Processed to 3590 feet, lots of intrusions

Today we boxed rock core to a depth of 3590 ft, 122 ft deeper than yesterday.  It was another day of excellent drilling progress, although the processing was more difficult due to the more fractured nature of today's core.  Nevertheless, the rocks were extremely interesting as usual - we saw lots of intrusions.  In fact, we saw at least two intrusions >10 ft in thickness, each with thinner intrusive offshoot arms above and below each main intrusion.  There were a number of striking intrusive contacts, like this one below:

Here an intrusion has invaded pahoehoe lava at a high angle, ~60°.  Some of the core showed nearly vertical intrusions next to the more vesicular lava.  A number of the intrusions had chilled, glassy rinds and had captured small clasts of rock from the flow units they had invaded.  Stay tuned to the blog for updates to see if this intrusive swarm persists as we drill deeper.       

Processed to 3468 feet, a new drilling record

Today we processed rock core to a depth of 3468 ft, 124 ft below the 3444 ft depth that we left off at yesterday.  The previous single-day drilling record for this project was 120 ft, the drilling crews managed to surpass that by just a few more feet.  My congratulations to both the day and night crews, each contributed equally to the achievement.  Although the HQ bit's smaller diameter cuts through the rock faster than the larger PQ bit, we're a lot deeper down the hole now than we were when the previous drilling record was set.  The rock itself also cooperated for a while, it was less fractured today than yesterday and easier to drill and process.  At the end of the day, we received another ~45 ft of core. 

Processed to 3344 feet, a partially filled fracture

Today we processed rock core to a depth of 3344 ft, 113 ft deeper than yesterday.  Processing was difficult because of how fractured the rocks were, some was too fractured to piece back together.  Below is an example of one of those fractures, but this one is more interesting than most:

This is a nearly vertical fracture that splits the core into two halves (one can see clear through the fracture in person, but the camera couldn't capture any light coming through the back side of the fracture).  Such features aren't rare, but this one is different because its top and bottom ends have been filled by clay and other weathering products.  We often see fractures that are open and others that have been filled, but this one shows both!  A partially open, partially filled fracture that you can literally see through is a unique sight so far for this project.  This feature supports my interpretation that fractures are commonly "healed" by groundwater flow and deposition of sediment through them.  Later compaction by subsequent flows and cementation by further alteration can make fractured rock more solid for our drilling.

Processed to 3231 feet, drilled to 3282.5

Today we processed 106 feet of rock core to a depth of 3231 ft.  We saw pahoehoe flows almost exclusively, and surprisingly little olivine in the rock units.  There were a number of baked flow contacts and compound pahoehoe units made up of multiple flows.  Tomorrow I'll be sure to post another photo of an interesting feature from the rock processing.

Drilling Update: At the end of the day the deepest rock delivered from the drill site was 3282.5 ft.  There are usually two deliveries of rock per day: The late-morning delivery is rock that the night crew drilled, while the evening delivery is the day crew's core that we process the following morning.

Processed to 3125 feet, a pair of contacts

Today we processed rock core to a depth of 3125 ft.  That's 119 ft of core since yesterday, which is just about the maximum amount we've processed in a single day during the project.  The HQ drilling is definitely going quickly!  During processing, we saw many of the features I've been mentioning lately in this blog: baked soil contacts, glassy margins between pahoehoe flows, elongate olivine, olivine settling within flows, clay filling fractures, slickensides or slickenfibres, etc.  Here are a couple of the contacts we saw today:

The contact on the left is something we're used to seeing; soil baked to orange when the overlying flow covered it (the underlying flow is in the next column of the core box and could not be included in the photo).  These kinds of contacts are obvious and easy to interpret.  The contact on the right shows no baked soil at all, but there is baking of the underlying rock to a reddish brown color.  That baking and the change in mineralogy across the coloration boundary define the contact.

Processed to 3006 feet, more core on the way

Today we went back to our core processing routine: We washed, dried, marked, and boxed 88 ft of rock core that was drilled yesterday and last night into this morning.  As of the time of this blog post, at least another 40 feet of core is on its way down the mountain for us to work on tomorrow morning.  This is HQ (2.625" diameter) core, so it is smaller and lighter and generally easier for us to work with.  It also can be drilled more rapidly because the smaller diameter means less rock to cut.  We expect to be very busy processing the core, but as the depth of the hole increases it will take longer to recover the core and send down an empty core tube, which will tend to balance out the faster rate of drilling. 

Logged to 2037.9 feet, a branching contact, our first 20 feet of HQ core

Today we logged core boxes to a depth of 2037.9 ft, 60.2 ft deeper than when we finished yesterday.  Here is a picture of one of the more interesting contacts that we examined (image is 16 x 9 cm):

As you can see, the baked soil at the top of the underlying unit has been invaded in roughly the viewer's direction by a toe of the flow that was emplaced on top.  As a result, this small toe cooled rapidly and has glassy margins.  The base of the overlying flow also cooled quickly and formed glass, along with abundant elongate olivine (click on the photo to see in more detail).

Drilling update: As of this evening, we have received our first 20 ft of HQ core.  Barring any major drilling issues, we expect to be busy processing this size core now for at least the next couple months.