Geochemistry - Science topic

I assume you analyzed this with EDS-capable SEM or electron microprobe? The high total suggests that the electron beam went through the inclusion and into the garnet. My guess it is a Fe-rich Al-garnet (almandine) and the inclusion was rich in silica (quartz or alkali-feldspar). You can't do much with this analysis because it is a mixture fo at least two minerals.

Bekhruz,

I suggest that you get a copy of "Chemical and Isotopic Groundwater Hydrology" (https://www.amazon.com/Chemical-Isotopic-Groundwater-Hydrology-Environment/dp/0824747046), then download the latest version of PHREEQC along with the PHREEQC manual. PHREEQC is a public domain program maintained by the US Geological Survey. I have used PHREEQC for many years. It has a bit of a learning curve but the manual is clearly written and includes many examples that you can use to set up your own geochem models.

Regards,

Bruce K Darling

dear Ioannis

The classification of lamprophyres, lamproites, and kimberlites has been a topic of ongoing discussion within the International Union of Geological Sciences (IUGS). Here are some key points from recent proposals and discussions:

These proposals aim to create a more accurate and comprehensive classification system that can be widely adopted by geologists.

Is there a specific aspect of this classification that interests you the most?

1: Integrating Ultramafic Lamprophyres into the IUGS Classification of Igneous Rocks 2: Classification of Lamprophyres, Lamproites, Kimberlites

Yusuf Mamman , Andongma Wanduku Tende Yunis Boga

Sediments are derived from the continental crust by crustal reworking processes such as weathering, erosion, transportation, and deposition. Especially, terrigenous sediments which are derived from reworking process of continental crust. In such case, distinguishing continental crust zircon from slab sediment is difficult. Infact, there no point to distinguish since they mean the same. There are volcaniclastic sediments that are derived being from proximal volcanic zone. However, zircon in volcaniclastic /pelagic/biogenic sediments are extremely rare.

Limitations in multi-element analysis can impact the comprehensive understanding of heavy metal interactions in a given environment in several ways.

1. **Incomplete Picture:** Multi-element analysis might not cover the entire spectrum of elements present in a given environment. Some crucial elements relevant to heavy metal interactions could be overlooked, leading to an incomplete understanding.

2. **Sensitivity and Detection Limits:** The sensitivity and detection limits of the analytical methods used can affect the accuracy of results. Some methods might not be sensitive enough to detect low concentrations of certain heavy metals, potentially underestimating their presence or impact.

3. **Interference Issues:** Interference from other elements or compounds in the sample can occur, leading to inaccuracies in measuring specific heavy metals. This can result in misinterpretation of interactions and relationships between different elements.

4. **Temporal and Spatial Variability:** Multi-element analysis might not capture temporal or spatial variations effectively. Heavy metal interactions can vary over time and space, and limitations in the analysis may hinder the ability to identify such patterns.

5. **Complex Speciation:** Heavy metals often exist in different chemical forms or species, each with unique behavior and reactivity. Some analytical techniques may struggle to differentiate between these species, limiting insights into their specific interactions.

Addressing these limitations may involve employing advanced analytical techniques, considering complementary methods, and ensuring a comprehensive sampling strategy. This enhances the accuracy and reliability of data, contributing to a more thorough understanding of heavy metal interactions in a given environment.

Dear Hengrui Zhu ,

In September this year I finished my next article about graviton:

(Hungarian)

But from it the next parts ha English version:

Abstract:

gravitonn:

and conclushion:

The metaphisicle is connectible to Tao philosophy and is has compatibility with geochemistry of Goldschmidt...

If the fundamental material nature of the world has been metaphysically well established with the help of the a priori entity

then it is possible to find explanations for many questions that the current concepts are unable to answer.

Regards,

Laszlo

1. Theory behind the Proxy: DCO3 is a commonly used paleotemperature proxy because the oxygen isotope composition of carbonate minerals, such as shells or corals, is influenced by the temperature of the environment in which they form. The ratio of heavy to light oxygen isotopes in the carbonate mineral reflects the isotopic composition of the water from which the mineral precipitated, which, in turn, is related to the temperature of the water.

2. Calibration: To establish a relationship between DCO3 and temperature, calibration studies are conducted using modern samples from environments with known temperatures. These studies aim to quantify the relationship between DCO3 and temperature, typically expressed as an equation or regression model.

3. Good Relationship: If DCO3 and temperature show a strong and consistent relationship, it suggests that the proxy is effectively recording changes in temperature. A strong relationship would mean that variations in DCO3 can be reliably interpreted as changes in temperature, providing confidence in using DCO3 as a paleotemperature indicator.

4. Poor Relationship: A weak or inconsistent relationship between DCO3 and temperature can indicate various factors. It could suggest that other variables, such as local environmental conditions or biological processes, are also influencing the DCO3 signal, making it difficult to isolate the temperature signal. It could also indicate that the calibration method used needs refinement or that additional factors need to be considered when interpreting the DCO3 data.

5. Consideration of Other Factors: When comparing DCO3 and temperature, it's important to consider potential confounding factors that can influence the DCO3 signal. Factors such as salinity, nutrient availability, or pH variations can affect the oxygen isotope composition of the water and, consequently, the DCO3 signal. These factors need to be accounted for or controlled for during the interpretation of DCO3 data.

6. Using Multiple Proxies: It's worth noting that paleoclimatologists often utilize multiple proxies to reconstruct past temperature variations. This helps to cross-validate and strengthen the interpretations. By comparing the results from different proxies, researchers can gain a more comprehensive understanding of past climate conditions.

Hope it helps: partial credit AI

Dear Sujay Nandi .

Two things are important:

The A-type granites from whar formed.

and what is the geochemical behavior of the elements you mentioned.

