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unknown find from slatey
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goldierocks said:
Do you have a more detailed photo that you could email me privately to pass onto a mate who is studying megafauna and dinosaurs etc (perhapos wuth a source to quote) - I want to ask him if it has significance to arguments about whether it has relevance to thew arguments about dinosaurs being warm or cold-blooded - but has your mate written on this? The mate also does the silcrete and opal work with me.
Also forget to mention to remember when discussing these things, many form as opaline silica but convert in place once formed to quartz with time. Common with silcrete.
I'm about silica'd out, it is not my main area, although a major area of study for me - I'm a gold man, if anyone wants a copy privately I have a detailed paper on gold recycling in streams (same process as gemstone recycling through subsequent streams - three main successive generations of streams in Victoria.)
I'm about silica'd out, it is not my main area, although a major area of study for me - I'm a gold man, if anyone wants a copy privately I have a detailed paper on gold recycling in streams (same process as gemstone recycling through subsequent streams - three main successive generations of streams in Victoria.)
Heatho may be able to help out more, but Shauno did a great writeup in the fossil section:
https://www.prospectingaustralia.com/forum/viewtopic.php?id=1973
goldierocks said:
Hey Goldirocks, no I don't but as Shivan said Shauno did a good write up on it. Just follow the link he posted, there is a better pic there too.
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Cheers Goldirocks.
My contention was merely that the pet wood, the chalcedonies and other materials found at the site are all related to each other and to the volcanics of the area based on a variety of observations. Happy to consider that the wood was already silicified before any eruptions ever occurred there - but I do feel that it's current state (overgrown and infilled with chalcedony of identical appearance to the (to my eyes) volcanic -looking globs of the same chalcedony lying there beside it) is strongly suggestive of the wood having been exposed to volcanic processes.
Like I mentioned, this is important for me since as we know, volcanoes tend to spit up all sorts of interesting things in many places. If I find something that seems volcanically related then it's a cue for me to have a good scratch around the hills and gullies of the area.
Also for this reason, I'd like to get some specimens of these agates and chalcedonies that have been formed with no relationship to igneous rocks. Firstly because I like to collect such things and secondly, to see if there's any difference that can be discerned without scientific instruments between igneous and non-igneous derived. Same reason as above - I find some agate nodules and think "there's been some hot activity, quite possibly close by" and start scratching around for other interesting things (not suggesting that the agates themselves are not worth collecting of course, I would gladly take them home) and likely be wasting my time if nothing igneous had ever been there. Most gemmy - but not all, a lot of precious opal for example - things have igneous origins.
It seems logical - though possibly still incorrect - to nonetheless assume that the amount of hot-rock formed chalcedonies in a given region is probably in proportion to the amount of igneous ground in that region - maybe this is why everything made of these types of silicas that I see appears to be directly related to igneous formations?
Yes, that sounds logical to me. But the one thing that appears less common here is "stand alone" volcanic necks. The volcanic plugs here are often in big groupings (there are over 70 on the Anakie gemfields) so there might have been a multiplier effect, even if all vents in a group as it stands today were not going off at the same time. The extinct volcanoes in this area seem to start (or finish, take you pick) near Yepoon (Mount Jim Crow national park). Actually, they seem to start right on the shore line and the Keppel islands may even be related, not sure. They stretch up past Rockhampton then out west toward this particular site and then seem to run roughly north towards Marlborough and south toward my area.
Queensland is a popular tourist destination today but there was obviously a time when it would have been rather unpleasant to be here, you would have been trying to dodge glowing hot boulders, lava bombs, flowing magma, choking ash and toxic gas
I'm glad it's quieter today
My contention was merely that the pet wood, the chalcedonies and other materials found at the site are all related to each other and to the volcanics of the area based on a variety of observations. Happy to consider that the wood was already silicified before any eruptions ever occurred there - but I do feel that it's current state (overgrown and infilled with chalcedony of identical appearance to the (to my eyes) volcanic -looking globs of the same chalcedony lying there beside it) is strongly suggestive of the wood having been exposed to volcanic processes.
