- Obianuju P. Umeji added an answer:15Why Cretaceous is so much important in geological time-scale?
I want to know the key importance and reference of Cretaceous in geological time-scale.
While the responses of contributors have been summarized above, I wish to add that the Cretaceous marks the end of the Mesozoic Era as well as the Mesophytic of palaeopalynologists and palaeobotanists. Not only did the angisperms evolve and expand in the Cretaceous but also, they were followed by phytoplanctonic algal (dinoflagellates) abundance in the Cenozoic/phytic. The oldest incontestable sediments overlying the basement rocks in Nigeria are continental pre- and syn-rift beds of Cretaceous age. The interior seaways connecting the Atlantic Ocean to the Tethys Sea traversed the Sahara through the Benue Trough of Nigeria during the Middle and Late Cretaceous.
Cretaceous rocks have shown a lot of evidence for plate tectonics, extinction and evolution of flora and fauna. and general environmental change.
The journal, Cretaceous Research, carries much peer-reviewed articles related to this important Period of the Mesozoic/phytic Era.
Obianuju P. UmejiFollowing
- Mobin Ebrahim Nejad added an answer:22What is this microfossills in Carboniferous carbonats?
I take this photosa from thin sections of Carboniferous carbonats in Iran. Who can identify these microfossils?
Dear Sergio Rodríguez
- Vittorio Garilli added an answer:8Can anybody help me identify the gastropod which was collected from a pond during this summer?
shell is minute with distinctive sculptures, however without a sharp boundary to distinguish the protoconch and teleconch.
I agree that something in Planorbidae (probably Planorbis) should be correct.
- Abelardo Cantú Chapa added an answer:16Is it possible to correlate sedimentary beds by their internal trace fossils?
I mean doing stratigraphic correlation by Trace Fossils. Thanks.
Which beds according to their ages ? Which kind of trace fossils ? It is a unaccurate question.Following
- Hans-Dieter Hensel added an answer:4How fibrous calcite form?
The attached photos are from Upper Eocene rocks in the Northern Plateau of Bahariya Oasis, Egypt. This is about 0.5m thickness bed totally formed of fibrous calcite. can anyone help me to identify this facies and the reason why calcite appears in this form?
It's not exactly fibrous. I would not be surprised if the darker parts (the rosette-looking structures) were ankerite and the relatively clear edges calcite. I have seen this a number of timesFollowing
- Robert Phelps added an answer:26Ideas on what these elongated shapes could be?
These are SEM and sample images of Cretaceous carbonates of Tucano Basin, Brazil.
An approximatelly 5 cm thick layer with high concentration of elongated shapes(coprolites, bioturbation?) forms a laterally continuous marker in the area, different of stratas bellow and above (microbial mats, ostracodites, etc.).
appear to be burrows in a totally homogeneous substrate. I ve only seen this type of bioturbation in mangrove swamps adjacent shallow lagoons in the modern.Following
- Subhojit Saha added an answer:8Hello to everyone, Why Whole rock plot below the plagioclase in Sm-Nd plot?
Can any body tell me or guide me. What will be the possible and correct interpretation when whole rock plot below the plagioclase in Sm-Nd isochron plot and high MSWD about 2.8( Basalt). There are some possible reason for this i.e Alteration and Contamination but here in my case these both possible reasons are not affected so much. There are some intergrowth present in these rock(basalt) may be the reasons for this. Give me your valuable suggestions and some good paper which is related to this kind of issues
Dear Perera, If alkali feldspar is present in basalt what are the possible interpretations?? can you please through some highlight..Following
- Hakima Belkhattab added an answer:3Which is the good paleoenvironment (s) for the development of orbitolina larger foraminifera?
Orbitolina larger foraminifera Paleo-ecology.
Look at this link it could be interesting for you.
Hope it helps,
- Felix Cambalt added an answer:9Any experience with creating SVG graphics for SedLog?I can create an SVG file in Adobe Illustrator, but when I try to import it to SedLog as a symbol, I get the error "Unable to read this file:" Anyone know how to get past this?
Update: Running Windows 7 64-bit OS.
