Martino Giorgioni

The Cretaceous period was marked by critical transformations of the Earth system, including a global climate transition to extremely warm conditions and the fragmentation of the Gondwana supercontinent. This led to the opening of the South Atlantic Ocean, associated with episodic marine transgressions onto the Brazilian continental shelf. In this context, the Parnaíba basin yields one of the best-preserved records of these environmental transitions. This study provides an inorganic geochemical perspective on the Aptian-Albian siliciclastic succession in the intracratonic Parnaíba Basin, aiming to refine interpretations of its complex depositional environments and identify major stratigraphic markers and events. Bulk rock, trace elements, and rare earth elements (REE) analyses were performed on samples from two boreholes, located about 50 km apart, encompassing the Codó Formation and the lowermost Itapecuru Formation. These novel elemental data were integrated with existing petrographic, biostratigraphic, and organic facies data, leveraging statistical tools such as Pearson correlation and Principal Component Analysis (PCA) for comprehensive interpretation. Key findings reinforce regional frameworks on the stratigraphic sequences of the northeastern part of the Parnaíba Basin. The Aptian-Albian succession starts with a fluvial system that transitions to a lacustrine system, evolving to a restricted hypersaline system, followed by the reinstatement of a fluvio-lacustrine system. Here, we elucidate fluctuations in salinity, the extent of marine influence, and the prevailing redox conditions. Furthermore, REE patterns indicate a consistent detrital provenance from REE-enriched felsic igneous or metamorphic source rocks, highlighting regional controls on the eastern portion of the basin. This integrated geochemical framework provides a comprehensive and nuanced reconstruction of the response of a large intracratonic basin to the Early Cretaceous opening of the South Atlantic Ocean.

The first breack-up breakup of Gondwana supercontinent in the Central South Atlantic is still contrversial and in particular constrain of the formation of Reconcavo Basin (Bahia State, Brazil). The Reconcavo Basin represents one of the best stratigraphical outcrop for lower Cretacesous sequence in Brazil. This study presents the first high-resolution age model for the Maracangalha Formation based on detailed paleomagnetic and rock-magnetic analyses. Rock magnetic results indicate that low-coercivity pseudo–single-domain magnetite is the dominant carrier of remanent magnetization. Paleomagnetic directions are highly stable, with maximum angular deviation values predominantly below 10°, ensuring reliable polarity determinations. Two well-defined magnetozones are identified, forming a Normal–Reversed polarity succession. Integration of magnetostratigraphic data with ostracod biostratigraphy allows correlation of these magnetozones with Chrons M11An.1r and M11An.2n of the Geomagnetic Polarity Time Scale, constraining deposition of the Gameleira section to the early Valanginian interval (~134.29-134.42 Ma). This refined chronostratigraphic model provides a well-constrained basis for syn-rift depositional dynamics during the early stages of South Atlantic opening. Finally, our new data show that syn-rift lacustrine sedimentation was synchronous with the first pulses of crustal extension in the South Atlantic and the beginning of seafloor spreading, challenging traditional Aptian breakup models.

The Neoproterozoic-Cambrian succession of the Parecis Basin, located along the southeastern margin of the Amazon Craton, remains poorly constrained due to its burial beneath a thick Mesozoic cover. This study presents an integrated subsurface analysis using well data, 2D seismic reflection profiles, and gravity data to reconstruct the stratigraphic framework and basin architecture of the Juruena Subbasin. The sedimentary succession exceeds 6,000 m in thickness and records the transition from Cryogenian glaciogenic deposits to Ediacaran carbonate platform and Cambrian foreland basin sedimentation. Two Cryogenian glacial events are recognized, including a previously unreported preMarinoan carbonate interval (Salto Magessi Formation). The Marinoan glaciation is recorded by the Bauxi and Puga formations, overlain by a regionally extensive cap dolostone (Mirassol d’Oeste Formation), marking post-glacial transgression. The overlying Araras Group defines a carbonate platform with pronounced lateral thickness variations, reflecting differential subsidence and erosion. This succession is unconformably overlain by the Serra Azul Formation and Raizama formations, followed by a thick siliciclastic succession of the Diamantino Formation, interpreted as a Cambrian foreland system. Seismic stratigraphy reveals three depositional sequences associated with sediment influx and tectonic loading during the foreland basin development. The subsurface architecture correlates with the exposed Neoproterozoic succession of the Paraguay Belt, supporting a model in which the Parecis Basin represents the cratonic continuation of a Neoproterozoic passive margin, incorporated into a foreland basin system during the following Brasiliano Orogeny. These results highlight the hydrocarbon exploration potential of this system through regionally extensive stratigraphic units and basin-scale architectural controls.

