Jump to content
mikemH

Mineralised Fossils from the Bowan Basin

Recommended Posts

mikemH

Hi,

Recently been shown a couple of mineralised, silicified?? ( hardness 6.5 ), fossils that are a bit unusual and might be of interest.

 

They were found in alluvial gravel at Tomahawk Creek, near Rubyvale, Queensland. I have been unable to access Geological Map ( Emerald SF 55-15 ?? ) on line, any directions, link or geological info ( formation, age) would be appreciated.

I believe Rubyvale lies in the Bowan Basin, which is late Permian, about 255Ma.

 

The first one appears to be Plumsteadia, a Glossopterid fruit. The seeds have been shed, leaving small recesses where they were attached.

"Fruits consist of a receptacle or core with seeds attached to it (all around it, if it is spherical or cylindrical; possibly only to one side in examples where there has been a flattening and fusion of parts).

( Mary White, 1988, Australia's Fossil Plants )

 

TC000.JPG.c5a90cef3f9b970606f3e612c1966daf.JPG

 

TC001.JPG.af185dc8187802f00b66e468f7320426.JPG

 

TC002.JPG.a3c3cef100578b1a995f4c1b4f5b925f.JPG

 

 

The second looks very much like a section of Vertebraria, Glossopterid root.

"...show a segmented structure when fossilised. They look much like vertebral columns , or backbones...... The structure is believed to be an adaptation for aeration of tissues, necessary in the waterlogged habitats of swamps."

( Mary White, 1988, Australia's Fossil Plants )

 

TC003.JPG.cd45d81884e9caead831d157b17b8753.JPG

 

TC004.thumb.JPG.7173ea4fd93c81802306110d2af6dec7.JPG

 

TC005.thumb.JPG.5a72b6a4dd63cf18de828e8e7d3c011c.JPG

 

 

Cheers,

Mike

Share this post


Link to post
Share on other sites
Foozil

Very interesting, following this thread for sure.

Share this post


Link to post
Share on other sites
WhodamanHD

Cool!

Share this post


Link to post
Share on other sites
Fossildude19

Very unusual fossils!  :) 

Thanks for posting Mike. 

Share this post


Link to post
Share on other sites
Tidgy's Dad

Hi, Mike, these are stunning! :)

I've got a couple of Glossopterid leaves, but nothing like these. 

Great acquisitions. 

Share this post


Link to post
Share on other sites
RJB

Never seen these before.  Very cool.

 

RB

Share this post


Link to post
Share on other sites
marguy

first time I see this, thanks for posting!

Share this post


Link to post
Share on other sites
Mike from North Queensland

sf5515.jpg

Share this post


Link to post
Share on other sites
Mike from North Queensland

The map above was found by googling ( geological maps emerald qld ) and looking in images.

I have done a bit of fossicking over the years in the area looking for sapphires and did find one small piece of fossilised wood about 40 mm in diameter just south of the tomahawk creek fossicking area.

The sapphires are in the alluvial ( old River ) material amongst the rocks and boulders where I assume your specimens came from. 

The index on the map is Czg - Gravel and sand

 

Mike D'Arcy

 

Share this post


Link to post
Share on other sites
mikemH

Mike, thanks heaps for that map.

Not exactly sure where in Tomahawk Creek they were found.

From the map the most likely origin is "undifferentiated...........fossiliferous."( Pb or Pue ) , Back Creek Group, Upper Permian. Near the junction with Sandy Creek. further west it is surrounded by" Retreat Granite" ( Dgr ).

The Vertebraria has been 'rounded', but both in remarkable condition after transportation in " Alluvium"  ( Qa ) and " Gravel and Sand" ( Czg ).

 

It would be nice if someone with more expertise than I could offer some insight.

Mike

 

Share this post


Link to post
Share on other sites
Mike from North Queensland

image.png.a298e54d656ab5c024d3c9b9c7caf596.png

 

The mining area of Tomahawk creek is the area to the left with the mining symbols.

People either dig in the area Czg or the reworked Qa.

Rubyvale is on the bottom right of the map with Sapphire just below not seen on the enlargement.

 

Mike D'Arcy  

Share this post


Link to post
Share on other sites
rodrex

 

 

Hi All,

 

I suspect that these are Tertiary, and probably replaced by silica in the same way that opal fossils are. The seed? at the top resembles whats in the photo below. image from http://www.apstas.org.au/gondwanan-flora.html.

fagaceae-8.jpg

Share this post


Link to post
Share on other sites
mikemH

I have confirmed that the 2 fossils were found in the same hole at the fossicking area indicated by Mike from NQ. They were looking for sapphires.

