After sitting an entire year at ca. 250 m depth (which means: also below sea-level) in hole 5071_1_B near Ornavasso, the broadband borehole seismometer has successfully resurfaced! After some initial tension in the cable and at the winch, all went smoothly and the UNIL+INGV team left the site clean and tidy well before dinner. The rain gauge has recorded 1.6 m of precipitation in 9 months.
Cheers to the end of drilling at drill site DIVE_1A! Today the site DIVE-1A got busy, with a nice party organized by the drilling company and DIVE, together with local representatives. Meanwhile borehole logging is starting to produce nice results!
Final depth has been reached at DT-1A! More than satisfactory lithological and structural variations, time constraints and some technical difficulties with the rig, contributed to the decision to stop the drilling at 909.5 meters. While the shipping of cores is being prepared, now on-site operations are all focused to prepare the borehole logging activities in the next weeks.
Three more cores on deck today, with nice mylonites and pyroxenites. Site is now being prepared for the Easter break and important decisions are being discussed for the ending of the drilling!
Diving to the deepest lower crust! Today the borehole reached 900 m, with new metagabbronorite and pyroxenite cores. A very nice goal reached just before the Easter holidays.
An issue with the rig has been slowing down drilling in the last few days, but today a temporary solution has been found and new cores arrived on deck. Drilled depth is 882 meters!
Another six cores today, which allowed to arrive to 855m depth. Very nice crystal-rich fracture zones make the cores even more attractive for the DIVE geologists and for the visitors of the day.
Six nice and intact cores reached the deck today, after some fracture zone crossed yesterday. We are at 837 m depth. And after the shady winter of Megolo, the sunshine starts to hit the site!
Almost two silent weeks passed, because of a malfunctioning pump of the drill rig. The problem has been solved and today drilling started again. Three cores on deck, and surprise surprise a nice transition from metagabbronorites to pyroxenites arrived! Bottom depth is now 783 meters. Meanwhile happy students and scientists visited the site.
A lot happened in the last few weeks. Many meters have been drilled, arriving to a bottom depth of 770 m. Some fracture zones were encountered and a lot of rods now need to be pulled at every drill bit change. But the intact cores keep showing new and variable structures and nice lithological transitions!
After getting to a bottom depth of 680 meters and recovering intriguing ultramafic rocks, rods had to be pull out because of drill-bit consuption. Meanwhile life on site is quite active, with visits from the local authorities and DIVE scientists planning for the next steps.
Eight more cores on deck today, with the drilling being more and more difficult due to the quickly changing lithologies and presence of fractures. The cores are rich of surprises and the day ended well, with a bottom depth of 674 m!
After a three-days stop for manteinance, drilling started again on Friday and brough on deck rocks that change toward ultramafic lithologies. More fractured rocks at depth seems to make drilling more demanding. Meanwhile today we had a nice visit from the happy and enthusiatic neighbours from the Megolo area.
After 60 m of hard work and arriving at 619 m depth, the drill bit decided that the moment to getting completely consumed arrived. So rods were pulled, drill bit was changed and now the rods are being put back into the borehole. Meanwhile in these days we had a nice visit from the staff of the University of Lausanne.
Happy science team and happy drilling crew in the last two days... fifteen cores, nice variations in lithologies and structures, the 600 m depth has been crossed, and the bottom depth is now 619 m!
Borehole 5071_1A just surpassed the first hole 5071_1B! After seven nice cores on deck, today we arrived to a bottom depth of 585 meters and placed a new record in DIVE. Cores never stop to surprise, with so many types of layering and a lot of cross-cutting veins, fractures and cataclastic zones.
After changing to a new drill bit, drilling continued in the afternoon and three cores arrived on deck, which include metagabbronites showing nice mineralogical layering. Bottom depth is now 565 meters. Meanwhile we had a nice visit by representatives of UNESCO, regional geological survey and Val Grande national park.
Busy days for divers and the drilling company, with important and productive discussions about the next steps in the drilling operations. Meanwhile busy days also on deck: bottom depth is now 550 meters and new mafic lithologies are being crossed!
The last two days brough 7 more cores on deck, the last one from a bottom depth of 476 meters. Nice lithological changes were observed in the last cores, right when visitors from Lausanne University were on site. And today we filled the core box number 100!
Less than half a day of drilling today, but three more cores were brough on deck. The bottom of the borehole now is at 456 meters. Drillers and science team will certainly enjoy a short break over the weekend, given the "chilly weather" on the site today (-8°C) !
The last two days were quite productive for the divers. A travel to a bottom depth of 447 meters brough on deck fifteen more cores. Geologists on-site are observing a large variety of new structures, including quartz-rich layers, fault gouges, large pseudotachylyte levels, and a possible transition to metapelitic lithologies.
Yesterday a problem with the inner barrel forced the drillers to pull the rods, but the problem was solved and three more cores were brough on deck today, crossing the 400 meters depth
After reaching 362 meters depth, the drillbit diameter has been decreased and today drilling with HQ started. Six cores have been recovered, arriving to a bottom depth of 377 meters.
A good start after the Christmas holidays! After a successful logging of the first 315 meters, in the last few days 45 meters of mostly intact cores have been brought on deck. Bottom depth today is 360 meters. Meanwhile outreach activities continue, with visitors from the national Swiss television shooting a short documentary about DIVE drilling operations.
And the last DIVE 5072_1_A core of 2023 just arrived on deck! It was a good day with nice intact cores of metagabbros including garnets as big as fists. At a bottom depth of 315 meters the drillbit arrived at its end and so it was time to pull the rods and start preparing the site for the Christmas break.
And 300 meters have been crossed! And it happened with a nice intact core made of garnet-rich metagabbro. The drill rig in the last couple of days kept the drillers busy also with some minor issues related to the must.
Six more cores were on deck in the last two days in the "chilly" weather of Megolo. A fractured metagabbro with nice epidote mineralization is one of the last gifts of the day. Drillbit reached 288.5 m depth. Meanwhile science team is planning for the work to be done before the Christmas break arrives.
After the weekend break, drilling brough five new cores on deck, some of which witness a new fracture zone. Bottom depth at the end of the day is 273 meters. Meanwhile some first core boxes have been wrapped and prepared for shipping, taking the chance of a nice sunny day.
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.
Containers for the science team finally arrived and the preparation is proceeding, despite quite a rainy day. Equipment for online gas analyses also arrived and is ready to be installed. Meanwhile, the sedimentary cover has not yet been crossed.
