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JeanB

Stromatolite?

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JeanB

Hello,

I would like to know if Kambaba Jasper stromatolites are really stromatolites from blue-green algae (cyanobacteria) or something else. As a microbiologist I find these kinds of fossils very interesting. Are they really fossils?

Here's a photo of one sample.

Many thanks for any help!

Jean

post-11707-0-64064500-1395763157_thumb.jpg

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Tethys

It is a form of ball algae, similar to modern Marimo. Stromatolites are microbial cemented sediments with many different growth forms. They usually have very clear laminations and different colored, layered construction.

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JeanB

Thanks Tethys,

from the description you gave it still looks stromatolitic, but I am no expert. It is as hard as a sedimentary rock and and have circular laminations.

Jean

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Auspex

From what I can find, it seems to be generally accepted that Kambaba Jasper is a stromatolite, but I find no consensus that it is from blue-green algae, necessarily.

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JeanB

From what I can find, it seems to be generally accepted that Kambaba Jasper is a stromatolite, but I find no consensus that it is from blue-green algae, necessarily.

Indeed, I did not find a consensus on the microbial composition of these stromatolites. I have a lot of reading to do to learn more about these microbial fossils.

Thanks a lot guys, very much appreciated!

Jean

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Tethys

The wiki entry for another growth form is concise:

"Thrombolites are clotted accretionary structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria.

Stromatolites are similar but consist of layered accretions."

There are lakes in northern Minnesota that have living, iron precipitating, freshwater stromatolites. I've also found ball algae in the lakes. They are a highly resistant structure for something formed of algal slime,filaments and chloroplasts.

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JeanB

Wow! Thanks Tethys for these info.

My professional field of interest is microbial biofilms on which I have done research for the past 20 years at University of Montreal. Stromatolites and Thrombolites are thus very interesting structures. They are probably the first witness of the ability of bacteria to organize in community and probably communicate between themselves (a process called Quorum Sensing). In short, bacteria in stromatolites may well be the first biofilm-builders in the history of the earth.

Thanks again Tethys and Auspex! You helped me a lot!

Jean

Edited by JeanB

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JeanB

After more reading, it appears that, based on morphology, the sample may be Girvanella or Oncolite which are also fossils of cyanobacteria from the cambrian to cretaceous.

However I do not know is Kambaba Jasper rocks (Madagascar) correspond to these periods...

Jean

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Tethys

I find them quite fascinating too. There has been some great research done on the stromatolites in Pavilion Lake, BC . I am highly amused that the researchers have named a particularly large formation the M.O.U.S. (mound of unusual size). :D

Edited by Tethys

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Wrangellian

It disappoints me to not be able to find out any solid info about this stuff - it is being sold all over the place! I see it most often identified is a stromatolite but I can't be sure as there are differing opinions. I'm always interested in adding more stromatolites or any fossils from the Precambrian to my collection, but if there is no info to be found, forget it.

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xonenine

I felt that way too Eric, but the answer remains to be found out there still :)

the name, Kambaba Jasper, (and several thousand references :wacko: ) seems to be a convention of the Mineral/Gem Clubs, and was preceeded by the name Green Stromatolite Jasper, (and to a lesser extent Crocodile Jasper)

The stone comes from Madagascar/South Africa. I'm sure with a little more searching we'll find a reliable reference...

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JeanB

I feel that way too guys. It is pretty frustrating . I have done a lot of reading on stromatolites, thrombolites, oncolites and Girvanella lately. This Kambaba Jasper rock looks like oncolite to me, but I would prefer to find real scientific infos to back it up. If this Kambaba stuff is really of bacterial-origin it would most likely be cyanobacteria (blue-green algae). I have looked at one «colony» under the microscope and it does ressemble oncolite. And if (and Oh! what a big if) it is oncolitic I would still have to find infos about its age.

Here's a closer view of one globule. From the cross section, these «colonies» are not columnal but spherical. The first image is a mosaic of 22 images merged in Photoshop. The second one is a closer view: if you carefully look at the dark radial stripes you will be able to see «beads» stacks.

The discussion is still open!

Jean

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post-11707-0-88975400-1396025406_thumb.jpg

Edited by JeanB

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xonenine

i completely agree w you there Jean, (I got sidetracked a moment today looking at tubular/columnar stromatolites).At this point is is more a matter of seeing that valid reference... :)

Carmine

Edited by xonenine

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Tethys

It appears that since Madagascar was colonized by France, much of the relevant literature is in french.

I found this paper in English.on green marine clays and ooidal ironstones that goes into very detailed chemical analysis of the different layers and their genesis, but only briefly notes the biogenic components involved in the diagenetic processes.

I cannot find anything that gives detailed age information for the mined Kambaba jasper, other than it originates from an ancient playa lakebed in northwest Madagascar. They have a core of algae that is coated with layers of iron sulfides. The algae has been replaced with green minerals, and the iron sulfides are black.

Many of the oncoids have evidence of repeated cycles of weathering, algal regrowth, and mineral precipitation tied to changes in water level and storm energy

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JeanB

Wow! It seems we are getting near the truth about this mystery.

Tethys, if you ca point me some french literature you found I will read it... french is my mother tongue.

Regards

Jean

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Tethys

Wow! It seems we are getting near the truth about this mystery.

Tethys, if you ca point me some french literature you found I will read it... french is my mother tongue.

Regards

Jean

It is a passing reference in my link. The foreward mentions that the green limestones with iron oncoids are well studied and much has been written about them.

I'm sure a search with proper french terminology will turn up relevant studies. Look for something about playa lakes in modern studies, Older literature refers to them by many names such as iron concretions, stromatolite algal limestones, green mudstones, packstones, etc...

