Questions related to Sedimentary Geochemistry
I am aiming to generate 3D profile of subsurface formation using VES techniques . I have DDR3 Electrical Resistivity meter (http://www.indiamart.com/proddetail/ddr-3-resistivity-meters-3894683488.html) to carry out this studies. Is it possible ?
If it is only software dependent, which software can be suitable for interpretation and 3D profile generation ?
The geological meaning of Cao* seems not to allow the occurrence of negative cases, but in the face of the high content of P2O5 (close to Cao), resulting in caO-P2O5 * 10/3 of the result is negative, how should I deal with this situation, what may be the geological reasons?
Looking forward to your kind suggestions in this regard!
Thanks & regards,
I have trace element data (using ICPMS) of the bulk sediments from the lake bottom.
I would like to calculate the elemental ratios (e.g., Rb/Sr; Sr/Ca, etc.).
Is there any method available to calculate apportionment of Sr in both silicate or carbonate fractions?
What kinds of additional parameters, do I need for this calculation?
I am removing carbonates from clay and sand samples. So, I treat the sediments with H2O2. I need to wash the sediments to remove acid residues. I am thinking of heating the sediments with ultra-pure water over hot plate and subsequent evaporation. The process can be repeated for 3-4 times over hot plate. Will it work and act as an alternative method of centrifuge washing?
To calculate CIA and also plot the data on A-CN-K ternary diagram, I need to know the CaO in silicate minerals only, so reliable correcting method.
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.
Hello Professors and colleagues
I am studying Neoproterozoic meta-sediments can i apply the indices of alteration on it or it has to be on sedimentary rocks only ?
Thanks in advance
1/Would you please suggest me some specific ideal rock unit/sequence of known provenance on which one can validate his /her provenance model. For modelling i am thinking of using whole rock geochemistry and trace element for less transported sedimentary rock .
2/what can be the approach when dealing with effect of hydraulic sorting and diagenetic process on geochemistry of sedimentary rock .
3/ Also i want your valuble opinion/critics on selecting less transpoterd diamictite,Non-metasomatised arkosic sandstone and tillites as for these modelling purpose.
Clay samples are heated at 950 degree centigrade (LOI method) before XRF analysis. Due to which Fe percentage increases in the XRF results. It is due to the oxidation of samples during fusion. Is there any procedure to correct the Fe value within the results?
I want to know whether these chemical proxies (like CIW or CIA) can be used for Pliocene lignite? or are there any other chemical proxies can be used to indicate the degree of weathering for young coals (e.g. Pliocene lignite)?
Greetings RG community,
I have yet another question! so I have been working on some project lately, and quite of lot of the samples I work on contain a portion on heavy hydrocarbons that corrupt the Tmax reading.
I was wondering if correcting it by just identifying the kerogen peak was correct. Also, there is the problem of representativity of such values because this problem occurs mainly when the S2 values are quite low (<1mg/g).
I was thinking of using the CO2 readings from the IR to determine when the kerogen cracking starts when the h.hydrocarbon and kerogen peak are hard to differentiate, is that possible? has it been done by someone else?
thank you in advance for your help and have a good day.
George, good to see you are still working on the DWM. Keep in touch. Any interest in organic mudstone resistivity analysis?
I) Thickness at which sediment was dated is 100cm.
II) Age is around 150 years at 100cm.
III) Estimated Sea level rise of the area is 0.314cm/year.
If I am assuming that in 150 years total rise in sea level was 47.1 cm and this much rise in sea level can only accommodate 47.1cm sediment in the basin without any subsidence, if is it ok?
In present study total sediment was deposited around 100 cm in 150 years with respect to the sea level rise in the area. 52.9cm (100cm - 47.1cm = 52.9cm, where 47.1cm is sea level rise in 150years) extra column of sediment was deposited during entire 150 years. Which happened to be only 47.1cm (as per the sea level rise), because the rise in sea level was only 47.1cm. So it is only possible when basin sediment was got subsided/ or subsidence.
So based on this, the rate of subsidence was 0.35cm/years
= 52.9 cm ( extra sediment deposited in 150 years) /
150 (age of the dated sediment)
Please suggest your views.
Elements analysis on different sequential leaching products of the samples are needed to strengthen the conclusion. Sedimentary carbonates can host various trace elements in their crystal lattices, with concentrations dependent on the geochemical compositions of seawater and their partition coefficients between carbonate and seawater.
Briefly speaking, the grain-size effect means the good correlation between geochemical data/proxies and grain size. To be more specific, the grain-size effect actually owns different kinds of forms, e.g. quartz dilution effect, absorption effect by clay, mineral sorting effect and weathering effect. Hence, Q1: How can we address all these aspects of grain-size effect and reveal “real” sediment mixing or chemical weathering? Previous studies mentioned elemental ratios, e.g. Th/Al/ Si normalization (e.g. Bouchez et al., 2011, 2012; Dinelli et al., 2007; Lupker et al., 2013), or special pre-treatment strategy (e.g. narrow grain-size window)? But neither of them may solve all the aspects mentioned above or be suitable for all the regions.
