Science topic

Radiometric Dating - Science topic

Techniques used to determine the age of materials, based on the content and half-lives of the RADIOACTIVE ISOTOPES they contain.
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Dear all
We know the use of Sr isotopes for carbonate and sulfate minerals has already been widely discussed! There are also studies which successfully dated carbonates using the U-Pb or Pb-Pb method, but there are much more unsuccessful approaches.
I need information about any other reliable dating methods for a Gypsum, dolomite, limestone ?
If there are references, I’ll be grateful
Thank you in advance
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You can use palyonological indicators, Charophyts and also ostracods, In addition to isotopic methods.
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I have found some bones in my village of human, but according to my elders where I have found these bones are not belong to villigers these are far older than the village history but I want to know that how old these are. For that reason please tell me that Carbon dating is a best option or there are other ways if any then please guide me and also tell me how much it will cost me to analyze.
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Yes, 14C (carbon dating) is the best for dating such relatively recent bones, provided that they are extracted with caution to avoid contamination by extant organisms. Th cost is variable depending on where it is done, but it is generally between $50 and $100
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When we understand dating methods as being based on models (i.e. representations of some portions of reality), we shall ask ourselves whether those models are linear deterministic, non-linear deterministic, stochastic, or hybrid. I am under the impression that often archaeologists expect dating methods to behave in a linear deterministic way, while they most often behave stochastically or in a hybrid way. It looks like this misconception may be particularly problematic when combinig the results of different dating methods (scientific, archaeological, historical) to obtain a general chronological framework for a site or a period. What do you think? Which examples would you provide to illustrate the deterministic, stochastic and/or hybrid models used in archaeological chronometry?
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Johan, I appreciate your perspectives on this question. Theories explain large scale processes in the natural world, i.e., movement of objects, evolution, the structure of the universe, etc. I like your characterization of the physics & chemistry behind dating methods as laws of nature, it's just the nuts & bolts of how our dating methods work. I don't know if Maria's initial question also concerned the statistical models used to evaluate the raw data from these methods to determine a range of dates from any particular sample, but I think you and I are in agreement these are just archaeological methods and not any higher level of explanation about the archaeological record, our questions about the past, or hopes to better understand human behaviors and our evolution.
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Dear Colleagues,
We found some pseudotachylite veins in Lesser Himalaya of varying thickness (2 - 20 cm). The photographs are attached. Regional geological settings suggests that the veins are younger than 10 Ma. 
What is the best (economically and scientifically) method to date these veins ?
Thanks for the suggestions
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If there is a suitable 'zeroing event' one could attempt OSL dating . There are number of  publications where the same has been undertaken in impact produced glasses.
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l am dealing with dating of anorthosite using U-Pb zircon LA ICP-MS.
Anorthosite is a rock type of the mafic-ultramafic succession, which is composed of pyroxenite (bottom), olivine-, and oxyhornblende gabbros, then anorthosite, and porphyritic quartz-diorite (top). Anorthosite is commonly traversed by felsite veinlets (1-5 cm thick). It intrudes the surrounding volcanics, older granitoids (615-735 Ma) but are intruded by the younger granites (610-550 Ma).
Petrographically, anorthosite is composed totally of plagioclase megacrysts with subordinate interstitial amount of augite, enstatite, and amphibole, biotite, K-feldspar, and quartz. Accessories are magnetite, ilmenite, apatite and zircon. Plagioclase is of andesine composition. Zircon occurs interstitially in the groundmass consisting of quartz, K-feldspar, and biotite. It is closely associated with magnetite and ilmenite. It forms subhedral to euhedral crystals, which are commonly found as aggregates and as single individual grains. Some zircons are broken and corroded but embayed forms are not common. Zircons are not found in the plagioclase megacrysts. Fine and irregular veinlets of alteration products of mafic components traverse the plagioclase (Fig. 2A). Schiller structure delineated by very fine opaque lines is characteristic of plagioclase. There is evidences of transformation of pyroxene to amphibole and then to biotite +/- chlorite+/- opaques. 
Geochemically, anorthosite exhibits calc-alkaline affinity and  low/intermediate Mg# (0.29 - 0.38). They have high contents of Zr, Ba, Rb, Y, and highly fractionated REE pattern with weak negative Eu anomaly.
