Daniel Baudet - Academia.edu (original) (raw)

Papers by Daniel Baudet

Nature Communications, 2022

The acquisition of photosynthesis is a fundamental step in the evolution of eukaryotes. However, ... more The acquisition of photosynthesis is a fundamental step in the evolution of eukaryotes. However, few phototrophic organisms are unambiguously recognized in the Precambrian record. The in situ detection of metabolic byproducts in individual microfossils is the key for the direct identification of their metabolisms. Here, we report a new integrative methodology using synchrotron-based X-ray fluorescence and absorption. We evidence bound nickel-geoporphyrins moieties in low-grade metamorphic rocks, preserved in situ within cells of a ~1 Gyr-old multicellular eukaryote, Arctacellularia tetragonala. We identify these moieties as chlorophyll derivatives, indicating that A. tetragonala was a phototrophic eukaryote, one of the first unambiguous algae. This new approach, applicable to overmature rocks, creates a strong new proxy to understand the evolution of phototrophy and diversification of early ecosystems.

Evaluate the thermal maturity of old sedimentary basins containing microfossils is crucial to rec... more Evaluate the thermal maturity of old sedimentary basins containing microfossils is crucial to reconstruct early life evolution on Earth. Here, we investigate carbonaceous shale samples containing exquisitely preserved organic-walled microfossil assemblages from three Proterozoic shallow marine sedimentary sequences: the Mbuji-Mayi Supergroup (Democratic Republic of Congo, Congo Basin), the Atar/El Mreïti Group (Mauritania, Taoudeni Basin) and the Kanpa Formation (Australia, Officer Basin). By comparison with Raman geothermometry, solid bitumen reflectance, illite crystallinity and Thermal Alteration Index, we evaluate and validate the use of Raman reflectance on Proterozoic carbonaceous material and especially for poorly-ordered carbonaceous material. We show that extracted kerogen (microfossils and amorphous organic material) is more accurate to estimate the thermal maturity of low-grade temperature Proterozoic sequences than kerogen in thin section. All the techniques provide cons...

Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republi... more Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republic of Congo). B.K. Baludikay1*, J.-Y. Storme1, D. Baudet2, C. François1 and E.J. Javaux1 1Palaeobiogeology-Palaeobotany-Palaeopalynology, UR GEOLOGY, Department of Geology, University of Liege, Quartier Agora, Allée du 6 Août, 14, B18, B-4000 Liège 1, Belgium. bkbaludikay@ulg.ac.be 2 Geodynamics & Mineral Resources Service, Royal Museum for Central Africa, 3080 Tervuren, Belgium.

1 PPP, Department of Geology, B18, University of Liege, 4000 Liège, Belgium. 2 Earth Sciences Dep... more 1 PPP, Department of Geology, B18, University of Liege, 4000 Liège, Belgium. 2 Earth Sciences Department, Royal Museum for Central Africa, Tervuren, Belgium 3 Laboratoire de Géochimie des enveloppes externes (UMR 7154 CNRS), IPGP, 1 rue Jussieu, F-75005 Paris 4 Laboratoire Magmas et Volcans (CNRS UMR 6524), Université B. Pascal, F-63 038 Clermont-Ferrand Cedex, France 5 Camparis, Université Paris 6, 4 place Jussieu, 75252 Paris Cedex 5, France 6 Laboratoire G-Time, Université Libre de Bruxelles, CP 160/02, 50 Avenue F.D. Roosevelt, 1050 Brussels, Belgium

Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republi... more Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republic of Congo). B.K. Baludikay1*, J.-Y. Storme1, D. Baudet2, C. Francois1 and E.J. Javaux1 1Palaeobiogeology-Palaeobotany-Palaeopalynology, UR GEOLOGY, Department of Geology, University of Liege, Quartier Agora, Allee du 6 Aout, 14, B18, B-4000 Liege 1, Belgium. bkbaludikay@ulg.ac.be 2 Geodynamics & Mineral Resources Service, Royal Museum for Central Africa, 3080 Tervuren, Belgium.

