Marine Geology - Science topic

The future of deep-sea mining presents a dichotomy of potentialities and risks that demand careful consideration. On the one hand, it holds the promise of accessing valuable mineral resources critical for modern technologies, potentially reducing the environmental impact associated with terrestrial mining, and fostering economic opportunities for resource-rich countries. Moreover, the development of deep-sea mining technologies could fuel innovation and drive progress in marine engineering and robotics. However, these potentialities must be weighed against substantial environmental and ethical risks. Deep-sea mining operations have the potential to disrupt fragile and poorly understood ecosystems, release toxic substances into the ocean, and trigger long-term consequences that are difficult to predict. Regulatory challenges, resource depletion, economic viability concerns, and ethical and social issues further complicate the path forward. Striking a balance between harnessing these resources and protecting the deep-sea environment will require robust scientific research, stringent environmental impact assessments, and comprehensive regulatory frameworks to ensure that the benefits of deep-sea mining are realized without compromising the health of our oceans and the well-being of local communities.

Thanks Antonio. These flakes probably date to around 1930 or a little earlier. They occur immediately above a charcoal layer (although we can't find any historical records for a fire at this time). Sedimentation rates probably between 1-2mm/year.

Satellite driven data integrated with local geology will give you good suface control and then seismic stratigraphy integrated with well loh sequence stratigrpahy can help you demarcate pockets suitable for hydrocarbons

Yes it does. You can read more about crustal thickness beneath 90⁰East ridge (Indian Ocean), Walvis ridge (Atlantic Ocean), Shatsky rise (Pacific Ocean) etc.

Oceanic crust under the influence of plumes may get thickened by magmatic addition at the base of the crust. Processes of such 'underplating' may depend upon prevailing tectonics. I suggest you read more about oceanic plateaus and aseismic ridges to discover more.

Wow, many thanks ! Indeed a piece of sweet cake for my project (Mariana Trench, Pacific Ocean).

I recommend Cemal's answer

Best Regards

It is difficult to get free softwares this days. Those ones tag free may not be able to do the work for you because some vital components in the software are some times deactivated

Macro- and micromorphological aspects of tsunami deposits in Crete were published in the following publication:

Bruins, H.J., MacGillivray, J.A., Synolakis, C.E., Benjamini, C., Keller, J., Kisch, H.J., Klügel, A. and Van der Plicht, J. (2008) Geoarchaeological tsunami deposits at Palaikastro (Crete) and the Late Minoan IA eruption of Santorini. Journal of Archaeological Science 35(1): 191-212.

RPH tools List of Matlab files The Rock Physics Handbook, 2nd Edition,Mavko,Mukerji, and Dvorkin, also QSItools another Matlab list with rock physics templates.

You can try using Pimpedance vs Vp/Vs and color code with Gas hydrate saturation I  think these files can help you.

I hope that it will help you.

best regards

Dear Syed Abbas Jafar, Sebastián Grande, Ashkan Vafadar, Drishya Girishbai,

Thanks very much for your great answers. Because my attention is mainly about the deposits of evaporites, I don`t think it has the ability to change all global seawater by MORB-RELEASE frequently. But, there are two papers（Heinrich D. Holland et al., 1996; Lawrence A. Hardie, 1996）, which give me a viewpoint that different type of marine evaporites in different geological times are caused by "seawater-basalt interaction", "seafloor generation rate" and "dolomitization". It`s remain difficult to difinite quantities of contributions by MORB. I believe it is a complicated exchange system.

Best wishe,

Qin

Dear Claudemir Vasconcelos,

Thanks for your help, it looks very nice!

I will try to use the Geomapapp to get it.

Cheers,

Xiting

First things to consider are advection and diffusion, and there are old (but not necessarily simple) models for chlorinity profiles in gas hydrate systems. See Davie and Buffett (2001,2003, in JGR and EPSL)

Sedimentation and compaction implies that pore water moves with respect to the solids, even in the absence of an external fluid source. Both hydrate distribution in the sediment and choride concentration are influenced by this process.