Read this article of mine, it has a novel geochemical suggestion:

​

If you understand and the idea described is good, you can benefit greatly from this article

Regards,

Laszlo

FYI, we have just released GCDkit.Mineral, which serves exactly this purpose (recalculation, statistical treatment and plotting of mineral chemistry data). You can download it from https://mineral.gcdkit.org.

Hello,

You can read this publication

Dear Taiwo,

it depends on what you want compare your rocks with.

In classical igneous petrology studies, a comparison is between the investigated rock and the hypothetical composition of Earth's mantle, best represented by CI (chondrite type Ivuna) meteorites. I use the King et al. (2021) estimate ( ).

Cheers,

Michele

Greetings Suresh,

With regards to your opening question of "Do we need an efficient Reservoir Engineer, or, a great team work, or, AI for characterizing complex reservoirs?", I agree with one of Scott's points and say "yes". We need all. You need a team of skilled reservoir engineers working collaboratively with differing (challenging) ideas and perceptions, who can appreciate and accept the range of possibilities. You need Monte Carlo type probability analysis, because with complexity comes unknowns and these still need to be accounted for. And AI will help, but only to the degree that its been trained.

And we need a work environment that is honest and based on integrity. Thankfully I don't work where Scott did, though I have seen what he's seen, in different ways. Greed and bias are out there but (and maybe I'm naïve) not all-pervasive.

Your other questions regarding how long it takes to acquire these skills are difficult to answer. It depends on the individual and their work environment & work scope. Will they have 10 years of diverse, challenging experience with good mentorship, or will they repeat one year of mediocre entry-level employment ten times? The former could be a talented, team-leading RE in 6-7 years. The latter may never acquire the skills you describe. Both of these work circumstances exist in our industry and the latter is painfully common.

Hope that helps,

R

Zircon has different advantages when it comes to find solutions to geodynamic and geotectonic issues.

1. Its is one of the most common minerals used for U- and Th age dating.

2. Due to its internal and external textural changes different growth zones and generations of zircon population can be distinguished from each other.

Particularly its X habits can be very well used for constraiining the P/T conditions . Please see the papers cited below

3. By means of trace elements the zircon generations can be attributed to different environments of formation. This is especially favored by its ultrastable behavior among the heavy minerals that enables zircon to survive multiple recycling and concentration in many placer deposits with its X morphology well preserved in marine to alluvial - fluvial placer deposits

I wish you much success

HGD

maybe also this

Gärtner, A., Linnemann, U., Sagawe, A., Hofmannm M., Ullrich, B. & Kleber, A. (2013). Morphology of zircon crystal grains in sediments – characteristics, classifications, definitions. Journal of Central European Geology, 59, pp. 65-73.

R-is good!

Alcohol and formaldehyde preservation solutions are commonly used in the preservation of skeletal carbonates. However, there is a concern that these solutions may leach elements from the skeletal carbonates, which could potentially affect the accuracy of isotopic and elemental analyses.Several studies have investigated the effects of alcohol and formaldehyde preservation solutions on skeletal carbonates. One study found that formaldehyde preservation did not significantly affect the stable isotopic composition of skeletal carbonates, but it did result in a slight decrease in calcium concentration. Another study found that alcohol preservation did not significantly affect the stable isotopic composition or elemental concentrations of skeletal carbonates. However, some studies have reported that both alcohol and formaldehyde preservation solutions can leach elements from skeletal carbonates. For example, one study found that alcohol preservation caused a significant loss of magnesium from coral skeletons. Another study found that formaldehyde preservation caused a significant loss of strontium from bivalve shells. Overall, the effects of alcohol and formaldehyde preservation solutions on skeletal carbonates appear to be dependent on several factors, including the type of carbonate, the concentration and duration of exposure to the preservation solution, and the specific element being analyzed.

PHREEQC (PH Redox Equilibrium) is a software program designed to model and analyze chemical reactions in water systems. It is commonly used in the fields of environmental science, geology, hydrology, and geochemistry to simulate and predict the behavior of aqueous systems.

Here are some of the main uses of PHREEQC:

Water quality assessments: PHREEQC can be used to assess the quality of natural waters, including groundwater, surface water, and soils. It can be used to model the behavior of contaminants and evaluate the effectiveness of different treatment methods.

Geochemical modeling: PHREEQC is frequently used in geochemical modeling to simulate the complex reactions that occur between water and rocks. It can be used to predict the formation of minerals and the release of dissolved solids, and to study the chemical evolution of geological systems.

Mineral dissolution and precipitation: PHREEQC can be used to study the dissolution and precipitation of minerals in aqueous systems. This can be important for understanding the formation of ore deposits, the weathering of rocks, and the transport of metals in groundwater.

Dear Eyob Abebe,

Looking at your two Spider plots - it is obvious that all 6 analyzes were not done at the same time in one laboratory and with the same methodic's... Therefore, one of the explanations can simply be "laboratory and methodic bias"...! Personally, I believe in those 3 analyzes that have complete Ree's = those with "normal" negative Pb anomaly. Other 3 analyzes were probably done by XRF analysis or are significantly older...

However, there can be lot of other explanations - like real homogeneity of these granitic gneisses = in one locality (big quarry etc.) you can have granitic gneisses that look by naked eyes identical, but have different ages... or only part of these granitic gneisses is partially sheared or melted etc. = you need a complex research with plenty of samples having thin sections and chemical analysis from one laboratory including isotopes if possible.

Not everything similar is exactly + actually the same...

Cheers,

Milan

***************

Dear Saifur Rahman Khan and Al,

lI wish you Happy New Year: success in your spiritual achievement, good health and prosperity for it!

I found the next on the facbook (https://www.facebook.com/USGSVolcanoes):

'A volcanologist is a person who studies volcanoes, but there are many different specialties within the field of volcanology. Which interests you and what steps should you take to achieve your goal? Find out more in #VolcanoWatch.