In addition, Q2: when the geochemical proxies show a high correlation with grain size, do they have to be abandoned or corrected for? In another word, the proxies showing no correlation with grain size always give “real” geological significance?
When we works on sediment mixing or chemical weathering, we want to find some proxies showing no correlation with grain size. However, what if grain-size effect just means provenance change or chemical weathering intensity? For instance, two sources exist in one catchment, i.e. slate and sandstone. When river collect materials from both lithologies, the geochemical proxies will always show a good correlation with grain size even though the hydraulic sorting is poor, because it is always a mixture between a Si-rich (coarse) end-member and an Al-rich (fine) end-member. Hence, grain-size effect here just indicates provenance mixing, which is exactly what we want. Another example is about chemical weathering indexes. CIA indicates the chemical alteration process from feldspar to clay minerals. Hence, when we sample finer sediments, the CIA will be higher. People say that this is not “real” chemical weathering signal, because of the bias of mineral sorting. However, it’s also possible that sometimes the fine sediments are just sourced from a highly weathered region, and the coarse sediments nearby may be derived from another region with low weathering intensity? From this perspective, the grain-size effect give the similar meaning with chemical weathering intensity. In addition, another chemical weathering proxy, WIP, is considered to show no correlation with grain-size and seems to be a better weathering proxy (e.g. Shao et al., 2012; Zhou et al., 2015). However, this phenomenon may be explained by the offset between quartz dilution effect (WIP increases) and weathering effect (WIP decreases) during the downstream transport (grain size decreases). Hence, sometimes WIP can give wrong indications in a specific watershed (Shao et al., 2012).
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.
I am studying Proterozoic granitic rocks and received a suggestion to do some apatite dating. I would like to understand what is the meaning of the ages I will obtain via this process and also would like some suggestion of papers to read in order to understand that better.
From the data I have, the general trend is that the bulk rock carbonates have heavier d13C values (around 0.5 per mil more) compared to brachiopod calcite shells from the same samples which the bulk rock powder was extracted. These are Ordovician samples from the western Baltic palaeobasin.
Major and trace element analysis are performed and different proxies are used on a 2m long soil profile. This does not show depth vise geochemical variation.
However, δ13C(SOM) varies from –14.2‰ to –22.6‰ with an overall variability of 8.5‰. What are possible interpretations?
For instance, can we say rounded grains are relatively older than euhedral ones?
Is the color an indicator for the relative age of the grain?
I am working on Fe nodules present in late Pleistocene- early holocene alluvium which is overlain by laterite. I want to know if i generate major and trace element data of laterite soil. How it can be useful in geological studies? If it can be used in studies of Fe nodules and alluvium or the major and trace element data of laterite has some other geological significance.
I have these plates which contain SEM images of Foraminifera from the Upper Cretaceous (Turonian) from the Ferron Sandstone Member, Utah, USA.
All the samples recovered from shales from this member, The Ferron Sandstone member belongs to the Mancos Shale formation.
This area range from shelf to deltaic environments. The preservation is poor in some samples but fairly good in others.
I am just struggling in identifying them, so I kindly ask for your help!
Ferruginous nodules are found in alluvium of holocene age overlain by laterite.. There are many theory proposed on their genesis especially of Ferro-manganese nodules. What is the point of view of fellow researchers on genesis of such Iron nodules or concretions ?
Before taking up geochronological studies we do detailed petrpgraphy with reference to deformation and alteration....to find its suitability for radiometric dating
what criteria should be used to determine whether the rock is suitable or not
in terms of fracturing/ crushing/ granulation and fracture filling
Just looking to quantify how much leaf litter actually falls in boreal, temperate, neotropical, tropical, etc. I know that I can get estimates of total production, but I'm looking for estimates of how much of that production enters the detrital pool.
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,
I am a doctor in China. Now I was study the metasedimentary rock and want know the sedimentary environment. So I ask you for how to study the Sedimentology of metamorphic rocks
I want to recover the the original environment of deposition of metasedimentary,such as Quartz schist, mica schist, or Felsic gneiss.There are no sedimentary structure. I don't know how to do a realiable work on this meta-sedimentary.
I would like to know the concentration of formic acid in produced water or flowback water from Marcellus shale gas production.
Do you know the reference for that?
Our results indicate that high sedimentation rate correspond to heavy isotopic signals, e.g. d34S can research 20‰, while low SD leads to light pyrite with d34S around -20‰. Could anyone tell me the mechanism for it?
I have some question about the relationship between granulometric size, majors elements, and mineralogy of sediments cores (retrieved from lagoon).
