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Tell me about the apps you can’t live without
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Hi
The UTM Geo Map software is so good for android.
Goodluck
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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.
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It is a vuggy a oligo- to polygomictic breccia/conglomerate cemented with carbonates, lacking any pronounced bedding or typical vein structures. It looks like a carbonate sinter be in hydrothermal or not. It should be of young geological age, maybe Quaternary or Neogene. If sedimentary processes were involved they should be colluvial (alluvial) in origin. That is my rather vague image interpretation.
With kind regards
H.G.Dill
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I would like to know the fast and easiest way to differentiate aeolian and fluvial silt by looking at the samples itself.
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- Aeolian silt and sand grains have frosted surfaces due to the the abrasion that they suffered when impacted to each other's.
- Aeolian silt might be better sorted than fluvial silts, while fluvial silts tend to be mixed with fine sand and clays and often have organic matter content.
-In a fluvial system, silts and finer sediments are related to flooding plains, so when the river level grows up and cover the plains around the river, after the energy decreases, the silts, clays and organic matter particles deposit on the flooding plain. Silts also occur in abandoned channels in meandering river systems.
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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.
Thank you.
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Mingdao, can you describe thin section photomicrograps, please ?
Thank you.
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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?
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Anderson's Theory assumes one of the principal stress axes to be vertical as the earth's surface (i.e. air) has no shear stress (like every fluid). Only normal stress is acting. Thus, the theory is only applicable at the earth's surface, not in deeper parts of the crust (where shear stress increases).
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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
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Nicolas has brought an interesting point. "Sexy" paper titles ARE IMPORTANT but need to be grammatically correct and fit the paper content and conclusions. A few hint regarding this and other issues on scientific publishing can be found in the link below. Regarding titles we have:
Titles and Abstracts
Title and abstract are the first things a reviewer will see.
First impressions count. The title and abstract are the first things that a reviewer will see. They are more likely to decide to review a paper that starts off with a clear scientific message. Here are some simple things to avoid.
Titles need to be about the science and findings, and not about how you did the science. For example, avoid titles with “Disentangling Impacts of …” or “Analysis of …” or “Revisiting …” or “Study of …” or “On the …” or “Insights into …” or “Toward the …” or “Assessing …”.
Abstracts should not have sentences such as, “The results of the analysis are discussed” or “the impacts are studied quantitatively.” Give the actual new science, and not a description of what you will discuss in the paper. You have to explain your methods, but then tell what you found.
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I want to take some samples, is there any particular method that I can use it to take a better sample in a relatively short time?
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Dear Mr Taheri
In general random drill sampling is more typical of the recent porphyry discoveries.
Sampling for any ore body must be actual representative all of the ore body. Generally, aims of the sampling such as evaluation, geochemistry, mineralogy, isotopes, fluid inclusions or all of them indicate the sampling process. Correct sampling technique requires a random selection of each sample from the ore deposite. most of the ore deposites display trends and variations in the spatial distribution of their grade.
 The porphyry deposits are low grade but usually very large in size, as a result of the low grade and size few porphyries support expensive underground mining techniques and most are mined by open pit methods.
Thanks
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Field inventory method for above ground biomass calculation for Uttarakhand Himalaya?
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Find here useful another manual for your purpose.
Sorry for too much late!
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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
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Dear Sanaullah,
You asked:
"[...] there could be a debate on the importance/non-importance of spatial context in a particular study, whether constructed/attributed or real? Please correct if I am wrong, that, if geographers succeed to explore or attribute a spatial context to the problem under study, only then it can be claimed as their domain. "
I hope I understand your problem as you raise it. However, I suggest a different approach. First, I try to provide an analogy.
Analogy: In physical geography vs. geology similar "authority"/"our domain" approach was typical for the second half of the 20th century. I would formulate what happened this way (please note this is strong simplification): (physical) geographers are responsible to study the landscape and what is on the top of the surface (say down to 1 m depth), what is below, belongs to geology. (Again, it is a simplification.)
What happened in the 1990s? A convergence took place, because many (real, interested) researchers realized the constraints of this division. Pedology, landslide research, erosion studies and a number of other fields needed urgently integrated data, because they could not solve their problems without this integrative approach. Many researchers coming from various fields (remote sensing specialists, engineering geologists, pedologist) invaded the field of geomorphology, coming up with valuable studies, quantifications, new models for surface processes. And now, if you look at the scientific programme of Geomorphology Division of the European Geosciences Union, you will find that a colourful variety characterizes this field, and many researchers of various disciplines present their relevant studies in this framework.