Fluid advection from below can occur, and seawater salinity varies during glacial-interglacial cycles. For instance, both processes where observed at Blake Ridge (see Egeberg and Dickens, 1998). Seawater is more saline during glaciations because there is more ice on the continents, and this is reflected in chloride advection-diffusion profiles worldwide (See Adkins and Schrag, 2002).

External fluid sources often invoked are clay and organic matter diagenesis. On the other hand, alteration of volcanic glass (that may be present in the sediment) into clay (dominantly smectites) takes up pore water. Volcanic ash diagenesis in the sediment (as well as basalt alteration in the oceanic crust) can thus increase in situ chlorinity at low temperature while smectite/Illite reaction will lower chlorinity as temperature increase (e.g. Henry and Bourlange, 2004). These processes happen beneath the gas hydrate stability field but can influence pore fluid composition in the shallow sediment by advection-diffusion.

Dear Mohammed! This specimen looks like a small fish otolith, however I can not determine it. If so, You may contact with Werner Schwarzhans (https://www.researchgate.net/profile/Werner_Schwarzhans) or with Bettina Reichenbacher (https://www.researchgate.net/profile/Bettina_Reichenbacher).

As noted earlier, water temperature is a big factor due to the retrograde solubility of CaCO3 minerals (calcite and aragonite). However, calcification decreases the saturations state of water (Ca + 2HCO3 --> CaCO3 + CO2). Photosynthesis (e.g., phytoplankton blooms) will decrease the pCO2 of waters in the euphotic zone, thus increasing the pH and saturation state of the waters with respect to CaCO3.

Have you considered fluid flow features e.g., pockmarks? For instance, crescent pockmarks ca. 1500 wide and ca. 150 deep have been documented in the South China Sea (cf. Morphologies, classification and genesis of pockmarks, mud volcanoes and associated fluid escape features in the northern Zhongjiannan Basin, South China Sea). Best wishes!

Kader,

besides dissolution below the CCD and in high latitudes, as referred by Syed, you have to consider also dissolution of calcareous foraminifer tests during the diagenesis of sediments in restricted environments poor in carbonate. Typically some brackish marginal environments like lagoons, marshes and mudflats but sometimes also in normal marine conditions. Foraminifer assemblages in such cases are solely agglutinated, but in case of early diagenetic pyritization or silicification you may find rare casts of calcareous forms or casts of isolated chambers.

The problem that I'm investigating is related to topics in atmospheric science, specifically the planetary boundary layer. A lot of overlap can be found between the two branches, but I'm looking at a specific problem that might require a detour in this direction. I have found laboratory experiments discussing the interaction of two jets, but these are narrow jets, and I'm not sure the same would result if the jets were much broader O~100km.

~2.4Ma is a component of eccentricity

Thanks so much Gemilang. I am gonna look at them and I am sure it will be helpful 

Dear Casper,

You may find pertinent articles, here:

Archie's equation remains the best option for estimate saturation from resistivity logs

 I think this article by Zoback et al (2003) may somehow help to answer your question: Determination of stress orientation and magnitude in deep wells

Dear Qunfeng,

You can separated the different sedimentary sub-populations by using a simple MS Excel software with SOLVER. The difference between the measured and modelled values (sum of two/three Weibull distributions) has to be minimized. See my attachment.

Cheers,

Gyuri

Hi Rasiq,

Prior to adding an answer to your question some questions back. are you considering organic or inorganic geochemical proxies? For what purpose would you want to reconstruct paleoproductivity and on what time scales - e.g. Do you want to see changes over glacial/interglacial cycles to see the monsoon intensity or are you interested in the anthropogenic influence on the environment?

