Andrew K. Rindsberg added an answer:Can anyone give me any suggestions of why there is not any Ostracods in a marine formation dated of Miocene?
I am working on a marine sediment dated as Miocene, from the northwestern of Madagascar (Ramihangihajason et al., 2014. « Miocene benthic foraminifera from Nosy Makamby and Amparafaka, Mahajanga Basin, northwestern Madagascar, Journal of African Earth Sciences 100, 409-417)
Last month, I processed those samples in order to check the diatoms into them, but I didn't find even one specimen. So, I wonder if there is any explanation for that. Thank you
Diatoms are commonly absent in samples of ancient marine sediments, presumably due to dissolution of the silica that they are made of. This can easily happen in limestones. Calcareous fossils such as ostracodes and foraminifera would be dissolved by HCl during treatment of the sample. If they are also absent in the untreated sandy limestone, that is peculiar, but possible if the samples were collected from weathered regolith. After all, they are small and many species are porous, giving them a large surface area for dissolution. To avoid this problem and collect the freshest samples, I try to collect material from horizons that are just above, or even below, the surface of a stream. This ensures that they have been kept continuously wet, which slows down the processes of weathering. This requires shifting up- and downstream within a stratigraphic section in order to collect at intervals, and stratigraphic accuracy is essential to get meaningful results. In contrast, the classic "channel sampling" technique practically ensures that the uppermost samples will be more weathered than the lower ones, making it impossible to generate comparative data.Following
Nathan j Wright added an answer:How can I estimate haplotype richness with analytic rarefaction 1.3?
I will be happy if someone help me to use Analytic Rarefaction for estimate haplotype richness of samples with different sample sizes.
what input file is needed when I have data; sample size=20,30,50,30, haplotype diversity=0.3, 0.5, 0.5, 0.4 ?
Or, I should make haplotype frequency table (in text) like;
10 5 0 0 5
I would like to see example file, but can not find.
for each sample?
Here is some more info on PAST
The website to download the program is the University of Oslo: http://folk.uio.no/ohammer/past/
Attached is the pdf manual and a screen shot of the program.
Across the top (columns) are the different samples if used and down the side (rows) are the categories, in this case species. The data is simple abundance data.
Hope this helps.
Thomas Skulski added an answer:Does anyone know locations of Arnheim Fm outcrops along the Nashville Dome, TN?
I am looking to measure and correlate as many Arnheim Fm outcrops along the Nashville Dome as possible however the literature is scarce. The few papers I do have with location data are on the older side and the locations don't all appear to exist anymore when checked on Google Earth.
Came across some older references with figures. But maybe you have seen these?
The Arnheim Formation within the Areas Traversed by the Cincinnati Geanticline
Foerste, Aug. F. The Ohio Naturalist. v12 n3 (January, 1912), 429-456 (see page 446)
Holt, R.D., 1931, The stratigraphy of the Arnheim Formation of the Central Basin of Tennessee: M.S., Vanderbilt University.
B. Charlotte Schreiber added an answer:What do you think of this textural relationship of gypsum and anhydrite crystallized in a dolostone?
I am currently working on a problematic evaporite-carbonate sequence. The dominant lithology is dolostone with different but minor siliciclast content. One of the most obvious feature is the overall presence of evaporites; satin spar filled fractures, gypsum rosettes, evaporite cemented dolomitized carbonate framework components (coated grains, bioclasts) and chicken wire structures can be find as well. The whole appearance of the sequence suggests an evaporitic sabkha environment. My question is whether the anhydrite hydrolized to gypsum or gypsum transformed to anhydrite?
Many thanks for your answer in advance!
You are looking at a complex section. Without the regional lithology and structure the section you show might have several interpretations (not compatible ones). Also the use of the particular terminology originally evolved from study of sabkha settings is coloring any possible interpretation. For example the use of "chicken-wire" texture implies a sabkha interpretation, but the nodular mosaic you describe is created in a number of ways. A true sabkha requires the presence of truncated erosion surfaces- do you have such features??? Does the faunal picture fit a shoreline?