Like I mentioned, this is important for me since as we know, volcanoes tend to spit up all sorts of interesting things in many places. If I find something that seems volcanically related then it's a cue for me to have a good scratch around the hills and gullies of the area.
Also for this reason, I'd like to get some specimens of these agates and chalcedonies that have been formed with no relationship to igneous rocks. Firstly because I like to collect such things and secondly, to see if there's any difference that can be discerned without scientific instruments between igneous and non-igneous derived. Same reason as above - I find some agate nodules and think "there's been some hot activity, quite possibly close by" and start scratching around for other interesting things (not suggesting that the agates themselves are not worth collecting of course, I would gladly take them home) and likely be wasting my time if nothing igneous had ever been there. Most gemmy - but not all, a lot of precious opal for example - things have igneous origins.
It seems logical - though possibly still incorrect - to nonetheless assume that the amount of hot-rock formed chalcedonies in a given region is probably in proportion to the amount of igneous ground in that region - maybe this is why everything made of these types of silicas that I see appears to be directly related to igneous formations?
Yes, that sounds logical to me. But the one thing that appears less common here is "stand alone" volcanic necks. The volcanic plugs here are often in big groupings (there are over 70 on the Anakie gemfields) so there might have been a multiplier effect, even if all vents in a group as it stands today were not going off at the same time. The extinct volcanoes in this area seem to start (or finish, take you pick) near Yepoon (Mount Jim Crow national park). Actually, they seem to start right on the shore line and the Keppel islands may even be related, not sure. They stretch up past Rockhampton then out west toward this particular site and then seem to run roughly north towards Marlborough and south toward my area.
Queensland is a popular tourist destination today but there was obviously a time when it would have been rather unpleasant to be here, you would have been trying to dodge glowing hot boulders, lava bombs, flowing magma, choking ash and toxic gas
I'm glad it's quieter today
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On reflection - maybe I do have some non-igneous chalcedony. The bloke in Montana sent me a variety of things. The agates were from the Yellowstone area but other things were from different places, some of which were not in the state of Montana if I recall. One such piece is what I think he called "flint". I'd describe it as a chalcedony in appearance and in the way it cuts and polishes from a lapidary viewpoint - responds just the same to the same approaches and compounds as most agates I've cabbed. Hard, translucent, "root beer" coloured material that takes on a good polish with cerium oxide.
But the outward appearance is very different. Whereas most such materials I have seen are in the form of an irregular, melted-looking glob and/or a nodule with bubbly vesicles all over it, this material has the look of something that was broken out of a thick, flat slab. It is like a sandwich, with a layer of white rock (which I can't identify) on both top and bottom and chalcedony in between. The seam agate near my home is also often in flat slabs and sheets but it is sitting in decomposed granite. Granted, the granite may have been stone cold when it formed but equally it may not have been since it was a superheated liquid rock when it formed. If I could tell what the rock associated is - if it's sedimentary - then I'd know.
But it definitely has a different character to most other things I've seen with my own eyes.
But the outward appearance is very different. Whereas most such materials I have seen are in the form of an irregular, melted-looking glob and/or a nodule with bubbly vesicles all over it, this material has the look of something that was broken out of a thick, flat slab. It is like a sandwich, with a layer of white rock (which I can't identify) on both top and bottom and chalcedony in between. The seam agate near my home is also often in flat slabs and sheets but it is sitting in decomposed granite. Granted, the granite may have been stone cold when it formed but equally it may not have been since it was a superheated liquid rock when it formed. If I could tell what the rock associated is - if it's sedimentary - then I'd know.
But it definitely has a different character to most other things I've seen with my own eyes.
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Been yacking to a geo in the US about it.