Earthquakes are one primary tool used to study volcanoes. A volcano seismologist studies the earthquakes that are generated as magma moves through Earth’s crust.

A volcano geodesist studies the deformation, or change in shape, of a volcano caused by the movement of magma and gases beneath the surface. Many features of volcanoes can be studied from space, as well, using satellite sensors. Tools like these provide clues about the state of the volcano.

Geologists and geochemists study the composition of lavas and gases to understand the source and style of the eruption. Measuring gas emissions is especially important, as the vog (volcanic air pollution) caused by toxic volcanic gases can contribute to breathing problems, acid rain, and agricultural problems downwind, especially during long-lived eruptions.

If you are interested in becoming a volcanologist, you’ll need to work toward a bachelor’s degree, preferably in a STEM field (Science, Technology, Engineering, and Math). Volcanologists frequently pursue degrees in geology, chemistry, physics, and/or mathematics, but that is not always the case. Oceanography, computer science, engineering, environmental science are all potential pathways, and the list goes on. Explore different fields to find what interests you most.

After achieving a bachelor’s degree, consider options for advanced degrees like a Masters or Doctorate. Many advanced degree programs in the sciences are funded, meaning tuition may be waived, and you might get a stipend for doing the work. Basically, you get paid instead of having to pay for school, and you gain valuable work experience at the same time.

You might consider working for the USGS or other agencies and companies. You have seen many photos of HVO scientists working during the eruptions of Mauna Loa and Kīlauea. The National Park Service also offers a variety of positions for people with either bachelor’s or advanced degrees, such as park geologists, archaeologists, botanists, guides, interpretive rangers, and law enforcement rangers. Science writing and journalism are also excellent ways to explore the excitement of volcanology, natural disasters, and cutting-edge science, while encouraging those passions in others. Similarly, eco- and geo-tourism are great ways to get close to the action and work outdoors, while also meeting, educating, and inspiring people from all over the world. Careers in emergency management will have you helping people stay informed during crises.

Check out usajobs.gov for positions within the federal government. There is even a special section for students and recent grads.

Volcano Activity Updates

#MaunaLoa is not erupting. Webcam imagery shows weak, residual incandescence intermittently in the inactive Northeast Rift Zone fissure 3 lava flow at night. Seismicity remains low and ground deformation rates have decreased. Sulfur dioxide (SO2) emission rates are at background levels. For Mauna Loa monitoring data, see: https://www.usgs.gov/volcanoes/mauna-loa/monitoring-data.

#Kilauea is not erupting. Lava supply to the Halemaʻumaʻu lava lake in Hawai‘i Volcanoes National Park ceased on December 9. Sulfur dioxide emission rates have decreased to near pre-eruption background levels and were last measured at approximately 200 tonnes per day (t/d) on December 14. Seismicity is elevated but stable, with few earthquakes. Over the past week, summit tiltmeters recorded several deflation-inflation (DI) events. For Kīlauea monitoring data, see https://www.usgs.gov/.../past-week-monitoring-data-kilauea.

There were three earthquakes with 3 or more felt reports in the Hawaiian Islands during the past week: a M3.3 earthquake 14 km (8 mi) S of Fern Forest at 7 km (4 mi) depth on Dec. 27 at 4:33 a.m. HST, a M3.4 earthquake 7 km (4 mi) WSW of Volcano at 2 km (1 mi) depth on Dec. 24 at 8:31 p.m. HST, and a M2.5 earthquake 1 km (0 mi) S of Mountain View at 11 km (7 mi) depth on Dec. 24 at 9:57 a.m. HST.

In the photo, an HVO technician adjusts a volcanic gas analysis instrument that was specifically designed for this Unoccupied Aircraft System (UAS) unit, which carries three one-liter analysis bags. The instrument transmits gas concentration information in real-time during the flight at Kīlauea summit. USGS has special use permits from the National Park Service to conduct official UAS missions as part of HVO's mission to monitor active volcanoes in Hawaii, assess their hazards, issue warnings, and advance scientific understanding to reduce impacts of volcanic eruptions. Launching, landing, or operating an unoccupied aircraft from or on lands and waters administered by the National Park Service within the boundaries of Hawai‘i Volcanoes National Park is prohibited under 36 CFR § 1.5 - Closures and public use limits.

USGS image taken January 14, 2022 by M. Warren.

#USGS #HVO #HawaiianVolcanoObservatory'

Maybe it can help you!

Regards,

Laszlo

Please read our paper:

Preparation methods in Mineralogy and Geology,

by Günter Grundmann and Herbert Scholz.

Thanks Ahmadbek Jalilov and Mário A. Gonçalves for the interesting details.

There is a Li mine project 2 km from where I live (Cáceres, Extremadura, SW Spain). It would be the second largest Li mine in Europe. The experts said that "the material is formed by Ordovician slates, quartzites and sandstones crossed by a system of quartz veins and dykes and mineralized quartz and quartzpegmatites of Sn and Li, which constitute in general a superficial stockwork originated by the potential influence at depth of a granitic intrusion". The green hydrogen is what the company says they would produce by electrolysis. That is why I asked. It is clear to me from their answer that they should treat the ore further away from the city. Thank you very much.

We can view fenitization is a type of contact metasomatism. The fenite may vary with host rock (syenite or ultramafics) and distribution of carbonatite within them. The fenitizing fluid composition will vary with the type and composition of the intruded carbonatite. Sodic fenite and potassic fenite are commonly associated with syenite. The sodic fenite develops 'albitite' along the contact zone and may be controlled by the fracture system present. Pre-existing potash feldspar is altered to massive albitite. Potassic fenite develops 'ultrapotassic' feldspar. This may be confirmed by variation in petrography from syenite to the suspected fenite zone (and carbonatite). If the fenitization is pervasive, massive and thick, it is possible to distinguish the original and altered minerals at the outcrop. Otherwise we may need geochemical confirmation. Accessory minerals such as pyroxene in the syenite, may be altered to blue riebeckite (asbestiform), following desilication reactions, the silica generated will possess riebeckite needles as inclusions and will be noticed as greyish blue to dark blue (quartz) pebbles (Samalpatti alkaline complex). Pyroxene may be altered to green epidote or dark to greenish black biotite or vermiculite (with or without apatite) , and may be distributed as streaks in the fenite zone. Carbonatite related minerals such as monazite, apatite, corundum may occur in the fenitized zone.

