21 February, 2010

Tools and Tricks: Dictionary of Applied Geology

Thanks to my friend Kathrin I discovered a lengthy and 4-language dictionary of applied geology published online in the free access journal Freiberg Online Geosciences. In the 2001 edition a dictionary in German, English, Spanish and French is presented that has been compiled by Freiberg hydrogeologists. Consindering that I used to study for several semesters in Freiberg it is rather embarassing that only now I come across this interesting dictionary. All 4 language versions and one index can be freely downloaded as searchable PDF-files.

Here are the direct links to the files:

Index file
German version
English version
French version
Spanish version

I also recommend actually checking out their website. It features a number of papers on investigations of Freiberg geologists.

06 February, 2010

Tools and Tricks: Image analysis software for the geosciences

Trying to find an easy way to do modal analysis on fotomicrographs of thin-sections I found two very useful and free programms to assist in such efforts. These programms are JMicroVision and ImageJ. Both of them are Java based and should function on any ordinary computer. I've been testing both of these in the last weeks and they have their uses. JMicroVision has been developed by Nicolas Roduit of the University of Geneva with image analysis of petrographic thin-section in mind and allows to do various tasks easily, like point-counting, area counting, grain-size measuring or pore classificaton to just name a few. ImageJ originated in the field of biology and medicine, was developed by Wayne Rasband from the National Institute of Mental Health, Maryland, and thus lacks a little the easy to find path as the other programm though offers a lot of tools and plugins that make-up for that short coming. What I found to be an enormously interesting feature is the possibility to make 3D images from serial fotographs or other well aligned image sources which sounds like a great tool to make 3D images from serial thin-sections of fossils. The biggest short-coming of both programmes I discovered to be the image analysis of contrast poor limestones which I am working. Neither programm manages to adequately seperate components and cements. So I have to stick to old-fashioned point-counting. Utilising contrast and color-richer sandstones or crystaline rocks easily gives great results though!

Being relatively new to the computer aided image analysis I recommend to check-out the respective websites yourself. I am sure to some of you these will be a value!

03 February, 2010

Ooids and De-Dolomite

Today in the lab I finally finished the thin-sections that I will be investigating as part of my Diploma thesis. I gave them their final touch with a mesh 1200 powder. There is a simple polarisation microscope in the lab allow a quick quality check. I took an ordinary digital camera and held it to the eye-piece. These are some selected results of that. The thin-sections were not yet cleaned, occasional dark spots are left-over polishing powder. No deeper interpretation, yet, I have still to begin with that.

 An Oolite in thin-section at low-magnification. Lots of ooids within sparitic cement.

 An ooid in high-magnification.

Blue-dyed epoxy has filled the open porosity. Here, rhomboidal dolomite has been dissolved. Undissolved examples directly above.