Also when asking tor interpretive help, please set the regional depositional picture- such a section may be created entirely during much later diagenesis due to structurally controlled fluid migration into a differently sourced matrix (or several other interpretations). You know the regional picture and the reader does not- thus seemingly logical interpretations may be imposed on an alien section...Following
Paul C. Lyons added an answer:What are the best ways to determine paleoclimate in the Pennsylvanian (ex Upper Carboniferous) and Permian?
These two periods of time were characterized by widespread peat (coal) deposits, great shifts in sea level as observed in cyclothems, and by continental glaciation. What was (were) the driving force (s) behind these great changes.
Hi Manika, Thank you for your response and your insightful suggestion. Best wishes, Paul Lyons.Following
Sean Ulm added an answer:When calibrating radiocarbon dates taken from marine Cardium edule shells in beach barrier sediments, should we use the Marine13 calibration curve?
I'm trying to build a Bayesian model for a coastal dune stratigraphy. The oldest date is taken from marine beach barrier sediments, while the other, more recent, dates are taken from gyttja layers (associated with archaeological remains) embedded within dune sediments
Yes, you should use Marine13 and apply the appropriate local/regional deltaR value (see 14CHRONO Marine Reservoir Database at http://calib.qub.ac.uk/marine/). Although the species appears to be a suspension-feeder, I note that it is densest in in-shore zones (http://www.reservebaiedesaintbrieuc.com/IMG/pdf/publication/etudes_scientifiques/Ponsero&al-2009-Cockle.pdf) so may be influences by terrestrial run-off or restricted in-shore/embayment circulation patterns. See the following for an interesting case study of the potential differences in bivalves living in different zones and with different dietary habits:
Petchey, F., S. Ulm, B. David, I.J. McNiven, B. Asmussen, H. Tomkins, N. Dolby, K. Aplin, T. Richards, C. Rowe, M. Leavesley and H. Mandui 2013 High-resolution radiocarbon dating of marine materials in archaeological contexts: Radiocarbon marine reservoir variability between Anadara, Gafrarium, Batissa, Polymesoda spp. and Echinoidea at Caution Bay, southern coastal Papua New Guinea. Archaeological and Anthropological Sciences 5(1):69-80.
Laura Maydagán added an answer:Can someone recommend some articles about the influence of oxygen fugacity on arc mamgma and its relation to the formation of porphyry deposits?
I want to learn about the influence of oxygen fugacity on arc mamgma and its relation to the formation of porphyry deposits. Can someone recommend some articles on this topic to me. Thanks a lot.
Also to this paper... Cheers, LauraFollowing
Mary Elizabeth Bernardes de Oliveira added an answer:Do you know of a multidisciplinary team to carry out studies on stratigraphical sequences reaching at least 20 m deep?
We are looking for a multidisciplinary team to carry out geological, chronological and environmental studies on stratigraphical sequences reaching at least 20 m deep. Our initial evaluations suggest that the deposits may present a continuous chronostratigraphical sequence dating from around 1.5 Myrs. The two volcanic structures are in a closed depression context linked to soil subsidence at the base of their lava emission centers. This situation is due either to the collapse of the craters under the weight of the lava or to the retraction of the lava during its cooling phase. These depression structures functioned as sediment traps which have yielded archaeological surface remains attributable to the Middle Pleistocene and through to the Holocene. They are located in the south of France, in the Baumes volcanic complex (communes of Caux, Nizas, Pézenas, Lezignan-la-Cebe ...). Exceptional sediment traps, the exhaustive study of these infillings would be a major asset for the paleoenvironmental restitution of the sector and more broadly of Western Europe since 1.5 Ma.
Please contact me if you are interested and I will be able to provide you with more information.
