Sven
"... If anyone had done this before me": In the early(ish) days of palaeomag people used drills with rigs - cumbersome things, first drill your bolt holes to lock the rig to etc. Then they realised that they could get away without them. So yes, there is a history - there are references in Collinson, DW, Creer, KM & Runcorn, SK (eds) 1967 Methods in Palaeomagnetism (Elsevier) - McElhinny talks of drilling 2 ft (60 cm). But I don't think it's much help to you!
Cheers
Bill
________________________________
From: Tectonics & structural geology discussion list on behalf of Sven Morgan
Sent: Wed 19/04/2006 18:51
To: [log in to unmask]
Subject: Re: deep rock core drill
thanks Zoe,
I have collected cores down to 15 cm using the standard paleomag drills (converted petrol powered chain saws), but I want to get deeper. I have seen a lot of deeper-going equipment from mining equipment websites, but I wanted to know if anyone had done this before me. Several folks suggested going with a mining/drilling contractor - which I might do.
thanks again,
Sven
[log in to unmask] wrote:
Hi Sven
I've used a petrol-powered palaeomag drill to collect samples from
sandstones. The longest core we ever managed to get was about 10 cm from a
more massive sandstone. A major problem in well-bedded sandstones is that
they tend to shear into little biscuit shaped pieces along the bedding. To
get cores longer than that the trick is holding the drill still enough so
you don't shear the core off at the base. The taller and heftier members
of the field team had more success (i.e. not me!). For over 50 cm you
might have to design some kind of rig to hold the drill still? And you'd
need longer coring bits than the standard...
The drill was petrol-powered and light enough for me to carry in a
backpack A second person had to carry the water needed to lubricate the
drill bit.
I've seen palaeoseimologists use a gadget for very long cores which
involved jumping up and down on a platform attached to the corer (again,
hefty folks required) - but that was in loose sediments.
Good luck!
Zoe
well, it depends on the rock type and the diameter of your bit.
standard 1 inch diameter drillbits, as used for paleomag are about 35cm
in length. with those bits, drilling basalts all the way wouldn't be
a problem, sediments are more tricky as well as granites and likewise
metamorphics. anyway, a lightweight portable rock drill, running on on
two stroke petrol should do the job. the best bits can be bought here
<http://www.marcrist.co.uk/> <http://www.marcrist.co.uk/> . as far as engines are concerned, try
ASC <http://www.ascscientific.com/drills.html> <http://www.ascscientific.com/drills.html> . alternatively, a
lighter and perhaps ergonimically superior model can be found here
<http://paleomagnetism.geophysik.uni-muenchen.de/images/montafon0007.AVI> <http://paleomagnetism.geophysik.uni-muenchen.de/images/montafon0007.AVI> .
Valerian
Sven Morgan wrote:
Does anyone have exerience using a portable rock core driller that
will go approximately 50 cm depth? And still be able to recover the
core? Deeper would be better, but 50 cm is the minimum goal.
The outcrop is about a mile from the road, so we need to drag the
equipment, but it is fairly flat terrain. I would be willing to drag
or roll out a generator (or have undergraduates do it).
thanks,
Sven
--
Prof. Dr. Valerian Bachtadse
Dept. Earth and Environmental Sciences
Theresienstrasse 41
80333 Muenchen, Germany
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--
Sven Morgan
Associate Professor
Department of Geology
Central Michigan University
Mt. Pleasant, MI 48859
U.S.A.
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(989) 774-1082
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