While we generally do not show operations at Site 3 to visitors because of its remoteness and location at the end of a forest road on a steep slope, Site 4A is easily reachable.
Our drilling engineer typically brings down the cores of the day after the end of the shift. We unload them in the dark to process them the next morning.
A third rig arrived this morning at Site 2 ("White tidal sandstone"); the trucker drove through the night. This site is located literally a few m from the popular r40 geotrail, a scenic winding route through the central Barberton Greenstone Belt.
Borehole 3 has penetrated 66 m of cross-bedded sandstones, is back in microbially laminated sandstones, and is heading to its final target, a micro-stromatolitic unit.
Newcomers to this project sometimes need to get used to our drilling geometry. Because the strata are overturned, we usually drill stratigraphically upward (but topographically usually downwards). Oldest strata are drilled first; the further we drill, the younger they get!
Drillers work Saturdays until 1 pm, and thus, so do we (on Friday's deliveries). Sundays are then dedicated to household chores and admin (such as uploading MoDs :-) ...)
Cores from borehole at Site 3, in contrast, give us few problems: They are quartz-cemented quartzose sandstones, either with abundant crinklies or large-scale crossbedded.
A delegation of the provincial environmental agency came to visit our exhibition, the core processing, and the drill sites. They were particularly interested in the significance of our research because this agency has been (controversially) been tasked to build up and administer the still-not-activated World Heritage Site.
Core from borehole 4A in the distal Lomati Delta is broken in such intensity by small stress fractures that rearranging, bandaging, slabbing and describing the core becomes extremely slow and cumbersome.
The Xmas and New Years break brought more rain than usual. Roads are a bit wet. Drilling switched from intermediate HQ to final (slim) NQ. We are now drilling somewhat faster but not yet fast enough and are still significantly behind schedule.
The reconstructed core, when slabbed, can actually be quite pretty. It resembles in composition the tuffaceous estuary channel fills from the White Outcrops.
We are processing the last core of the year. It is, as the previous several cores from site 4A, of good quality but terribly fractured - not clear whether due to geology or due to drilling.
The drillers had their best day so far yesterday and brought us 8 trays (of 5 one-m cores each). We all put in a Saturday morning shift to start processing this heap.
It now rains once, twice or thrice daily. This is not usual even though this is the subtropical monsoonal summer rainy season. While we are unaffected in the hall where we process the core, the two rigs and their crews face all kinds of problems.
Repairs on rig MDX315 are coming to an end but MDX317 at Site 3 has started to deliver high-quality core through sandstones with abundant microbial mats. The rig at Site 4A had a mechanical breakdwon but the rig at Site 3 produced 12 m of fresh core through "crinkly" quartzose sandstone.
Summer in South Africa is turning out unexpectedly cool, today not more than 18° C. Drillers have a long weekend. Dora and Christoph went with visitor Jeff Moyen and his PhD student Steve on a field trip.
Rig MDX317 began drilling its first few m at Site 3 in silicified sandstones with microbial mats. After completing stabilizazion on soft ground, rig MDX315 drilled 15 m of weathered and altered rocks, mostly tuffaceous sandstone, now at 55.45 m MD; ca. 30m vertical depth.
We oriented MDX317 at Site 3 perpendicular to strike prior to site preparation and rigging up. MDX 315 at Site 4A set surface casing. We spent much of the day giving Jean-Francois Moyen and PhD student Laurine Traverse an intro to the project; JF also took some great footage using his drone.
Dora, Phumi and Christoph conducted a field trip along the geotrail for 2nd-year UJ students, including a visit to Site 4A. The drill crew there supported the rig and the drilling platform by heavy cement blocks to prevent any further sinking into the mud, then started to install surface casing to bedrock. MDX817, parked outside Barberton, was loaded on a powerful flatbed truck at 6:30 a.m., swiftly transported up the mountain, and unloaded at Stn.6 pass. From there, it tracked itself ca. 3 km along forest roads and reached Site 3 by mid afternoon.
Drilling at Site 4A by MDX315 is still halted, with an open hole waiting for surface casing in steady rain. The site is becoming difficult to access. Technicians repaired filters at the SRU. Rig MDX317 arrived per flatbed truck outside Barberton 11:30 a.m. The truck meant to transport it up the mountains was found to be underpowered; now waiting for a stronger replacement truck. The rig may have to drive itself in to Site 3 for several km because roads are currently too wet and weak to support heavy wheeled vehicles.
Steady rain has set in. Drillers stabilized rig on soft ground, battled with stuck drillpipe and washed-out hole. One core run to 34.30 m retrieved 1m core of increasingly firm pink sandstone. Sunday is off-day; plan to set surface casing on Monday.
Drillers continue to struggle through deeply weathered rock, had temporarily stuck pipe. The base of the last core run, 30.30m MD (ca. 21 m TVD) showed indications of bedding in pink sandstone.
Drillers continued to struggle today with getting through deeply weathered clayey-sandy strata, reached 19.3 m depth with about 50% core recovery. Christoph and Dora set up the photo stand (frequent trips to the hardware store across the street :-))
Drill hole 4A (renamed from 4-1 to align with ICDP terminology) was spudded this morning 11:40 a.m, initiating the BASE drilling campaign. We drilled 7 m of inclined borehole and recovered ca. 4 m of sandy-clayey soil. The drillers plan to set surface casing tomorrow, once they are through the soil.
Drilling was supposed to have started this morning, following a briefing on the SRU (Solid Removal Unit, in my understanding akin to a mud centrifuge), but the truck delivering drill rods broke down outside Barberton. We have not received an update from the drillers but hope for tomorrow.
The hall for outreach activities and core processing is almost set up and the on-site team is eagerly waiting for the drill rigs to arrive in the next days.