Je cherche une équipe pluri-disciplinaire pour l'étude géologique, chronologique et environnementale sur des séquences stratigraphiques de minimum 20 m de profondeur susceptibles de recouvrir une chronologie continue depuis 1,5 Ma. Il s'agit de deux structures volcaniques en dépression fermées dues à l’affaissement de sol à l’aplomb de centres d’émission de lave soit liées à un effondrement des structures du cratère sous le poids de la lave soit à la rétractation de la matière lors du refroidissement de la lave. Ces structures dépressionnaires ont fonctionné comme des pièges sédimentaires et livrent des éléments archéologiques en surface depuis le pléistocène moyen jusqu’à l’holocène. Elles sont localisées dans le sud de la France, dans le complexe volcanique des Baumes (communes de Caux, Nizas, Pézenas, Lézignan-La-Cèbe ...). Pièges sédimentaires exceptionnels, l’étude exhaustive de leur remplissage serait un atout majeur pour la restitution paléo-environnementale de ce secteur et plus largement de l’Europe de l’ouest depuis 1.5 Ma.
Merci de me contacter pour de plus amples renseignements.
J`AIMERAI BIEN VOUS INDIQUER PROF. DR. PAULO EDUARDO DE OLIVEIRA ET PROF. DR. MARIA JUDITE GARCIA, DU LABORATOIRE DE PALÉOBOTANIQUE ET PALYNOLOGIE, DE L`INSTITUTE DE GEOSCIENCE DE LÚNIVERSITÉ DE SÃO PAULO, POUR DES RESEARCHES EN PALYNOLOGIE PLEISTOCÈNE ET QUATERNAIRE.Following
Lionello Morandi added an answer:Does anyone have a clue to this Holocene microfossil?
In polar view it appears circular and strongly resembles HdV-119, whereas in equatorial view it is more similar to a fern spore. It's got a characteristic circular/polygonal rupture pattern (this latter feature is shown also by some smooth dinocysts).
It is from a coastal fresh/brackish-water alluvial plain.
thanks for your suggestion.
I think it does look similar to Isoetes in one plane, but it's circular in polar view, and sistematically has a rounded break, features that should not be found on a monolete spore.
I also have reference slides for Isoetes here and I have checked them today.
Rogerio de Lucena Alves added an answer:Can anyone provide a reference for papers about rare elements (Ag, Au) in black shales?
It is known that rare elements (e.g., Ni, Cu, Zn) can be enriched in black shales. Can anyone provide papers on trace element analysis on the Toarcian Posidonia Shale and/or the Middle Jurassic Opalinus Clay (Opalinuston-Formation)? In particular, I'm interested in a possible Ag and Au content in these deposits.
I beleive that the bigest gold deposit in black shale is the Paracatu mine in Brazil from Kinross. The deposit is formed by deformed quartz veins hosted by black shales. Paracatu is a low grade (around 0.3g/t cutoff) high tonnage deposite. I know that some Ag, Pb and As are also present. There are several papers available on internet about Paracatu, you for sure will find what are you looking for.
Mateen Hafiz added an answer:Can anyone provide the information on vindhyan basin and its prospectivity for shale gas exploration?
I have been looking for the detailed information about the vindhyan basin evolution, its stratigraphy and also its prosectivity for shale gas exploration. I found some links online but are not accessible. Can anyone provide the links from where I can directly download? Thank you in advance.
In Vindhyans, the Rampur and Bijaigarh shales seems to be promising for shale resources exploration. Other formations are organically lean. I have attached few articles which discuss the source quality of different shales of Vindhyan Basin.Following
Bing Song added an answer:Which perspective of age-depth modeling is better, regression analysis or interpolation?Two perspectives of age-depth modeling prevail: (1) regression analysis, which represents a statistical expression of the data; (2) Interpolation, which reveals a deterministic relationship of the data. Which one is better?
Hi, Prof. Yu,
Where are you service now? Do you remember me? I am very interesting about your research.
I think the second method is better than the first one. Because the age model always effected by sediment hiatuses. If we use the first statistic method, the hiatus will affect all the age-depth line, but the second method will decrease the effected, maybe only make err in a short span.
Helge Niemann added an answer:Can someone help me about the formation of gas hydrate ?
hi, can you helpe me about the formation of gaz hydrate ?
