Questions related to Field Geology
I want to know scientists idea about paper writing and field geology.
I ask about a very strange case that not very common but maybe some body faced it or suggest a reliable interpretation. Is it possible to find diagenetic unmetamorphosed phanerozoic carbonate sandwiched between old assemblage of precambrian volcanics that underwent metamorphism ? and there is no conglomerate or breccia lies at the contact between the basement and the sediments ? noteworthy is the presence of faults is a familiar case in that area.
i attach a simplification sketch cross-section for the case
I would like to hear from you all
I'm dealing with Upper Cretaceous microfossil association that consists of ostracods and foraminifera. Source material – sandstone and marly limestone – was disintegrated in water with some Hydrogen Peroxide (30%) added to solution. The problem is that microfossils are not totally liberated from the rock and still have pieces of it attached to their carapaces and tests.
Can somebody please give me some hints on how to remove unwanted material?
The exposures form a "castle" (maybe old volcano) on the Greek island of Skyros.
There is an abundance of calcite in both the rock and veins. There are numerous mostly rounded siliceous (very hard) pebbles of many colours.
The area has been mapped, but there are no details on this most prominent rock that I could find.
The study area, located in the circum-Pacific accretionary complex, mainly consists of intra-oceanic surface rocks including chert, shale, pyroclastic rocks and basaltic lava. The basaltic rocks are mostly OIB-type (Jurassic Paleo-Pacific seamount) according to previous research.
Photo 3 shows two basaltic pillows within a matrix of basaltic tuff. The handspeciman of the pillow is black in color and heavy in weight. It also has scattered vesicles, and looks much like typical fine-grained basalt. However, its thin section looks not...
I need help to identify the rock type. It will be perfect if you also have such kind of rock.
I would like to know the fast and easiest way to differentiate aeolian and fluvial silt by looking at the samples itself.
The paleostress orientations inferred from the orientations of dikes (see attached figure) indicate that none of the principal stress axes is oriented at neither vertical nor horizontal orientation, rather all of them are oriented at the intermediate orientation between the vertical and horizontal orientations. Hence, the fact violates the Anderson theory of faulting, where one of the principal stress axes must be vertical due to the stress boundary condition at the surface of the earth.
What could be the plausible explanation?
Not really a question here but attempting to initiate a discussion on a problematic issue that is getting widespread across various journals. I see more and more papers in my field (Geology) that use and abuse of the words "evidence" and "inference" without having the slightest idea of what these words actually mean. If you use "Evidence" in the title of your article, please precise Evidence for what. An evidence is a proof of something. If you use evidence in your title without precising the fact or the hypothesis that it supports, then your title is a nonsense.
Similarly for inference, it may be expected to either add an adjective to that word or to use "inference from (...)" in order to precise what kind of inference is referred to with respect to, for example, the adopted methodology (chemical, biological inferences) as well as to where these inferences lead to, i.e. the fact or hypothesis which is the main conclusion of the paper.
In the past 6 months, I have seen at least 5 papers in well-established journals in Earth Sciences that use either one of these words in their title without making any sense at all, some either use these two words without the actual fact. I understand that non-English native authors have a hard time writing their manuscript but the least we can expect is to provide a comprehensive title. I understand that Editors and Reviewers are worked up and do this job for free, but the least we can expect from a well-respected journal is for them to focus on ensuring that papers are published with a comprehensible title.
P.S.: I will not provide evidence for such grammatical inferences of a decreasing quality of language in high IF journals
In social sciences, knowledge and research is shared among different disciplines and fields of studies. For example, geography shares knowledge and research with many other fields such as geology, sociology, social work, economics, international relation, public health, public administration and development studies.
Here comes a point, where researchers debate over the scope and delimitation of a Geographical (having spatial context) and "Non-geographical (Having no spatial context) research.
Moreover, what can be the features/types of spatial context?
I need to understand this issue. Your help will be highly obliged. Thanks
Let me know both intensity and Transmittance are same in identifying the minerals based on wave number and nature of peak.
If the metamorphosed igneous body is younger to the metasediments, then I would expect to observed the following points in the field:-
1. Presence of dykes, sills, tongues or apophyses within the metasediments.
2. Presence of metasediments as xenoliths within the igneous body.
Friends, please help me with some more points. Your contributions to this question will have a crucial impact in my research work. Thank you in advance.
It is made of very fine quartz (steel can't scratch it) with a vesicular-like structure. The "vesicles" are rounded, yet on the side view are elongated and look like human teeth. The "vesicles" are calcite with a thin green clay cover on the weathered surface.