Returning back to your problem: Taking the aforementioned example into account, I suggest a different approach.
Consider that some researchers (not preferring spatial approach) simply leave out that context and carry out their study like this. Is their study complete?
If yes, there was no (known) spatial relevance to their study.
If no, that means someone can suggest a proper concept using geospatial approach.
This way the outcome verifies the applied tools and IMHO it does not matter who could provide a tool for that.
The statements like "You are not a geographer, therefore you cannot/are not allowed to study that problem" are simply outdated. ("Geographer" here can be replaced by "social scientist" or other.) This is because the fields of competences became wider; inter- and transdisciplinary approaches are proven to be successful in many cases.
I think the evolution of regional science is a good example for that. 50-60 years ago these studies would have been categorized either to economics or (human) geography or perhaps sociology. But the interactions of these research objects (cities, urban areas, rural zones, etc.) could not be studied properly anymore, if you insist to keep these categories. The discipline first gained attention then recognition. It was certainly not easy and not short, but Paul Krugman in 2008 in his Nobel Prize lecture referred to aspects of regional science, too . (Just around that time [surprise, surprise] a department of our university was renamed to Dept. of Regional Science.)
Summary: the battlefield of authority/competence over a certain research area or using certain tools will fade out as the belligerents get older/die out, or if a new approach dismantles the battlefield into unimportant, therefore negligible chunks.
I would be happy to read your comments on that and/or experience, case histories showing contrasting patterns.
Kind regards, Balázs
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Hello everyone,
Let me know both intensity and Transmittance are same in identifying the minerals based on wave number and nature of peak.
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Dear Mr. Dalwai,
if you refer to spectroscopy, the answer wil be no. Transmittance is the way of measuring (opposed to reflectance) and the intensity the height of a peak or its strength. This is the only way to give you a rather general and simple answer to a general question which is difficult to come to grips with.
Kinf regards
H.G.Dill
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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.
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Dear Mr. Pdah,
your question finds an answer in the unmetamoprhosed lithological setting as well.
A granite intrusion into country rocks,  effusive rocks overlying basement rocks or dykes and sills are younger than the enclosing country rocks.
With kind regards
H.G.Dill
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I am working on GoogleTM Earth images.The geometry of dykes makes difficult to count the number accurately. Interested to prepare the rose diagram.
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Simply save the GoogleTM Earth images as KMZ. Then import them to Global mapper.
 Then export them to shape file to Arc Gis. 
 Run Geometric calculate. you will find satisfy answer. 
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This sedimentary structure has a sandstone core and clast supported conglomerate rim. Always related with diamictites
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I also see a marine origin and in upper case probably a turbidite.
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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.
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The rock is a limestone with some type of coral (Syringopora?) that is cut so you are looking down on it.  I do not see any kind of glacial striations on the rock, but could have easily been transported by a glacier.  What part of the country is the sample from?
Good luck,
Paul Grover
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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.
Best regards,
Gianna Garda.
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Dear Gianna,
many thanks for your kind message. It should be very nice exchange our ideas and make some comparisons between these two localities. Please keep me up to date on the developments in your work.
My best regards
Michele
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The highly kerogenous Upper Jurassic limestone is black and thick. The formation is located in northern Iraq.
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The rolled, concentric shape and internal spiraling suggest to me an algal (microbialite, thrombolite) origin for this, perhaps rolling into this position by falling  off a nearby algal buildup, down the steep open-water face into the euxinic basin. Three dimensional form and thin section work might confirm, but I have seen similar pictures and wondered....unable to get back to the outcrop. 
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i'm looking for information about weathering and/or zeolite alteration of CAMP basalts in the High Atlas Mountain in Morocco. 
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 Thank you again!
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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
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Volcanic rocks and red beds generally involve punctuated volcanic activity and either the development of soil profiles or in some cases the input of easily oxidized ash, palaeo-climate is also very important. There is no requirement for subduction, these features are extrememly common on rifted margins both in the form of continental flood basalts and more localized volccanism on magma poor margins. The chemistry of the volcanic rocks can give good insights into the tectonic setting.... and the literature depending on where in the world you are looking at!
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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.
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Rock fragment. Veins are standing out on the weathered surface. The fragment is too weak to be of real use as a tool.
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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.
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Certainly not mud cracks.  Mudcracking normally develops roughly polygonal patterns due to contraction towards central foci.  The feature shown is jointing, in which the long partings going across the picture are bedding joints and the shorter partings at right angles to the bedding are dilation joints.  Indeed these carbonate rocks are not dissimilar to Carboniferous limestones found in northern England - see photo.