The question: Zircon occurs as core-rim structured crystals and homogeneous zoned crystals; the core gave age of about 625 Ma, and the rim gave 595 Ma, which is similar to age given by homogeneous zoned zircons in the same rock. The obtained 595 Ma is similar to the age of the nearby younger granite intruded anorthosite. The age difference between rim and core of zircon is about 30 Ma, which might be a result of a later magmatic event. But How? 
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Good luck with this project. It is going to be very difficult to determine the youngest overgrowth on the zircons. It will  take at least a dozen U/Pb ages to get the reliable age.
Let me know how you make out.  Best wishes, Paul Lyons.
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I am performing radiometric calibration of Landsat-OLI images. I have  facing error at the conversion of Top-of-Atmosphere Planetary Spectral Reflectance to trueTOA Reflectance. After performing this task images giving negative pixel values.Anyone can help in this regard 
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Hi, Biswajit
Better than NASA you do not do. Take ready to
Good luck!
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I am looking at correcting TLS Intensity for range (distance) and incidence angle error. I have found a many sources for this that have used commercially available reference targets, however I want to know if it is possible to perform the correction without the calibration target?
In order to perform the correction I need values for receiver power, transmitted power, receiver aperture, range, transmitter beam width, and backscatter cross section. I am unsure as to how to work out the values for these parameters. Are they worked out with the used of the calibration target? Or are they values that I can get from the instrument manufacturer?
I will be using a Topcon GLS-2000 scanner.
Is the reflectance target used to derive the values for the parameters? Or is it used as a control for the intensity values as it has known intensity ranges that can be compared to the scanner surface that needs correcting.
Any and all input would be greatly appreciated.
Thanks,
Lorcan Scully
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May be this publication can be of interest to you:  http://www.isprs.org/proceedings/XXXVI/part5/paper/1238_Dresden06.pdf 
Regards, Klaus 
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DATING using vitrinite reflectance and fission tracks for coal and
paleogeometria?
that studies have been conducted on paleogeometria? in basins where coal is using vitrinite reflectance?
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I did a fair bit of this over the years, and yes vitrinite reflectence does not help much with the timing of maximum burial but when combined with fission track dating and track length analysis and using that information to create a burial history plot you are on your way to getting to a Tt path.  Please try both forward models and inverse model to best understand the thermal history.
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Limit cycle, isochron
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Lets assume you have a time series of data x1, x2, x3 ....and you want to compute the 2-dimensional projection of the attractor for this series It can be one of  a point, a limit cycle or  strange (fractal) attractor. It follows from the Ruelle-Takens theorem that if you plot pairs of points {x1,x2}, {x3,x4} {x5,x6} ....etc then the resultant plot will converge to a 2-dimensional projection of the attractor. This result was one of the main insights of Chaos theory which applies when the attractor is strange/fractal giving rise to an apparently random time series from non random assumptions. 
Hope that helps :))
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I've carbon-dated a number of micro charcoal samples collected from soil in hopes of determining when the most recent fire event occurred.
However, upon receiving the result back from the lab, they explained that a definitive date for the charcoal could not be determined because of the Suess Effect. In other words, the charcoal was dated between 1650-1950 and due to the highly variable atmospheric concentrations of C13/C14 (because of combustion of fossil fuels), the age could not be determined beyond + or - ca. 150 years.
Is it possible to correct for the suess effect somehow to narrow the margin of error for date estimates?
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Dear Aaron,
14C datings are reported in either of two forms, which always start with the laboratory-identification code like OxA (Oxford), GrA (Groningen), MAMS (Mannheim), just to name a few here from Europe, followed by the lab-number. Then you either get a date followed by its confidence-interval or the percentage modern radiocarbon with its standard error. Here two real life examples from a paper that we published last month (see below).
J-8544 842±23 BP 90.05 0.26
J-8543 665±24 BP 92.06 0.27
Now if you feed these data into either CALIB or OxCAL (I happen to use the latter) you get the calibrated data. Now look on the graphic representation (with Oxcal there is the dropdown menu showing table, where you choose ‘single plot’). With the first value you see the probability-distribution in red on the vertical axis, which is then ‘projected’ on the calibration curve, which results in the grey distribution on the horizontal axis. This procedure results in the calibrated date, which lies with 95.4% probability between 1161 and 1255 AD.
