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Clastic Sedimentology - Science topic
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This was found in shallow water (deltaic) deposits of late Cretaceous age - middle Campanian (central Poland, Europe).
On the left there is an imprint of a tree, but the most interesting structures are encircled by red lines. Additionally there are some "double hollows" marked by blue.
Do you have any proposition what is this?
Best, Zbyszek


Hi All!
Can anybody clarify, if the weighted mean average of multiple concordant U-Pb ages (A)(considering concordance >95%) in detrital zircon grains is almost similar to the weighted mean of three youngest concordant ages (B) (following Dickinson and Gehrels, 2009), can I take the overall weighted mean (A) as the maximum depositional age of that sedimentary rock? And do I need to consider any cut-off concordance to select the youngest grains?
Any answers or suggestions are highly appreciated.
Many thanks,
Harshita :)
Hello Everyone, I am working on paleoclimate of northwest Australia. I have been searching for the sediment discharge/sediment load of ''Ord River'', ''Victoria River'' and ''Fitzroy River'' but cannot find it anywhere. Can anyone guide me where can i find the sediment discharge data of the mentioned rivers?
Thank you
I noticed that there was some sandstone interval contains some considerable amount of Siderite. I know that this is diagenetic. Could we attribute some specific depositional environment to these sandstones with some initial specific mineralogical &/or chemical composition that led to the transformation to siderite in time. ???
I have analyzed few marine samples on the Mastersizer software for the grain size analysis. I calculated the mean grain size, and median data from it but i don't know how to calculate the sorting data from it. I would really appreciate it if somebody guide me how to calculate the grain sorting from this data.
Thanks

Sediment is relatively younger than the soil in the depositional environment as the sediments are consequence of the accretion of particles transported either by waters or by winds, whereas, soil profile is stable lacking any sort of movement. Soil profile is developed with time span which is a stable one, but the movement of the sediment particles developed those soil profiles in so many physiographic set up, are they (soils and Sediments) differed chemically, do they possess different chemical environment?
Hello, I am currently working on the design of a device that measures thermal conductivity of sediments and I am not sure if i estimated heat losses and heat flux in the correct way. The device is a 0,0034 cubic meters (200 cubic inches aprox) box with a resistor (curved alloy wire) in contact with one face of the sample, connected to a power supply. The resistor is in the middle of one face of the sample and a heavy insulator, like glass wool (i am not sure if this is the proper term for the material).
This is not my work area, i'm a geologist, but given my current research i am in the need to resolve this issue
Please feel free to answer any of this questions, also any comment will be helpful.
My questions are:
- If it is ok to estimate heat losses considering an estimation of the temperature at a middle point in the box and thickness and the thermal conductivity at the five walls that surround the internal sample considering that one side of the device is in contact with the surrounding air
- If using a common insulator (say 0,02 to 0,04 W/m.C°) will yield an aproximate heat loss of less than 1W, considering 0,1 m wall thickness (4 inches aprox).
- If the sample will reach a quasi steady-state heat flux or will be far from it, considering the room temperature stays aproximately constant.
- How much heat will disipate the wire if the power output of the power supply is, say 6W. In other words what will be the heat flow at the resistor, through the first face of the sample near the resistor, given that supplied power.
Regards
In a delta front context, How can we discriminate between sands deposited by river floods & sands deposited in wave dominated deltas
esp when we don't have any sedimentary structures observed except few horizontal lamination, no bioturbation. 4 to 5 meters of structurless/massive fine sandstone with abundance of mud clasts and few convoluted bedding (attached some core photos)?



In deltaic system; Very fine to fine grained compact sandstones with planar laminations and no bioturbation. could we consider this a wave or fluvial dominated delta front?
* some intervals of fluid mud (Non bioturbated shales)are observed within the prodelta facies
* only a half HCS observed
* sand intervals are very clean and can form 4 to 5 meters of sandtones
* Some sediment gravity flow and dewatering structures were also observed
Wave dominated or River dominated delta front ???
I want to know the ideal tectonic setting with example on which sediments experienced very little transportational history with no signature of deformation and post depositional metasomatism.
I would like to know the fast and easiest way to differentiate aeolian and fluvial silt by looking at the samples itself.
These photos taken at Sandstone layer . Please can somebody help me in the identification of these concentric and parralel laminations ? And which is the origin of this process ? NB : outcrops located on the coast influenced by marrine erosion.