Tracking gas (assuming methane or other light hydrocarbons) in paleo systems is quite tricky. One way is as Bernie suggested, another one is to look at remnants of organisms that were involved in cycling of the gas (eg. methanotrophs/methanogens) or looking for geological structures related to the gas (chimneys, carbonate precipitates). However, that mostly depends on whether some of the gas in question has been produced/transformed in the stratum you're looking at.Following
Jooly Jaiswal added an answer:What are the main points during Speleothem sampling?
Can somebody tell me the proper site for speleothem sampling?
I am little bit confused whether is taken from the location where it is equilibrium with external atmosphere or deep from the cave where humidity is near about 100. Some one told me the sample collected near from the cave entrance are most significant for the climatic study because it records the diurnal variation of the atmosphere. but here the kinetic fractionation also goverened the precipitation process please tell me the exact things.
Thank you so much Mr. Silviu Costantin for your answer. Now I am understand the point of consideration during the speleothem sampling.Following
Syed Haroon Ali added an answer:What is the Sequence Stratigraphy, High Resolution Stratigraphy and Cyclicity of Mixed Carbonate-Clastic Successions?
While working with Mixed Carbonate-Clastic successions, how do we mark Sequences and High Resolution Stratigraphy? Any recommendation of reference or research paper will be appreciated.
Thanks Sir for sharing your experience and research!Following
M. Levent Artüz added an answer:Will anyone be able to identify the foraminifera?Image is attached.
Dear Priscilla Philip,
Take a look at Haynesina germanica (Ehrenberg, 1840)
Diego Kietzmann added an answer:Could you recommend me a software for creating stratigraphic column (for Mac)?
I've googled and I've found a bunch I was just wondering if anyone had used any that they particularly enjoyed.
I usually use StratDraw, which builds logs in CorelDraw and then you can edited easily there.
Paul Aharon added an answer:Can somebody help me about the trace element incorporation in speleothem in Lesser Himalayan Region?
In general Mg incarporation in speleothem is temperature dependent and Sr and ba is not dependent on Temperature. Their incarporation in Spoeleothem is depend on soil dust activity. Can some body tell how trace element incarporated, the source and the governing factor of their concentration,the relation between them.What can be other trace element other than Mg,Sr,Ba,U, Na,P incarporated in speleothem and the importance?
Interpretation of trace element ratios (typically E/Ca) in speleothems in terms of climate is complicated by their partitioning in the epikarst. There are a number of papers dealing with the subject, some suggested by other responders.
Additionally check the papers by Dan Sinclair who dealt with trace element partitioning in the epikarst.Following
M.Cemal Göncüoglu added an answer:Are there any recent publications on Silurian and/or Devonian "Orthoceras Limestones" in NE Gondwana?We are compiling a correlation and would appreciate any (published/unpublished) data with reliable ages.
Ioannis T. Alexandridis added an answer:What kind of structure is this?I found this suspicious structure in fragments of Iron ore (magnetite). Its original structure is difficult to me. The main belt is a metamorphic volcano-sedimentary environment with relative proposed age of Neoproterozoic to lower Paleozoic.
It resembles some volcanic structure, sedimentary structure or even fossil or stromatolite?
You could also check the case of having "fold rodding lineation" (crenulation lineation). The specific sample, could easily be a remnant of fold limp, so the parallel structures could be the aformentioned structure.
About the network of fractures I agree with Michael.
M.Cemal Göncüoglu added an answer:Can someone advise on the sample preparation techniques of isotope dating of dolerite?I have collected some dolerite samples from Proterozoic sedimentary sequence. I want to know about the sample preparation techniques of isotope dating of dolerite.
Do you have the thin-section view of the rock?
Are there any unaltered primary minerals?Following
Valentina Yanko added an answer:Who is interested in collaborating on a project on quaternary freshwater and brackish water ostracods of the Lower Volga and Caspian region?We have samples from several boreholes and outcrops. Please contact me if interested.
