Even within our existing research themes we refocus our projects. In the diagenesis and

geochemistry theme, the focus is on the rate and mechanisms of cementation in two

environments that are not often studied. The first is the diagenesis on the slopes of the rift

basin in the Gulf of Aqaba. This basin is unusually warm to great depth and could serve as

an analog for diagenesis in the warm Cretaceous oceans. The second project aims to

establish the early cementation rates of skeletal sands.

After successfully refining and calibrating the clumped isotope method for both the of

D47 and D48 proxies, the methodology is now used to decipher multiple diagenetic overprints

of meteoric and marine waters that is occurring in all shallow-marine succession affected

by high-frequency sea-level fluctuations. In another project the dual clumped proxy is used

ascertaining the degree of equilibrium in Modern carbonates, which is not possible with

conventional stable isotope methods.

Project Objectives:

• This work aims to establish and refine a new approach to unravel the temperature and δ18Ofluid values of carbonates that have been overprinted numerous times by diagenetic events.

• In this method the Δ47 and δ18O values are measured in the carbonates which allow the determination of the δ18O of the diagenetic fluids (δ18Ofluid). Once the temperature and the δ18Ofluid values are determined, the covariation of these parameters provides estimates of the fluid composition during changes in sea level.

• Preliminary data show that cores, previously interpreted as either being affected only by fresh or marine waters, have more complicated histories and supports evidence that regions of the cores previously thought to have been only affected by meteoric fluids, also have had significant cementation by calcite formed in the marine realm.

Project Objectives:

• To elucidate the effect of microbial communities in diagenetic processes that lead to the cementation of skeletal grains. Toward this end, in vitro incubation experiments will be conducted with skeletal grains in the presence and absence of microbial marine communities.

• To characterize the microbial communities that are potentially involve in skeletal cementation processes.

• To determine whether microbial exudates of exopolysaccharide substances (EPS) influence agglutination and early cementation of skeletal grains.

• To document the development of inter/intragranular cements and identify textural forms and mineral microstructure composition of early marine cementation areas using petrographic thin-sections and SEM/EDS.

Project Objectives:

• Measure the Δ47 and Δ48 values in modern biogenic and abiogenic sediments.

• Using the dual clumped proxy to ascertain the degree of equilibrium in Modern carbonates.

• Understanding the mechanisms of sediment formation (e.g. direct precipitation or breakdown from existing allochems).

Project Objectives:

• Analyze slope carbonates from the Gulf of Aqaba, with the goal of revealing what organic and inorganic mechanisms are at play to stabilize and bind sediments in this location.

• Determine the role of microbial cements on the stability of the slope.

Project Objectives:

• Examine whether reordered dolomite and calcite can preserve the primary oxygen isotopic composition of formation fluids.

• Decipher the formation process of the Marinoan cap dolostone (primary versus diagenetic origins).