Hello !how are you!how is thé reseach

There are many studies about that and most of them proved that XRF (X-ray fluorescence) is a more recommended and precise technique for major oxides/ elements than ICP-AES. These studies showed that there are big differences between those two techniques in the case of measuring majors. XRF is also used to determine the traces, however, ICP-AES is especially more appropriate for elements lighter than Na (sodium) and this is not available in XRF. Finally, XRF is more recommended in your case.

I am old-fashioned (geology-mineralogy-chemistry-advanced-level geosciences, .e.g., isotopes).. Therefore, in this case where only a chemical ratio forms centerpiece of a discussion of such a far-reaching issue, I can only respond in a way like that:

"One swallow does not make summer"

HGD

I work as a mineralogist and I am not a specialist in NASICON phases, but the reason that these substances have not yet been found in nature will most likely be the strong hydrating ability and oxygen affinity of Ti and Zr. In even slightly hydrothermal environment there is anatase, resp. zircon (resp. hydrated zircon phases, gelzircon etc.) strongly stable. It is necessary to assess under what conditions, from which input components NASICON are synthesized and whether it is at least a little realistic for a similar synthesis to take place in nature. However, some Zr and Ti phases with PO4 or SiO2 have been found in nature. It is possible to use the search at: https://www.mindat.org/chemsearch.php

IT depends on the zircon textures. If the zircon is still in a good shape, maybe yes. If the Zircon shows evidence of recrystallization and disequilibrium, this method can be applied but results must be evaluated carefully.

Unlike Ce, Eu redox behavior is more strongly governed by pH and temperature (Bau and Möller 1992). At Earth surface conditions, Eu behavior is similar to that of the trivalent REEs, except in highly alkaline, reducing conditions and marine pore waters (Sverjensky 1984). Seawater features a slight positive Eu anomaly, which may reflect the admixture of river waters or the preferential mobilization of Eu relative to the other REEs (Leybourne and Johannesson 2008; Xu and Han 2009).

But in your case the strong Eu anomaly could be diagnostic of i) the bacterial reduction coupled to the drop of the pH that incorporated more Eu(III) in your system, ii) a more reduced and alkaline conditions with a relative low pH.

Best regards

Clément

Dear Afshin Majidi

Please refer to the following trademark paper.

1. https://www.tandfonline.com/doi/abs/10.1080/00206814.2021.1972352?journalCode=tigr20

2. https://onlinelibrary.wiley.com/doi/10.1002/gj.4236?af=R

3. https://personal.utdallas.edu/~rjstern/pdfs/Moghadam%20Early%20Paleozoic%20Lithos%2017.pdf

I hope this helps.

Best Wishes,

Haroon

Abdelaziz Zine http://www.gcdkit.org/. This is the best one so far recommended to me. Hope you find this helpful.

R studio!

Dear Dr. Gupta

IOGC (iron-oxide-copper-gold) deposits is a new-fashion classification scheme in economic geology with the number of old and well-known metal deposits categorized as such.

The majority of these deposits and their locus typicus of origin is located in the paleo- and meso Proterozoic settings of the old cratons in Australia and South America. The kick-starter was Olympic Dam a big animal found by the application of mega-shear zones by Western Mining during the early 1980s by Driscoll. While this blind ore body was a new discovery on the Stuart Shelf a lot of well-known deposit such as Kiruna were re-classified and also attributed to this type of deposit. A series of others hosted by Mesozoic and Cenozoic strata in Chile, Peru and different modern fold belts followed suit.

They contain substantial amounts of Fe, they are bound to felsic and intermediate intrusive rocks of the granite clan and lack a special zonation. Their origin is held to be linked to hydrothermal and metasomatic processes affecting large crustal sections so that the above features need not be restricted to one ore body but found within a metal district, see e.g. Kiruna where you have Fe ore bodies like Kiruna Vara, P-enriched ones, e.g. Henry ore body and Cu deposits like Viscaria.

The ore structure is said to be caldera- or maar like with strong faulting all around that controls the accumulation of magnetite and hematite. Brecciation is a common textural feature of IOGC deposits. There is still a lot of debate around this type of deposit as to its link to volcanic and granitic rocks and the related processes which are normally not closely linked in time and space with each other .

The ore mineralization contains chalcopyrite, pyrite, Fe oxides like magnetite and hematite, REE minerals such as orthite, U minerals and gold.

It is the common way of handling new discoveries in economic geology. Olympic Dam also often named as Roxby Downs named after its mining camp is a giant deposit and exceptional in own rights which stands for great success in exploration and could only be brought on-stream by the joint venture with another big animal from the oil and gas business. The logical process was that of finding a plethora of new IOGC deposits worldwide covering now the timespan from 2.0 Ga to 20 Ma simply by re-examining old animals and re-naming it. Thereby you can increase the values of old deposits simply by a hype. As a result of that the features were more and more watered down. And this is why at the beginning I used the term fashion also to shed some light on how the marketing of “economic geology” often works and how it is adopted by those riding the paper tiger in this business.

This is the opinion of a geologist working since more than 40 years in economic geology with facts and data and who is rather skeptical of all these new finds here and there. I was in the early 1980 in Australia when the “genuine” giant type was discovered by one of the smallest mining companies taking a simply handy-craft geological approach was successful and subsequently was draped around by a wealth of ideology.