What are the main reasons when HI values are more than 100 but Oxygen index values are equal nil ?
What is the best method for measuring the age of clastic rocks which has no fossils ? Your advice is highly appreciated.
This facies belong to upper Cretaceous in the Azarbailan, NW Iran. this is a lime sandstone or sandy limestone that deposited in marine environments. I need more discusstons about this facies with references .
Photos take by 4 and 10 lens of microscope.
Tanks
Mobin

I was reading a past question (https://www.researchgate.net/post/how_to_calculate_the_degree_of_discordance_of_zircon_ages) where people were debating the cutoff age for switching between calculation of discordance/concordance based on either 206/238/207/206 or 206/238/207/235 and the related cutoff age applied when reporting detrital zircon ages. I decided to ask this question to start a debate on the pros and cons of using concordia ages (Ludwig, 1998) which removes the necessity for a cutoff and filters data by probability and MSWD of concordance. The issue has recently been raised by Zimmermann et al (2017) who recommend the latter approach and has been applied as far back as 2004 (perhaps before) by Peter Cawood. The concordia age approach seems to be the most sensible one but I cannot understand why it is not becoming widely adopted by the 'detrital zircon community'. All opinions welcome.
This sand body is located on the southern edge of the Pannonian Basin, on the southern slopes of the Papuk Mountain, and the age is Pleistocene, approximately 1.6 million years. The sand is medium to coarse grained with 2-31% of gravel. It contains a lot of fossil remains (fish bones, dolphin bones) from a nearby older sediments (Pliocene and Badenian). No structures were found on site that would help us to determine sedimentary environment.
Could it be a quick slope movement of sediment triggered by earthquake?
Hello,
I deal with detrital heavy minerals. I found quite numerous topaz grains in several samples. I wonder if this is possible to distinguish between different source rocks (e.g., various pegmatites and skarns from the Bohemian Massif, Central Europe) using chemical composition of the topaz grains/crystals (major and minor elements using electron microprobe, and/or trace elements using laser ablation). This subject is completely new for me, I will be grateful for any tips.
Monika
Dear all,
I have done XRD analyses of modern fluvial unconsolidated sediments (soil- clay, silt and sand) to identify the mineralogy and their proportions. I require to select the best minerals to interpret the provenance & paleoclimate of the modern fluvial sediments. Do I need to select different mineral group for provenance & Paleoclimatic interpretation? I would be extremely grateful if you kindly help me in this regard.
Best regards,
Ashok
while we drill we face hard formation sandstone plenty of mica.
There is a significant variation in gamma counts of borehole sediments collected in fluvial environments. The sediments belong to clayey Flood Plain deposits without any sandy sediments. This may not be related to the organic matters since most of the sediments are yellowish brown in appearance. The lower value is concentrated in a particular zone only. Does it relate to drainage condition of the area? If yes, well drained sediments should have lower gamma value relative to poorly drained one. Is it correct ? What would be the possible reasons for such a variation in terms of depositional environment?
The method of Springer-Lilje (1988) is a probabilistic extinction-date determination with the following equation for a confidence interval of 95%:
Dext = Dmin - ([In(0.05)] / - [(N - 1) / Dmax - Dmin])
where Dext is the extinction date, Dmin the geologically youngest date, Dmax is the geologically oldest date and N is the number of datings.
However, typically, ASR and EER dates are provided as +/- 20% for the 95% confidence range. Do I have to use for Dmin the youngest date minus 20% (and for Dmax the oldest date plus 20%), OR I ignore this 20%?
Dear all,
The fluvial sediments are highly enriched in Carbonates due to the presence of calcrete nodules (Kankars). It is thereby giving higher percentage of CaO in XRF results which in turn is reducing the concentration of other oxides, especially SiO2% (Attached Excel File). Kindly suggest me best and easiest way to remove the carbonates from sediment powder (oven dried) before doing the XRF analysis. The procedure should not be time consuming since I have huge data.
Looking forward to your kind replies ASAP.
Thanks & regards,
Ashok
I am building a 3D orthomosaic of a Carboniferous coal face and I have projected it in agisoft. However, it has projected with the z-axis coordinates in reverse, I think this may be due to the camera as this is the first time that this has happened. How do you change these coordinates? Does anyone have a link to a tutorial for the coordinate system on agisoft?
I am studying sandstone with high ferruginous and matrix content, existing schemes do not account high Fe content, any suggestion will be appreciated.
Have you know that the last or/and the best sedimentary basin classification?
Is there a classification for (of) an energy source or (of) a tectonic evalution source?!
How do we get source from these classification?
One would expect the volume of clastic sedimentary rock to steadily increase from zero in Hadean times. But how much has this been affected by processes like subduction?
I'm studying a stratigraphic section where clastic sediments are up to 400 meters thick. I have recognized three depositional environments being alluvial fan, fluvial, and marine. In the upper parts of the stratigraphic column where fluvial system turns into marine I was wondering if I've missed to record delta where these two systems intersect. The lithology in the upper part consists of an alternation of large cross-bedded conglomerate and sandy bioclastic limestone which clearly shows the sea-level fluctuation for a fair amount of time before marine conditions dominated. Did I miss recording Deltaic environments or fluvial deposits were transported to the sea with some sort of channels?
attached photos may be helpful.
Thanks for the comments in advance.