Figuring out the formation names of northwest Madagascar would be extremely helpful in finding information.

I found this study on a modern playa in Madagascar that observes;

The lake directly precipitates carbonate in a closed evaporite basin defined by cliffs of Eocene marine limestone to the east and a wide strip of alluvium capping low outcrops of limestone to the west. The extremely low gradient within the basin produces dramatic changes in areal extent in response to seasonal changes in precipitation. These fluctuations create broad hypersaline mudflats, which form a broad apron around the perimeter of the lake. Prior to the orally recorded history of the region, a paleolake of much greater size and depth occupied the basin. Expansive strand lines ring the extreme edges of the basin and deltaic sediments produced by a paleodrainage system are present as well. Strandlines along the cliffs to the west are marked by a 10 meter wide band of oncolites, representing the maximum extent of the paleolake.

I hope you can find something based on my clues. My french is quite limited.

Edited by Tethys

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JeanB

Thanks!!!!

I will try to contact the author of the study. I wrote to Norcross - Madagascar Minerals (Tucson), the mining company exploiting the Madagascar Jasper to get more infos about

the géological period of their site.

I will keep you informed.

Jean

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Wrangellian

I hope you will post the info here when you get it, Jean... I wish the scientific papers would quote the rockhound name for things (eg. Kambaba jasper'), just so that research would be easier for us.

But based on your microscope photo I wonder if these aren't biogenic after all, considering what those papers Xonenine posted under 'Documents' say ( http://www.thefossilforum.com/index.php?/topic/45281-microbialites-stromatolites-and-thrombolites/ ). Basically, they said that the 'stromatolites' that exhibit 'sparry' (crystalline) layers are likely abiogenic. The biogenic ones those that are not sparry, but combinations of the two also exist. The Kambaba stuff looks sparry to me, at least partially.

I can't say for sure though, so I hope some info turns up! Maybe you can comment on this?

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JeanB

Thanks for the link, Wrangellian, I have now some more reading to do to have a better idea. Remember I am still beginning in this field. As for the microscopic image, it is still hard to tell. These beads-like structures remind me similar structures in microbial biofilms, but then I would wonder if that's even possible in a fossile. Some scientific papers show cyanobacteria in oncolites, but these samples are rather «recent».

I plan to look at a higher magnification. But you are right: this stuff is at least partially crystalline.

Meanwhile, I will wait for the answers of Norcross minerals and see what they have to say. You ca go to their site:

https://www50.instantestore.com/secure/merchant3242/contact_us.cfm?CFID=64468949&CFTOKEN=4d9172ac6695f086-09F61EE6-9840-1A65-72D7B196F80E6C1A&jsessionid=ee30cafb2e7e7752e4b6

Regards

Jean

Edited by JeanB

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Wrangellian

The differences in spelling will compound the difficulty - I see Kambaba, Kabamba, and now on that site Kambamba!

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JeanB

Here's the response of Norcross Minerals about Crocodile (Kambaba) Jasper:

«Dear Jean Barbeau,

Kambaba Jasper is a stromatolite which is a clump of fossilized algae ( greenish or blackish orbs of petrified algae with predominantly black centers).
Geologic Age: Precambrian

I wrote to Robert Riding, University of Tennessee, Knoxville, TN, USA to have his opinion on this.

I will keep you informed.

Jean

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Tethys

I wish they would cite a geology report that describes them within the column. Its certainly possible that crocodile jasper is Precambrian, but many of the other green ooid and oncoid bearing rocks worldwide are Jurassic.

I found this old article about Bernardo Cesare. He is a petrologist who takes amazing micro-photos of ocean jasper and other materials.

His website is called micRockScopia. I hope there is some info on the jaspers, in addition to the photos.

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xonenine

great follow up Jean, thanks, for those who don't know, Robert Riding also wrote the last two papers we are reading bout Stromatolites :)

http://www.thefossilforum.com/index.php?/topic/45281-microbialites-stromatolites-and-thrombolites/

http://www.thefossilforum.com/index.php?/topic/45236-the-nature-of-stromatolites-3500-million-years-of-history-and-a-century-of-research/

Edited by xonenine

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JeanB

I am still waiting for the answer from Pr Riding.

I searched the geological maps of Madagascar:

Two geological entities:

- 2/3: The Precambrian crystalline

formations (the 'crystalline basement')

composed of five blocks (PGRM, 2008)

- 1/3: the Phanerozoic, nonmetamorphosed

sedimentary formations

(the 'sedimentary cover').

http://www.mineafrica.com/documents/B5%20-%20Madagascar.pdf

It seems that the mining site is precambrian but I have no independent source confirming that.

One source says that «Kambaba jasper is known to be over 2,200 MILLION YEARS OLD

Kambaba Jasper / Stromatolite is an orbicular sedimentary fossil. 3.5 T0 1.5 billion years old.» http://www.cs.mun.ca/~zubayer/myhome/fossil.htm. If it is known, I wonder who verified that and what competence he has. Again, no published scientific assessment of those claims.

The frustration continues... Hope to get to the bottom of this soon.

Jean

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JeanB

Some more info from the owner of Norcross minerals Madagascar: Mine is SouthEast Madagascar. The geological studies maps indicate this region is in the Anyosen Domain (Late Neo-Proterozoic). Don't know if it helps. I am way out of my expertise area here... and, I might add, it gets over my head.

http://nora.nerc.ac.uk/7209/1/Betsimisaraka.pdf

http://www.sciencedirect.com/science/article/pii/S1342937X10002418

So unless Norcross minerals are not completely honest, the Kambaba Jasper is likely precambrian.

Any comments?

Jean

Edited by JeanB

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