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Impact Ejecta


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Hi to you all,

I understand that this is for meteorites but since cheeze seems to get a look in here, I am going to post a photo of some ejecta material that I have over here in Ireland - its all relevant in developing the bigger picture! & they are interesting pieces also..

So in the photo you will see a number of brecciated rocks - the large one at the back is a limestone breccia component which is encased in impact matrix material, I think there is black impact melt to be seen in the lower area, this is also noticeable in the piece on the right. This large piece would suggest it has broken away from a large size breccia, worth pointing out that limestone is the bedrock in the find location.

The next pieces below are sawn & polished pieces, both polymictic impact breccias - The large piece that looks like concrete, however is not concrete, has a white matrix (which I believe may be white silica), with clasts of varing sizes, there is also some green glass inclusions in this material, although not visible in this piece. The piece next to the large one is interesting as it includes breccia in breccia components - up to three generations ... not your average breccia!

The two small pieces to the front are great! The one on the left, a limestone pebble encased in a thin layer of fine grained impact material - this piece is fragmented off a larger piece, which suggeats an explosive occurrence. Then the piece to the right - limestone again, this piece shows signs of high pressure deformation, the two sides have been pushed together so that the centre is pushed upwards.. think about plate tectonics & mountain building!

Apologies, I did not include a marker to indicate size, the large piece to the back will sit on the palm of your hand!

Thanks

Jon

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Hi Jon,

Please give us some more detail on impact products. Also, I'd like close-up photos of

the breccias. Are these all pieces that you've collected locally?

Ben

Okay guys, someone dig out your photos of Alamo Breccia to compare.

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Hi Reg,

Best thing i can do is to share the below link where you can have a look at some photos, there is only three there now, however I will upload more throughout the day. The 1st three are closeups of the two breccias in my original photo, the 1st photo is a microscope still of a glass inclusion which is to be found in the breccia with the white matrix.

There seems to be different types, I have a number of what I would describe as component breccias, that is single stones that are incased to some degree in fine graned material as in the large single piece to the back of the above photo. These single pieces look as if they are compressed into the fine grained material & all have a fragmented type shape. These rocks are limestone, I am not sure as to what the material is that covers them, possibly silica? Another group of these rocks, again limestone, have styration type patterns in them, one in particular looks like two rocks pushed into one with deep lines running along its side.

The two breccias in the middle of the photo I cut up & polished, the white one is a lttle scratched to the left of the piece, I was afraid of loosing that big clast as it is rather exposed on the opposite side. These two are are more abundant in the clast size & distribution, the rest seem to have less, although it is hard to determine without cutting them open as all have a smooth exterior.

All have been located in the same area which is about a 400 square meter plot of land in the corner of a 1 acre field, they seem to concentrated into one area of this plot. I have not really checked outside of this area for now, my brother has dumped a trailer loads of topsoil around the area & digging will be more difficult however I think I have enough to work on for now.

There is something that is of interest that is worth mentioning - while II have been working away on all of this, I also researched the local geology for abnormalities, something of interest turned up by what is refered to as a geological anomaly in the area - An infilled basin that is 1km in area & is infilled with mostly white silica. My find site is approximately 1km from this basin formation & I am not sure if I am clutching at straws here but a basin formation of that size would be interesting?

Here is the link to the photos..... http://jonny74ie.imgur.com/all/

I will get more posted up a little later on..

Thanks

Jon

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what is the source of the ejecta? Ejecta implies an impact...I see only concretions and conglomerates with my limited knowledge and vision.

fred

Hi Fred,

I have provided details in my reply to reg which gives details on what is refered to as a geological anomaly in the area of the find location & that is a basin formation. This formation has not been subjected to a geological survey except for a mapping survey that was carried out in the 1970's. I am looking at the possibility of this site being a impact location, If it is, it would be 1000's of years old & I admit that I may be clutchig at straws here, however the items in the attached photo are somewhat revealing & may help to support my theory on an impact site. What I know about ejecta is that you will find breccias & deformaties in the rocks close to the rim of a crater.

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This formation has not been subjected to a geological survey

Until confirmed as an impact structure, it is premature to call your finds impact ejecta. I don't see anything in your pictures to indicate any other than terrestrial origin.

Edited by Mikestang
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Thanks for that!

Well it is terresterial in origins.. if it was extraterresterial then this would be another "is my rock a meteorite" thread & we would be having a different conversation, also just to be clear.. I am talking about terresterial rocks that have gone through a shock metamorphosis brought about by an impact event, I did not mention meteorites.

The quote you used is intended to show that there is no definite history on the site & any suggestions to its origins are somewhat speculative, I did not come out & say that it is a crater, more like I proposed it as a possibility due to it's irregularity in the local geology & I am working on the basis that it is a possibility & worth looking into, I mean why not? At this point it could be just as plausable as any other possibility of its originations & I would like to apologise if I mislead anyone in my title, or through the thread.. that is not my intention,

So you are right, I should not be jumping the gun, so what I will do is to close down the photos until such a time as I can optain confirmation.

Thanks

Jon

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Just keeping things real, dude...

Jonny, no one is beating on you..we (some of us) are simply saying that giving a title to something implies facts-those facts donot appear to support your tenative conclusions.

You will live in the halls of meteorite history if you can lay claim to an undiscovered impact site...don't go away...but give facts as facts and opinions/wishes as what they are...keep digging!

fred

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Terrestrial origin meaning, the process that formed those breccias is probably terrestrial.

The only impact evidence you can provide without an electron microscope would be shatter cones; if you can find one of those then you're on to something.

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Just keeping things real, dude...

Jonny, no one is beating on you..we (some of us) are simply saying that giving a title to something implies facts-those facts donot appear to support your tenative conclusions.

You will live in the halls of meteorite history if you can lay claim to an undiscovered impact site...don't go away...but give facts as facts and opinions/wishes as what they are...keep digging!

fred

Thanks for that Fred!

I am not going away, it was probably premature for me to make this post & I was thinking that it is probably better if I remove the photos until I have confirmation on their origins. I am going to follow basin idea & see where it goes, I will post anything of interest.

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The only impact evidence you can provide without an electron microscope would be shatter cones; if you can find one of those then you're on to something.

The only impact evidence you can provide without an electron microscope would be shatter cones; if you can find one of those then you're on to something.

I need to get the shovel into action again & start digging down further, maybe there is a debris layer below the topsoil. I will look into the shatter cones, I have spent the last four months researching meteorites & now I need to focus a little more on the impact structures & if I can dig closer to the anomaly.. well who knows what might turn up.

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