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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?
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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?
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Dear Mr. Sobolev:
Chakhmouradian (2006) recorded it from carbonatites, where its crystallization is controlled by other Ti, Nb, and Zr minerals, such as perovskite, pyrochlore, ilmenite, baddeleyite, and zircon. It is present in the Chilwa Alkaline Province (Malawi) and it is common in pegmatites as demonstrated by Szełęg and Škoda  (2008) from the Y, REE-rich Skalna Brama pegmatite near Szklarska Poręba. Maybe this paper comes closer to your issue: Zaccarini , F., S tumpf l, E .F. & Garuti, G . (2004): Zirconolite and Zr–Th–U minerals in chromitites of the Finero complex, Western Alps, Italy: evidence for carbonatite-type metasomatism in a subcontinental mantle plume. Can. Mineral. 42, 1825-1845.
Best regards
H.G.Dill
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Whether all ophiolites represent ancient plate boundaries? If there are some exception, can anyone show me typical examples with references? Many thanks.
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Dear Ming Chen: one things are ophiolites, another are peridotite-serpentinite bodies. Real ophiolites are tectonized parts of oceanic plates, small or big, complete or dismembered, frequently metamorphosed and deformed. Other peridotite-serpentinite bodies are not real ophiolites,a s they represent mantle lithosphere located originally under volcanic arcs or even continental blocks. A large body here in Venezuela, the Tinaquillo Peridotite, results to be a part of subcontinental mantle lithosphere of South America, tectonicalley emplaced in a complex traspressional setting, during the collision of the Caribbean Plate with the South American continental margen. As such, it is in direct contact with granulites of the lower continental crust, in one or two creeks the continental Moho itself is actually exposed. Other ophiolites, as described by Mark Keiter, are slices of back-arc basins, which actually are a sort of oceanic crust in most respects. And others, quite rare indeed, are intraoceanic blocks, like that described by Bo Liu... So there are classical ophiolites and other ophiolites, and alpine-type peridotite bodies which represent subcontinental or subarc lithosphere! Regards, Sebastian.   
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this interval is underlain by poorly sorted cross-bedded sandstones and overlain by black mudrocks
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Dear Aitalokhai,
It is not easy to see on these photographs, but I think, theses deposits could be related to volcanism. The last picture looks like a lapilli tuff, the first picture seems to show convolut bedding. The stratigraphic situaton (underlaying, water-saturated sandstones and overlaying, impermeable claystones) would fit the scenario of convolut bedding as the result of spontantenous dewatering of the sandstones during an (volcanic driven?) earthquake. But the deposits are obviously intensely weathered and coated by Fe oxides, making it hard to visually analyze the deposits. Hope this helps!
All the best,
Elmar
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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!
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Dear Mrs. Patridge,
If you are a novice in pyroclastic deposits but have some knowledge in sedimentology apply what you have learnt for arenaceous and fluvial deposits to what you suspect of being  a surge deposit. Pyroclastic flow deposits are more difficult to interpret due to the complex mode of transport and the welding process which may be occur in these deposits also known as ignimbrites and nuees ardentes. For a more detailed interpretation I refer to the textbook: Fisher,R.V., Schmincke,H.-U. 1984. Pyroclastic Rocks. Springer-Verlag, 196 pp which is still worth to be consulted in a case like that.
You may also download the paper "DILL, H.G., TECHMER, A., BOTZ, R., DOHRMANN, R. and   KAUFHOLD, S. (2012) Hypogene and supergene alteration of  the zeolite-bearing pyroclastic deposits at  Tell Rimah, Jordan, and rift-related processes along the Dead-Sea-Transform Fault System during the Quaternary.- Journal of Volcanology and Geothermal Research,  239-240: 49-68.
It may provide you with some kind of a guideline how to deal with such pyroclastic deposits (of economic interest) in the field, from the bird’s eye view and the laboratory.
As far as the interpretation of your images are concerned I concur with Mr. Lages, even if I am a bit reluctant to hand down remote-controlled diagnosis of this kind.
I wish you much success
H.G.Dill
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The illustrated structures (isolated or bifurcating furrows) are on the bedding planes of thin-bedded rhythmite that is part of a Carboniferous glacial marine/lacustrine succession (Paraná Basin, southern Brazil). Does anyone has seen something similar?
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Dear Fernando,
I think it could be both ice-keel scour marks in low depth near shoreline (because some structures seem to be curvilinear) and also ice-crystal imprints if it is possible that the surface was emerged. Indeed, ice-crystal growth in fine sediment could leave such structures.