Just thought I'd chuck another professional opinion into the mix Truckloads of info in this thread so I can't recall it all - but if the above is correct, that would make some of this stuff possibly among the 0.1%?
Regardless of whether it is or isn't, some of it is nice display and lapidary material - just walked past the newspaper stand at the shop and there on the front page of my local rag was one of the region's MP's telling the Rockhampton city councillers to hurry up and get behind the weir construction.
Time to go and grab as much as I can, it's days above the waterline are numbered 8.(
Just thought I'd chuck another professional opinion into the mix
Truckloads of info in this thread so I can't recall it all - but if the above is correct, that would make some of this stuff possibly among the 0.1%?Regardless of whether it is or isn't, some of it is nice display and lapidary material - just walked past the newspaper stand at the shop and there on the front page of my local rag was one of the region's MP's telling the Rockhampton city councillers to hurry up and get behind the weir construction.
Time to go and grab as much as I can, it's days above the waterline are numbered 8.(
From my understanding flint is very close to chalcedony being it is cryptocrystalline silica, though i believe it is more closely related chert with its formation. I have a couple of small pieces from england, but most of what i have seen is opaque though and not translucent
Queensland is a popular tourist destination today but there was obviously a time when it would have been rather unpleasant to be here, you would have been trying to dodge glowing hot boulders, lava bombs, flowing magma, choking ash and toxic gas yikes I'm glad it's quieter today smile
Yeah, we still have molten lava down here under Bass Strait, because the continent has moved north and we arwe over the hot spot. There is good reason to suppose another eruption will occur - the aborigines record them ion legend here and the last ones were less than 4500 years ago (a small gap in the millions of years they have been erupting here). Great for tourism but might make flying in tricky. Have you ever heard of the carbonate volcanoes of the African Rift (had friends and daughter climbing over there in the past). No silica, just molten carbonate that solidifies as a dolomite lava flow (still flows below 500 degrees C).
It is like a sandwich, with a layer of white rock (which I can't identify) on both top and bottom and chalcedony in between.
Drip some hydrochloric acid on it and see if it fizzes
Arizona petrified forest
Great place - over there two years ago
what I think he called "flint"....From my understanding flint is very close to chalcedony being it is cryptocrystalline silica, though i believe it is more closely related chert with its formation. I have a couple of small pieces from england,
Yes, microquartz being the mineral, and close to the rock chert in appearance, can be nearly black. Typically forms as nodules and layers in limestone (eg White Cliffs of Dover). Stone Age man loved it for spear tips, as with silcrete and Australian aborigines. Seen the same use in the Canadian Arctic.
I'm not a billionare by the way - leave that to Trump. My job takes me places for companies and I visit things on days off, although sometimes spend longer in USA and Africa as have a son in the USA and family in Africa.
Yeah, we still have molten lava down here under Bass Strait, because the continent has moved north and we arwe over the hot spot. There is good reason to suppose another eruption will occur - the aborigines record them ion legend here and the last ones were less than 4500 years ago (a small gap in the millions of years they have been erupting here). Great for tourism but might make flying in tricky. Have you ever heard of the carbonate volcanoes of the African Rift (had friends and daughter climbing over there in the past). No silica, just molten carbonate that solidifies as a dolomite lava flow (still flows below 500 degrees C).
It is like a sandwich, with a layer of white rock (which I can't identify) on both top and bottom and chalcedony in between.
Drip some hydrochloric acid on it and see if it fizzes
Arizona petrified forest
Great place - over there two years ago
what I think he called "flint"....From my understanding flint is very close to chalcedony being it is cryptocrystalline silica, though i believe it is more closely related chert with its formation. I have a couple of small pieces from england,
Yes, microquartz being the mineral, and close to the rock chert in appearance, can be nearly black. Typically forms as nodules and layers in limestone (eg White Cliffs of Dover). Stone Age man loved it for spear tips, as with silcrete and Australian aborigines. Seen the same use in the Canadian Arctic.
