Naroa Martinez-Braceras

• PhD
• PhD Researcher at University of the Basque Country

Several processes can contribute to the formation of hemipelagic limestone–marl alternations as a consequence of astronomically driven climate change. The aim of this work is to decipher which environmental factors governed the formation of three Eocene hemipelagic successions of the Basque–Cantabrian Basin using a comprehensive set of physical and...

The astronomical timescale accuracy generally exceeds other dating methods. Precise age models are pivotal for paleoclimatic research. The middle Eocene astronomical timescale has been poorly constrained due to scarcity of suitable records leading to the so call ‘Eocene astronomical timescale gap'. We present magnetic susceptibility and color proxy...

Multivariate analysis of the elemental composition of hemipelagic sedimentary successions has provided invaluable information about palaeoenvironmental evolution, including records of short‐lived Eocene hyperthermal events. However, few studies have analyzed the sedimentary record of these climatic events in turbidite‐rich continental margin succes...

The early Eocene paleoclimate record provides one of the best analogues for today’s global warming. In order to reconstruct the evolution of the early Eocene paleoclimate, and understand how environmental feedback mechanisms acted on it, an accurate time framework is necessary. In this regard, the astronomically calibrated time scale (ATS) provides...

Lower Pliensbachian hemipelagic successions from the northern Iberian palaeomargin are characterized by the occurrence of organic-rich calcareous rhythmites of decimetre-thick limestone and marl beds as well as thicker black shale intervals. Understanding the genetic mechanisms of the cyclic lithologies and processes involved along with the nature...

Turbidity currents are thought to occur randomly and to be inherently non-cyclical events. Furthermore, as they commonly involve erosive processes, turbiditic successions are seldom continuous and the probability of any cyclical process being fully recorded is low. Consequently, turbiditic successions are not ideal for cyclostratigraphic analysis....

In order to reconstruct the evolution of sedimentary systems and understand how environmental feedback mechanisms act, an accurate time framework is necessary. The accuracy of astronomical timescale generally exceeds other age dating methods, but orbital models fail beyond 40-50 Ma and actual geological data are incomplete. The expanded lower Ypres...

Paleocene deposits of the Subbetic Zone (southern Spain) provide outstanding evidence of the influence of sea mountains on deep marine currents. This part of the Betic Cordillera External Zones corresponds to the distal and deepest area of the original basin, where hemipelagic sedimentation prevailed during most of the Turonian-early Lutecian inter...

Lower Pliensbachian hemipelagic successions from the north Iberian palaeomargin are characterized by the occurrence of organic-rich calcareous rhythmites of decimetre-thick limestone and marl beds and thicker black shale intervals. Understanding the genetic mechanisms of the cyclic lithologies and involved processes along with the nature of the car...

Our understanding of the stratigraphic expression of astronomically driven climate-change cycles in the Milankovitch frequency band has improved significantly in recent decades. However, several aspects have been little studied to date, such as the nature of the climatically regulated environmental processes that ultimately control cyclic sedimenta...

Experts have noted that the interest of the general population in geology has decreased. is seems to be related to an exclusion ofgeology from compulsory education curriculum. However, it is mandatory that the students who complete compulsory secondaryschool acquire a correct literacy in Earth Sciences, in which understanding external geological p...

Durante el Eoceno se desarrollaron muchos de los rasgos que caracterizan la Tierra actual. Importantes reajustes entre diversas placas tectónicas produjeron nuevas configuraciones geográficas y las consecuentes modificaciones en las pautas de circulación oceánica provocaron la transición de un clima global de tipo “invernadero” a otro de tipo “cong...

Expanded deep-marine sedimentary successions were deposited on the North Iberian continental margin in Eocene times. These deposits are well exposed along accessible coastal cliffs of the Biscay province, being of great interest for paleoenvironmental and paleoclimatic studies. This study dealt with the 110 m-thick lower Ypresian (early Eocene) suc...

Supplementary data: APPENDIX 1 ETP (normalized eccentricity and precession) time series from the La2004 orbital solution (Laskar et al., 2004) for the interval 40.9-42.5.8 Ma. APPENDIX 2 Sedimentation rates and age model for the Oyambre section APPENDIX 3 Stable isotope data from the Oyambre succession APPENDIX 4 Mineralogical data from the Oyambre...

The last hyperthermal event in the Eocene, the Late Lutetian Thermal Maximum or Chron C19r event, took place at ~41.5 Ma, during a long-term global cooling phase which occurred between the warm Early Eocene Climatic Optimum and the icehouse Oligocene Epoch. This paleoclimatic event was first identified in the Equatorial Atlantic Ocean Drilling Prog...

Supporting text for magnetostrigraphic results from Oyambre (Text S1), correlation of the Oyambre section and IODP Sites (Text S2) and Cenozoic Time Scale construction and calibration (Text S3) and their related figures (Figures S1 to S7)

The team during magnetostratigraphic sampling in 2013

EGU2017 poster Oyambre section

The Eocene Epoch was crucial in the development of many present day Earth features. Tectonic plate rearrangement resulted in new paleogeographic configurations and ocean circulation patterns, and eventually led to a switch from greenhouse to icehouse climatic conditions. From a sedimentation point of view, assessing the relative significance of tec...

Undoubtedly, the legacy of DSSP/ODP/IODP programs that have targeted deep-sea records around world oceans to paleoceanography and chronostratigraphy is invaluable. The advent in the early 90’s of the strategy to drill multiple holes at a single site for construction of complete composite sections, thus overcoming one major drawback for high-resolut...

High-resolution analysis was carried out on a about 30 m Early Eocene interval of pelagic marl and limestones succession at Sopelana (Basque-Cantabrian Basin, western Pyrenees). The aim of the study was to characterize the orbitally controlled sedimentary cyclicity. To this end a high-resolution (1 sample/1000-1500 years) analysis of CaCO3 was carr...

The formation of hemipelagic limestone-marl alternations is commonly related to cyclic environmental changes in sedimentary basins. Although several potential forcing mechanisms can produce such calcareous couplets, they have mostly been related to changes in the orbital parameters of the Earth (Milankovitch Cycles). The aim of this work is to cast...

The influence of astronomically driven short-term climate change (Milankovitch cycles) on deep-marine turbidite systems is not well-known, particularly in the case of long-term greenhouse intervals with no significant glacioeustatic sea-level fluctuations. This study, carried out at the Gorrondatxe section (Global Stratotype Section and Point for t...