ThESIS BY Xavier Mangenot*
Determining the temperature conditions of past geological episodes is a major challenge for research in geosciences. The interest lies in the fact that they govern the physical and mechanical properties, as well as the chemical reactivity of geological materials and determine the formation of underground energy resources.
Since the 1960s, the reconstitution of the thermal history of sedimentary basins has been largely based on the chemical and physical properties of the organic matter present in sediments and then of mineral markers, with varying degrees of reliability.
Over the past few years, two promising isotopic tools have emerged:
- the Δ47 thermometry
- and the U-Pb chronometry using LA-ICP-MSa.
They make it possible to determine, respectively, the absolute temperature and age of crystallization of carbonate minerals with an unprecedented degree of accuracy(1, 2).
This thesis combined them in a new approach called Δ47/(U-Pb) carbonate thermochronometry(3), furnishing more accurate contraints for basin modeling thermal calibration. Tested on the Paris Basin, this approach was used to directly and accurately reconstruct the time-temperature evolution of a geological layer over more than 150 million years (figure). Due to its performance and ease of use, this technique represents a small revolution in the field of geosciences for the study of sedimentary basins.
a - Inductively coupled plasma mass spectrometry, with laser ablation.
*Thesis entitled "Pairing Δ47 thermometry and U/Pb chronometry to reconstruct the diagenetic, thermal and fluid-fow histories
of carbonate rocks in sedimentary basins: case of the Paris basin"
(1) X. Mangenot, M. Gasparrini, V. Rouchon, M. Bonifacie, Basin‐scale thermal and fluid flow histories revealed by carbonate clumped isotopes (Δ47) – Middle Jurassic carbonates of the Paris Basin depocentre, (2018), Sedimentology.
>> DOI: 10.1111/sed.12427
(2) X. Mangenot, M. Bonifacie, M. Gasparrini, A. Götz, C. Chaduteau, M. Ader, V. Rouchon, Coupling Δ47 and fluid inclusion thermometry on carbonate cements to precisely reconstruct the temperature, salinity and δ18O of paleo-groundwater in sedimentary basins, (2017), Chemical Geology.
>> DOI: 10.1016/j.chemgeo.2017.10.011
(3) X. Mangenot, M. Gasparrini, A. Gerdes, M. Bonifacie, V. Rouchon, An emerging thermo-chronometer for carbonate bearing-rocks: ∆47/(U-Pb). Geology (2018) 46 (12): 1067-1070
>> DOI: 10.1130/G45196.1
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