We have just started working with native copper-mineralized basaltic rocks from the Serra Geral Fm. (Southern Brazil) and your paper in Periodico di Mineralogia is helping us a lot.
Maybe we could exchange some ideas in the future.
i'm looking for information about weathering and/or zeolite alteration of CAMP basalts in the High Atlas Mountain in Morocco.
hello colleagues and my professors
i want to ask what would be the tectonic shifting ( change from setting to another ) that may occur to lead to the formation of volcanic rocks + red beds ( More recent ) over limestone.( older )
thanks in advance
Recently we found this sample from Ayodhya Hills, Purulia, West Bengal, India. Sample was collected considering as an hand axe. The site is known for its rich microlithic assemblage. Expert opinion sought.
This photo belongs to a Coniacian deposit. it is located at the top of repetitive sequences represened by
bioturbated and bioclastic carbonates well bedded at the base (rich with benthic
foraminifers and peloids),and more massive (rich with rudist, lamellibranchs,
gastropods, algae and bryozoans) and dolomitic toward the top.
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?
Whether all ophiolites represent ancient plate boundaries? If there are some exception, can anyone show me typical examples with references? Many thanks.
I have attached a few pictures below, wondering if people might offer their interpretation about some rhyolite tuffs in central Washington. I'm interpreting the first two photos from section of surge deposits, and the last two photos from a section of block and ash flow deposits. The tuff section in the last two photos contains large 5-7 m vitric blocks, presumably transported from near the source? Any feedback, or start of dialogue much appreciated!
I want to know about geological structures (features) can be inferred from a zone between extensional and compressional stress regimes.
I read this paper from Butler and Paton (Butler R.W.H., Paton D.A., 2010. Evaluating lateral compaction in deepwater fold and thrust belts: How much are we missing from “nature’s sandbox”?, GSA today, v.2 , n° 3, 7pp, 4-10, doi : 10.1130/GSATG77A.1) that shows on the Namibian margin how shortening related to gravity gliding can be accommodated by direct lateral compaction within the sedimentary layers. Lateral compaction could thus accommodate 18 to 25% of the shortening and then the amount of shortening evidenced by the reverse faults is lower than the true shortening.
Do you know other examples/references concerning lateral compaction process?
Does a low amount of shortening (say less than 25%) could be entirely accommodated by lateral compaction within the sedimentary layer, then without any reverse fault?
Many thanks in advance!
These are the the end results which I produced and I want a little interpretation. the first image is a geological map of the area and the next is with faults activated. i want to ask what interpretations can i make from this data.
And the next question is about the cross section ? can i interpret as graben structure in between the fault lines. ?
help would be appreciated.
We would like to collect some oriented drill cores. Could someone, kindly guide us on the possible sampling sites, etc. The project may be a stepping stone for further collaboration.
I have made peperites in the lab using basaltic melts and wet sediments (silty sand and silts). I have 3 different textures (block, globular and ragged) but my field area contains mostly ragged textures.
The photos would be a great help in comparing what I have done in the lab with example from nature. If you are interested, please contact me and I will provide you with my email.
Does anyone know a locality/area displaying well-exposed sand-filled contractional/extensional faults? Anywhere in the world. Not California.
I tried to produce an image as a result, but the p.out file was not built by postscript structure. The p.out file seems to be still in the velocity model and picks dataset. Is it possible that the problem came from the uncompleted compilation? Or is there anyone got a complete instruction to install RAYINVR on Linux machine?
I have attached a table showing the simplified integrated geological fieldwork techniques which I had prepared after undergoing some training.
Kindly suggest, correct or comment, so that I can improve it.
Most of the geochemical characteristics of a volcanic-plutonic complex show island arc characteristics. However, in U-Pb dating analysis of just volcanic rocks (not in plutonics) we have found some different ages, derived by inherited zircons.
Presence of inherited zircons is in conflict with island arc setting?
The burrows in question (shown in attached photos) are built of fine sand and occur in a thin layer of a shiny sub-bituminous coal overlain by heavily burrowed lagoonal muddy sands (Coniacian, SW Poland). The underlying sediment shows plant roots as much as 20 cm long.
Can the burrows represent Camborygma ichnogenus if they seem to be exclusively horizontal? Their vertical section resembles that of Thalassionoides igen. but their horizontal pattern seems to have not much in common with this ichnogenus.
Mineralogy of the boulder (?) and host rock is same. Host rock is quartzite. The density of the boulder is higher than the host rock. What does the presence of vesicles centrally indicates? I am unable to identify this so please help me.
