CORES DESCRIBERS : 3 teams, 3 specialties, 1 goal EPISODE 1: IGNEOUS PET

IGNEOUS PETROLOGISTS

Jim, Lyderic, Tomo, Chuan-Zou, Biswajit, Alessio

They focus on lithology and mineral composition. They have to determine grain size, modal composition (percentages of olivine, plagioclases, pyroxenes), texture … observing the cores. And the thin sections are carefully chosen to tell the story of the magmatic chamber !

Grain size is determined thanks to the expertise of these guys that can observe and measure, on a sample section, the maximal size of each kind of mineral and estimate the percentage and the average size in a few seconds. Lyderic, Tomo, Alessio, Biswajit are specialized in these type of description.

Tomo and Alessio, Igneous pet. Carlotta, structural pet.

Texture is the way the minerals are organized one with the others. Here, in the olivine-gabbro we get from the oceanic crust, we can observe almost subophitic texture and some kind of layering when they are deformed.

Left to right : Biswajit, Natsue, Tomo, Lyderic and Alessio

Subophitic means plagioclase and olivine crystallized first and then pyroxene grow around them. Such precise observation are done thanks to thin sections observation with microscope.

Thin section of fine grains and coarse grains contact.

Jim and Chuan-Zhou also track the oxides and zircons, ten hours per day !

We are the 31st of December, no more cores but there is stillwork to do : personnal sampling to obtain the material to work on onshore, Hole A1125 report to correct, and

And … Happy last day of the year 🙂