Leçon :
Histoire et définition : Les Ophiolites sont un ensemble de roches appartenant à une portion de la lithosphère océanique, charriée sur le continent lors d'un phénomène de collision (convergence) de deux plaques lithosphériques. Dans ce cas, il s'agit de formation de basalte en Pillow-lavas (laves en coussin), ils se sont formés par la mise en contact de lave basaltique chaude et l’eau de l’océan très froide. Dans les Alpes françaises et italiennes, les ophiolites, reliques du plancher océanique de la Téthys alpine, ont environ 160 millions d'années ; leur obduction sur la lithosphère continentale est un épisode de l'orogenèse alpine.
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With Flo, we share a great passion for geocaching: EarthCaches 🥰. We are intense rock hunters! 🪨😄 You could even say it’s a real crush 🤢. Our second geocaching passion is GeoArt 🤩. So we pushed ourselves a bit and decided to mix the two. A big headache to set up 😵, but in the end, totally doable.
Questions : Locate the blue dot in the photo above and answer the following:
1 - What type of basalt formation is this ?
2 - Based on your observation, what color is this ophiolite ?
3 - What type of pillow lava is this?
4 - Take a photo in front of this wall (without the ophiolite), with your geocaching username visible, and make a ☝️ sign with your hand.
EarthCache Rules: "Log this "Found it" cache and send me your suggested answers either via my profile or via email, and I will contact you if there is a problem."
Lesson :
History and definition : Ophiolites are a group of rocks representing a portion of the oceanic lithosphere that has been thrust onto the continent during a collision (convergence) between two lithospheric plates. In this case, the rocks are basalt in pillow-lava formations (also called pillow basalts). These formed when hot basaltic lava came into contact with very cold ocean water, causing rapid cooling and the characteristic rounded shapes. In the French and Italian Alps, ophiolites are remnants of the oceanic floor of the Alpine Tethys Ocean and are about 160 million years old. Their emplacement onto the continental lithosphere, known as obduction, was a key event in the Alpine orogeny
Happy Géocaching everyone 😎