Its clearly surrounded by Devonian/Carboniferous formations and volcanics.

 

The Permian exposures I pointed to as a possible source are well down stream and an unlikely source for recent transportation.

The "Diagrammatic Relationship of Rock Units" does show the area overlain by Permian strata.

 

Referring to the map, the Telemon Formation ( D/Ct ) is noted as being fossiliferous.

Leptophloeum Australe, Giant Clubmoss,  has been found in this formation. "...is the most characteristic plant of Late Devonian strata....Parts of the young stems...were probably fertile regions with sporophylls instead of leaves."( Mary White, 1988 )

Lepidodendron, also a Giant Clubmoss,  has been found at Clermont, Bowen Basin ( a bit further north). ".....dominated in the Early Carboniferous.....Root systems....were Stigmaria, with patterns of circular scars with central spots.....Cones, known as Lepiodostrobus, containing male and female spores in sporangia on their sporophylls were well organised. ( MW, 1988 )

The authors reconstruction bears little resemblance.

Are there any other contenders from these periods?

 

I guess the fruit/seed could be considered similar to those belonging to a number of plants, ID depending on age.

Glossopterid fruit are generally ID by their attachment to, or association with, a glossopteris leaf.

My ID was influenced by my assumed age, by its resemblance to Mary White's reconstruction and fossil photo and by its association with the Vertebraria.

 

If it is not Permian, it is not Glossopteris and therefore not Vertebraria.

Is it Flora, Fauna or neither.

 

More questions than answers, hope someone can provide clarification.

 

Mike

 

 

 

 

 

Share this post


Link to post
Share on other sites
doushantuo

I'd recommend using (1)the Ryberg thesis for glossopterid fructifications

5:multiovulate P. Semnes

epokietlanthc.jpg

(2)Also useful might be:

 

 

 

 

 

 

 

 

 

 

epokietlanthc.jpg

whole-plant recon:

epokietlanthc.jpg

(3)OR: Adendorff(containing a wealth of information on Glossopterids,frankly indispensable if you ask me):

 

 

epokietlanthc.jpg

epokietlanthc.jpg

 

 

White's  1978 "Glossopterid Fructifications in the Australian Museum ain't bad either

Share this post


Link to post
Share on other sites
Phevo
21 hours ago, rodrex said:

 

 

Hi All,

 

I suspect that these are Tertiary, and probably replaced by silica in the same way that opal fossils are. The seed? at the top resembles whats in the photo below. image from http://www.apstas.org.au/gondwanan-flora.html.

fagaceae-8.jpg

 

Looks like Digüeñe, a type of fungi found in Chile, highly unlikely to fossilize?

 

They do taste very nice in an omelet though ;)

Share this post


Link to post
Share on other sites
piranha

Here is the response from a colleague familiar with the paleobotany of Queensland. 

 

 

"One of these specimens looks like an endocarp of Athertonioides glencoensis from the silcrete of Capella of Oligocene age.

The other one looks like a zeolite rosette, probably stibnite from the local basalt."

 

 

Rozefelds, A.C. (1990)

A mid-Tertiary rainforest flora from Capella, central Queensland.

Proceedings of the Third International Organisation of Palaeobotany symposium, Melbourne, 1988.  PDF LINK

 

IMG.thumb.jpg.d34b1f1ae46bb29c6831a21c240d6419.jpg

Share this post


Link to post
Share on other sites
mikemH

Piranha, thanks for the interest and input.

 

The Zeolite rosette makes sense.

There are a number of Hoy Basalt ( Th ) plugs ( of porphyritic olivine basalt ) in the area, including Mt. Hoy and Mt. Newsome, Early Tertiary.

 

Stibnite has a hardness of 2 and is easily fused. The "vertebraria" scratches glass and is scratched by quartz ( 6.5 ? ), it is not easily fused.

 

I have been duped by minerals looking like fossils on more than one occasion !!!

 

The Athertonioides glencoensis  bears strong resemblance and is in the same time frame as the Zeolite.

I have no expert knowledge, only a basic understanding of the subject, so hesitate before questioning the relationship of the TS figs. I, J and H to the flattened, cross section ?, area best shown in the 3rd. photo.

I will study the text for enlightenment. ( Perhaps an aberration due to mineralisation?? ).

 

Thanks,

Mike

 

Share this post


Link to post
Share on other sites
mikemH

Been reading Rozefelds,1990 and looking again at Fig.3 A-E and H.

 

With respect, and acknowledging poor understanding of the terminology, there are a number of inconsistencies that I would like to question.

Athentonioides Glencoensis surface and shape has a strong resemblance but is 36-43mm long, even allowing for "considerable variation in size" the "fruit/seed" seems a bit short at 15mm. Other features, e.g. depressions, are in proportion, i.e. less than half.