We would be intresetd in collaborating with you on the project. We have enormous data bank on forams and ostracods of the Ponto-Caspian region used for Quaternary stratigraphy and paleogeographic reconstrauctions.
Prof. Dr. Valentina Yanko
Head of the Department of Physical and Marine Geology
Odessa I.I.Mechnikov National University
2, Shampansky Per.
Odessa, Ukraine 65058
Tel: +380 (482) 63-33-17, +380 (48) 723-02-08
Kenneth M Towe added an answer:Is there a simple method to differentiate coal from charcoal?Maybe at the petrographic microscope there are some details like fractures that indicate burning.Following
André Klicpera added an answer:Can anyone help with lithological patterns to draw a stratigraphic column in Corel Draw?Particularly I need sedimentary rocks patterns.Following
Kenneth M Towe added an answer:What is the best estimate for the duration of the Cambrian Explosion?Which animal and protistan phyla appear simultaneously (within the resolution of chronostratigraphy)?Following
Om N. Bhargava added an answer:Does anyone have information about Ordovician diamictite in the Indian subcontinent?I'm referring to Gondwana sedimentary rocks.In Bhutan Nake Chu Fm was regarded as Ordovician, our work found that it rests below the Cambrian hence could not be Ordovician, it is Neoproterozoic equvalent of Blaini in the Himalaya and Nantuo in China.Following
Jahn Hornung added an answer:For a species is a stratigraphical range up to 140 Ma realistic ? (e.g. the dinocyst "Spiniferites ramosus" is mentioned from Valanginian to Present)To reflect on the limits of the application of actualism in paleoecology, I wonder about the significance of paleontological species that have a wide stratigraphic range.It depends on how reliable you consider the morphological information preserved in the fossil record. Lungfish teeth from the Early Cretaceous of Australia have been considered to be identical to those of the living species Neoceratodus forsteri. This would give this species a range of 100 myr, the longest known for a vertebrate. However, we do not know whether the Cretaceous lungfish would not have been quite different in other body parts than the tooth-plates. However, if you have most of the animal preserved you can make better assumptions. The tadpole shrimp (Triops cancriformis) is known from morphological indistinguishable fossils dating back to the Late Triassic (220 Ma). Single-celled organisms may be prone to very slow evolution, there have been records of amoebae indistinguishable from extant species from Triassic and Cretaceous amber. They may also have extremely long individual lifes, as they are not subjected to cell death and may theoretically enjoy an eternal live, if they are not destroyed by predators or environment. There have been repeated reports of Permian, possibly even Cambrian, bacteria from rock salt deposits which went into stasis when their water environment dried up and they were encapsulated by a salt crystal. It was reported that it was possible to revive them in the lab, though these reports are somewhat disputed...Following
John M McArthur added an answer:PaleosolCan anyone recommend a good text book or papers on the red colored, carbonate free paleosol? What are the physical features? How do you identify them in the field? What is their geochememistry?The second paper on the last-glacial-maximum palaeosol is attached.Following
John Jones added an answer:Why the Great Permian extinction happened?Nobody knows what happened, but my theory is that there was an impact by a comet in Siberia, which triggered the extinction.I agree with the view that more than one single event caused that and other mass extinctions. One cause which was not mentioned is the creation of Pangaea. That event would have caused the loss of a great deal of shallow marine habitat, and formed large deserts because of new mountain ranges and continental effects. While impacts and increased vulcanism may be factors, loss of habitat and climate change certainly figured in. Migrations often mean invasive species which can greatly upset the local ecosystems as well. After all, I don't think there is a strict boundary for the extinction(s). John Paul JonesFollowing
Romain Liard added an answer:Can anyone help with drawing logs with sedlog?I need new symbology as none is there for fluvial deposits. I tried to follow the steps provided in help, where svg/svgz files are to be imported. But the sedlog is not reading the files. Can someone help or suggest some other software? PS: I am using coral draw to draw the new symbols.Personally I use the Gimp. It usually open SVG format with no problem even if layers are very often flattened by the transfer from a soft to another.Following