I saw similar both structures (but on different surfaces) in the Late Ordovician sedimentary record. See Fig. 11e and Fig. 12 in Girard et al. 2015 (Earth Sciences Reviews - ask me if you want the pdf).
I also observed present-day ice-crystals in a puddle in Alps Mountains that could leave similar structures that you found, if their growth occurred in fine argillaceous sediment and their imprints were then preserved. See photography :
Best regards,
Flavia
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it's between the warmer Eocene and colder Pleistocene.
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Xu,
Congrats on this question that has generated very useful responses from fellow researchers.
Note also that during the Mid-Late Pliocene, the tropical vegetation of inland Indian landmass  gradually declined as subtropical- temperate  forms took over. A result of post-collision uplift of the peninsula. Montane vegetation occupied much of the area. This is useful for interpretation of  temperate (montane) vegetation in  tropical lands undergoing tectonic uplift, the tropical vegetation of warm climate gave way to temperate or warm tropical flora of high elevations.
Obianuju P. Umeji
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I want to know about geological structures (features) can be inferred from a zone between extensional and compressional stress regimes.
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In internal parts of folded belts extensional collapse can occur following thrusting because the crust is overthickened, becomes unestable and collapses, in these areas Negative Inversion is common ( i. e. Thrust faults that reactivate as normal faults) and additional normal faulting above thrust sheets. Himalayas, Western Alps, Canadian Rockies, Pyrenees and Betic Cordillera are examples of those.
In foreland areas in front of compressional structures, flexural extension characterized by normal fualts occurs due to the flexure generated by thrust sheet loading. If compression further propagates also inversion of previous flexural normal faults can occur. In other caes thrusting can use normal fault steps for ramping generated complex wedges. The best example I know is the Western Venezuela fold and thrust belt just north of the worlds oil larges accumulation the so-called Faja de Orinoco ( Heavy oil belt).
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Hello all,
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!
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Hello Gaël,
Layer-parallel compaction (LPC) or tectonic compaction is a significant component of shortening. In couple of papers we quantified LPC in sand models it to "lithology", basal friction, stratigraphic location, and amount of bulk shortening. This is easy to quantify in models where the initial dimensions and boundary conditions are better known. We have also compared LPC in models to that in Pyrenees where we measured 16-23% depending in different sections. If you are interested, send me your email address and I will send the PDF of those articles.
Cheers,
Hemin
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It is a pebble found in alluvium deposits.
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Again thank's to Professor Kamenov the pertrographic expertise has shown that this spicement is actually - slight metamorphosed Biotite Granite. Prime minerals are Quartz,  Potasium Feldspar and Orthoclase.  Accessory minerals are Magnetite, Titanite, Zirconium, Anatase.
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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.
Regards
Abdul Rehman 
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Please check if the boundary between quartenary deposits and the limestone has the same orientation like the other geological boundaries. It could be that the quartenary deposits hide geological units below them.
There is a drilling dtabase of the BGR where you can check this topic:
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These rocks were extrated from a complex deposit superposed by iron skarn deposit and porphyry molybdenum deposit. And the porphyry molybdenum deposit was seen as pipes with cutting the iron skarn belt and the mother igenous rock of iron.
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the first photo appears to be of a brecciated rock.  Brecciation could either be caused by faulting or by forced intrusion of magma.  Personally I feel it is the former.  Check the matrix for calcite/quartz/ore content; any of these are likely to be present if it is a fault breccia.  If the matrix is fine-grained igneous, then David's suggestion is most likely.  I am afraid that I cannot suggest anything for the second photo.
George
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Hi,
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. 
Many Thanks 
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When the field work is planned? Is it organzed by UNAM?
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Both of the specimens are found in upper Miocene sediment strata in Blagoevgrad graben- SW Bulgaria.
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Dear Miroslav,
I am afraid it's just sandstone concrections - no fossils, sorry.
thomas
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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.
Thanks
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There are a couple of good field photos and drawings on blocky and fluidal peperites in the attached JVGR paper. These are examples from the Miocene to Pliocene Bakony-Balaton Highland volcanic field in Hungary.
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Does anyone know a locality/area displaying well-exposed sand-filled contractional/extensional faults? Anywhere in the world. Not California.
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Hi, thank you for the very useful suggested papers!!
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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?
Thank you.
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The p.out file of RAYINVR is a postscript with the results seen in the RAYINVR window: the velocity model, the traced rays, and the predicted and picked arrivals. If RAYINVR is compiled with the graphical libraries it should produce both the image on screen and the postscript file.