I can not see the "incipient ridge continuous from apex to base of endocarp" (  Fig.3 D ) on the "fruit/seed". 

As mention previously, Fig.3 H, showing the endocarp inner wall, seems a bit inconsistent.

 

The mineralisation of both specimens appears the same and quite common, replacement of organic material with silica minerals, most probably some type of Chalcedony, hardness 7.0.

Both specimens easily scratch glass but not so easily scratched by quartz, perhaps a closer approximation would be 6.8.

 

 Assuming the same origin for both specimens;

I think the ID is dependant on the "vertebraria" by a process of elimination. Is  it a fossilised ( back ?? ) bone, or mineral growth as proposed by piranha.

If not, then I am not aware of any other plant/root that has a similar structure.

But, as always, I invite input from those more knowledgeable than myself.

 

Cheers, Mike

Share this post


Link to post
Share on other sites
piranha

Checking the more recent literature and 'Athertonioides' is now treated as a synonym of Wilkinsonia glencoensis.

 

Rozefelds, A.C. (1992)

The subtribe Hicksbeachiinae (Proteaceae) in the Australian Tertiary.

Memoirs of the Queensland Museum, 32(1):195-202  PDF LINK

 

"Rozefelds (1990a) erected Athertonioides glencoensis for fossil fruits collected from the Glencoe locality in central Queensland. Re-examination of Wilkinsonia bilaminata also indicates close affinities with Athertonia. It is not warranted to maintain two form genera for fossil Athertonia like fruits and so Athertonioides is here reduced to a synonym of Wilkinsonia."

 

 

Attached for side by side comparison shows Wilkinsonia glencoensis appears to be a very good match. 

 

figure from:

 

Milroy, A.K., & Rozefelds, A.C. (2015)

Democratizing the collection: Paradigm shifts in and through museum culture.

Australasian Journal of Popular Culture, 4(2-3):115-130  PDF LINK

 

IMG.jpg.9d49cd1942da5d41f6d2e1f984eb4d5c.jpg

Share this post


Link to post
Share on other sites
Mike from North Queensland

It may pay to upload the photos to the Queensland museum site for identification, as that is where Andrew Rozefelds works.

 

Mike D'Arcy

Share this post


Link to post
Share on other sites
mikemH

Thanks for the additional papers and comparison photo ( 3d image ).

 

There is no doubt that the "prominent reticulate lacunose ornamentation" on the surface of Athertonioides/Wilkinsonia glencoensis  is almost identical to that on my fruit/seed.

 

There are significant characteristics of A/W glencoensis that are missing.

 

5a7d7e3c6a7ab_endviewbase.JPG.211c83d1a6ed5173aa713d15572994d7.JPG

end view, base

 

5a7d7fdfa09e5_endviewapex.JPG.bb7bbe83d9b0aa9908495cad8f009358.JPG

end view, apex

 

5a7d7ff60d62f_sideview0deg.JPG.fa21a18b2fd0e8179abc27b9d1410d95.JPG

side view,0 deg

 

5a7d81fd1ec9e_sideview90deg.JPG.3cfbd5deb9df5751c068e4c0a811b4ba.JPG

side view, 90 deg

 

5a7d8207d930d_sideview180deg.JPG.391d4d92dd052a8f77aa94d95fde051b.JPG

side view, 180 deg, cutaway, natural break.

 

5a7d82119cdf8_sideview270deg.JPG.9c1a39dfd895c1e476d1e5d2b27d0042.JPG

side view, 270deg

 

There is no "incipient ridge" and there is no "edge", as seen in the texts and 3d image.

There is no symmetrical flattening, flying saucer shape, as seen in the texts, Rozefeld 1992 Fig4 B and 3d image.

There is no "thick endocarp wall", as described in the texts and Rozefeld, 1992, fig.4 C

 

The small size, less than half, may be explained if the fruit/seed was immature, but I would expect to see some sign of the missing features.

 

Regards, Mike

Share this post


Link to post
Share on other sites
mikemH

Just an idea of what I was thinking when first trying to ID these two specimens.

 

Images and descriptions of reconstruction, Fig.124 and Fig. 139 are from Mary E. White, 1986, the Greening of Gondwana.

 

side.JPG.1cf04bdd1e93dfec0f413c9829ad7462.JPGcutaway.jpg.76225f872c0a1f8044847665fde0b61f.jpg

 

reconstruction.JPG.7852ad965ee4f28b82b368fc419678d6.JPG

reconstruction

5a7eb8abc7728_Fig_139.JPG.b21b1b744fc03f566fc2e52175563ad7.JPG

Fig.139. A Plumsteadia fruit, part broken away, with its cover leaf seen behind it......from Late Permian at Mudgee....The seeds, which seem to be immature in this specimen, are on the outside of a receptacle which is conical.