Now take the second date and feed it into the program. In this part of the curve there is a nasty wiggle which causes the distribution to hit the curve twice, giving two well-separated probability intervals. Your 95.4% probability is now split nearly equally between the two date-ranges of 1278-1316 and 1355-1390 AD. So you can be pretty sure your piece of charcoal doesn’t date to any period outside these two intervals (including the range of 1317-1354), but there is absolutely no way to decide in which of the two humps the actual date lies. And this is exactly the effect you get with any date younger than ca. 270 BP, which is spread out over at least three intervals, as the calibration curve (which corresponds to the concentration of 14C in the air), starts to yo-yo very badly after ca. 1520.
Hope this clarifies the procedure a bit and shows why 14C after the (European) Middle Ages aren’t of much use.
Greetings,
Rengert
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I would be interested in the specifics.  What did you do and when?  How did your effort turn out?  Were there independent means of cross checking your derived dates?  What did it cost?  Was it a destructive technique?  Did the analyst have to visit the site where you acquired the rock art or artifacts?  Has anyone tried to use a dating technique for desert varnish on ancient flaked stone artifacts?  I am only aware of one published study in Argentina.  That one seemed interesting and rather helpful.
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There is an interesting attempt by: Dietzel, Martin, Kolmer, Hans, Pölt, Peter & Simic, Sanja 2008. «Desert varnish and petroglyphs on sandstone - Geochemical composition and climate changes from Pleistocene to Holocene (Libya).» Chemie der Erde 68: 31-43.
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Most people think the Rb-Sr dating of sericite is not reliable? What‘s the problem? or it is OK. Any help is appreciated and welcome. Looking forward to getting some answers or related papers.
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Dear Mr. Zhang,
I will not add up to the age dating itself but focus on the preparatory stage which is crucial whether the next step is useful or wasted time and money.
If your work is aimed at constraining the age of formation of a faultbound mineralization taking the samples from the fault gauge you must identify the sericite which is coeval with the fault movement or the mineralization. It needs a meticulous petrographic study and separation of the sericite in question. This approach can also be taken for alteration zone, e.g., in epithermal deposits.
In argillites of sedimentary origin I suspect that you constrain the age of formation of the host sediment. In this case you will have to take similar steps in order split apart detrital minerals indicative of the unroofing and uplift story in the provenance and diagenetically formed micaceous minerals. The data will let you know something about alteraton of the sediment.
It is a very rough scheme but if this is not done properly the finest device and the most skillful scientist will only produce numbers.
This is not to discourage you but these are the facts.
Good luck !
H.G.Dill
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Are there approaches to change or manipulate the stable isotope ratio of (large dead) wood (e.g. a cut tree trunk or tree branch) to allow tracing of xylophagus organism?
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O18 cellulose extracted from wood is the most used to study climate variations (paleoclimate). Tree rings Such parameters as tree ring width and wood density-have long-been used as climate proxies By Many investigators. In the last Decades, Numerous studies-have Demonstrated the potential of carbon stable isotope ratios in tree rings as proxy indicators of past climatic condition.But Anyhow, I wonder if that signal will be strong (and long-lasting) enough to track trophic interactions.
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Is the origin of sample, hydrothermal, plutonic, volcanic, sedimentary, and metamorphic geological environments, regarded for selection?
What are the cautions and warnings should be cared for sampling?
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We studied in Tertiary aged coals in Denizli Basin (West of Turkey). There are two kinds coal bedding in this basin. Is there any methods (radiometric ones) for determining ages of coals. 
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Dear Dr. Koralay,
The age interval indicated does not allow any method related to C isotopes. Therefore one question is key. What do you want to achieve with radiometric dating of coal. Is it a process related to the diagenesis/coalification or any other kind of epigenetic alteration ? In this case we have to look at the coal type, whether it is a high-ash coal which contains datable minerals or not. In this case you have to be quite certain whether the minerals are detrital or not. Based upon an answer to these questions a more advanced level may be embarked upon to discuss the radiometric methods applicable in this case.
Best regards
H.G.Dill
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I've had 3 "sub-samples" of a sediment core analyzed to ascertain the 10Be concentration levels. The sediment was taken from a closed basin - centripetal drainage pattern. The results indicate that I have a trend from top to bottom, but no age range was offered to me from the lab who ran the analysis. I've been looking for papers regarding this dating method, but I'm hoping that someone on this website maybe able to narrow down my search scope. If you need further information from me - please let me know.