However, the postscript identifier on the first line (%! xpltlib) may be unknown for some programs. You can try to replace it with %!PS-Adobe-3.0 EPSF-3.0 or some other identifier that your editing program uses.
Your problem is most likely related to the file identifier. You should also consider checking the BoundingBox parameters in case the image seems to be croped.
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In the city of SAKAKA in Saudi Arabia, this hole is observed, which it expels the sand over than 20 meters in the air. What is this phenomenon?
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I suggest that the hole is the top of an abandoned well originally drilled for oil and gas exploration, but finding a natural accumulation of N2 (nitrogen) that is left venting to the atmosphere.
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It is harder than steel and glass. 
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Well, strictly hornfels perhaps not flint - flint has a more specific meaning Miroslav. But you know more than when you began :-) Paul, I agree that colour is the least important, but if it were say dark green (and lots of men have trouble with distinguishing green and brown, and poor image reproduction can make it look very dark grey because it is their mist common colour blindness) one might expect some other possibilities involving green minerals. And the enquirer can see the colour so it is no extra work. My message being that such enquiries need the enquirer to do all their home work before posting an enquiry, and I am not sure that these basic approaches are always still taught, because we pampered geos with access to equipment in First World laboratories simply x-ray, probe and thin sections. I work in some obscure places and also often want to have some idea what I am looking at while still there. Hence my attempt at mentoring :-). Amazing what you can do with a flame platinum wire, borax and a blow-torch as well, but you would have to be permanently in such a place to bother, and I think those skills are pretty much dead and superfluous (but they are easy with things like K-rich rocks etc - emission spectroscopy by bunsen burner). And yes, I missed mentioning fracture, although flint, rhyolite and horfels can all give that.
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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.
Thank you.
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Dear Damepaia,
I will add to your list:
  • HCl bottle to check carbonates
  • camera
  • plastic bags to collect samples of your representative rocks according to the lithology, stratigraphy,etc...
  • hand auger, usually use by soil scientist, it is helpfull also in geological mapping especially if you don't have nice outcrop. See the following  papers.
  • check soil maps if available, they contain usefull informations on the geological substratum of the above soil. See the following papers.
Furthermore, I will advice you to follow road and rivers to find outcrops. I will also not make to deep pre-fieldwork processing of Arcgis,etc...let it for post-field work. I will just focus on topographic maps and use steoreoscopic image
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While taking traverses along hilly stream in Rajgir, Bihar, India, came across a few bed-load rock samples that looks like tools- artifacts. Expert opinion sought. 
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I supported the views of Dr. James A Green, USA. It is very difficult to say something on the bases of photographs only. It is true that the rocks samples in Sujit's photographs are not identical bifacial tools or it does not looks like an artifact. It does not show clear man-made flakes scars. These may be broken pieces of rocks of nearby source as these were found along hilly stream in Rajgir, Bihar, India.
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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?
Regards,
M.R. Hosseini 
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There are indeed inherited zircons in island arc setting. They can result from remelting of some parts of the arc and are only slightly older; they can also be much older, coming from continental areas. In that case, the interesting point is to understand how they came there. More the island arc is located far from continents and more the origin is difficult to constrain. For discussion on that topic, you could have a look at 2 publcations concerning the Neoproterozoic juvenile Arabo-Nubian shield in which much older zircons have been found while the Nd isotopes of the enclosing rocks are strongly positive:
Liégeois, J.P., Stern, R.J., 2010. Sr–Nd isotopes and geochemistry of granite-gneiss complexes from the Meatiq and Hafafit domes, Eastern Desert, Egypt: No evidence for pre-Neoproterozoic crust. Journal of African Earth Sciences, 57, 31–40
Stern, R.J., Ali, K.A., Liégeois, J.P., Johnson, P., Wiescek, F., Kattan, F., 2010. Distribution and Significance of pre-Neoproterozoic zircons in juvenile Neoproterozoic igneous rocks of the Arabian-Nubian shield. American Journal of Science, 310, 791–811
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Hi, Ichnologists,
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.
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Hi if you check out the Ferron Sandstones in Utah you will find a copy of your last picture. From it I may say that this is a transegressive surface, highly burrowed with Thalassinoides. You can also notice that the burrows are compacted and the shape is no longer circular, but oval.
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Dear all, Some one can tell me when can I use DN and when can I use reflectance to compute band ratios for lithologic information. Thanx.
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Dear Lofti,
Like Brian said, if you just have one sensor image you can use DN whitout any problem, and for other images processing before you convert to reflectance you must do the atmospheric correction for all the sensors.