I'm not a billionare by the way - leave that to Trump. My job takes me places for companies and I visit things on days off, although sometimes spend longer in USA and Africa as have a son in the USA and family in Africa.
Lefty, this might interest you if you don't have it. It is a description of how the Mt Hay thunder-eggs form. I would reckon that the agates on the Fitzroy River near the weir are probably derived from the same group of Cretaceous volcanics (rhyolites and basalts) that extend far west from Mt Hay if you look at the first map, and probably into the heads of the west-flowing tributaries of the Fitzroy River. This belt of plugs and flows extend north and south from here and would probably shed into the river elsewhere (eg for 35 km from Mt Salmon to Native Cat Range, including Mt Lion). I imagine that they are supllying agates in various areas. Agates etc might be more abundant in drainages feeding the Fitzroy River from the east.
Sorry, too large for this site - if you want it let me know and I will reduce the file size. Here is the map anyway. Note that basalts are extensive in the area, and I suspect your pet wood may be coming from gravels beneath the basalts. The mistake I made was only searching for Tertiary basalts in your area - I forgot that your area was among the earliest to move over the hot spot, so that the hot spot basalts extend back as far as the Cretaceous in your area.
Sorry, too large for this site - if you want it let me know and I will reduce the file size. Here is the map anyway. Note that basalts are extensive in the area, and I suspect your pet wood may be coming from gravels beneath the basalts. The mistake I made was only searching for Tertiary basalts in your area - I forgot that your area was among the earliest to move over the hot spot, so that the hot spot basalts extend back as far as the Cretaceous in your area.
I figured there had to be basalts near ther upper Fitzroy River because of my predjudices re pet wood origin.
They are part of this Cretaceous volcanic field around Rockhampton:
You can see the Cretaceous trachytes and basalts here, just east from the upper Fitzroy River - you can see another large area to the north (any wood there?) but more to the point, you can see tiny patches of basalt all over the place, indicating that the flows were much more extensive. The weir on the Fitzroy is straight west from MT Hay on the easternmost poinht of the big loop:
They are part of this Cretaceous volcanic field around Rockhampton:
You can see the Cretaceous trachytes and basalts here, just east from the upper Fitzroy River - you can see another large area to the north (any wood there?) but more to the point, you can see tiny patches of basalt all over the place, indicating that the flows were much more extensive. The weir on the Fitzroy is straight west from MT Hay on the easternmost poinht of the big loop:
Here is the Hot Spot story. I simplified it a bit previously, because not only are there two Cenozoic Hot Spots, but because other basalts formed by a different mechanism as well. as NZ split from Australia and the Tasman Sea developed between, and as Bass Strait formed by faulting, and as Antarctica split from Australia to open the Southern Ocean.
There are two Hot Spots, EAH on eastern Bass Strait (with fluid magma still) and TH to the east of it.
"Southward-migrating" means "apparent southward-migrating" younger ages (the Hot Spots are stationary and Australia has been moving north, so the oldest volcanics are in the north, the youngest are in the south - we are slowing to a stop now as we collide with southeast Asia beneath the Timor Sea). You can see that one set of volcanic fields are submarine off the east coast and related to the TH Hot Spot, volcanoes erupted approx 22 My ago in the north (perhaps up to 35 My or so in the extreme north but not yet dated), and less than 7 My ago in the south (probably not stopped yet).
The other "Hot Spot trace" (line) of volcanoes is onshore, and are shown on the legend as "Central Shield Volcanoes" (lightest shading). These are the ones that bring up zircons, sapphires, rubies etc. related to the EAH hotspot
The EAH volcanoes are around 30 My old in the Central Queensland gemfields to 21 My in the NSW/Qld southern New England district to arond 17 My west of Tamworth to 6 My around Trentham in Victoria.
The parallel linear patterns of volcanoes clearly show how Australia was moving north - in a previous BLOG I discussed how we get these linear patterns in the Hawaaiian chain of islands.
