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Geobiology, Geochemistry and Diagenesis of Carbonates

Diagenesis continuously alters carbonate rocks and consequently their petrophysical properties. Our research projects have thus a double focus; one to understand the diagenetic processes, and two, to relate the diagenetic alterations to the resulting rock properties. 
Modern sediments on Great Bahama Bank and elsewhere provide baseline information about the geochemical signature of “unaltered” carbonate platform sediments. Cores from the shallow subsurface along the western margin of Great Bahama Bank and in Florida document the effects of early diagenesis on porosity, velocity, and permeability in platform carbonates and grainstone shoal complexes in particular. The geochemical studies of the dolomites and limestones from deeper cores on Great Bahama Bank and the Marion Plateau are ideal to examine the influence of burial diagenesis on the petrophysical properties and to assess the fluid flow in isolated carbonate platforms. Deeply buried rocks that were later uplifted such as the Mississippian Madison Formation underwent several episodes of diagenesis from shallow to deep burial. Our current geochemical projects in this formation try to unravel these different episodes and to document the importance of each event on the reservoir quality of the formation. In addition, we test the applicability of geochemical tracers, in particular δ13C for the stratigraphic correlation of the widely spaced section in Wyoming and Idaho and to other sections around the world.

Current Projects



THE GEOCHEMICAL EXPRESSION OF SEQUENCE BOUNDARIES

Swart_geochemSB_CSL2021

Project Media
     
Swart_geo...2021.pdf
Media Type:Media Type
File Size:611KB

 

Investigators: Peter K. Swart, Greta J. Mackenzie, Amel Saied, Amanda M. Oehlert, and Gregor P. Eberli

Project Objectives:

  • To examine the geochemical expression of sequence boundaries.
  • Complete the stable C and O isotopic and XRD analysis of the carbonates.
  • Conduct stable C isotopic analysis of the organic material from the Bahamas
  • Transect (ODP Sites 1003-1007) and the Clino and Unda cores.

 



     

A GLOBAL DIAGENETIC SIGNAL?

Smith_globaldiageneticsignal_CSL2021

Project Media
     
Smith_glo...2021.pdf
Media Type:Media Type
File Size:475KB

 

Investigators: Megan Smith, Colleen Brown, Evan Moore, Peter K. Swart, and Amanda M. Oehlert

Project Objectives:

  • To construct a high resolution, multiproxy geochemical record of cores from Enewetak Atoll in the Pacific Ocean.
  • To compare with the Great Bahama Bank sediment core records in the Atlantic Ocean basin.
  • To ascertain whether shallow-water carbonates can express a global diagenetic signal.


     

BORON, SULFUR, AND CLUMPED ISOTOPES AS DIAGENETIC INDICATORS

Moore_BSisotopes_CSL2021

Project Media
     
Moore_BSi...2021.pdf
Media Type:Abstract
File Size:452KB

 

Investigators: Evan Moore, Megan Smith, Sean Murray, and Peter K. Swart

Project Objectives:

  • Conduct boron, sulfur, and clumped isotopic analyses of carbonates from the Bahamas, Enewetak, and various ODP, IODP, and DSDP sites that have experienced meteoric and marine diagenesis.
  • Combine these with traditional geochemical indicators of diagenesis such as δ13C and δ18O values to better define the sedimentological systems with respect to temperature, pH fluctuation, and bacterial sulfate reduction.
  • Compare data from Clino to similar geochemical data of Enewetak Atoll to constrain the global influence of diagenetic resetting on sedimentological records.

 



     

EVALUATING DRIVERS OF REEFAL TRANSITIONS OVER ~16MYR, ENEWETAK ATOLL

Brown_Enewetak_CSL2021

Project Media
     
Brown_Ene...2021.pdf
Media Type:Media Type
File Size:419KB

 

Investigators: Colleen Brown, Megan Smith, Peter K. Swart, and Amanda M. Oehlert

Project Objectives:

  • Examine trace element and stable isotopic composition of well-preserved corals and sediments from Pliocene and Miocene sections for comparison with the Modern.
  • Quantify geochemical signatures including 11B, B/Ca, Sr/Ca, P/Ca, U/Pb, δ13Ccarb, δ18O, and various trace elements.
  • Consider the timing and causes of transition from reefal boundstones to skeletal grainstones over the past ~16 Myr.

 



     

APPLICATION OF THE Δ48 PROXY TO THE REAL WORLD

Swart___48_CSL2021

Project Media
     
Swart___4...2021.pdf
Media Type:Media Type
File Size:484KB

 

Investigators: Peter K. Swart and Chaojin Lu

Project Objectives:

  • The goal of this project is to apply the newly calibrated Δ48 proxy to (i) issues of non-equilibrium precipitation of carbonates, and (ii) the geothermal resetting of the Δ48 proxy during heating.


     

SEARCHING FOR ELEMENTAL SIGNATURES OF SWEET SPOTS IN THE VACA MUERTA FORMATION

Oehlert_elementalsweetspots_CSL2021

Project Media
     
Oehlert_e...2021.pdf
Media Type:Media Type
File Size:1MB

 

Investigators: Amanda M. Oehlert, Ralf J. Weger, Gregor P. Eberli and Laura Rueda

Project Objectives:

  • Conduct high resolution elemental analysis on ~400 samples collected from short cores drilled into outcrops of the Vaca Muerta Formation.

  • Apply the increased analytical sensitivity (ppt to ppq) and elemental range of QQQ-ICP-MS to search for diagnostic elemental signatures of high TOC ‘sweet spots’.
  • Statistical analysis of elemental composition (rolling window regression, principal component analysis, pairwise correlations).
  • Synthesize with previously collected data (Aavatech XRF Core Scanner and TerraSpec Halo Mineral Identifier) for integrated geochemical perspective on the Vaca Muerta Formation.

 



     
 

 

 

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