Marine Geochemistry - Science topic

The Mn/ Fe ratio is not a constant aone nd strongly depends on the origin and source of

ore- forming fluids

•Classification of manganese nodules of deepmarine environments

•(1) hydrogenous, i.e., formed due to slow deposition of metals out of sea water and characterized bya high concentration of base metals and varying Mn/Fe rations (from 0.5-5)

•(2) hydrothermal, i.e., rich in iron and depleted of other metals, and turns out to be having an extremely wide range of Mn/Fe rations, near mid-ocean ridges and rift systems

•(3) diagenetic, i.e., characterized byhigh Mn/Fe ratios and relatively low concentration of base metals, halmyrolitic processes

•Origin:

•Oceanic nodules may be formed from the ore material of polygenic origin, with a predominant role of hydrothermal sources. Manganese nodules may grow due to a supply from oceanic water and out of host sediments. Ore control strong redox changes

HGD

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.

You can use my hydrate dissociation curve calculation module of my EQ-COMP software for calculation of hydrate formation curve between 0.4 bars to 800 bars (0.04 MPa to 80 MPa) for mixture of methane and carbon dioxide. More information and sample results are available at

Results can be requested against a nominal payment through

Sample result file is also attached

hi see this attach can help  you 

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.

Thanks a lot Wokil!

Naoufel:

The outline of microfossil indeed shows affinity with genus Calcarina in possessing blunt spines, which abound in reefoidal facies. Let Joshua furnish asked for details (source and method of preparation including mineral composition etc.) to come closer to the solution.

Best

Syed

Thank you friend.

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

Also check early papers of D Loveley and R Howarth 

I got a good answer to this on stack exchange:

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

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.

As Niko Finke said, you need to know two of the following parameters to completely describe the inorganic C system: alkalinity, total DIC, partial pressure of CO2, and/or pH. Once you have those measurements, you can use a variety of computing platforms to make all the calculations:

• Matlab (http://cdiac.ornl.gov/oceans/co2rprt.html),

• as an application on your computer (http://pubs.usgs.gov/of/2010/1280/), or

• as an iPhone app (http://itunes.apple.com/app/co2calc/id407782321?mt=8).

On the other hand, if your question is about how to measure (in the field or lab) the concentrations of the various species in the carbonate system, I suggest consulting the "Guide to best practices for ocean CO2 measurements" (http://cdiac.ornl.gov/oceans/Handbook_2007.html).

Hope this helps.

We have done some experiments to understand the sedimentation process in our seaweed cultivation farm. We have used small glass bottles with round bottom and placed them for 24 hr in  the field. The samples were collected and data was expressed over area of the bottle. The only precaution which you need to take is the bottles remained in the same plain as the topography of the sea bed.

OK. I am usually working in NIR in an aqueous sample. You work immediately on a solid sample, isn't? So, my question doesn't apply. Sorry. But the question of the sample preparation remains. Can you better eliminate what you don't need to mesure?

Dear Gnanamoorthy and Vinod,

that is in principle true, but the mixing ratio (in ppm) is defined as 'mixing ratio in dry air', i.e. in going from partial pressure you have first to substract out the water vapor pressure. The conversion is

pCO2 = xCO2 * ( p(air) - p(H2O) )

where pCO2 is the partial pressure of CO2, xCO2 is the mixing ratio, p(air) is the air pressure and p(H2O) is the water vapor partial pressure. Because of that, the number for pCO2 is somewhat lower than that for xCO2. How much depends in temperature and relative humidity, but for an xCO2 of 360 ppm you get typically numbers of pCO2 around 350 microatm.

Cheers, Christoph

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

Actually, most researchers working with oxygen isotopes in different genera of benthic foraminifera use the so-called 'uvigerina' scale, so all genera are corrected to the uvigerina values. For carbon there are more discrepancies as uvigerina is an infaunal species and the measured carbon deviates from bottom seawater values. You can check this reference for a comprehensive comparison:

Shackleton, N. J., & Hall, M. A. (1997). The Late Miocene Stable Isotope Record, Site 926. Proceedings of the Ocean Drilling Program, Scientific Results, 154, 367–373.

Hope this helps.

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. 

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

Of course this depends on your research question! But, to get insights to what is possible with grain size data from marine sediments, I suggest: Weltje & Prins (2003):  Muddled or Mixed? Inferring palaeoclimate from size distributions of deep-sea clastics. Sedimentary Geology 162 : 39 - 62

Thank you sir.

My personal view is that it's almost impossible to get an SRM/CRM for every matrix in existence, especially one that's certified for the substance for which you're monitoring. The comparability of the physicochemical properties of the two matrices will determine whether the results are comparable. To Neus's point, numerous soil-based matrices exist, and depending on the analysis and extraction method, and the nature of the chemical you're analyzing, the results between two can be considered comparable.

However, there appear to be a couple of SRM's and CRM's for both inorganic and organic components in marine sediment (NIST SRM's 1941b, 1944, 2702, NIES CRM 12, etc). While it would probably be best to use matrices that are closest to your matrix, you could possibly make an argument for the urban dust depending on what you're measuring. Which compound are you looking at?

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.

This looks like (on a very brief look) a good example of the point I ended on in my previous answer. They conclude not that they have found the physiologies of the groups they have correlated with porewater compounds but that they can now have some real data that allows them to hypothesise about the physiologies of these groups. As these hypotheses may be testable experimentally that is a pretty good outcome form a piece of work! Don't expect correlation to answer questions, but to help you pose better ones!

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).

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