If you have your image in reflectance, like you said, you can do it too.
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Carbonate deposit.
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Bencaabane:
The answer provided by Dr. Martin Rittner would have some meaning if you would kindly take the trouble of making thin sections of the Limestone and provide pictures in higher magnification.
Best
Syed
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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.
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I guess I could add to the confusion a bit. So what do you mean by the density being different? What is the suspected environment of deposition of the "host" rock? I suspect that if you showed an enlarged photo of the cavities it might help, but it really needs a fully description if you wish people to do meaningful remote- sensing identification. :-) I am very doubtful that it has anything to do with glacial activity given the rock types involved, and I even wonder if it is really a boulder (and of course vesicle is not an appropriate term). I also wonder if the cavities are really cubic, and I would be very surprised if they were after sulphide minerals given the lack of iron-staining or other ochres in their vicinity formed from weathering of the original minerals. The cavities look to me as if they are confined to a zone that forms an internal shell, that may be of different composition to the rest of the "boulder". The cavity shapes and matrix might help to give an answer - my first guess would be a sulphate or a carbonate, perhaps some late diagenetic redistribution. Some cavities look almost rounded, and I wonder if these cavities could be after bladed, disc-like crystals of gypsum?
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Log analyst
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Sorry, I just saw this question.
GMD bhai I have no idea about shale gas.
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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?
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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?
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Check out the clinker beds of the Eocene Wasatch Formation in the Powder River Basin of Wyoming.
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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! :)
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Dear Mr. Koehl:
The mineral aggregates have a birefringence of between 0.030 and 0.100 (it is difficult to give a better assessment based upon the images), its color and pleochroism attest to an Fe-bearing phyllosilicate. Phyllosilicates which fulfill these optical properties belong to the
-biotite-group
-nontronite-group (dioctahedral Fe-bearing smectite)
-stilpnomelane-group
 Intermediate optical properties may be attained in case of an intimate intergrowth of biotite (< 0.100) and vermiculite (approx. 0.02).
As it is a postmagmatic process and a typical fault gauge I suspect of a mineral of the nontronite- or biotite-vermiculite alteration.
Any further classification on my part would be speculative.
I suggest a separation of the material either for XRD and/or CEC analysis.
Best regards
H.G.Dill
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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
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Within the last three samples the crystallinity seems to increase. Therefore the radiating arrangement of the crystals  in the "aggregates"is barely , but is recognizable. In the last two sample in particular in the last, the spherulitic nature is obviuos.
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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".   
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Is this a previously polished surface?? or a natural surface?
In either case Jane is right no acid at all..... Mild near neutral soap can be used with a soft (very) brush do not apply too much pressure.
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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? 
Thanks,
David Evans
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Hi David, it seems that classic thermobarometry is going out of fashion. For a study on metasedimentary rocks in Pyrenean gneiss domes I have applied several thermometers and barometers, GB-GASP of Holdaway (2000, 2001, in the 2005 DOS program), TWQ 2.03 (Berman 2007) and several from Wu et al. (GBMAQ, GM-GMPQ, GBPQ). Some of my schist and gneiss didn't have plagioclase but cordierite, so GASP wasn't applicable to all. Then I tried Average P and T from the ThermoCalc package. Its approach is similar to TWQ, e.g. it calculates and independent set of reactions of all phases in chemical equilibrium. I found the greatest agreement between GB-GASP and AveragePT.
However, when I put an extensive chapter in the manuscript my co-author suggested it's way to long; the editor voiced a similar opinion. In the end all that was left was a small paragraph and a table. Most of the metamorphic data was derived from pseudosections. The main criticism on traditional thermobarometry is that the assumption that the phases involved in the calculations are actually in chemical equilibrium as it is required is really hard to prove. So, forward modelling à la ThermoCalc or Theriak. I am sure you are aware of that. I think it would be difficult today to publish a paper on metamorphism of say pelitic rocks based only on classical thermobarometry.
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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 ?
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Another key reference should be that of Blenkinsop 2011 in the GSA special volume. Search for it online with this reference.
Blenkinsop, T.G., 2011, Archean magmatic granulites, diapirism, and Proterozoic reworking in the Northern Marginal Zone of the Limpopo Belt,  Geological Society of America Memoir 207, p. 1–24, doi:10.1130/2011.1207(13).
David
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I need information about Argentina or even South America
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Martin:
Youmay like to consult: The Cambrian System in Northwestern Argentina: etc. (2003) by Acenolaza, Geologica Acta, Vol. 1, 23-29.