info:eu-repo/semantics/nonPublishe

The question of how and when plate tectonics and subduction processes initiated on Earth is still... more The question of how and when plate tectonics and subduction processes initiated on Earth is still a subject of debate. Subduction requires the oceanic lithosphere to sustain differential stress without creep. Today, mid-to high-pressure mineral assemblages are commonly interpreted in terms of plate tectonic processes including subduction. While in the Early Earth, mid-to high pressure assemblages could have been also produced by sagduction (or stagnant-lid tectonics) of dense mafic lithology into their light silicic crustal basement, the first evidence of high pressure rocks (i.e. eclogites) seems to appear only at the Neoarchean-Paleoproterozoic boundary. In fact, this limit seems to be a crucial period and a time of major change in tectonic style regime. Here, we characterize and date the oldest compelling eclogites discovered so far, dated at 2089 ± 13 Ma from the Northern margin of the Kasai block (Democratic Republic of the Congo). We also identify the protolith of these eclogites as being originally a gabbro formed at 2216 ± 26 Ma in an intra-cratonic rift-type basin, which was buried at high pressure and low temperature (20-25 kbar and 550-600°C) in a subduction zone and then exhumed during a Wilson cycle of ca. 130 Ma, testifying a modern style plate tectonics at 2.2-2.1 Ga.

Nature Communications, 2022

Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republi... more Thermal maturation of carbonaceous material from Mbuji-Mayi Supergroup (Kasai, Democratic Republic of Congo). B.K. Baludikay1*, J.-Y. Storme1, D. Baudet2, C. Francois1 and E.J. Javaux1 1Palaeobiogeology-Palaeobotany-Palaeopalynology, UR GEOLOGY, Department of Geology, University of Liege, Quartier Agora, Allee du 6 Aout, 14, B18, B-4000 Liege 1, Belgium. bkbaludikay@ulg.ac.be 2 Geodynamics & Mineral Resources Service, Royal Museum for Central Africa, 3080 Tervuren, Belgium.

info:eu-repo/semantics/nonPublishe

The Mbuji-Mayi Supergroup, deposited between 1170 ± 22 Ma and ca. 800 Ma [1], outcrops in the eas... more The Mbuji-Mayi Supergroup, deposited between 1170 ± 22 Ma and ca. 800 Ma [1], outcrops in the eastern Oriental Kasai Province and western Katanga Province of the Democratic Republic of Congo. It is the youngest Precambrian unit of the Kasai block and was deposited in the SE–NW trending failed-rift Sankuru-Mbuji-Mayi-Lomami-Lovoy basin filled with siliciclastic and carbonate sediments. In the northern part of this basin (Oriental Kasai Province), the Mbuji-Mayi Supergroup rests unconformably upon the Archean Dibaya Granite Complex, but in the southern part (northeastern Katanga Province), it overlies the Mesoproterozoic Kibaran Supergroup. The Supergroup is divided into two groups: the lower, ∼ 500-m thick siliciclastics-rich BI Group and the upper, ∼ 1000-m thick carbonate-rich BII Group. Our own and previous sedimentological observations [2] indicate facies ranging from subtidal, low-energy stromatolitic environments to overlying intertidal to supratidal evaporitic settings of lagoon and sabkha. In order to characterize the diversity of microfossil assemblages, their paleobiology and paleoecology as well as redox conditions in their depositional setting, we have sampled three drill cores (KAFUKU 15, B13 KANSHI, and S70 LUBI) from the collections of the Royal Museum for Central Africa (RMAC). Our bios-tratigraphic and chemostratigraphic data also provide further constraints on the age of the Mbuji-Mayi Supergroup. Here we present preliminary data on microfossil diversity from the Kanshi drill core and carbon isotope chemostratigraphy for all three drill cores. The well-preserved and diverse assemblage of acritarchs and filamen-tous forms includes prokaryotes and eukaryotes, and is similar to other coeval assemblages described worldwide outside of Africa. The presence of the acanthomorph acritarch Trachyhystrichosphaera aimika is significant as it is indicative of the late Meso-to early Neoproterozoic age elsewhere, and is reported for the first time in Central Africa. So far, 52 species belonging to 31 genera were identified, dramatically increasing the previously reported diversity [3, 4]. Chemostratigraphy based on δ13Ccarb values for 290 samples, records, for the BI Group, predominantly negative values down to-8 to-9 VPDB with few samples having more positive, up to +3 values. Although the siliciclastics-rich sediments in the lower part of the BI Group likely record early diagenetic signal, carbonates in the upper part of the BI Group show similar patterns in both the Lubi and Kafuku drill cores with the sharp fall from +1 to +3 values to-8 to-7 and recovery back to +1 values over 40 to 70 m of section. The BII Group shows a less dramatic rise from-1 to +4 to +5 over more than 150 m of section. These large-scale variations differ from the steady-state carbon cycle of the late Mesoproterozoic [5] and are typical of the Neoproterozoic record leading to the Cryogenian [6], specifically the Bitter Springs Stage [1]. The project is supported by the EU FP7 ERC Stg ELITE.