Perhaps it is the interpretation of estuarine that is wrong. The transgression of the Pleistocene glacial termination was very rapid. I published about a lake site in Maine (Borns et al., 2004), Ross Pond, with glaciomarine clays in the bottom 2 m of core, then a narrow (ca 3 cm) pyrite-rich deposit that points to anoxia such as occur in a salinity stratified lake or fjord, then organic rich lake gyttja. The transition from marine to lake occurred within 50 yrs. Other researchers examining late glacial sediments in Maine and New Hampshire (i.e. Belknap and Kelley) have published many papers about offshore transgressive sequences. Perhaps you can find an analogous situation there.

Mr. Ma,

Let me see if I missunderstood your problem. What you need is to export that information?

If that is the case, consider using the "wcoher" function, this returns the numerical values, and when you plot your results, you can save the graphics in EPS or other formats.

I hope this helps.

Best regards,

Luis M. Gato

The predominance of rutile over zircon and tourmaline in beach sand sediments occurs when the area of origin consists of high temperature, high pressure igneous rocks, granites, pegmatites and anorthosites. Furthermore, the rutile came from schists, high pressure gneisses and metamorphosed limestones.

Conversely, tourmaline predominates when tourmaline-rich granites and pegmatites or as well as high-temperature hydrothermal veins are present in the area of origin.

The predominant occurrence of zircons points to areas of origin with mafic pegmatites and carbonatites, as well as zirconium-rich igneous and metamorphic rocks.

 Thank you all for attention and suggest :)

Dear Robert,

I'm glad to see so nice bedrooms. It's now quite clear this does not correspond to artifacts. The visible particles from the camera indicates you're in a quite energetic area with strong currents, probably of tidal origin, but this has to be proven. The regular double pattern you see is for me an indication of a probable tidal origin. I don't understand your last statement. To my point of view, there is no chance that these dunes are of aeolian origin, even formed during last ice age. The seismic profile is of poor quality, but displays a 10ms-thick unit probably of Holocene sediments truncating ancient sediments. If there is a chance to get a core there, you can look for a place where the underlying unit outcrops. The sediment could be hard and make strong reflection on side-scan sonar. You may find some elements to think about dunes looking to the abstracts from the 3 first Marid conferences. I already sent you the link for the next conference in Bangor. Best wishes, Alain T.

Don"t worry. It's a French site having very few French instructions you can manage easily. I'll ask the Marid 2013 (Brugge) conference abstracts to be included.

Additional references that will be helpful:

Coxall, H.K., Wilson, P.A., Pälike, H., Lear, C.H., and Backman, J., 2005, Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacifi c Ocean: Nature, v. 433, p. 53–57, doi: 10.1038/nature03135.

Coxall, H. K., and P. A. Wilson (2011), Early Oligocene glaciation and productivity in the eastern equatorial Pacific: Insights into global carbon cycling, Paleoceanography, 26, PA2221, doi:10.1029/2010PA002021.

Lear, C.H. et al., 2008, Cooling and ice growth across the Eocene-Oligocene transition: Geology, v. 36(3), p. 251-254.

Dear all,

An unfortunately uncompleted list of ice sheet models could be found https://en.wikipedia.org/wiki/Ice-sheet_model

You may have a look at seaRISE web page: http://websrv.cs.umt.edu/isis/index.php/Main_Page for some aspects about ice sheet modelling.

Also some articles in the framework of the European Ice2Sea project have done some model intercomparions, which should guide your selection as well.

However before you may go into the business of selecting an ice sheet model, you may shall first thing about the points below:

Dear Ivan,

The only instrument that will penetrate sand to the depth you have in mind (up to 3.5 m) is a vibrocorer. Without vibration no coring device will penetrate more than a few decimetres (at most) into sand, irrespective of how much weight you add; the friction along the pipe/box wall is simply too large. As far as I know, there are a number of vibrocorers on the market, although usually designed for core pipes up to at least 5 or 6 m. You should therefore get in touch with the companies constructing such instruments (you'll probably find them on Google) and specifiy the size you need. I'm sure most corers on the market can be modified to suit your purpose.

