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.

The Early Cretaceous was dominated by greenhouse conditions coupled with increased ocean crust production rate, which led to critical climate, geographic and oceanographic changes and abrupt shifts in redox conditions in the oceans. Regarding Earth’s magnetic field, the Aptian time interval recorded a high rate of polarity reversals. However, after 121.4 Ma, a long period of polarity stability, known as the Cretaceous Normal Polarity Superchron (CNPS), was established for ~38 Myr. Although, there is debate on the causes and consequences of this extreme event, the exact behavior of the geomagnetic field during the Aptian–Albian is still poorly understood, and data from volcanic and sedimentary rocks are usually conflicting. Here we integrate paleomagnetic and biostratigraphic data across the Aptian–Albian transition in the Sergipe-Alagoas Basin (Brazil). Studies suggesting the correlation between magnetostratigraphic and biostratigraphic data for this interval in the Brazilian sedimentary basins are rare, as well as for the South Atlantic marginal basins. Additionally correlations with the Tethyan realm are still unclear. Magnetic parameters, such as magnetic susceptibility, with a resolution of 25 cm, and anhysteretic remanent magnetization (ARM), with a resolution of 2.1 m, were collected over the ~200 m-long succession of Core SER-03 in the Sergipe-Alagoas Basin. ARM acquisition curves were separated into discrete coercivity components and they were interpreted as related to detrital magnetite and/or eolian dust inputs. The entire section spans 6 Myr, including the Aptian–Albian boundary. Our interpretation of environmental magnetism parameter, therefore, allow us to trace shifts between wet and dry climate conditions. Therefore, these data will aid to develop an age model framework in order to assist this uncovered region and future comparisons with Tethyan sections (e.g., Vocontian Basin - France and Poggio Le Guaine - Italy).