Dimension and text on image are mine.

 

 

TC005.jpg.662a849c7d4de40af01751c412c1775f.jpg

 

5a7eb8cd77994_Fig_124.JPG.74138bb91b25d23c0ebebbf6db29dcab.JPG

Fig. 124. Vertebraria indica, From Newcastle, N.S.W.. The name given to these root fossils reflects the similarity in appearance to the vertebral columns or backbones of animals.

Dimension is mine.

 

Mike.

 

 

 

 

 

Share this post


Link to post
Share on other sites
mikemH

Just finished reading The Geology of the Emerald 1:250000 sheet area, Veevers et al..Dept. of National Development, Com. of Aust.

https://www.data.gov.au/dataset/the-geology-of-the-emerald-1-250000-sheet-area-queensland

 

A couple of relevant extracts from the text;

Page 54

Foreign rock and mineral inclusions and 'olivine nodules'
are commonly found set in the basalt.^The fragments are rounded
to sub-angular and range from microscopic size to a foot across.
Weathered surfaces of basalt are commonly studded with cavities
where inclusions have been removed.^The cavities are frequently
found with a lining of the included rock.

Page 55

All but three of the plugs consist of porphyritic
olivine basalt, containing inclusions, very similar to that
described above. Plugs at Mount Ball, Mount Scholfield
and Wilford Homostead differ in that the rock is coarser
than basalt and does not contain inclusions. Mount Ball
(fig. 39) consists of olivine dolerite with only minor porphyritic
olivine some of which is iron-rich. Andesine labradorite
zoned plagioclase laths are ophitically enclosed by augite which
is also ttergranular and occasionally twinned.

 

The plug at Mount Scholfield, tentatively allied to
the Hoy Basalt, is oval in plan, about a mile long by half a
mile wide, with almost vertical flanks and a flat top.^It
consists of medium to coarse grained olivine gabbro in the
centre and olivino dolerite in the peripheral parts.^The
gabbro and dolerite appear to have an irregular junction with
'veins' of gabbro extending into the doleritu.^The gabbro
consists of large laths (up to 5 mm. long) of zoned plagioclase
(andesine labradorite) and zoned alkali feldspar (microcline and
possible anorthoclase) set sub-ophitically in ferro-augite,
titanaugito, and optically concurrent patches of olivine.
Aegirine-augite commonly rims the augite and magnetite forms
skeletal intergrowths with minor biotite. Fibrous zeolites
occur interstitially.

( Mount Scholfield is about 35km SSE from Mount Hoy, near Tomahawk Creek fossicking area. )

Page 61

Gravls -L7 '
L large part of the Emerald Sheet area is covered by
Cainozoic gravels. In the Rubyvale-Tomahawk Creek area
sapphire-bearing gravels consist mainly of sandstone and pebbly
sandstone similar to the Mount Hall Conglomerate. They vary
considerably in thickness and in places are covered by soil.
Similar gravels occur near Mount Hoy and probably represent
outwash fans from the range formed by the Mount Hall Conglomerate.
Longman (1932) descritas n jawbone of a giant marsupial of the
Nototherium type from the gravels near Rubyvale which indicates
a probable Pleistocene ago.

 

Turns out that Tomahawk Creek fossicking area, where the specimens were found, is in the Anakie Inlier, near the eastern margin of the Drummond Basin.

 

Neither specimen is Glossopterid or Permian.

 

TC003.JPG.8d6b030ec95f187343291ff7f25e137c.JPG

Most likely Zeolite, Fibrous, from Hoy Basalt, Early Tertiary.

 

 

5a7fc18d82ab0_sideview0deg.jpg.12999c293b45d01d99d656623bd015f2.jpg

A mineralised plant fossil, most likely Tertiary to early Quaternary.

Mount Hall formation is early Carboniferous ???

Athertonioidides/Wilkinsonia glencoensis is the right age, similar mineralisation ( silicified ), slightly different stratigraphy.

Glencoe station is near Capella, around 55kms north east of the Tomahawk Creek fossicking area, in the Minerva Volcanics ( Tb ), mid Tertiary.

Extract from Rozefelds, 1990;

image.png.48de0187555929882c918be13640cf78.png

Is there an explanation of why the outer surface, prominent reticulate lacunose, is well preserved, while other characteristics cannot be seen.

 

Mike

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Recently Browsing   0 members

    No registered users viewing this page.

×