H.G.D.

The end-member model is a mass-balance model, the mixing line basically reflect the ideal mixing process of end-members. However, beyond the ideal mixing process, there are some additional processes influence the mixing processes, like dissolution-precipitation, ion exchange, oxidation-reduction, et. al. For the different season (like dry season and wet season), the concentration of major elements in groundwater (always shallow groundwater) and river can be influenced by rainfall, there are surely some different. However, the concentration of major elements in seawater is far more than groundwater or seawater, and the season different is not very obvious. Using logarithmic coordinate system, the positions of seawater samples in different seasons are similar (There may be some differences if the seawater is sampled from different places). In the study of groundwater, if there are different season, I will choose samples from same monitoring well for the end-members. I do not know if it is same in the surface water research, but I hope this way can give you some ideas.

I am not certainly the right person to give you an answer on your question. What it cough my attention was your way you start your message: "Hello gents", I do know at least 3 women that can give you a Master class on this, so please be more inclusive next time.

This article will help you to start with PCA and understand when to standardize the datasets https://www.reneshbedre.com/blog/principal-component-analysis.html

Dear Zhuoqi,

The formation of pyroxenes and phlogopites at contact zones between carbonatites and silicate rocks is a very common feature. There are different facts to consider to answer your question on why these two phases react with each other.

1. The genetic link: Whether there is actually a genetic link (formation by liquid immiscibility) between the two rock types has not yet been clarified in detail for ALL occurrences. Some occurrences probably only show an accompanying ascent of both melts/magmas within the same ascent channel (see Gittins & Harmer 2003, Per. Mineral.; (3) A model for the formation of carbonatite-phoscorite assemblages based on the compositional variations of mica and apatite from the Palabora Carbonatite Complex, South Africa | Request PDF (researchgate.net)). For others, liquid immiscibility in depth is assumed.

First of all, it should be clarified whether a separation by liquid immiscibility between your two magmas has occurred at all. This does not necessarily have to be assumed for all carbonatite complexes. At least not at the crustal level.

2. For those melts that might be formed by liquid immiscibility: A separation between carbonatites and silicate melts occurs at depth. If such a process happens the separation would start from a rather primitive carbonate-bearing silicate melt. In particular experimental studies indicate that the separated silicate melt would be rather nephelenitic. This means it needs evolution of the nephelinitic melt until it represents a syenitic magma. So, the observed rock “association” of syenites and carbonatites already experienced a strong change in physico-chemical conditions (due to magma evolution, fractional crystallization, cooling) of the magmas since they separated.

3. Timing of crystallization: Carbonatites have a much higher volatile content, much lower viscosity and much lower liquidus temperature, therefore carbonatite melt/magma activy might still exist, while silicate magma activity has already ebbed and e.g., syenite is already crystallized. In this case, a solidified silicate rock (in your case syenite) coexists with a carbonatite magma, that is very volatile rich and might react with the syenite (Anenburg and Mavrogenes 2018).

When the volatile-rich carbonatite melt reacts with a silicate rock, Al and Si rich phases (dominance depends on the composition of the silicate rock) precipitate at the contact “interface”, as both Si and Al have very low solubility in the carbonatite melt and are therefore immediately precipitated as corresponding mineral phases. In terms of the typical chemical composition of a carbonatite melt (K, (Na) and Mg-rich), phlogopite and clinopyroxenes (orthopyroxenes are not stable in carbonatitic melts) are simply the most likely minerals to be formed (see Giebel et al., 2019… already mentioned previously in answers from colleagues).

Hope that helps.

Best,

Hannes

Yes I am agreeing with you.

Dear Dr. Adikaram,

the term major or minor element can hardly be quantitativel by defined, particularly for an element which pertains geochemically to the top-ten element making up the crust. There are figure between 1 and 5 wt. % to qualify for a minor element and above to be a major one but this depends on the chemical setting. As mineralogist dealing with the basic entity of rocks and ores I have established my own classification scheme. A major element is relevant in the crystal structure for the build up of mineral. In pyrrhotite S and Fe are the major elements making up 38 and 62 % in the Fe _0.95 S lattice. In sphalerite ZnS (ideal formula) may be present as a minor element , e.g. Zn 0.95 Fe 0.05 S (= 64 % Zn, 3 % Fe,

I think that the introduction of this paper will help you for more comprehension

Clow, D. W., Mast, M. A., Bullen, T. D., & Turk, J. T. (1997). Strontium 87/strontium 86 as a tracer of mineral weathering reactions and calcium sources in an alpine/subalpine watershed, Loch Vale, Colorado. Water Resources Research, 33(6), 1335-1351.

MDPI journals, 100s of them now, largely fall into the "predatory" journal category, promising editors of special issues that they do not have to deal with editing, since the journal does this. They do not have technical staff, just those who use an algorithm to choose reviewers and ask for a quick reply, then return these quickly to the author and accept whatever the author returns. A colleague reviewed one paper and requested major revisions; she saw the paper published a week later, none of her comments incorporated. This publisher is in business to publish lots of papers and make money on OA fees from most of them. Do your science a favor, and submit manuscripts to journals with serious reviewers and editors that will improve the quality of your research and the published papers.

Archi, you are correctly identified all the volcanic tuffs deposited in aqueous conditions. and described in the paper.

The answer to this question can only be provided as a function of the grain size and composition of the host rocks.

In siliciclastic sedimentary rocks, there are three particle intervals, (1) gravel (psephite), (2) sand/arenite (psammite) and (3) clay/mud (stones) (pelite).

Ad 1: Use thin sections/ polished sections combined with MLA and EMPA for a precise lithoclast analysis (>2 mm)

References: Textbooks on igneous and metamorphic petrology for diagnostic lithoclasts

Ad 2: Use allogenic heavy minerals and light minerals (grain size interval 63 µm to 300µm) making use from the routine particulate sections under the petrographic microscope through MLA, EMPA, SEM-WDX/EDX. Micro-Raman and MLA.

