是一本适合研究生使用的好教材,虽然内容并不新颖。但是,其中存在一些问题。其中一个构造问题,我与这位教授有一段电子邮件对话。这个构造问题具有普遍性,是有关专业人士容易犯的错误。这类理论上的小错误,可能会导致巨额的实际经济损失,例如:一口费用达亿元钻井的失败,可能就是解释地震勘探资料人员犯这类错误导致的。因此,借用这段电子邮件对话科普一下很有必要。

     这位欧洲顶级大学教授的母语不是英语,但他的英语水平应该很高(曾经和现在是多个著名英语期刊的主编和编委,纯欧洲血统,通晓法语、德语和英语,现在工作的大学世界排名一般是排在前15-20)。不过,由于对话是informal,他的英语似乎informal。我是土鳖,英语informal“理所当然”。下面是我与这位教授关于这个构造问题电子邮件对话实录(仅更正了几个字母),其中,Prof. KQC是这位教授(不必写真实姓名吧),XU是我。

 

XU:

Prof. KQC,

I am pleased to learn that you have published the teaching materials-------extension, strike-slip and thrust systems. I believe that the materials will help many Chinese students. However, I find some figures in the materials may be wrong. May I discuss this issue with you? Thanks!

Best wishes,

Dr. Junyuan XU

 

Prof.KQC: sure. tell me which figures?

 

XU: Is the offset of the antithetic fan fault (left of the central high) in the figure extension system on page 155 too large? The section cannot be balanced.  But if this figure is not wrong, could you please tell me how to balance this section?

 

注:the figure on page 155就是下图

 

Prof.KQC: No it is fine like that. The section is not balanced and cannot be balanced (the left hand side of the hanging block is not represented, it should be beyond the limit of the footwall. Note that you cannot balance such sections if you admit strain (which the roll over implies), i.e. deformation is not only brittle, limited to slip on fault planes.

 

XU: However, the faulting in the section means deformation is dominantly brittle. Sections with the rollovers generally can be balanced (e.g., page 190).  

Could you tell me whose paper the figure on page 155 comes from? I am interested in further studying it.

 

Prof.KQC: It comes from no paper, it is a self-generated figure for teaching purposes and emphasize main features; you can find them in the Spec Pub Lond 56. Only some rollover sections can be balanced, as mentioned; it depends on the internal deformation of the hanging wall, and often also the internal deformation of the detachment level.

Best wishes

[注:他也许把最原始的参考文献一时给忘了]

 

XU: In fact, all the sections (or volumes) should be balanced whether they undergo brittle or ductile deformation. The figure shows upper-crust deformation, that is, mainly brittle, and the section should have easily been balanced. Similar problem may occur in the lower figure (upper right) on page 164?

Thank you again for your supplying beautiful and excellent teaching materials to all students from all over the world.

Best wishes.

 

注:the figure on page 164就是下图

 

 

Prof.KQC: In fact, as soon as strain (non brittle deformation) is involved, NO section can be balanced. This is a well-known, major caveat of the balancing technique, as you can find it in many publications and textbooks. This is partly due to out-of-plane displacements.

Thanks for your encouraging remarks, and do not hesitate pointing out other problems, I might try to improve them for the next script generation, which is in progress.

Best regards.

 

上面讨论,我点到为止,Prof.KQC也表明他的认识,该结束讨论,但昨天他又给我发了个邮件:

 

Prof.KQC: I looked at and restored the figure of elements in an extension system and think that you would be happier if the duplex were placed below the left synthetic fan of listric fault; this if you want to balance the figure; however, it also depends on the amount of movement (which is not represented there) and on the order in which faults are formed (some may appear late during movements and rotations, therefore cannot be represented on the initial stage); for teaching reasons, the sketch is made only to display the main features and explain the geometrical classification; for this purpose it is acceptable, but I will think about it and might try to construct something more appropriate in the future.

Regards。

 

XU:I will be really happy to see your restored section if you have done this, even if the original figure is modified.

Best wishes.

 

    至此,关于这个问题对话结束,或许将来有一天会收到这位认真又有点固执的教授修改后的原图及其restored section。

 

    应当说明的是,图有问题不意味着全错的,只是需要修改(不改会误导读者),这个问题是“量变到质变”问题,减小“量”就改过来了,例如:将the offset of the antithetic fan fault减小,降低central high高度,等。

 

    最后,希望通过这个讨论,年轻学者能认清这个构造问题,并在将来工作中加以注意。当然,如果有读者认为Prof.KQC的那两张图是对的、无需修改,请与我讨论。

 

==============================================================

 

今天(2013-03-22),收到洋教授的那张图的修改稿了:

 

Prof.KQC: I attach a "balanced" version; thanks for drawing my attention to this question, which I had not treated properly. Strain is limited to the rol-over (area conservation). The rest is brittle (line-length conservation).

 

XU: Thanks. The revised vesion seems better.

 

注: the figure on page 155的修改版如下:

 

 

 

 

向 Prof.KQC 致敬! Let's salute Prof. KQC!



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