In my project, I have petrograhic data ( SEM, thin section, Core/sw/cutting samples) and calibrated Gamma Ray curves to identify the reservoir's quality. My target is the arkose sandstones with abundance of granitoid fragments. The sandstones are interbedded with clays. Both granitoid fragments and clays shows high GR values. How can i distinguish them ?
Thanks for your answers
The paleocene eocene thermal Maximum Events t associated by several minerological and chemical changes .The Sr 86/87 ratio may clarify that.
In Dabdaiba section from Eygpt auch phenomena have been cheked.
In kurdistan region such boundary associated by Incised valley deposits and apperance of Giant Gastropods.
Does anyone know how to use NTG and porosity to know the depositional environment in a clastic environment?
Most of the known successions interpreted as tide-dominated deltas (e.g. Lajas, Tilje Fms.) have recently been reclassified as fluvial-dominated, tide-influenced because of the recognition of typical fluvial-derived features, such as forward-accreting, coarsening-upward mouth-bar deposits, crevasse-mouth-bar deposits, signs of seasonal variations of the fluvial discharge, etc.
Following this trend, it is arguable that the sand-rich successions that are commonly interpreted as tide-dominated deltas might be more fluvial that what was originally thought and that ancient tide-dominated delta successions have not been described yet. Does anybody know ancient deltaic successions that are convincingly and extensively tide-dominated? Why?
Thanks in advance to anyone that will contribute to this discussion.
I have 10 microfacies for Permian Mixed-Carbonates as follows:
Calcareous Sandstone Facies
Crinoid, Bivalve, Brachiopod, Fusulinid, Bryozoanal Calcareous Sandstone Facies
Bryozoan, Bivalve, Fusilinidal Calcareous Sandstone Facies
Fine grained Dolomitic Calcareous Sandstone Facies
Bivalve, Brachiopodal Sandy Packstone
Bryozoan, Bivalve, Brachiopodal Calcareous Sandstone Facies
Crinoid, Bivalve, Brachiopodal Sandy Wackestone Facies
Brachiopod, Bivalve Calcareous Sandstone Facies
Medium grained Dolomitic Calcareous Sandstone Facies
Quartz Wacke Facies
..... Also straight Vertical burrows at places and branching burrows as well. Pic1:Vertical Burrows, Pic2:Dasycladacean(green algae, Pic3:Complex burrowed horizon (may be Thalassinoides, Pic4:Fusulinds, Pic5: Horizontal and vertical branching Burrows, Pic6:Thalassinoides (Skolithos burrows.





+1
My sample is only identified as boulder clay from Marks Tey in Colchester UK. How can I find the predominant clay mineral in it?
Hello everyone,
Have any of you used CT scans of sediments to get a density profile/trace? Specifically, I am working with marine and lake sediment cores. I have used CT scans before for their imagery and have exported profiles of their densities based on their grayscale values in ImageJ, Sante DICOM Viewer, and Osirix, but we'd like to move into using our CT scans a bit more quantitatively. I processed the dicom files with the same window and level settings within individual cores, but was not always able to use the same settings from one core to another when I created images (.jpegs, .tiffs, etc.) from the dicoms (sandier cores would be washed out or muddier cores would be too dark to see detail otherwise). Now, though, we'd like to access the actual, or as close to actual, densities as possible. I've read a little bit about calibrating CTs to a known value (I was thinking air that got imaged around the cores, or their PVC/plastic core liners) and about using the Hounslow scale to at least approximate actual densities. I was wondering if a) anyone's got any thoughts on finding good ways to tie CTs to actual densities, and b) if anyone can think of any pitfalls to watch out for while I do this.
Thank you for any help or suggestions you can give!
- Bran
I mean how fast will they be disintegrated? How far from the Bryozoan reef will they be in less then a millimeter in size? Do you know any experiment concerning this subject?
Thanks for any news. Zbyszek
The annual nature of what we now call varves was independently suggested in Sweden and in several places in North America in the late 1800's. We know of these because of the universality of the english language and the pioneering work of the Swede DeGeer in showing the usefulness of varves. HOWEVER, it has always occurred to me that other countries (Germany, Lithuania, Estonia, Russia, etc.) have varved sediments, AND there could have been early geologists that also made the conclusion that they were annual. The rest of the world is not aware of these because these early descriptions are 'locked' in these other languages. Does anyone know of any non-english, non-swedish papers that independently deduce that 'varves' are annual?
Other major oxide values are within limit of PAAS value.