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You may see the attached file. Also the following paper might be useful to your work.
A review of burial dating methods using 26Al and 10Be
Darryl E. Granger
Truly
ARK
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It has been observed  that when I make a plot for Isochron diagram using Nd isotope data it shows very scattered distribution and unable to make the best fit line. So kindly suggest me how to find the age and (143Nd/144Nd)i. 
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Thank you sir
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I want to measure a mafic rock age with Sm-Nd isotope system (Sm-Nd  isochron). I have no idea what mineral has low Sm/Nd and what mineral has high Sm/Nd. I need your suggestion. Thank You.
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It may be a problem to get a precise age, since many gabbros and basalts do not contain minerals with high Sm/Nd, which is what you need to get a well-defined isochron. If there is garnet around, you're in luck. Otherwise, it may be a futile exercise, depending on the expected age of the rocks. If you really have no idea of their age, and are happy to know whether they are ca. 500 or 1000 Ma old, take cpx (and/or hbl) and WR; plagioclase contains very little of anything. If you have an alkalu-gabbro, you could use apatite. If you want to know whether the rocks are 400 or 450 Ma, you may have a problem to get an age that is precise enough to be meaningful.
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I'm trying to build a Bayesian model for a coastal dune stratigraphy. The oldest date is taken from marine beach barrier sediments, while the other, more recent, dates are taken from gyttja layers (associated with archaeological remains) embedded within dune sediments
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Dear Jos,
the choice for the calibration is based on environmental considerations. If you believe that your shells lived in a marine environment you can use Marine 13. But beach barrier could be a more complex environment so if the shells lived in a lagoon you can take into consideration the possibility of a different calibration.
Best regards,
Luigi Vigliotti
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I know about the Carbon dating but facilities are not available in our laboratory. Is any other laboratory methods for the study of fossil sample? How can I start my study on a fossil sample. Please suggest and guide about the procedure.
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It depends. What kind of fossil you are talking about? Every absolute age estimation has its limits in material and method. A lot of geologists and palaeontologists would insist, that something that can be dated by C14 can not be called "fossil" because of the limited time range of this method.
Without more specific informations about your object of interest and issues you want to study nobody can give you specific answers to your questions.
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Does anyone know any papers or unpublished report/s on the effect of marine water on the stable isotope signature of sub-fossil wood. I'm wanting to start an isotopic project on sub-fossil wood removed from ancient beach deposits. And my student is concerned about the effects of marine water and bacteria on the stable isotope results.
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For a precautionary measure, use only the wood within the log that had no direct exposure to the water, and where there is no possible contamination from fungus or other organisms that contain cellulose (e.g. root systems of other plants). Then use only the alpha-cellulose of the wood with the proper pre-treatments for the stable isotope analyses.
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The sample after 210Po determination is left for 6 months and then is to be replated for 210Pb determination. If the recovery is not high should the sample be respiked with tracer or not?
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I shall grateful if you can send me two or three planchet holders to my address given below:
Dr. V. Kannan
Scientific Consultant
National Centre for Sustainable Coastal Management
Government of India
Anna University Campus
Guindy, Chennai-600025
Tamilnadu State
India
At present I am planning to determine Po-210 in surface sediment sample in India.   Your device will be helpful in alpha counting using alpha spectrometry.
v.kannan
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We date zircon U-Pb ages: the standard zircon is 91500; the unknown sample is Plesovice; We got the 206Pb/238U ages of Plesovice are 350-360Ma, which is ~20 Ma older than those dated by SIMS (330-340Ma)? I do not know reason. Any suggestions?
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I would suggest you provide more information about the technique you are using (LA, SIMS), what mass spec you have (Quad, MC?), and how you are processing (what software?).
CommonPb is unlikely to be an issue within the zircons as both those standards are very low in common Pb (that is why they are standards), and should get good ages by SIMS or LA-ICPMS. And so the only way you are going to introduce common Pb is through your preparation, and hopefully you are doing that carefully. Also be wary of the Anderson correction method until you know more about your sources of error!
It maybe seems more likely there is an issue with your technique. Are you keeping all the conditions the same? e.g. changing spot size between samples will result in an offset. 
