Lone Hunter Posted March 31, 2022 Share Posted March 31, 2022 In my favorite creek with water levels so low there is a facinating little stretch exposed that is unlike any other part of the creek I've seen. There's about 100 ft of this grey marl in lower bank going into water, it's gritty, some still soft some like cement, loaded with gastropods, bivalves, and coalified wood. Running through it are the biggest calcite veins I've ever seen, some 10-15 ft long and almost pink, have no idea how far down they go. I was barely able to break a section off, this is part of one the smaller veins. Wondering if anyone has seen something similar. The other odd part is above that, there is a layer about 3ft deep of what I call cobblestone clay, it's hues of yellow and orange layered and rounded easily falls apart. Found shark teeth in it but I've never seen anything like it in Eagle Ford. Is there an association between the layers or do they even belong together? 1 Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 First off, are you looking at the Arcadia Park Formation which is the top part of the Eagle Ford Group? I have seen lots of calcite veins in that formation especially along faults and joints.” My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
doushantuo Posted March 31, 2022 Share Posted March 31, 2022 Concretions in the Eagle Ford might be found wherever microbial sulfate reduction and or methanogenesis is thought to have taken place(low sedimentation rate, plentiful organic matter) 1 Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 Not sure if its Arcadia park, this is close to airport, and the very top layer above the cobblestone almost looks like Woodbine, heavy red sand and ironstone gravel, and it's only in this one part of creek. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 (edited) 8 minutes ago, Lone Hunter said: Not sure if its Arcadia park, this is close to airport, and the very top layer above the cobblestone almost looks like Woodbine, heavy red sand and ironstone gravel, and it's only in this one part of creek. Are you above or below the Kamp Ranch Limestone? Generally, if you are east of the Kamp Ranch, but still in the Eagle Ford, then you are in the Arcadia Park Formation. Edited March 31, 2022 by DPS Ammonite My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 See this what I haven't figured out yet, since the creek is in QT and QAL zone it's been rearranged and there's no consistency. Did a quick look at Arcadia park info and I think the grey marl is definitely it, but what does it make the layer above it with cobblestone clay? Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 5 minutes ago, Lone Hunter said: but what does it make the layer above it with cobblestone clay? You might have to show us a picture of the “cobblestone clay.” The Arcadia Park Formation is not uniform everywhere. There are local areas of sandstone and limestone. 1 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 Paranoid about taking phone along since I slid on algae covered rocks and took a plunge, but yes I want to get pics of it. About 1/4 mile down creek it completely changes to huge ugly sandstone outcrops where right above that is a culvert these concretions come from, some a couple feet around along with slabs of oysters. Link to comment Share on other sites More sharing options...
doushantuo Posted March 31, 2022 Share Posted March 31, 2022 Lone, I'm posting this because the subject matter intersects several geological subdisciplines, which might be instructive: THE EAGLE FORD OUTCROPS OF WEST TEXAS:A LABORATORY FOR UNDERSTANDING HETEROGENEITIES WITHIN UNCONVENTIONAL MUDSTONE RESERVOIRS Arthur D. Donovan, T. Scott Staerker, Aris Pramudito, Weiguo Li,Matthew J. Corbett, Christopher M. Lowery, Andrea Miceli Romero, and Rand D. Gardner GCAGS Journal, v. 1 (2012), p. 162–185. 1013531755_Donovanetal.2012-GCAGSLozierPaper(1).pdf Figure 11. Buda/Eagle Ford contact and the basal portions of the Eagle Ford Formation at Lozier Canyon. A six-ft tall micropaleontologistis holding 5-ft Jacob staff for scale. Note: (1) characteristics of sub-facies A1, A2, A3, A4, B1, and B2 and (2) the undulatory surface at the top of the Buda Limestone. PS = parasequence Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 Oh wow thank you! I have a lot of homework to do! I don't know if it's just me but Eagle Ford group seems to have so many variations and differences within, it's not so cut and dried like other formations. Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 We may have to find you some literature on the local Eagle Ford Group. The Eagle Ford in western Texas is different. A good place to start is the website northtexasfossils: http://northtexasfossils.com Look at the descriptions and references for the Eagle Ford Group and the formations contained therein. 1 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
doushantuo Posted March 31, 2022 Share Posted March 31, 2022 Relax, it's NOT just you. The Cretaceous of Texas and/or the Western Interior Basin("WIS") are inherently fascinating. Lone: it might be good to remember that the piece I posted is somewhat geared to hydrocarbon exploration, which might introduce some bias. 1 Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 (edited) 6 minutes ago, doushantuo said: the piece I posted is somewhat geared to hydrocarbon exploration,which might introduce some bias The hydrocarbon related literatures tend to emphasize the micro fossils such as forams which can’t (in my book) compete against echinoids, ammonites and clams. Edited March 31, 2022 by DPS Ammonite 1 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 This came from same place the concretions did, the walls of culvert, would this be cone in cone if not what is it? Wondering if it's indicative of something that happened in the area ? Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 Sort of looks like cone in cone which are somewhat of a mystery as to why and how they form. I remember seeing some at Lake Texoma. https://serc.carleton.edu/NAGTWorkshops/sedimentary/images/cone.html 1 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
doushantuo Posted March 31, 2022 Share Posted March 31, 2022 Agree with DPS there, possibly cone-in-cone ("beef"). We talked about hydrocarbons - they can overpressure reservoirs, leading to such structures. Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 Beef? Link to comment Share on other sites More sharing options...
doushantuo Posted March 31, 2022 Share Posted March 31, 2022 Yeah. Not the edible variety, but "bedding-parallel calcite veins". 1 Link to comment Share on other sites More sharing options...
DPS Ammonite Posted March 31, 2022 Share Posted March 31, 2022 15 minutes ago, doushantuo said: cone-in-cone ("beef") I guess that a lot of the geologists in the field are longing for a good steak. Paper on cone in cone beef: https://www.sciencedirect.com/science/article/abs/pii/S0264817213000299 My goal is to leave no stone or fossil unturned. See my Arizona Paleontology Guide link The best single resource for Arizona paleontology anywhere. Link to comment Share on other sites More sharing options...
Lone Hunter Posted March 31, 2022 Author Share Posted March 31, 2022 Thank you that clearly explains it. I left out picture that I thought determined if it was, and just saw YouTube vid of fossil hunters in north Texas that found the exact same thing in a creek. Now wondering if this is related to the large veins, some sort of event that caused both maybe? Link to comment Share on other sites More sharing options...
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