Good luck and best regards, Burg Flemming

Many thanks to all of you fir your feedbacks.

Kind regards

Hocein

 A simple model used for different purposes (pdf attached) by the way we have the sandwave as an complete outcrop

The shells are acting as sedimentary particles

The evidence from sedimentary structures and the stratigraphic and biostratinomic context of shell layers are used here to describe how shell beds are formed within a sedimentary sand wave. Shell beds in the Pliocene San Nicola´s Formation,

within the Baja California Central Domain, were accumulated through the physical processes of gravity induced flow currents. The hydraulic regime and sedimentary differences between the up-current slope and the leeward slope part of

the sand wave can be explained by flow stratification. The taphonomic differences between the fossil concentrations of the bottom and the upper layers in the leeward slope are a result of a change in the current dynamics for the basin. The

leeward slope side of the sand wave represents episodic, short-term, dynamic bypassing in gravity-induced, low-flow current beds creating shell beds.

You can refer to Materials and Methods section in article entitled : Recovery of temperature records from slow-growing corals by fine scale sampling of skeletons by Anne L. Cohen1 and Simon R. Thorrold (2007), GEOPHYSICAL RESEARCH LETTERS, VOL. 34

link: http://onlinelibrary.wiley.com/doi/10.1029/2007GL030967/pdf

Regards

Massih

Velocity will also vary with flow height and concentration, not easily derived from channel geometry.

In warm seas diatoms may not survive during diagenesis - I've never encountered diatoms in my own Paleogene material. However, I note in your paper, that your smallest size fraction is 0.2 mm. This is too large for all but perhaps the largest diatoms. Also for foraminiferal studies you should better use smaller size fractions, at least 125 microns or better even (when preservation permits) 63 micron. The diversity of your assemblages will increase significantly. Absence of planktic forams is no surprise in a very shallow environment, but you may find them also in the smaller size fraction, possibly washed in from the open sea.

Dear Mr. Balaji,

barium is primarily controlled in marine environments by magmatic processes, being, in places, instrumental for the emplacement of Kuroko-type (VMS) and Rammelsbergy-type (SMS) base metal mineralization, dependant upon the geodynamic setting. It goes  along with the precipiation of baryte. Ba can substitute for K in all K-bearing silicates and as such increases along with the detrital input into the basin. Gallium can replace to some degree aluminium in its host minerals and as such will also act as a marker of the detrital input.

Best regards

H.G.Dill

Hello Mihai and Ferdinand,

Thank you both for responding so quickly! Mihai - looks like you've confirmed some of my concerns about properly calibrating my scale. I think it's going to take some special consideration. Thank you for the link, Ferdinand. I will take a look. 

The source varies.  Only a minority of described seeps are from melting clathrates. This is more common in deep water and in the Arctic.  Some seeps are of thermogenic methane and there are examples of carbon dioxide seeps that contain only a minor amount of methane.  Most shallow-water seeps are from biogenic gas reservoirs and the gas is channeled to the surface along fault lines.  For example, in the North Sea nearly all the described seeps are of shallow biogenic methane, even though there are thermogenic gas reservoirs deeper in the sedimentary column. The methane may have been generated in interglacial deposits, as in the shallow Danish seeps, or have come from more recent carbon in fast-sedimenting areas such as the Skagerak and northern Gulf of California, or be from mixed sources.

Dear Mr. Sergiu,

I take three different steps.