I found this: http://mattbk.com/content/sedlog-symbols-windows-7-64-bit
To solve this problem, first you have to uninstall sedlog, then you can download and run the installer again selecting troubleshoot Compatibility. I installed sedlog 3.1. It worked for me in Window 8, 64 bits.
I added a word file for the explanation step by step. My window version is in spanish language. I try to do a tutorial in english, sorry if my english writing is not good... :)Following
- Krisztina Sebe added an answer:31Could 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 would recommend SedLog as well. However, just having changed to Windows10 I have the same problem with sedlog as Jelle. If someone knows how to fix this please share.
- Harald G. Dill added an answer:3How is the error in Sr stratigraphy ages estimated for Neoproterozoic period?
How is the error in the ages estimated when we use global seawater Sr curves to estimate the age of a carbonate formation? How is it done in Neoproterozoic?
Dear Mr. George,
Sr-isotope-based stratigraphy may work in some parts of the Paleozoic, Mesozoic and Cenozoic eras but in my opinion it means overstretching the method extending it into the Precambrian.
See as an example for successful use the file attached.
- Silviu Constantin added an answer:9What 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.
For anyone who's looking for more reading, check this out: https://www.researchgate.net/publication/280923434_3er_Simposio_Internacional_de_Espeleologia_en_el_Ecuador_-_Boletin_Cientifico_Tena_13_-_15_marzo_2015
Go to page 74 - there you'll find a "beginners guide" I was asked to provide. It is only my advice,based on multiple sampling and dating of speleothems from around the world. I don't hold the absolute truth, just trying to help people emabrking in this bussiness and also help caves to remain as nice and pristine as they were when we first saw them.Following
- Nusrat Siddiqui added an answer:13What is the age of the Khwra trap in the Salt Range of Pakistan?
The classical stratigraphic sequence of the Salt Range contains thin flows of an ultrapotassic rock at its base. Commonly known as Khewra trap, it occurs at the top of the very late Proterozoic to Early Cambrian rocks consisting of marly anhydrite/gypsum, and oil shalis overlying evaporites. The trap is an unusual rock consisting of euhedral to skeletal, spinifex, stellate phenocrysts
in a very fine-grained to cryptocrystalline, locally glassy, matrix. The phenocrysts (up to 3 cm long) are considered to be Mg-rich enstatite now complliely pseudomorphed by a mineral aggregate principally made up of talc with subordinate amoun'ts of Mg-rich clays and, locally, quartz. The matrix is unaltered and almost entirely made up of Na-Ca-poor and
Mg-Fe-rich K-Feldspar (sanidine-orthoclase), with granules, specks and dendroids of Fe-Oxide. Talc, Mg-rich clays, quartz, dolomite, and Fe-oxide constitute the amygdules.
Chemical analyses ofthe rock samples from the trap are remarkably similar in composition except for some variation in iron oxide due, probably, to leaching during alteration. The rocks consist approximately of 60 wt% SiO2, 0.7VoTtOy ll%o Al2O3,2-5% FeO, 10% MgO, 0.4% CaO, O.5% Na2O, 9% K2O, and 0.04% P2O5, Normatively the rocks are eisentially made up of orthoclase and orthofyroxene.
Thank you Qasim Jan Saheb,
So, if we consider that the N-S rifting stretch is not expected then what could be the genesis for such a massive magmatic intrusion, and at two different times. Regarding the K-Ar dating, the age difference of magma emplacement and the eventual cooling is too small in terms of geological time. Can't we take it as the closest possible date?
Some details available with me for Kashmir volcanics/subvolcanics are as under:
The subvolcanics emplaced in sedimentary rocks are also reported from Kashmir and Zanskar-Spiti region, which are sandwiched between the Nilawahan Group and the overlying Zaluch Group; these subvolcanics are confined to Kungurian to Midian (275 Ma and younger) Stages (Bhargava, 2008). However, the Marvi mafic sill in Pakistan, was intruded at the base of Permian.. Regarding Panjal volcanics Bhargava (2015) mentions “…a Kungurian Stage to Middle Permian age was assigned to the Panjal Volcanic by Bhargava (2008), which now has been confirmed by radiometric date of ca 289 ± 3 Ma (Shellnutt et al., 2011).”
Will check about your papers on RG.Following
- Paul C. Lyons added an answer:18Are palynomorphs or megafossils better for biostratigraphy?