The major element is measured by ICP-MS, and grain size measurements were performed with a laser Diffraction equipment (Malvern Mastersizer 2000).
The result showed an important percentage of sand in the depth layer of cores, also the distribution of calcite indicate a high percentage in depth layer, but the concentration of Ca and Sr decrease with depth.
I found that all majors elements (Fe, Al, Ca, Sr, Al, Mg, K) are significantly correlated with sand, and negatively correlated with fine fraction.
how can I explain that? because the concentration of this element should be higher in the depth layer.
The relationship between granulometric size, majors elements and mineralogy of sediments cores ?
1) How to extract and dating zirconolite (CaZrTi2O7)?
2) What rocks of basic composition it is present as an accessory mineral?
3) What is the temperature of the closure of U-Pb isotopic system in zirconolite?
1) Как извлекать и датировать цирконолит (CaZrTi2O7)?
2) В каких породах основного состава он присутствует в качетсве акцессорного минерала?
3) Какова температура закрытия U-Pb изотопной системы в цирконолите?
Greetings Research Gate community,
I have been bugged for some time now about this question. this is the third time i encounter this case:
A high TOC concent measured by a LECO elemental analyser (3% wt). Compared to this, the parameters i get in the Rock Eval analysis are very poor: very low S1, low S2 (about 0,2 mg/g) and also a low S3.
the samples are shales from varying formations (Upper Devonian, Mesosoïc,...)
could anyone help me with this question please? some references could help too.
Weathering and alteration are usually near surface phenomena.
I am observing rocks collected from>100 meters depth...which are highly altered.
what kind of alterations are prominent at greater depths?
what are the factors the govern this kind of alterations?
Is it structure/ mineralogy or something else?
I'm specifically looking to determine the ratio of Hg:Al in this particular formation.
What sedimentological interpretations can be made if a carbonate succession shows significant trough cross-bedding?
I am studying sandstone with high ferruginous and matrix content, existing schemes do not account high Fe content, any suggestion will be appreciated.
I search a recent map that estimate reverine sediment fluxes to the sea on a global scale.
I am doing extracting for different type of iron mineral from sediment. I test the method like 1 M CaCl2 for exchangeable fe2+ and 0.5 M HCl for Fe2+and Fe3+ in the standard sample. However, the result is really terrible. I add the solution(reagent all in DDI water) to sample and mix them in the glovebox for sufficient time like paper said. Than I measure them outside of glovebox with Hach for Fe2+ measure and ICPMS for Fe3+. Though I haven't got the result from fe3+ analysis, the results from Hach measurement shows that just 1% of fe2+ of standard mineral are extracted in the solution.I following the paper by Gorm Heron(1994) which successfully using 9 methods targeting different iron mineral.
Is that because I test fe2+ outside of the glovebox, giving time for fe2+ transfer into fe3+, which cause my experiment fail? or anyone have same extraction experience can share with me?
I would like to study and run some analysis on pyrite grains present within black shales. For that, I will have to separate them (I will need at least 200 to 500 mg) physically to avoid alteration. Please let me know if you are aware of any paper with detailed description of the method?
In the PM-normalized diagram, my data for some basaltic rocks show slightly positive Nb-Ta anomalies. They all show positive Pb anomaly but no correlation of MgO versus 87Sr/86Sr and 143Nd/144Nd?
I am looking forward to your help. Thanks in advance.
I have been analyzed sediment samples for d15 N in EA-IRMS.I am in need of formula for analyzing Total Nitrogen from same sediment samples.Kindly help me in this.
Is it feasible to separate/isolate the heavy metals (or inorganic compounds, in general) in riverbed sediments? And if it is, what is the best/cheapest way to do so? We are planning to measure the toxicity of the isolated compounds by exposing them to bioluminescent bacteria.
I have detrital mica separates that I would like to mount in EpoThin resin for microprobe analysis and I would simply like to know the best method for mounting them. With zircons you can mount on double sided tape and then simply pour the resin over them. But with micas I am worried that they will not peel away easily from the tape once the resin has cured. I am also concerned about polishing them. Any advice would be much appreciated.
How to take a deep sediment core from a very shallow and a hard to reach lake? I can't use a platform. Lake is only 3 metres deep. The area around the lake is wooded. Any methods/ideas?
I have a Speleothem isotope record of Indian summer monsoon(NW Himalan region) in which oxygen isotope shows wetter phase (16O enriched values). At the same time for the same speleothem (same depth and time as for oxygen) carbon isotope record shows C4 vegetation(13C enriched values).
How can it be possible? In which condition would it happened?
Because in tropical region the vegetation is governed by rainfall. If more rainfall then It should be C3 type vegetation(12C enriched) vegetation.