I think you said there were no sapphires on the upper Fitzroy? That is probably because they are not Cenozoic (pre-Cenozoic volcanic fields are not shown on the map) and are not related to the EOH Hot Spot Central Shield Volcanoes that have sapphires etc.
Enjoy.
There are two Hot Spots, EAH on eastern Bass Strait (with fluid magma still) and TH to the east of it.
"Southward-migrating" means "apparent southward-migrating" younger ages (the Hot Spots are stationary and Australia has been moving north, so the oldest volcanics are in the north, the youngest are in the south - we are slowing to a stop now as we collide with southeast Asia beneath the Timor Sea). You can see that one set of volcanic fields are submarine off the east coast and related to the TH Hot Spot, volcanoes erupted approx 22 My ago in the north (perhaps up to 35 My or so in the extreme north but not yet dated), and less than 7 My ago in the south (probably not stopped yet).
The other "Hot Spot trace" (line) of volcanoes is onshore, and are shown on the legend as "Central Shield Volcanoes" (lightest shading). These are the ones that bring up zircons, sapphires, rubies etc. related to the EAH hotspot
The EAH volcanoes are around 30 My old in the Central Queensland gemfields to 21 My in the NSW/Qld southern New England district to arond 17 My west of Tamworth to 6 My around Trentham in Victoria.
The parallel linear patterns of volcanoes clearly show how Australia was moving north - in a previous BLOG I discussed how we get these linear patterns in the Hawaaiian chain of islands.
I think you said there were no sapphires on the upper Fitzroy? That is probably because they are not Cenozoic (pre-Cenozoic volcanic fields are not shown on the map) and are not related to the EOH Hot Spot Central Shield Volcanoes that have sapphires etc.
Enjoy.
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Thank you very much for that Goldirocks, that looks like some fantastic information!
I'll have a good read and post some replies when I get home, I'm currently sitting in a motel room in Brisbane using a rather unreliable little wireless device. Yes, I would definitely like that file.
Thanks again, reply soon.
I'll have a good read and post some replies when I get home, I'm currently sitting in a motel room in Brisbane using a rather unreliable little wireless device. Yes, I would definitely like that file.
Thanks again, reply soon.
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Aha, I think I see it on that coloured map showing both the early and late Cretaceous volcanic a of the area. The river crossing is north of Gogango and West of Westwood. I didn't see at first because I'm using a tiny little touch screen here but I just noticed a tiny green spot that is colour coded to represent trachyte and rhyolite flows and Imbrignite by the looks. I don't have another map to overlay and compare it to but going on relative distances, I'd say that little volcanic site looks to be more or less smack on top of where Riverslea crossing is.
The various volcanic a of the area were very numerous but this spot is just one tiny little dot on the map - no wonder the material seems restricted to such a small stretch of river!
I think you've solved the mystery of the origin of the materials of Riverslea crossing Goldirocks
The various volcanic a of the area were very numerous but this spot is just one tiny little dot on the map - no wonder the material seems restricted to such a small stretch of river!
I think you've solved the mystery of the origin of the materials of Riverslea crossing Goldirocks
Good. There is some pattern in these things - I think we understand the origin of these things sufficiently to use them as predictive tools. We do that in other areas such as gold, but there are less of us geos working on gemstones (for the obvious reason that they are far less important in terms of the national economy). My main area is gold, one must eat, but I have always had an interest in gemstones as a hobby, and in putting their origins into a coherent geological framework.
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Goldirocks, would you happen to have the companions to that colour-coded early and late Cretaceous volcanics maps, the one or two immediately to the south, say to roughly Gin Gin on the Bruce highway. Together, they would represent the area that is within reach for a weekend fossicking trip. The Anakie field really requires about 4 days to make it worth it for me. If you're able to post that, I'd be much appreciated.
Cheers
Cheers
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A couple of drops of vinegar from the kitchen be safer and show the same.