Both methodologies have limitations. Name some of them.
I am giving you an up-vote on your very thoughtful and informative answer to my question. Paul.Following
- José A B Daudt added an answer:3What is the practical significance of studying multi-order sequence stratigraphy?It is a common experience that from seismic sections one can identify mostly the first order unconformity surfaces and if the data quality is too good, second order events can also be detected. However, when in the same area, well log data is studied, we start getting third order and sometimes still higher order unconformities. I just want to know the practical significance of studying multi-order sequence stratigraphy and ultimately where should we stop.
I think that a good answer would be: it depends! In large scale exploration, it may be enough if you keep the sequence stratigraphical analysis in the lower frequency packages. But if you are working in a field development, you may need to go to higher frequencies to understand the facies distribution. In many cases, you may also find difficult to define the "end" of the stratigraphic approach (end of external controls as sea level or tectonics). In this case, you will be entering in the world of architectural element (facies associations) and sub-environment of deposition (architectural element association), "packages" that not necessarily have external control. I have a good summary of this question in the attached paper.Following
- Massimo Zecchin added an answer:10How possible is it to have several forced regression surfaces below and immediately above major sequence boundary?We are working on Cretaceous shallow marine to deltaic successions. The upper part of the shallow marine seems to have repetitive cycles of forced regressive units (identified by several levels of Glossifungites), the last of which is capped by a major sequence boundary. Temporally across the boundary are other repetitive cycles of forced regressive units (similar to lower units) before the normal deposition of coarsening upward deltaic successions.The information provided is not sufficient to make a reliable interpretation. The description looks like that of multiple ravinement surfaces recording a high-frequency cyclicity.Following
- Pedro Correia added an answer:5Anyone have a PDF of Leary (1979?) from Compte Rendu 8th International Congress on Stratigraphy and Geology of the Carboniferous, Moscow, 1975?
I HAVE NOW RECEIVED A PDF FROM CHRIS CLEAL. THANKS TO EVERYONE WHO ANSWERED!
Anyone have the volumes from the Moscow ICC congress in 1975. I do not know what volume, pagination, or even the exact year! of Richard Leary's publication, but this is the citation information I have:
Leary, 1979??. Namurian paleogeography of the western margin of the Eastern Interior (Illinois) Basin. Compte Rendu 8th International Congress on Stratigraphy and Geology of the Carboniferous, Moscow, 1975. Seems to be on around page 49 or so, and may or may not have associated plates/figures.
Thanks Simunek. I will ask to Leary.
- Roderick B. Salisbury added an answer:3Please suggest good literature on 2D Resistivity conducted on thick alluvial plains to demarcate subsurface stratigraphy?
Need some literature on 2D resistivity surveys done on alluvial plains to reconstruct sub-surface stratigraphy or palaeochannel drainage network.
Some successful subsurface reconstructions have been done in the Körös basin in eastern Hungary using ERT, in an archaeological context (meaning a focus reconstructing human activity and the late Pleistocene and early-to-mid Holocene environment). The papers below describe a 2D resistivity inversion algorithm for geologically recent sediments and stratigraphy (again, archaeology).
Papadopoulos, N.G., Tsourlos, P., Tsokas, G.N. and Sarris, A. 2006. Two-dimensional and three-dimensional resistivity imaging in archaeological site investigation. Archaeological Prospection 13(3):163-181.
Papadopoulos, N., Sarris, A., Parkinson, W., Gyucha, A. and Yerkes, R. 2013. Electrical Resistivity Tomography as a tool to reconstruct the palaeoenvironment of Neolithic sites. In Archaeological Prospection: Proceedings of the 10th International Conference on Archaeological Prospection, edited by Neubauer, W., Trinks, I., Salisbury, R.B. and Einwögerer, C., pp. 390-393. Austrian Academy of Sciences, Vienna.
Papadopoulos, N.G., Sarris, A., Parkinson, W.A., Gyucha, A., Yerkes, R.W., Duffy, P.R. and Tsourlos, P. 2014. Electrical Resistivity Tomography for the Modelling of Cultural Deposits and Geomorphological Landscapes at Neolithic Sites: a Case Study from Southeastern Hungary. Archaeological Prospection 21(3):169-183.