Best
Syed
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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.
thanks
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I understand that you are investigating dead or past oil seeps, as detectable at the surface in outcrop, not necessarily exumed oil fields.
On this basis, I suggest to distinguish oil seeps in incoherent terrain and oil seeps in rocks.
Incoherent terrain or soil: the main physical characteristic is presence of some kind of hydrocarbon-related substance, like tar, asphalt, or even wax, concentrated in the soil at the spot of the dead seep. This may also indicate an active seep, possibly with low seepage rate. The main difference would be the absence of gaseous or liquid active seepage in a really dried-up paleo-seep.
Rocks: like-wise, the presence of some  kind of hydrocarbon-related substance, like tar, asphalt, or even wax, at the spot of the dead seep is the main indicator. It would be useful to distinguish seeps in porous rocks (porous and permeable sandstone, porous and permeable calcarenite or grainstone in case of carbonate rock) and naturally fractured rocks (tight clastic rocks, massive limestone or dolomite, without matrix porosity). In porous rocks, the rock in the immediate vicinity of the paleo-seep would be impregnated of heavy hydrocarbons or asphalt/tar, indicating irreducible saturation in the matrix porosity. In naturally fractured rocks, the main sign would be asphalt/tar stain on the walls of the natural fractures where hydrocarbons were seeping out. Again, a live seep can be differentiated from a dried-up seep by the presence of gaseous components and light ends, that are absent in a dead seep.
An oil spill on incoherent soil, even decades old, could be detected by the absence of bio-indicators typical of active oil seeps, because an occasional oil spill is generally not enough to induce the start of a local colony of hydrocarbon-feeding micro-organisms. An oil spill on rock would be easy to detect becouse of lack of deep impregnation in the rock matrix.
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Do you recognize the chert structure in attached pdf from the early Eocene Rus Fm of Qatar, Middle East? Is it stromatolitic?
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Interesting photos and discussion.
Need to look at TS and CS in thin sections for texture and structure. as pointed out, the photos are insufficient to justify any concrete conclusion.
Possible options:
Hydrothermal vent deposits (observed in marine sediments deposited in proximity of volcanic vents where the gaseous fluids create tubular deposits of chert / carbonates with a concentric laminate pattern;
Ichnofossils - organic chert / calcite binding along tubular habitats of burrowing organisms - that leave behind such features
Simple fluid escape structures produced during lithification of silicic sediments under special conditions, where the fluids remain trapped in the lower strata and then are triggered into escape through tubular vents....(akin to mud-volcanoes)
....
I am assuming that since these are found in sedimentary rocks, other processes should not be brought into consideration, although even biogenic superficial weathering by soil-dwelling burrowers could also yield such features.
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Required for excursion.
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Hi.
I can send you the maps in question via Dropbox to your e-mail, probably this afternoon...
Best regards from the Canaries,
Rubén
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Can anyone send or recommend me a good paper about Upper Jurassic Carbonate Geologic settings in Western Desert, Egypt??
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Dear Aser
you can check the link below which deals with Tassy et al. (2015) entitled Egyptian Tethyan margin in the Mesozoic: Evolution of a mixed carbonate-siliciclastic shelf edge (from Western Desert to Sinai).
Abdou et al. (2009) have been documented subsurface Jurassic sediments of Western Desert (see link below0
Regards
Massih 
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Hey guys,
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!
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We used in our EM modeling:
brine flushed sandstone 0.6 Ohm m
and for reduced (+-70%) oil saturated 16 Ohm m  
So you see that it can range a lot depending on porosity and saturation. 300 Ohm m is certainly not the minimum.
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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?
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Dear Mr. Xaba:
4 terms need to be distinguished: Paleosome, neosome, melanosome, and leucosome. As the prefix indicates paleo is old, neo new, leuco light, and melano dark. Whereas paleo and neo is timely, leuco and melano is the color. In practice this means that the neosome is the product of anatexis that can be formed by reactions that produce for example graitic melt + garnet during fluid absent melting. In this case the quartzofeldspatic part is the leucosome, together with garnet forming the neosome. If you don't have an additional melanocratic phase like garnet or cordierite during anatexis, leucosome and neosome is the same. On the other hand the melanosome is the restite that did not melt and is formed by dark minerals, whereas the paleosome is the original rock of which the melt was extracted. The latter two terms are very difficult to distinguish is field and often chemical analyses is necessary.
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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?
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Another detail of the same taxon.
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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?
Thank you!
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Acetic is good for phosphatic and occasionally silicified microfossils but it will dissolve calcium carbonate. Ostracods and forams are calcium carbonate so be careful not to dissolve them!