This ancient (Miocen to Pliocene) saprolite (half-weathered basalt rock) was discovered in a dril hole under thick layers of fulvial sediment. There seems very limited studies with ancient saprolite, let alone the rich weathering informaiton it contains. If you happen to know some reseach on this topic. could you recommond me some relative publications to open my mind and carry out the study? Or, you don't know any of this kind of papers, but could give me some advice on how to deal with this situation? I mean what kind of scientific puzzle could we solve with this rare sample type?
In an upper Miocene lacustrine sequence, we found very small volumes of volcanic-like rocks (see the picture) that nevertheless have not any crystal or any volcanic geochemical signature. It looks like in situ melting of narrow clay-bearing layers between limestones. Volcanic-like rocks reach a volume of only few cubic centimeters, along a discontinuous layer, but limestone above them show 2-3 meters of a strong rubefaction. There is not a heat source under the layer (only the unaltered lacustrine sequence). There is not any evidence of impact, and rocks reached only a few meters deep in his young history. Thus the only thing we can suppose is that the sedimentary rocks, that are very rich in organic matter, burnt below ground. Please, someone knows published examples that could be similar to this one?
The mineral I am referring to is located at the center of both photos. The photos correspond to a thin section viewed in non-polarized (to the left) and polarized light (to the right). The fault-rock is from northern Norway and kinematic indicator point towards extensional tectonics. Does anyone have any idea? Any input would be very appreciated! Thanks in advance! :)
I am currently studying thin sections of a wyomingite (leucite lamproite) from the Leucite Hills, Wyoming. The illustrated structures are common and make me think of spherulites, at least in XPL view (especially the last example), but in PPL, there's no visible acicular, needle-like crystal, only a slightly mottled texture with round darker rims. It looks as if devitrification had not occurred yet (this rock is about 0.9 My old); however the color in PPL (very realistic on the 400x and 600 px photos) is much yellower than the unfrequent glass found elsewhere on the slides; but since the groundmass of the lamproite consists of leucite and yellow-brown K-richterite ("magnophorite"), it could be some sort of "K-richteritic" glass? In XPL, especially in the LHG-13 sample, the vivid colors could be due to the interaction of water with the lava during supercooling? What do you think? Your answers will be appreciated. Fields of view: 40x-2.85mm, 400x-0.285mm, 600x-0.19mm
Patina on limestone, how it is identified in relation to depth and type. While cleaning how do you establish at what point you stop cleaning to retain this protective layer. How do you retain the "Patina of age".
Wu and Cheng (Lithos vol 89, p1-23; Valid garnet–biotite (GB) geothermometry and garnet–aluminum silicate–plagioclase–quartz (GASP) geobarometry in metapelitic rocks) compared the various geothermometers and geobarometers for metapelitic rocks and came up with their favoured/recommended calibrations. For garnet-biotite these were Holdaway (2000, Am. Mineralogist) and Kleeman and Reinhardt (1994, Eur. J. Mineralogy), and for GASP they were the Holdaway (2001, Am. Min.) and Newton and Haselton (1981; Thermodynamics of Minerals and Melts).
Are these still the best models/calibrations of these geothermobarometers?
I am currently doing a research on the boundary between Zimbabwe craton and Limpopo belt mainly focusing on the Northern marginal zone. Does anyone have suggestion of articles or rather have a different perspective on the events that took place, I mean the different subdivisions of the Limpopo belt consist of different ages. For example the the Central zone shows ages of around 2 Ga whilst the southern marginal zone shows both 2Ga and dominantly 2.7Ga not quiet sure about the Northern marginal zone. What does this mean, Or maybe the Zimbabwe craton collided with something first before ?
Has anyone personal opinion of the matter? If so, please answer in terms of: colour, fabric, texture and anything else you think you must. Your knowledge/opinion is critical to compare with my field observations until lab.
Can anyone send or recommend me a good paper about Upper Jurassic Carbonate Geologic settings in Western Desert, Egypt??
I am trying to find values for the resistivity or resistance for the seeberger sandstone (any other sandstone will do as an approximation). Is there literature available on the mater?
Thank you in advance and until then let's keep making the world a happier place!
I've been having difficulties in terms of identifying or being able to tell the difference between the paleosome and neosome visually. How do you tell if the paleosome exist in the migmatite rock by just looking at the hand specimen?
This fossil Himenofitales fern was collected several years ago by R. Rojas and myself from a Jurassic pre mid-Oxfordian exposure of the San Cayetano Formation in western Cuba. Any suggestion as to species or genera or distribution in time and space?