Carbonate sedimentary systems represent one of the best examples of interactions between the biosphere and the geosphere throughout geologic time

The timing and duration of oceanic disturbances linked to Oceanic Anoxic Event (OAE) 1b, as well as the mechanisms driving anoxia and carbon burial during this period, remain subjects of debate. We conducted cyclostratigraphic analyses on magnetic susceptibility (MS) and elemental Ti and Fe series within the upper Aptian‐lower Albian interval of the Poggio le Guaine core in the Umbria‐Marche Basin, Italy. This interval provides a detailed sedimentary record, supported by variations in magnetic mineral content, Ti, Fe, and significant global shifts in the δ¹³C curve. Orbital control of MS, Ti, and Fe suggests a duration of 2.84 Myr for the OAE 1b event. Our chronostratigraphic analysis reveals ages of 114.07 ± 0.12 Ma for 113/Jacob, 113.28 ± 0.12 Ma for Kilian, 112.49 ± 0.12 Ma for the central age of the Monte Nerone cluster, 111.70 ± 0.12 Ma for Urbino, and 111.28 ± 0.12 Ma for Leenhardt sub‐events. Stable δ¹³C chemostratigraphy correlations enable the transfer of tiepoints across various sedimentary basins. Key features of the carbon isotope curves were identified, named, and dated using astrochronology. Our findings suggest that the organic‐rich layers associated with the OAE 1b event exhibit distinct characteristics influenced by several factors, including a warm climate driven by volcanic CO₂ emissions, heightened precipitation, intense weathering, and marine transgressions. These factors amplify orbital forcings on paleoclimate changes, leading to oceanic‐atmospheric disturbances that promote deoxygenation and carbon burial during OAE 1b.

The study of Neoproterozoic carbonate sequences is complicated due to several variables influencing the geochemical and mineralogical composition, compounded by the scarcity of environmental analogs. The Tamengo Formation in the Corumbá Group is one of the most extensively studied archives of the Neoproterozoic in South America and encompasses Ediacaran guide fossils of Corumbella werneri and Cloudina lucianoi. This research focused on a marl sample containing well-preserved bioclasts of exoskeletons of Corumbella werneri, which is one of the earliest biomineralizing organisms. By utilizing diverse techniques such as optical and SEM microscopy, QEMSCAN imaging, electron microprobe, in situ ICP-MS, and isotope analyses, this study reveals primary and secondary signals in the bioclastic exoskeletons and the matrix within. These findings shed light on the sedimentary environment and diagenetic history of the Tamengo Formation. It is revealed that Corumbella werneri likely inhabited calm conditions, just below the base of storm waves and above a sharp chemocline at the bottom. In addition, the presence of distinct hydrothermal signals in the composition of REEs indicates a potential magmatic event that occurred in the region after the deposition of the succession. This pilot study highlights that the history recorded in the Neoproterozoic rocks of the Tamengo Formation is complex, and thus more detailed studies integrating lithological, paleontological, and geochemical parameters are necessary to reach a correct interpretation of this sequence.

Cyclostratigraphic analyses were performed on magnetic susceptibility (MS), and elemental Ti and Fe series along the upper Aptian-lower Albian interval of the Poggio le Guaine (PLG) core, a Cretaceous pelagic succession in the Umbria-Marche Basin (central Italy). This interval represents one the most detailed and complete sedimentary archives and records oceanic perturbations associated with Oceanic Anoxic Event (OAE) 1b. The MS, Ti and Fe orbital control indicates a timespan of 2.68 Myr for OAE 1b event (114.10 to 111.34 Ma) and short eccentricity cycles played a key role, in controlling the amount of detrital input from weathering during monsoonal periods. Our chronostratigraphic study also provides age of 114.09 Ma for 113/Jacob, 113.25 Ma for Kilian, 112.67 Ma as a central age of the Monte Nerone cluster, 111.70 Ma for Urbino and 111.37 Ma for Leenhardt subevents, and a timespan of ~20 kyr for 113/Jacob, 70 kyr for Kilian, 670 kyr for Monte Nerone cluster, 60 kyr for Urbino and 60 kyr for Leenhardt levels. This study provides compelling evidence of the enormous potential C-isotope stratigraphy as tie points for cyclostratigraphic studies and as a valuable way to evaluate diachronism of bioevents. The organic-rich levels encompassing OAE 1b event has particular characteristics resulting from the combination of warm climate triggered by volcanic CO2 input, heavy precipitation, intense weathering and rapid marine transgressions, which leads the oceanic-atmospheric perturbations, acting as amplifiers of orbital forcings paleoclimate changes, resulting in deoxygenation and carbon burial during OAE 1b.