References: Textbooks on igneous and metamorphic petrology for diagnostic heavy minerals

You can browse my list of publications where you will find a couple of papers which I can send you on request.

a) The (calc-alkali) gabbro clan:

b) The alkali-gabbro clan:

Ad 3: Clay minerals have to be separated from the sediment samples by settling tubes or centrifuges to get batches of high purity (the interval < 63 µm is suitable for XRD, IR). In this case they may be use for radiometric age dating, e.g., K/Ar, Ar/Ar of micaceous clay minerals and for crystallinity measurement in context with vitrinite reflectance in samples of (1). This grain size fraction and age dating methods are especially useful for low- to very-low grade metamorphic source rocks expected in the provenance area.

For calcareous rocks only procedures referred to under (1) and (2) in combination with micropaleontology makes sense

References: Textbooks on igneous and metamorphic petrology for diagnostic clay minerals

H.G.Dill

You may use this link:

Dear Ahmed A. Rashad which kind of rock are you referring to? Because geochemical behaviour of trace elements and Rare Earth Elements (REE) changes according to the petrological system.

Some elements are closely related to the crystallization (or fusion) of some mineral phases depending of their compatibility with the solid phase. So the residual melt (and future rock) could presents enrichments or deplation on that particular element (e.g Eu with plg). Futhermore, the element aboundance is closely controlled by % of partial melting of the source and a lots of secondary processes (e.g. fluid/rock interaction and consequent enrichment).

Best regards,

Gabriele

Dear Zehra,

Only one criteria; the Aim, Goal, or Objective.

Without a clearly defined objective it is virtually impossible to measure success of any program. That is why you got such different answers - all of them true and valid, but not really answering your question. Each answer addresses a different measure of success, because each evaluates a different objective.

A simple example of an objective could read something along the lines of this: To delineate a CCC Code-compliant Resource/Reserve of TTT tonnes/ounces of mineral/commodity MMM, within a period of YYY years and budget of $BBB, in country/region RRR, etc.

Dear Srinjoy Datta,

dating and source identification with U-Pb and Rb-Sr are ratehr well established (yet necessary) approaches. From an analytical point of view, If you are looking for recent advances, I would suggest looking into non-traditional isotopes, e.g., Mg, Fe, Si, Mo, Cr, Cu + Zn... . There are several possibilities to constrain magma pathways, assimilation, metasomatism, temperature, fractionation... you name it. You could look into Young et al. 2015 (10.1016/j.chemgeo.2014.12.013) for ideas.

If you are looking for more ideas, geochemical perspective letters are always a good adress to look for recent advances (https://www.geochemicalperspectivesletters.org/current-issue).

Hope this helps.

Many thanks for the exposure to literature.

Dear Chandra Bhushan Verma: I agree with Luke Hilchie, kyanite is a metamorphic high pressure mineral, the ultrabasic and ultramafic composition of kimberlites doesn't allow it to form, as too little Al2O3 is present in them. If it exists inside a kimberlite body it is quite surely a xenocryst from the lower crust, or as inclusions in eclogitc diamonds. which are those formed from subducted organic matter present in sea floor sediments, as their high negative values of delta 13C suggest. Eclogitic diamonds have inclusions of omphacite, garnet, rutile, and of course, kyanite.

Regards, Sebastián.

You can find it in the following paper:

Dear Sumit,

you can simply check the famous MELTS code (it works better on Linus-based computers, but you can use also an on-line version with Windows software) or its variants (P-MELTS or Rhyolite-MELTS). You can simply go to the MELTS web-site (http://melts.ofm-research.org/) and then you can choose the best option for you. Note that it is not easy to work with this software.

Alternatively, you can use the much simpler PELE software ( ).

Please forget the classical Bowen's sequence of crystallization. About one hundred years of petrological investigation have demonstrated the existence of much more complicated variants in the sequence of mineral crystallization.

Please avoid the Bowen's reaction series! It is a very old concept no longer valid. It can be chosen as a general rule, but each case requires specific considerations, rendering this concept no longer valid. Variation of H2O and CO2 content, magma mixing, crustal contamination processes and AFC processes can strongly influence the sequence of minerals appearing when a melt crystallizes.

Things are much more complex than the Bowen reaction scheme claims.

michele

According to an author, it is best to recalculate all major oxides including TiO2. No need to recalculate trace elements.

Dear Mr. Morad,

Unless you have carried out a geological survey and studied the mineralogical association of your rocks the chemical studies and the use of any index based upon chemical data is meaningless. It is a repetive critics of mine.

It is good for riding the “paper-tiger” but in practice these figures are of no use. Because what it is all about, is the futile attempt to circumnavigate experience and knowledge in geology and mineralogy. To gather experience needs time and to pile up knowledge even more in combination with a series of physical and mental endowments.

We cannot delegate geosciences to the technicians in the chemical lab.

Sorry for this harsh critics which is a general statement rather a reference to your question.

Sincerely yours

Harald G. Dill

Dear Mr. Pratihari,

there is only one way to come close to a solution in provenance analysis.

1. Given there is enough information available on the geological setting investigate the mineralogical assemblage which is based upon heavy , light minerals and lithoclasts

2. Conduct further studies either based upon whole rock chemistry of major and/or trace elements or mineral chemistry, even better.

If you put the cart before the horse it is poking around in the fog, or to be more precise wasted time and wasted money.

With kind regards

H.G.Dill

Hello,

sorry but the previous answer had nothing to do with the question! Read the question before you answer.

