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Showing results for tags 'hanonet formation'.
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I have assembled quite the collection of stromatoporoid fossils in the last year and a half since I began this hobby. They are my 'main focus' for now, together with brachiopods and corals to a lesser extent (especially Gypidulid Brachiopods). I have been reading scientific papers on stromatoporoids for a few days because I hope to get a full understanding of them. The articles were mainly by Stephen Kershaw and collaborators and by the late Colin Stearn who have both produced some great stromatoporoid literature. I am currently reading https://journals.ku.edu/treatiseonline/article/view/4088/3855 (Internal morphology of the Paleozoic Stromatoporoidea by Stearn 2015) in order to identify my fossils. I have found it a good tool but I'm having a hard time distinguishing between pillars and pachysteles and between laminae and pachystromes. I understand pachysteles and pachystromes are thicker and more robust versions of their counterparts, but the problem is that the figures provided in the paper don't have a scale (only magnification is mentioned) and it subsequently becomes very hard to distinguish. I have also not found any other clear illustrations of the difference on the internet. Here's a useful table by Stearn for determining the type of stromatoporoid: cyst plates and pillars (Labechiida) laminae and pillars (Clathrodictyida, Stromatoporellida) pillars and colliculi (Actinostromatida) pachysteles and pachystromes in an amalgamate structure (Stromatoporida, Syringostromatida) My questions are: Does anyone know a useful way to determine genus/family other than what I'm doing? Is there any particular way to distinguish pachystromes and pachysteles from laminae and pillars other than looking at their robustness? If anyone has some interesting literature about this, please tell me about it. I have provided close-up pictures of an example specimen below (I have dozens more, so I'm able to provide them if necessary). Is anyone able to say if it is composed of laminae and pillars, pachystromes and pachsteles or any combination thereof (maybe also cyst plates)? Also, I assume all my specimens are the same genus because: They were all found at the same locality in the same formation (Middle to Upper Hanonet fm.) Stromatoporoid assemblages typically have low species diversity, having one genus more abundant than others ( as stated in Kerschaw 1990; Da Silva, Kershaw, Boulvain 2011) I will look at every specimen before assigning it a genus/species though, just to be sure. There's also a question I have about why there are less stromatoporoid fossils in units 1 and 2 of Hanonet fm relative to the later units (at least in my experience). They are more abundant where there are argillaceous limestones than where there are calcareous shales. I know stromatoporoids preferred to grow on carbonate substrates so it might be because there's simply more carbon in the limestones. Then there's the question of why the shales are followed by limestones, which I think is because of a transgression resulting in the deepening of the sea (as mentioned by others in research). Limestones are more characteristic of deeper areas so that's why I think that. I have read articles about this in the past but I'll have to re-read them to fully understand. Also, if there's anything I got wrong please point it out.
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Fossil hunting trip to Couvin (Devonian of Belgium)
ziggycardon posted a topic in Fossil Hunting Trips
Hi everyone! Today I went on another fossil hunting trip with the fossil club the BVP. https://www.paleontica.org/sites/fossil_site.php?plaats=3&language=en We visited the "La Couvinoise" quarry in Couvin, Belgium. The rocks in this quarry are part of the Hanonet Formation which lies at the boundry of the Eifelian & Givetian. But the layers we searched in today where all Givetian in age (387,7 - 382,7 mya), I mainly searched in the Crinoïd & Brachiopod layer. Although I have to admit that we probably visited the quarry at a bad moment, as the yield was quite poor in the quarry this time according to members who've been there before. Which was quite obvious as I think we only found our first fossil rich rocks after 50 minutes of searching and even then the first hour of finds where few and poor in quality. But after a while of searching I found some good and rich blocks and managed to get some decent Crinoïd stems, Brachiopods and some rugose coral pieces. But the best 3 finds we did during the last 30 minutes of being in the quarry. The 1st one was the only Trilobite I found during the hunt! Trilos are very rare from this quarry and I believe only 1 other member found one before me on this trip. I found a pygidium which is still partially enbedded in rock. At first I wasn't sure whether I was a trilo or a brachiopod but after having a couple of other members checking it out, they all believed it to be trilobite. The excursion leader time was quite amazed by the find as this trilo came from the Crinoïd layer, which is a layer where he believed no trilobite had ever been found. The trilobites are usually found in another part and layer a bit further in the quarry. So yeah I am very pleased with that find! The 2nd best find, was one I didn't find myself but recieved from our Excursion leader Tom, which was a piece of very nice Stromatoporoidea which I wasn't lucky enough to find. The 3rd best find an perhaps my favorite was something that Tom told me to check out. He had discovered the remains of a cave that collapsed during some excavations in the quarry. You could clearly see the remains of dripping stones on the walls and luckily for us, some pieces of those dripping stones where also laying on the ground. So I managed to take a nice piece of them home with me They are encrusted with a layer of dried mud but I am sure they will look gorgeous once they are cleaned! The rings are already clearly visable in some areas. Here are some pictures from inside the quarry. This was the way to the newly excavated plateau which unfortunatly was a complete was of time as not a single fossil could be found in those rocks. After that we went to the other lower parts of the quarry where I mainly worked in a single piece of wall in the Crinoïd layer. I was lucky enough to find a few good fallen blocks and some good places in the wall with some decent Crinoïds and Brachiopods. One of the nice Crinoïds stems I found in the layer. And here is the piece of wall that has some of the dripping stones in it.