厦门海滨长廊的花岗岩、石英脉与风化作用
中文
您的任务：
-
仔细观察花岗岩台阶：您能发现哪些颜色和结构？描述石英脉的分布情况，并解释它们如何与其他矿物区分开来。
-
重点寻找花岗岩块上的红色染色。哪些区域受影响最严重？在现场您能推断出关于风化过程的哪些信息？
-
触摸花岗岩的表面：它的手感是否均匀，还是有些区域比其他地方更为风化？解释这揭示了不同矿物的耐久性如何。
-
在现场给自己或写有自己名字的纸张拍一张照片，但不要完全泄露秘密。照片是您的日志中必须完成的一项任务。
将此缓存记录为 “找到了”，并将问题答案发送至 “silka03.earthcache@gmail.com ”或通过 Geocaching 消息中心发送给我。不要写在日志中！然后您可以立即登录。我会与您联系。
玩得开心
欢迎来到厦门的海滨长廊，这里巨大的花岗岩块形成了通向水边的台阶。这些令人印象深刻的岩石构造讲述了一段跨越数百万年的地质故事。在这里，您可以了解更多关于花岗岩、其中的石英脉以及造成特有的红色染色的风化过程。
什么是花岗岩？ 花岗岩是一种侵入性火成岩，在地壳深处由冷却的岩浆缓慢结晶而成。在缓慢的冷却过程中，石英、长石和云母等矿物逐渐形成了较大的晶体。这个过程通常需要数百万年，并且发生在地壳深处，那里岩浆被周围的岩石隔离。花岗岩的主要成分包括：
-
石英： 半透明至白色，通常以脉状形式出现。石英是一种非常坚硬的矿物，比其他成分更能抵抗侵蚀和化学风化。
-
长石： 通常为浅色（白色、粉红色或灰色），风化时常常是导致红色染色的罪魁祸首。在化学风化过程中，长石与水和二氧化碳反应，形成黏土矿物和铁氧化物。
-
云母（黑云母/白云母）： 深色、闪亮的矿物，使岩石呈现出“斑点状”外观。黑云母容易风化，最终分解成细薄的片状。
石英脉： 您在花岗岩中看到的石英脉形成于岩石形成的晚期阶段。当剩余的岩浆仍然处于液态时，炽热且富含矿物质的溶液渗入冷却岩石的裂缝和缝隙中。这些溶液含有溶解的二氧化硅，在冷却时结晶，留下明亮、突出的脉络。石英脉特别坚硬，通常在周围岩石风化时保留为凸起的结构。
风化与红色染色： 花岗岩的风化通过物理和化学过程发生。物理风化是指由于温度变化引起的岩石反复膨胀和收缩，导致小颗粒脱落。化学风化则是当水和氧气与矿物质发生反应时产生的。特别是长石，会分解成黏土矿物，而铁含量氧化后产生特有的红色染色。这些铁氧化物积聚在表面，赋予台阶铁锈色的外观。
EN
Your Tasks:
-
Examine the granite steps closely: What colors and structures can you observe? Describe the distribution of the quartz veins and explain how they stand out from the other minerals.
-
Look specifically for reddish discolorations on the granite blocks. Which areas are most affected, and what can you deduce about the weathering process on-site?
-
Feel the surface of the granite: Does it feel uniform, or are there areas more weathered than others? Explain what this reveals about the durability of the different minerals.
-
Take a picture of yourself or a piece of paper with your name on site without completely giving spoilers. The photo is a mandatory task for your log.
Log this cache as “Found it” and send me the answers to the questions to “silka03.earthcache@gmail.com” or via Geocaching Message Center. Not in your log! You may then log immediately. I will get in touch with you.
Have fun!
Welcome to the Xiamen Promenade, where massive granite blocks form steps leading down to the water. These impressive rock formations tell a geological story that dates back millions of years. Here, you can learn more about granite, its quartz veins, and the weathering processes responsible for the characteristic reddish discolorations.
What is Granite? Granite is an igneous intrusive rock that slowly crystallized from cooling magma beneath the Earth's surface. During the slow cooling process, large crystals formed from the minerals quartz, feldspar, and mica. This process often takes millions of years and occurs deep within the Earth's crust, where magma is insulated by surrounding rock. The main components of granite are:
-
Quartz: Translucent to whitish, often visible as veins. Quartz is a very resistant mineral, better withstanding erosion and chemical weathering than other components.
-
Feldspar: Usually light-colored (white, pink, or gray) and often responsible for the reddish discoloration when weathered. During chemical weathering, feldspar reacts with water and carbon dioxide to form clay minerals and iron oxides.
-
Mica (Biotite/Muscovite): Dark, shiny minerals that give the rock its "speckled" appearance. Biotite weathers easily and breaks down into fine layers.
Quartz Veins: The quartz veins you see in the granite formed during the late stages of rock formation. As the remaining magma was still liquid, hot, mineral-rich solutions seeped into cracks and fissures in the cooling rock. These solutions contained dissolved silicon dioxide, which crystallized as it cooled, leaving behind bright, distinctive veins. Quartz veins are particularly resistant and often remain as raised structures while the surrounding rock weathers.
Weathering and Reddish Discoloration: The weathering of granite occurs through physical and chemical processes. Physical weathering happens when the repeated expansion and contraction of the rock due to temperature changes break off small particles. Chemical weathering occurs when water and oxygen react with the minerals. Feldspar, in particular, breaks down into clay minerals, while iron content oxidizes, causing the characteristic reddish discoloration. These iron oxides accumulate on the surface, giving the steps their rust-colored appearance.
https://de.wikipedia.org/wiki/Granit