I am critical about a porphyry Cu-S ore occurrence while working on a porphyry granitoid in a cratonic shield of NE India . As my study shows positive indications in many parameters I studied like Sr and S isotopes, hypogene alteration pattern, detail geochemical signature etc. I need to investigate oxygen isotope and fluid inclusion to enhance my claim for drilling as geophysical works seems to be difficult in view of inaccessibility.
In the study of groundwater circulation in large sedimentry basins, it is neccessary to predict permeability variations with dpth. Different models have been proposed, such as linear and logrithmic ones. However, exceptions are often encountered. Is it now a question if such rule exists for all basins or it is entirely site-specific.
I am a Master student in Aix-Marseille University, Reservoir Carbonate Geology faculty, France. I am looking further information about the techniques Back-Stripping in sedimentary basins in particular for my higher studies.
Thank you in advanced for your priceless help.
Need some literature on 2D resistivity surveys done on alluvial plains to reconstruct sub-surface stratigraphy or palaeochannel drainage network.
In the past I was using 2-inch PVC pipe that fit inside a sledge corer and cutting it open with a small, electric, circular saw. This saw unfortunately had a habit of shredding the PVC into millions of tiny bits and spraying them into the inside of the core at times, and I'm concerned this will contaminate our results since PVC contains quite a bit of carbon.
Has anyone come up with an alternative to this? I was mulling over the idea of wrapping aluminum foil around the inside of the stiff PVC pipe so that the core can be pulled out, still wrapped, without smearing against the pipe and then split easily with a knife.
The marsh sediments with which I'm working are generally quite easy to work with, there are only a few thinner sand layers that become loose and friable, and a clay layer that has a bad habit of sticking to PVC so much that I have had to freeze the cores to extrude them.
I'm open to your suggestions to improve any step of this process at all. Thanks!
I want to measure the portion of adsorbed water in a mudrock. There are some references where the adsorbed water is measured in clays, but not in shales or mudrock.
So I asked myself if thermal analysis is a suitable method. If yes, is it better to use differential thermal analysis or thermogravimetry?
Working on interstitial water from sediment samples that have been trapped already and I have difficulties the protocol to get a good read of my samples.
Medhods to calculate the carbonate production within divers types of platform models.
I am trying to calculate PAH input into the sea through river sediments (I am not talking about input through river water). However, I couldn't do it. Let suppose the sedimentation rate in the sea is 0.4 g/cm2/y and the concentration of PAH in river sediment is 656 ng/g dry weight. I calculated PAH input through river water input which is 3.4 tons/y. I also calculated atmospheric deposition in the sea water, dry deposition is 3.05 tons/y while wet deposition is 6.1 x 10-4 tons/y (610 g/y). Theoretically we consider dry and wet deposition almost same (1:1). Mater of fact is the precipitation in Japan is three times of US annual precipitation. Keeping in mind this rule the wet deposition in Japan should be three time of US values (Here I am talking about the average values of both countries not very specific values as they are depend on range of factors and can vary even on micro-scale spatial resolution). I am looking for any suggestion that why wet deposition values are low compared with dry deposition.
Hello collegues what is the relation betwen hydrochemical analyses and karst identification ? from geochemical analysis how we can reconise a karstic aquifer
Biogenic Si or amorphous Si, how do they exist in the sediments, I mean after the degradation of siliceous phytoplankton, the silicious frustule is organic or inorganic? Is it possible to separate biogenic Si from non-biogenic part in the sediments with physical method (without changing their chemical characteristics)?
Feel no problems with rocky-shores: dominated by canopy-forming fucoid seaweeds, barnacles and mussels. Spans in E Atlantics from Northern Africa to the Barents Sea, by phytogeographic data (i.e. Van den Hoek 1975, Jüterbock et al. 2013). But what about sedimentary shores? How to define, how to contour?
The modern sedimentary pyrite always has light d56Fe composition. The main Fe source of such pyrite should be derived from the terrigenous reactive Fe. The iron compounds involved include Fe oxyhydroxides (ferrihydrite, goethite, lepidocrocite) and Fe oxides (hematite and magnetite). In theory, the Fe oxides involving ferric iron should behave heavy d56Fe. However, study focus on iron isotopic composition of such terrigenous iron oxides is quite limted. Can anyone offer some special cases to prove that such Fe oxides behave heavy d56Fe.
Gypsum and pyrite are two essential minerals that are being used in the reconstruction of past environmental condition. Several evidence indicated that the authigenic precipitation of gypsum mineral is associated with the evaporation processes. However, authigenic pyrite mineral is linked with the anoxic environment within the lake basin.
My questions are:
1. What are the factors affecting the precipitation of gypsum and pyrite minerals?
2. Is it possible that the gypsum may also precipitate in the fresh water (non-evaporitic) condition?
3. Is there any evidence that indicates the association of gypsum and pyrite in a freshwater condition?