Jurassic Microfossils. Tips For The Starting Micropaleontologist.

[yurish]

I would like to share some pictures with you from my first hunt on microfossils. Hope, that you will help me to identify some of the fossils.

Description:

Gray clay with foraminifers.

Bed of the river Losis, 100m from river Venta.

J2 Callovian

Sample taken in year 2005

Processing of the sample:

2. First, I cut a small amount of clay from the sample (~35-50 gr.).
3. 
   
4. This piece was then desintegrated with hydrogen peroxide(3%).
5. 
   
6. Then I washed this sample, using 2 sieves (100 microns and 63 microns) for about half an hour.
7. 
   
8. Both fractures (>100 and >63 microns) were separated between two envelopes for drying.
9. 
   
10. Then sample dried for 2 days within the room temperature.
11. 
    

Looking for fossils:

I don't know, what I did incorrect, but after drying, sample solidified a bit, and I needed to grind it a bit with my hands. It seems, that not all clay went away from the sample. The color of remains still was dark grey.

I am using a simple 20x-40x scope, and I saw, that sample is full of something, that reminded me fish scale. A lot of small, blinking pieces. For now, I have searched through only >100 micron fracture. A lot of interesting stuff was found there. I need to apologise for the quality of the pictures. I don't have a special scope camera, so I took some pictures with my phone through the scope.

Some pics(pictures are large, so I include only links to them):

1) http://i.imgur.com/5rfKmss.jpg

Here I separated those shells in two groups, because the group on the left is more yellowish. I think, this can be another species. I was trying to identify this using foraminifera.eu and it seems for me, that these can be some Lenticulina ?

2) http://i.imgur.com/u4ljqJv.jpg

Could not find any one similar. Looks like what I see on the top of the shell are chambers without a top layer? Or this is some kind of special ornament?

3) http://i.imgur.com/MQw5BOb.jpg

These looks like Discorbida ?

4) http://i.imgur.com/pOP6QWy.jpg

Have not found any similar in "Key to species".

5) http://i.imgur.com/TzPH3OJ.jpg

Also no idea.

6) http://i.imgur.com/7niz8hW.jpg

Same story

Some other photos of microfossils, that are only in 1 sample :

1. http://i.imgur.com/LgTMDPR.jpg
2. http://i.imgur.com/IRHw12P.jpg

Thank you for your time reading this post. I hope to see some answers. If you have any tips or you see something, what I did wrong, please, advise me! I am just starting, but I really like micropalentology and I want to study!

[Herb]

pretty good pix, nice forams. You might try our LINK "Foraminifere.eu"

#4 and #6 are gastropods

wash the matrix until the water runs clear of wet sieve them through a # 200 sieve.

It looks to me you did a pretty good washing job.

Edited November 15, 2014 by Herb

[yurish]

Thank you! Next time I will try to wash fossils in 2 parts - wash and dry, then I will repeat all the process again. It seems, that all clay parts are too hard for the peroxide. Maybe, the secondary wash can break all the solid parts to the smaller one.

[Mediospirifer]

You might also try boiling your clay. It may not break things down as quickly as peroxide, but you can repeat until the water runs clear fairly cheaply.

[Herb]

Electric disherwasher powder/detergent or TSP will help break down the clay.

[yurish]

Herb, you mean Calgon? Sodium hexametaphosphate?

[Herb]

yes, give it or similar compounds.

[yurish]

Ok, during weekend I plan to do the second wash of my sample. I will go "Calgon" way. Can you give me some briefe instructions on washing foraminiferas with calgon? As I thought, I will need to put my dry clay sample into solution of water with calgon (proportions?) and then wait for a week. Afterwards to wash through sieves, as I did before. Right?

[Herb]

correct, you might want to boil it in a pan that you will never want to cook in again. maybe a teaspoon per gallon.

[yurish]

A week has passed. Tomorrow, I will wash my clay-calgon solution. Can't wait! It has been there for a week, I hope I will get some good results.

By the way, 4 days ago I went to the beach and took 4 different samples of sand there. All samples were taken from different places of the beach. I was hoping to find some foraminifera there, but, after sand was dried, I did a brief prospecting and found nothing. I will sieve these samples too, maybe on Thursday. Will see, if there will be something.

Have you, guys, found any foraminifera in beach sand? Why I haven't found any?

[Auspex]

...Have you, guys, found any foraminifera in beach sand? Why I haven't found any?

Some beaches are rich in microfossils, some are pulverized coral, and some are composed almost completely of silica sand.

It all depends on the source of the material, and how quickly it 'turns over' (only hard silica can endure protracted, continuous surf tumbling).

[yurish]

Today I went to our professor palaeontologist. He was very surprised, that I took those samples, because no one had a chance to find any foraminifera in our sand. Our sand from Riga Gulf is almost completely of silica sand. I have found something, that can be a part of devon placoderm. Not sure about it, will try to make some pictures.

[Herb]

FYI, on a modern beach you should collect just above and below the high tide line. The tests will float to that point.

[yurish]

Herb, I will try to dig deeper next time.

By the way, today I washed my Calgon solution, and results were amazing! Now it is drying, but I am already impressed with it! I will try to examine it on weekend.

[Herb]

excellent!

[beesouka]

FYI, on a modern beach you should collect just above and below the high tide line. The tests will float to that point.

This is a great bit of info to keep in mind for the next time I am at the shore! It makes sense, but I wouldn't have known for certain if there was a sweet spot. Thanks!

[yurish]

Some updates:

I started another experiment. I have a sample of limestone, which, possibly, has some ostracods in there. A week ago I put a half of this sample in a bottle and added glacial acetic acid. I will wait for ~2 weeks and maybe I will have some clear matrix there. Will see.

Has anyone tried to dissolve carbonates in acetic acid? How were you decanting the solution after experiment?

[Mediospirifer]

I'd keep a close eye on that! Glacial acetic is powerful stuff. I recommend using as little acid as possible, and pour it off as soon as the effervescence stops. Too much acid for your matrix can dissolve the fossils as well.

I've used 5% acetic acid (ordinary vinegar) to dissolve limestone with good results. I fill a pint-size container with rock chips, pour in enough vinegar to cover them, place a lid over the top (loosely; I want to contain the spray without trapping the gases), and let it stand overnight. When I return to it, I'll pull out the large rock chips by hand and rinse them in water, then pour the residue into a tub of water to wash away any remaining acid. I'll go through a few cycles of slowly pouring off cloudy water and adding more (letting it stand for about 10 seconds after adding water before pouring: this lets the larger particles settle out before I pour), then when the cloudiness starts settling out quickly I'll pour the rest through my sieves.

If you don't have fine-scale sieves on hand, coffee filters work fairly well. In my experience, they'll catch nearly all of the particles from limestone, although the finest particles from dissolved shale will pass through. A coffee filter set in a kitchen sieve or colander (or coffeemaker basket) is a good place to start. I recommend using plastic or something else that doesn't rust!

You can pour the cloudy water through a filter and catch the particles if you want to. I found that they clog up the filter fairly quickly, and tend to clump together as they dry. With my sieves, those particles are small enough to pass through the smallest mesh I have (75 micron), and I've never found anything of high interest in the filters I did catch them in.

Good luck, and have fun!

[jpc]

yurish.. I have no advice for you, but this looks like a fun project. Good for you.

[Herb]

glacial acetic is mean stuff, I would try vinegar or really dilute the glacial acetic. It will also eat fingers as well as fossils.