Carbonate rocks generally precipitate from seawater and there is a ratios of those elements in seawater. Now by determining those ratios in the precipitated carbonate rock and comparing to the seawater ratio we can deduce environmental parameters, such as pH, temperature, etc. This is thermodynamically controlled through the Distribution Coefficient "D".

One of the first papers ever written about that would be:

Thompson and Chow, 1955

T.G. Thompson, T.J. Chow The Sr/Ca ratio in carbonate secreting marine organisms

Deep-Sea Res., 3 (1955), pp. 20-30

Other papers:

Calculation of simultaneous isotopic and trace element variations during water-rock interaction with applications to carbonate diagenesis

JL Banner, GN Hanson - Geochimica et Cosmochimica Acta, 1990 - Elsevier

[PDF] geoscienceworld.org

Diagenesis of carbonates in deep-sea sediments; evidence from Sr/Ca ratios and interstitial dissolved Sr (super 2+) data

PA Baker, JM Gieskes… - Journal of …, 1982 - pubs.geoscienceworld.org

Dear Zainab,

Hope you are doing well.

EAGE gives funds for students but it has focused on sedimentary processes.

Regards,

Rahim

Dear H-J Förster and Swayoma Bose,

The Nb-Ta composition of your granites is quite interesting. What I can say from my own granite whole-rock compilation is that such Nb-Ta composition (e.g. Nb/Ta ~17.5, Nb~55 ppm, Ta ~3 ppm) is generally only reached by mantle-derived A1-type peralkaline to metaluminous granites.

If you think that this granite is purely crustal in origin. It could suggest that it formed from the melting of either a residual crust or, for example, mantle-derived andesite rocks characterized by high Nb/Ta ratios. If, for example, sediments are submitted to a first event of partial melting at low temperature (until muscovite breakdown), the accumulation of biotite and ilmenite can induce an increase of the Nb/Ta value in the residue. If this residual crust is then submitted to a second partial melting event at high temperature (above biotite breakdown condition), the generated granitic melt can reach a high Nb/Ta value. See Stepanov et al. (2014) for some discussion about such processes.

Regards,

CB

Chemical Speciation and Potential Mobility of Heavy Metals ...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330713/

Excellent question and answers, according to our team study in Iran: lead in water pipes , traffic intensity , residential wastes , vehicles and urban industries !

Please kindly see the attached article!

Dear A. Mannan Rouhani

A mere 11 elements constitute 99.9% of the atoms in the human body. These are typically divided into major and minor elements. The four major elements, H, O, C, and N, make up approximately 99% of the human body, and seven minor elements, Na, K, Ca, Mg, P, S, and Cl, make up another 0.9% of the body (Combs 2005). Approximately 18 additional elements — called trace elements — are considered essential in small amounts to maintain human life. However, human health experts do not universally agree on the exact number and identity of these trace elements. Out of the approximately 29 elements considered essential for human life, 18 are either essential or beneficial to plants and are obtained from soil, and most of the other elements can be taken up from the soil by plants (Brevik 2013a).

Negative Health Effects

Heavy Metals

Exposure to heavy metals through soil contact is a major human health concern. Arsenic is a metalloid, but it is commonly grouped with the heavy metals. The heavy metals of greatest concern for human health include: As, Pb, Cd, Cr, Cu, Hg, Ni, and Zn (Fergusson 1990). Heavy metals enter soils naturally through the weathering of rocks, but they have also been introduced into soils through human activity. Heavy metals are the by-products of mining ores, and they are present in mine spoils and in the immediate surroundings of metal processing plants. Heavy metals are released into soils from landfills that contain industrial and household wastes and from sewage sludge that comes from wastewater treatment plants. E-wastes, or wastes associated with electronic appliances, are an increasing source of Pb, Sb, Hg, Cd, and Ni in the soil (Robinson 2009). Urban soils are particularly susceptible to significant accumulations of heavy metals from automobile exhaust, coal burning, erosion of metal structures, and refuse incineration. In agricultural settings, the use of fertilizers, manures, and pesticides has also contributed to the accumulation of heavy metals in soils (Senesi et al. 1999). Arsenic has been used in pesticides, and the build-up of arsenic in orchard soils is problematic since it may persist for decades (Walsh et al. 1977). The heavy metals with the most toxicity in humans, including Cd, Pb, Hg, and As, are those with no biological function that disrupt enzymatic activities commonly affecting the brain and kidneys (Hu 2002).

Organic Chemicals

Organic chemicals have been deposited into the soil both naturally and anthropogenically, and many of the organic chemicals deposited into the air and water eventually end up in the soil. Soil contamination with organic chemicals is a serious problem in all nations (Aelion 2009). A large amount of these organic chemicals come from the agricultural application of herbicides, insecticides, and nematicides (Figure 2). Soil pollution with organic chemicals is not limited to farming areas. Soils in urban areas are also polluted with organic chemicals as a result of industrial activities, coal burning, motor vehicle emissions, waste incineration, and sewage and solid waste dumping (Leake et al. 2009). Both farming and urban areas have soil contamination that includes a complex mixture of organic chemicals, metals, and microorganisms caused by municipal and domestic septic system waste, farm animal waste, and other biowastes (Pettry et al. 1973). A more recent health concern includes pharmaceutical waste derived from antibiotics, hormones, and antiparasitic drugs used to treat humans and domestic animals (Albihn 2001).

The most common types of organic chemicals found in soil include polyhalogenated biphenyls, aromatic hydrocarbons, insecticides, herbicides, fossil fuels, and the by-products of fossil fuel combustion (Burgess 2013). These organic chemicals are highly diluted in the upper layers of the soil, and they form chemical mixtures used in reactions involving microorganisms. We have very little toxicological information about the health effects of these chemical mixtures (Carpenter et al. 2002). Studies of the health effects of low concentrations and mixtures of these chemicals in soil have been very limited (Feron et al. 2002). Due to the very long half-lives of many organic chemicals, they are referred to as "persistent organic pollutants." These persistent organic pollutants are organic chemicals that resist decomposition in the environment and bioaccumulate as they move up the food chain. An example of this is 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), which was shown to disrupt the hormonal systems of raptors (Vega et al. 2007).

