Three more beautiful cores arrived on deck on Thursday, the last one from a bottom depth of 261.5 meters. Now the drillers have a little bit longer break for weekend, due to italian holidays. A good chance for the science team on site to catch up with some core logging.
... and the core production keeps going! Another set of eigth cores today, and we arrived to a bottom depth of 252 meters. Fresh metagabbros with big garnet porphyroblasts, garnet-rich layers and mylonites are just some of the nice structures revealed by the cores of the day. Meanwhile an enthusiastic visit from the representatives of a nearby local company kepts some of the divers busy with some outreach.
After another good day with 4 intact cores on deck, PQ rods had to be pulled out and the drill bit has been thanked for its long lasting and efficient service. Meanwhile the magnetic susceptibility logger has been repaired and the drilling site has been visited by the Swiss Geophysical Commission.
Another efficient day today: crossing the 200 meters depth and getting eight intact cores on deck. Nice garnet-rich mafic lithologies, often crossed by sealed fractures and shear zones with various mineralogy. Quite some work for the new science crew which arrived yesterday, together with the first snow of the year!
After a bit "frightening" fragmented zone, with interesting cavities, breccia and vein-filling minerals, the cores continued in the lithology we got used to in the past days: metagabbro, with cm to dm scale variability, and many pseudotachylyte/cataclasite zones. Another productive day, with 21 m of new cores, and current hole bottom at 184 m depth. Rain, but in exchange not that cold
A very efficient day in Megolo di Mezzo: 8 cores for a total of 24 metres of cores, mostly metagabbros with some additional nice features. The on-site density estimator had been set up: metapelites at 2.90 and metagabbros at 3.29 g/cm³, is this the Moho?
After a series of clarifications on the actual depth, a productive afternoon brought us many cores, less and less fractures, and gabbro: the last core was broken only in one place! Fluid sampling from early morning to afternoon, and a third microbiology sample was also taken. If every drilling day could be this productive...
Rock consistency varies more rapidly than the rate at which drillers can adapt the drilling bit type. As a result, only 6 meters of cores today, we are past another fragmented zone at ca. 123 m depth. Nevertheless, the rocks and the fractures remain very interesting. In the waiting times we could catch up with some paperwork.
Today the new science crew arrived and had quite a productive day, after we have crossed a depth of 100 m over the weekend. Drilling now is at 115 m, a small fractured zone was crossed and five more cores arrived on deck.
Even so a minor issue with the drill rig slowed down the work on site, we arrived at 97.3 m today and microbiological sampling started! Interesting cores rich of metamorphic and tectonic structures keep arriving on deck.
Nice and productive day, with 18 m of mostly intact cores showing a variety of lithologies and structures. Bottom depth is now 94 m. Busy day but quite a satisfaction for drillers and geologists on site!
The cement is dry and drilling into the much-awaited bedrock could begin. Two days of drilling got us to a depth of 75 meters. Many of the retrieved cores are considerably fractured, but do contain a wide variety of structures that will certainly be of interest to the DIVE scientists. The microbiology team arrived, ready to work on the most suitable samples for the search for deep life.
After tasting the bedrock at a depth of 57.8 meters, a new borehole had to be drilled to adjust for an optimal inclination. Two days of destructive drilling were enough to be back on track and the corrected borehole has already been secured with cement. While waiting the curing, our on-site scientific team is actively analyzing the initial crystalline cores retrieved at the interface between the alluvial deposits and bedrock.
After getting to a depth of 48 m into the sedimentary cover, some difficulties aroused due the presence of very heterogranular sediments. With some changes of drill bits and a temporary use of polymer we got the first rock cores on deck today!
Few more days of drilling into sediments led to a depth of 46.1 meters. Cores on deck were mostly homogeneous silt and fine sand, but the last ones included some angular rock fragments suggesting we might not be far from the bedrock. Meanwhile the preparation of the containers and tent for the science team had been completed and the site is ready to host the first team arriving next week.