1.Make use of non-destructive methods by capturing digital data (gamma ray, magnetic susceptibility, micro-resistivity with the Wenner Array)

Advanced level: core scanning for structures, textures... and chemical analysis, including portable XRF. This depends upon the goal of your work. There are more non-destructive methods

2. Take one half of the core slap for mineralogical analyses:

Grain size analysis with the CAMSIZER (sand only)

Separation of grain size fraction

- clay mineralogy < 20µm

- heavy and light minerals 20 to 300 µm

- take a larger rock chip for thin section

Clay mineralogy is performed using XRD + IR spectroscopy + CEC-SEM-EDX/WDX

Heavy minerals routine analysis (under the petrographic microscope) advanced level SEM- WDX/EDX or EMP

3. Take the second half for chemical analysis

- XRF (more than 40 elements)

-ICPMS (trace elements + REE)

4. Age dating depends upon the age expected and your goal

I wish you much success

Harald G. Dill

Dear Salvo

You may visit the following link for more information:

The attached files can help you further.

Xiaolin,

What you ask does not have a simple answer and the ability to calculate palaeodepths will vary depending on what data you have available. It will also become more difficult depending on the location and how far you go back in time, as tectonic factors will complicate matters.

There will also most likely be a significant degree of uncertainty.

Broadly speaking though, the factors you will need to consider will be:

I don't mean to over complicate things - but there is a lot going on! So the further back in time you are looking the harder it is. Considering the tropical Atlantic 20 ka ago it is a fairly simple matter, looking in the eastern Mediterranean 40 Ma ago will be harder (at this point I think it was still the Tethys).

In my opinion one of the better methods to do this involves looking at the palaeoshorelines, for instance the Orangeburg Scarp, which demarcks a Pliocene shoreline in the US. It is also possible (on a coarse scale) to look at benthic foraminiferal tests and see if you have any species that are depth limited.

Again though, these measures are influenced by those factors I listed above.

I think the best advice I could give would be to try and find as much information concerning the area and period you are looking at, and once you know what data you have available then make a decision about whether it is possible to reconstruct the palaeodepth.

If you do, then you can begin to look at the specific influences in the location and the begin to try and assign numbers. Though again, depending on where you are there may be large uncertainty.

Hope this helps.

Matt

Hi, I have CT and X-ray. I have already split the core using a technique which was emailed to me. I froze the core and cut it with a diamond tipped saw. The end product was a split core with a polished surface and no apparent sediment disturbance. Thank you. 

Hi Devi,

maybe these are not really "paleostrandline" maps, but they could possibly help with their Figs. and references.

Check out the paper by our RG colleague Jan Golonka: https://www.researchgate.net/publication/234000859_Phanerozoic_Paleoenvironment_and_Paleolithofacies_Maps._Cenozoic

Then there is Smith et al. 2004: Atlas of Mesozoic and Cenozoic Coastlines

All-time favourites are of course the paleogeographic maps by Christopher Scotese (http://www.scotese.com/earth.htm), Ron Blakey (http://jan.ucc.nau.edu/~rcb7/index.html), as well as the Ziegler maps, although I am not sure whether maps for South Asia are available from the latter. As far as I know, Gérard Stampfli might also have some paleoglobes in his papers.

Hope this helps, good luck with your work!

Cheers, Martin

Last year Roger Urgeles published this pretty extensive database of landslides in the Mediterranean:

The increase in temperature and the increase in pressure of the

Atmosphere means the Atmosphere can store more water , and release more water.

The relationship is PV = nRT

P is the pressure,

V is the volume

and T is the Temperature in Kelvins

The increase in Atmospheric Pressure from

100,000 pascals in 1700 ( approximately )

101325 pascals in 1976 will eventually result

in a Temperature increase.

The old temperature was 13 + 273.15 = 286.15 kelvin

The new Temperature will eventually be

101325/100000 = 1.01325 x 286.15 = 289.94 Kelvin

which is a rise of 289.94 - 286.15 = 3.79 Kelvin or Centigrade.

So far it has only increased about 2 C of the future 3.79 C

based on the 1976 standard pressure.