If this helps you, the authors are on ResearchGate if you need more info.Following
- Obianuju P. Umeji added an answer:7What are the limitations of facies analysis in paleoclimatology?
Related to paleoecology and latidudanal controlled facies.
The limitations of facies analysis in paleoclimatology include the absence of environmentally controlled biota. Flora and fauna could be so adapted that their presence indicates the environment including climate. Such biota are called facies fossils.Cosmopolitan biota are not so tied, they are "all-weather" types and do not indicate any particular environment.Similarly, there are physical sedimentary structures that are climatically controlled as well as soils, eg, glacial tillite and boulder-clay for glacial lands; dunes for hot deserts and so on. Absence of these environmental (including climatic) determinants limit facies analysis in palaeoclimatology or any other palaeo studies, since they are the "tell tales" of the environment.
Facies, after all, are the different aspects of the environment that may be existing at a particular time, which also is often the name- bearer.
All the best.
Obianuju P. UmejiFollowing
- Rameshchandra Phani added an answer:2I am looking for lithologs (Borehole scan data) in and around Basanti, South 24 Parganas, West Bengal. Can anyone help me?
I am assessing the sustainability of the groundwater resources in Basanti. One part of my research project is to build a three-dimensional, hydrostratigrafic model of Basanti's subsurface. If I get to know the approximate volume of the aquifers, I will be able to calculate the potential useable amount of freshwater.
Yes, As Virendra said rightly, GSI is your destination. Or else, as you are dealing with groundwater, its worth consulting CGWB also.Following
- Karwan Mustafa added an answer:3Can somebody provide me a stratigraphic column of Holy Cross Mountains of Central Ppland?
I'm in need of a stratigraphic column of Holy cross mountains in Poland. I want to have a lithostrat column that displays all rock units in Kielce and Lysogory regions. There are some papers but I could not compile column of each region separately.
I would be grateful if someone give me a link or a paper or a map that I can get what I'm looking for.
Thanks for your concerns.
Dear Mike and Simon,
Thanks for your suggestions, they are good papers. I wanted to get a Lithostratigraphic column that has all Paleozoic rock units, not only one part of the column.
- Simona Avnaim-Katav added an answer:9What kind of foraminifera is that?
Greeting agglutinated salt marsh foram's researchers,
I have encountered in southern California salt marsh the following live&dead species in surface samples. Test flattened, ovoid in outline, planispirally enrolled and its wall is very coarsely agglutinated. I thought it might be Ammobaculites labvthnangensis (Loeblich and Tappan, 1988) but I'm not sure. I would appreciate your advice on that- see SEM images. Thanks:)
Dealing with taxonomy is occasionally not as straightforward as one might think (!) as this case demonstrates- but you know that already. I am assessing the taxonomic identifications based on all diagnostic criteria, not merely on test granulometry, of course.
Anyhow.. I'm going to do some more SEMs that show better the aperture and other significant characteristics. I am sorting as much as possible into species level, nonetheless I'm going to lump all Ammobaculites genus- into a single group following your work, Robin, and others (e.g. Kemp et al., 2009; Milker et al., 2015) because they were occasionally broken making it difficult to assign them to species level and also because they are not key species for sea level studies.
I must say that I find the communication via this platform very meaningful and enlightening…thank you guys.Following
- Tamar Beridze added an answer:5Could anyone reccomend me examples of application of ichnology to the interpretation of the rocks hosting VMS deposits ?
There are many examples of the use of ichnology in hydrocarbon reservoir studies.I'm interested if there are any examles of application of ichnology to theinterpretation of the rocks successions hosting VMS or even other types of metallic deposits (bathymetry,depositional enviroments,relationship of trace fossils development to the sedimentary basins with volcanic actyvity). I have one paper of Sainty R.A.(1992)Shallow-Water Stratigraphy at the Mount Chalmers Volcanic-Hosted Massive Sulfide Deposit, Queensland, Australia. Maybe there is some more recent information?
Thanks for useful information
- Hakima Belkhattab added an answer:1Can anyone help to identify the fossil appearing feature in the photograph?It is from Krol Formation, Nainital, India which is considered Terminal Proterozoic sequence
I think that the fossil should be Treptichnus pedum.