Also you must consider your uncertainties which you have not mentioned. If your age for Plesovice is 360 +/- 25 Ma then technically your answer is correct, but if it is 360 +/- 5 then it is not!
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I have collected some dolerite samples from Proterozoic sedimentary sequence. I want to know about the sample preparation techniques of isotope dating of dolerite.
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Do you have the thin-section view of the rock?
Are there any unaltered primary minerals?
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I would like to date dolomite cements of supposed Cretaceous age and calcite cements of Cretaceous to Miocene possible age.
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Hi Carlo,
about 1 year later I have to revise my answer to this question. My answer now would be Yes, I know a lab in Germany doing it by U-Pb LA-SFICP-MS. Results/data look very promising and I have to admit that my statment last year was a bit too pessimistic. If you are still interested in dating of your dolomite and calcite cements, please contact me but you might have found already a way/lab....
regards Axel
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Eg: Hiroshima Bomb and Chernobyl disaster.
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The peaks of chernobly and bomb test are usually very useful for creation of historical profiles.
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Or provide a list of laboratories, the results of which are acceptable for most of the IF journals.
I want to date some sedimentary deposits using 10Be surface exposure dating. However, I have little experience with cosmogenic nuclide laboratories.
Thank you very much for the feedback
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Hi Thomas,
I also suggest my lab, the CEREGE in Aix-en-Provence, France. For exposure dating, you can contact Pr Didier Bourlès (bourles@cerege.fr) the head of our team or Dr Régis Braucher (braucher@cerege.fr).
We organize also the AMS 13th conference at the end of this summer 24-29 August 2014. http://ams13.cerege.fr.
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Age of Earth
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In contrast with what Eason Hong said, the oldest terrestrial rocks (i.e. zircons from the Yilgarn craton, Westen Autsralia) are actually dated at 4.4 Gyr (= Hadean age) (as Jorg Hausmann already stated). Obviously older rocks are not retrieved, because the earth's crust took some million years to form and solidify. Before this date the earth's surface consisted most likely of a magma ocean.
Interestingly, this dating method has been doubted for some reasons because of intracrystalline Pb mobility due to radiation damage. Recently, however, the dating method been confirmed in Nature of Geoscience (http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2075.html) to be correct by atom-probe tomography. I can advice to read this paper for those interested in the topic ;)
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locality: Danube Basin, Central Europe
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Hi Michal,
we started to do this in alluvial and aeolic deposits of Quaternary age (Vienna Basin, Slovakia) through OSL (Optical Simultaneous Luminiscence). In cooperation with the people from Texas, Germany and India. The results are particulary usable. For more information, see my e-mail.
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When we estimate the equivalent dose of soil samples in 3-6 meters depths we find 400-500 Gy using exp+lin or double exp fit procedures in growth curves. Are these results reliable?
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This depends on your samples. For some quartz grains, these doses are OK. Signals from other samples may be close to saturation. In this case, you have to analyze the shape of the growth curves as mentioned above, and try to find indepentent age controls to determine the reliablility of the ages obtained.
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Many disasters like volcanic eruptions or major floods, or even earthquakes took place along the recent periods on the geologic time scale, along with that, speleothems inside caves, and rings of old trees were recording those event synchronized with them, looking for any research that has touched upon or approached this area of science.
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Check these papers on speleothems and earthquakes in Israel:
Braun, Y., Kagan, E., Bar-Matthews, M., Ayalon, A., Agnon, A. 2012. Dating speleoseismites near the Dead Sea Transform and the Carmel Fault: Clues to coupling of a plate boundary and its branch. Isr. J. Earth Sci. 58: 257-273.
KAGAN, E.J., AGNON, A., BAR-MATTHEWS, M., AYALON, A., 2005. Dating large, infrequent earthquakes by damaged cave deposits. Geology, v. 33; no. 4; p. 261-264.
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Methods in Enzymology
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Are you aware of HPLC techniques to characterize the product or the substrate?
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dating of Pliocene fluvial sediments in Danube Basin, Central Europe
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The most important thing is collecting the most representative samples for the feature you are trying to date. You should consider origin, transportation, deposition and erosion/burial history of the sample. All of these factors will affect the age your sample yields. Detailed geomorphic documentation of the sample and its surrounding always helps.