Notice here that burning fossil fuels increases the volume of the

Atmosphere which will increase the pressure of the Atmosphere,

which will increase the Temperature of the atmosphere, which will

increase the water storage capacity of the Atmosphere, which means

when it rains, it will rain harder and longer.

notice also that there is a very great time delay between

when a system changes, and when all of the other changes will

eventually catch up. The enormous volume of the oceans has a

major effect in this long term delay of temperature increase.

notice also that the standard was the 1976 value, it would be higher

now, and will be higher yet in the future, and will continue to grow

even if we can by some miracle stop releasing CO2, and stop

increasing the Volume of the Atmosphere.

Even if we could stop the CO2 increase in volume now, the temperature

will continue to rise for the next two hundred to three hundred years.

The melting of all glaciers on the planet will raise sea levels by

216 feet / 3.28125 = 65.83 meters, and the expansion of the water will

increase that number.

so if you are planning a new house, make it at least 70 meters above

the current sea level elevation to stay above storm surges.

Dams will continue to fill up with sediment, but at a faster rate,

so design Dams that can be drained completely to allow the

sediment to flow through to the ocean.

At the mid oceanic spreading ridges, the magma rises in the rift to the

elevation of the equilibrium pressure, so a rise in ocean elevation will

mean a lower elevation of cooling and hardening of the magma in the

crack, and the opposite will be true if the ocean level falls.

The shape of the ocean floor is thus a geologic record of the

cyclical changes in the ocean elevations, and of its overall trend

toward a thinner ocean with a greater surface area.

Heavy metals are more likely to attach to organic matter and clays (mud have these) than sand. Clays and organic matter have surface functional groups (net negatively charged) that bind heavy metal (cations; positively charged). Thus, muddy samples will have more heavy metal than sandy sample simply because muddy samples has more clays and organic matter.

Thinking for a while about this question allows me to realize that we need to test the flooding hypothesis by the increase of sea-level. We live in a habitable planet. Sea level may rise and temporary cause destruction to the coastal cities around the world. However, this will not last for long. Diversity of species (species richness) will increase due to warm and more humid climate. The earth will recover so fast similar to the fast diversification occurred after the K/Pg boundary when diversity and radiation of species increased only 50 ka after the asteroid impact (Pospichal, 1996). We are going to see many positive effects, however, not in our time. This probably will take from hundred of years up to thousands of years.

Hi Zhanhong, the attached paper might help.

Regards,

Deborah

I recorded Au concentration of up to 11.7 ppm in basaltic intrusion cutting granite in south Western Australia.

USGS has a searchable database of monitoring stations. Are you in Florida? Check DBHydro run by the water management districts.

In Mid 1990's with H. Kozlu we had found out that the so called Silurian basal conglomerates in S Turkey actually correspond to Late Ordovician glacio-marine sediments (dropstones in G…oncuoglu, M.C. 1997. Distribution of Lower Paleozoic units in the Alpine Terranes of Turkey: paleogeographic constraints. In: Göncüoğlu, M.C. and Derman, A.S.(Eds), Lower Paleozoic Evolution in northwest Gondwana, Turkish Assoc. Petrol. Geol., Spec. Publ.No:3, 13-24, Ankara.). Monod et al (2003) and Ghienne et al (2010) then performed field work on these and have described the details of the Hirnantian glaciation. The most recent information is given in Kozlu, H. & Ghienne, J. F. (2012) Ordovician. In: Goncuoglu, M.C.& Bozdogan, N (Eds.) Paleozoic of Eastern Taurides-Guidebook . Gondwana and Its Petroleum Potential: A Field Workshop. Turk. Assoc. Petrol. Geologists. Spec. Publ. Nr. 7, 42-60.

for marine sediments, its sediment rate is low and less than 10mm/ka. Centurial resolution may be more likely to get but decadal resolution is trying to achieve.