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I am asking in general.
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Dear colleagues,
another answer from the point of view of an economic geologist:
1. Lamproite-group rocks are dark-colored magmatic rocks enriched in K and Mg and hypabyssal or effusive in origin. Lamproites are peralkaline ultrapotassic Mg-enriched magmatic rocks with all hallmarks of ultrabasic rocks such as elevated Cr and Ni contents ( Mitchell 1991). They may contain leucite, phlogopite, and glass (fizroyite), plogopite, diopside, leucite (wyomingite) or phenocrysts of diopside and phlogopite in a fine-grained glassy matrix which chemically can be approximated to the composition of leucite (madupite). They may also contain amphibole, olivine, sanidine, spinel, apatite and nepheline together with some wadeite and priderite.
2. Kimberlite-group rocks are close to porphyritic alkaline peridotites. They contain phenocrysts of olivine which frequently serpentinized, phlogopite converted into chlorite, geikelite (= "Mg ilmenite"), and. chromian pyrope-enriched garnet. They float in a fine-grained matrix of calcite, olivine, and phlogopite (2 nd gen.). Accessory minerals are ilmenite, magnetite, spinel, monticellite, apatite and perovskite. Chrome diopside mineralization in kimberlites is an important guide to diamond deposits. Kimberlite is by definition a K-enriched ultramafic rock which derived from a depth of more than 150 km below surface (Clement and Skinner 1985, Kirkley et al. 1991). Moving upwards, the hypabyssal intrusions grade into diatreme breccias and pyroclastic rocks
3. Lamprophyre-group magmatic rocks are dark-colored like the afore-mentioned subcrustal rocks abundant in biotite, hornblende, pyroxene, present as phenocrysts in a fine-grained matrix of K and Na/Ca feldspar and/ or feldspathoids. According to the abundance of these minerals mentioned above they are subdivided into minette, kersantite, spessartite, camptonite, monchiquite, fourchite and alnoite.
No 1 - rocks are host of diamonds predominantly in Western Australia.
No-2- rocks are host of diamonds predominantly in Tanzania, Botswana, Angola, DR Congo, South Africa, Russia, Lesotho, Canada, Zimbabwe, Greenland, Gabon (metakimberlites)
No -3 - rocks gave besides diamonds (Michipicoten and Abitibi greenstone belts) also host to sapphire in Yogo Gulch, Montana, USA. It takes an outstanding position as it is bound to lamprophyre dykes classified as ouachitite ,a biotite monchiquite devoid of olivine with a glassy or analcime-bearing groundmass.
Best regards
Harald G.Dill
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I have the following thin section of alkali feldspar granite. Are blue minerals arfvedsonite?
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Dear Mr. Athari,
unlike many  other Na--bearing amphiboles arvedsonite has a negative optical character along the major elongation. It shows an oblique extinction between 10° and 25° which is different from that of glaucophane, crossite and riebeckite. So I suggest you do some further routine optical tests and disclose it to the audience. Thereby you can narrow down the field of speculation and in context with the associated minerals you may get a sound result. Have you got also aegirite in your rocks ? Arvedsonite is confined to agpaitic magmatic rocks with alk>al. Is this the case ?
If I had no further information and taken a closer look at the texture and the epidote,  I would have also tended to a low-T-high-P enclave as it was already mentioned by Dr. Keiter.
Best regards
H.G.Dill
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in the case of construct a model by petromod software for ex. we need a comprehensive tool to check the validity of hour hypothetical  model if the vitrinite refelctance analysis is absent what we can do 
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Apatite (U-Th)/He dating (~80-60 degrees)
Apatite fission track dating (~120-60 degrees)
Zircon (U-Th|/He dating (~180-150 degrees)
Zircon fission track dating (~240-320 degrees)
thermochronometers
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The Dongfanghong ophiolite of NE China, as part of the Paleo-Pacific accretionary complex, consists of meta- peridotite, pyroxenite and (layered) gabbro. The ophiolite has P-MORB geochemical affinities including depletion of Th, U and LREE. However, its crystallization order is Olivine+Cpx+Pl, similar to SSZ-type.
Is it possible that SSZ ophiolite has P-MORB geochemical affinities, or P-MORB ophiolite has Ol-Cpx-Pl crystallization order?
Fig.3 a,b: meta-peridotite; c,d: meta-pyroxenite; e,f: meta-gabbro; g,h: amphiboles in the dark layer of the mata-gabbro
Fig.5 a: chondrite-normalized; b: PM-normalized, after Sun & McDonough, 1989.