The Mbuji-Mayi Supergroup is a sedimentary sequence in DRC unaffected by regional metamorphism [1... more The Mbuji-Mayi Supergroup is a sedimentary sequence in DRC unaffected by regional metamorphism [1]. It consists of two distinct successions: a lower, ~500 m thick siliciclastic sequence of the BI Group (dated at 1125 Ma [2] or between ca. 1175 Ma and 882 Ma [3]) and an upper, ~1000 m thick carbonate sequence with stromatolitic build-ups and black shales of the BII Group directly overlain by basaltic lavas dated at 948 ± 20 Ma [4]. Five boreholes from Sankuru -Mbuji-Mayi region have been sampled in detail. Siliciclastic rocks were investigated for microfossils. The typical late Mesoproterozoic -early Neoproterozoic acritarch, Trachyhystricosphaera aimika, is reported herein for the first time in central Africa, and co-occurs with other eukaryotes and prokaryotes forming an exceptionally diverse (55 taxa) and well-preserved microfossil assemblage. However the absence of the pre-Sturtian index species Cerebrosphaera buickii [5] and of other taxa typical of pre-Ediacaran Neoproterozoic deposits such vase-shaped microfossils VSM [6] suggest that the Mbuji-Mayi Supergroup was deposited before ca. 820 Ma. Moreover, δ 13 C carb positive and negative excursions in the BIe -BIIc interval [3] are similar to variations in late Mesoproterozoic -early Neoproterozoic carbonate successions [7, 8], with no evidence so far for the Bitter Springs Stage as previously suggested [2, 9]. This is consistent with the previous age constraints and with the preliminary results on dating diagenetic monazites from the BI Group, which gave an age of ca.

The Mbuji-Mayi Supergroup is a sedimentary sequence in DRC unaffected by regional metamorphism. I... more The Mbuji-Mayi Supergroup is a sedimentary sequence in DRC unaffected by regional metamorphism. It consists of two distinct successions: a lower, ∼500 m thick siliciclastic sequence of the BI Group and an upper, ∼1000 m thick carbonate sequence with stromatolitic build-ups and black shales of the BII Group directly overlain by basaltic lavas [1]. Radiometric data suggest a Latest Meso-to Early Neoproterozoic age [2, 3, 4, and 5]. A well preserved and diversified microfossil assemblage is reported including 54 taxa belonging to 32 genera. The potential Late Mesoproterozoic-Tonian index fossil Trachyhystrichosphaera aimika, is reported for the first time in central Africa, and co-occurs with other eukaryotes and prokaryotes [6]. Thermal maturation calculated on macerate residues, using geothermometer for low-grade metamorphism [7] reveals thermal palaeoenvironments of organic matter, ranging from 180 to 279 • C (average = 249 ± 37 • C). The range of thermal maturity is similar, in both microfossils and amorphous organic matter. Raman reflectance (RmcRo %), which is also an index indicative of maturity [8], ranges from 1.05 to 2.55 % (average = 2.01 ± 0.42 %). So, organic matter from Mbuji-Mayi is likely into a maturation stage corresponding to oil window.