I don't think you need any clarification, your succinct definition is right on the mark. In "Glacimarine Environments: Processes and Sediments," Dowdeswell and Scourse (1990) defined glacimarine as "all those areas where sediment is deposited in the sea after release from glacier ice (including tidewater ice fronts, floating glacier tongues, ice shelves and icebergs) or sea ice." Since marine basins are more highly represented in the geologic record, even though this can be indeed be considered a subset of glacigenic, it is an important area of study. The book "Climate Modes of the Phanerozoic" (Frakes, Francis, and Syktus, 1992) is full of references to using marine sediments with increases or decreases of ice-carried dropstones as a proxy for ice-volume change.

To be honest there are so many.

This is a good old one from the New England Margin:

McMaster, R.; Ashraf, A., 1973, Drowned and buried valleys on the southern New England continental shelf, Marine Geology, vol 15, pp. 249 - 268

And one from the North Sea:

Praeg, D, 2003, Seismic imaging of mid-Pleistocene tunnel-valleys in the North Sea Basin—high resolution from low frequencies, Journal of Applied Geophysics, vol 53, pp. 273-298

This last article has been cited quite heavily by other articles you may find useful.

Matt

just check woodshole site and teh NOAA data on CO2 concentration. They have given a nest time series.

Hi Yen Yi,

the programmers provide instructions on their homepage: http://www.nova.edu/ocean/cpce/index.html and a QuickStart PDF: http://www.nova.edu/ocean/forms/cpce_quickstart_guide.pdf

Regarding your question if you should use random or uniformed points: I would go for the random selection since you exclude biases from potential patterns (like sand strips or linear wave impacts or whatsoever) that might be present in the uniform selection.

Furthermore, I can recommend an article by Pante & Dustan (2012) on how many points should be used in Point-Count Assessment:

Good luck with your analysis!

And this is Herron's

The short answer is no, it is not a good idea. Unless you can stratigraphically match all the intervals in a core (by varves or other markers) and can show that sediment thickness (taking into account compaction of the core as it is taken out of the ground) is the same between these markers, then their is likely to be differences in accumulation rates even in relatively closely spaced cores. If you look at a paper on Lake Mead cores (Rosen and Van Metre (2010), two cores taken less than a kilometer apart or so show a peak in DDE at different depths. When both cores were dated, the beaks were synchronous in time.

Full Reference:

Rosen M.R. and Van Metre, P.C. 2010, Assessment of multiple sources of anthropogenic and natural chemical inputs to a morphologically complex basin, Lake Mead, USA. Palaeogeography, Palaeoclimatology, Palaeoecology, 294, 30-43.

You don't.

I suggest to have some non-destructive scaning of the core first and use the results as a template for research strategy, including what kinds questions you can ask, and accordingly set up our sampling plan. Recently I have seen a lot of XRF profiles of cores and realized to have a general understaiding of the core is very important, I plotted elemental ratios such as Ca/Fe, Mn/Fe, .... and so on, usually I can recognize major lithologic units, redox front, lamination, turbidite, salphate-methane interface, tephra and so on. Multisensor of physical properties (density, magnetic susceptibility and porosity) as well as color relfectance profiles are also very helpful.

One prerequisite for well developed anoxic conditions is that the bottom-near waters remain stratified preventing oxygenation through overturn. Such a stratification can be due to salinity or temperature stability.

The Baltic Sea is a typical example of a large water body frequently experiencing anoxia in its deep basin due to inflow of more saline North Sea waters through the Danish Straits and further enhanced by lengthy periods of warm climates, e.g. during the Medieval Warm Period with strong algal blooms (high bioproductivity).

It is impossible to answer your question without knowing more about what you are currently doing and what type of equipment you have at your disposal. I myself worked for 4 decades building up a very successful marine geological research group at the Geological Survey of Finland whilst our main working area was the Baltic Sea. I should add that the Baltic Sea is in many senses like a miniature ocean.

I think it could be a very interesting topic for research to re-investigate plume hypothesis.

Many times, proxies for such studies are location specific due to differences in biodiversity and anthropogenic activities from a region to another region. So approach with several proxies will give reliable information

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