Airborne dust can impact human health, especially when the particles are less than 10 microns in size (Monteil 2008). The main direct health effect of inhaled dust is irritation of the respiratory passages and diseases, such as lung cancer. However, airborne dust can carry additional materials, such as pathogens, harmful gases, organic chemicals, heavy metals, insects, pollen, and radioactive materials, that can cause other health problems (Bartos et al. 2009). Humans can breathe airborne dust containing toxicants into the lungs, where the toxicants may enter the bloodstream. Cultivation for agricultural production and deflation (wind erosion) from unpaved road and work sites and denuded fields can introduce dusts into the atmosphere. Airborne dust from Africa is a significant health concern for North American soils. Clouds of dust from the Sahara and Sahel deserts follow the trade winds across the Atlantic Ocean, and African dust has been linked to elevated levels of Hg, Se, and Pb in North American soils (Garrison et al. 2003). The number of asthma cases in the United States more than doubled between 1980 and 2000, and asthma rates have also increased in the Caribbean (Brevik 2013a). Airborne dust from Africa has been tentatively linked to increased asthma in North America (Monteil 2008).

Soil Pathogens Although most organisms found in soil are not harmful to humans, soil does serve as a home for many pathogenic organisms. Bacteria are the most abundant type of organism in soil, and they are found in every soil on Earth. Most fungi are saprophytes that absorb nutrients by aiding in the decomposition of dead organisms, but approximately 300 soil fungi species out of the more than 100,000 total fungi species are known to cause disease in humans (Bultman et al. 2005) (Figure 3). For example, the soil fungus Exserohilium rostratum was responsible for the 2012 fungal meningitis outbreak in the United States (Brevik & Burgess 2013a). Protozoa are single-celled eukaryotic organisms. Most protozoa found in soil feed on bacteria and algae, but some cause human parasitic diseases such as diarrhea and amoebic dysentery (Brevik 2013a). Helminths are parasites that may inhabit the human intestines, lymph system, or other tissues. Diseases caused by helminths require a non-animal development site or reservoir for transmission, and the soil is a common development site. Billions of people are infected by helminths worldwide each year, with an estimated 130,000 deaths annually. Helminth infections generally occur through ingestion or skin penetration, and in most cases involve infection of the intestines (Bultman et al. 2005). The soil is not a natural reservoir for viruses, but viruses are known to survive in soil. Pathogenic viruses are usually introduced into soil through human septic or sewage waste. Viruses that cause conjunctivitis, gastroenteritis, hepatitis, polio, aseptic meningitis, or smallpox have all been found in soil (Hamilton et al. 2007; Bultman et al. 2005).

Guideline value; 0.02 mg/l (20 µg/l) Occurrence; Concentrations in groundwater less than 0.001 µg/l; concentrations in surface water less than 0.2 µg/l; concentrations in drinking-water appear to be less than 5 µg/l .

Tolerable daily intake (TDI) 6 µg/kg body weight, based on a NOAEL of 6.0 mg/kg body weight per day for decreased body weight gain and reduced food and water intake in a 90-day study in which rats were administered potassium antimony tartrate in drinking-water, using an uncertainty factor of 1000 (100 for interspecies and intraspecies variation, 10 for the short duration of the study).

I agree with previous comments on orientation studies and would like to emphasise that you should not just look at Au in reconnaissance exploration, but also relevant pathfinders and lithological/ alteration indicators of the mineral system. This is where aqua reqia has its limits.

Thank you so much. Will check that.

Yes but one should have basics of data analysis

The seasonal migration of the intertropical convergence zone (ITCZ) over the latitude of maximum insolation regulates the monsoon circulation. During summer (June to September) ITCZ shifts towards the low pressure area (~23°N) and surface winds bringing large amount of precipitation from SW ocean (Arabian sea) to central India.

In lacustrine sequence, Ti can be used as proxy (tool) to understand the surface runoff from the catchment. Higher Ti concentration means higher surface runoff. High atmospheric rainfall leads to increase in the surface runoff and thus high Ti concentration in sediments.

There are lot of paper, deals with the relation between Ti and monsoon intensity.

1. Haug et al., 2001: southward migration of the intertropical convergence zone through the Holocene.

2. Doberschutz et al., Monsoonal forcing of Holocene paleoenvironmental change on the central Tibetan Plateau inferred using a sediment record from Lake Nam Co (Xizang, China)

3. Mishra et al., 2015, Reconstructed late Quaternary hydrological changes from Lake Tso Moriri, NW Himalaya

Clinopyroxene is common in most mantle rock-types including peridotites, eclogites, Cr-diopside and augite-bearing pyroxenites as well as in most metasomatic associations formed by interactions with plume- or subduction-related melts. Not all mantle rocks have the correct mineralogy to work with garnet–orthopyroxene barometry (Nickel and Green, 1985, Brey and Kohler, 1990) or orthopyroxene barometry (McGregor, 1974) which is thought to be the most reliable methods (Taylor, 1998, Wu and Zhao, 2011). However, monomineral single-grain clinopyroxene thermobarometry of Cr-bearing associations (Nimis and Taylor, 2000), based on the Cr-tschermakite has a broad range of applications in mantle petrology. Examples include studies of mantle metasomatism in orthopyroxene- and garnet-free associations (Nimis et al., 2009; Ziberna et al., 2013) in cratonic lithosphere and processes of refertillization in oceanic mantle. But this thermobarometer has some restrictions because it works only in Cr-rich rocks and is worse when applied to Fe-enriched and Al-Na-rich rock-types and is sensitive to Fe3+.

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