PAOC Spotlights

How to Spot a Mass Extinction Event

Fri July 19th, 2013
Helen Hill



How to Spot a Mass Extinction Event


Funded by the MIT International Science and Technology Initiatives (MISTI) – Global Seed Funds – Spain, members of the Summons’ group carried out a geological field trip in northwestern Tunisia in Spring 2012.

This activity formed part of an international collaboration between Prof. Roger E. Summons and research scientist Julio Sepúlveda (MIT), Prof. Laia Alegret (University of Zaragoza, Spain), and Prof. Hedi Negra (University of Tunis El Manar, Tunisia), to study the recovery of planktonic communities following the Cretaceous-Paleogene (K-Pg) mass extinction event.

Tunisia hosts the world most expanded and complete K-Pg sections, including the Global Boundary Stratotype Section and Point of El Kef, thus allowing for the recovery of high-resolution records.

The team was led by MIT research scientist Julio Sepúlveda and Prof. Hedi Negra, and included MIT graduate student Marie Giron, Dr. Jens Wendler (University of Bremen, Germany), and University of Tunis graduate students Salwa Bey and Marwa Barouni.

Samples recovered from the K-Pg sections of El Kef, Elles, and Ain Settara, are currently undergoing geochemical, isotopic, microfossil, and sedimentological analyses. The results are expected to help reconcile the long-standing controversy about post-extinction ecosystem recovery and the perturbation of the carbon cycle, as inferred from carbon isotopes and microfossil records.

Organic geochemical work performed in the Summons’ lab is aimed at unraveling the role of phytoplanktonic organisms lacking hard skeletons in sustaining carbon cycling and food supply to deep-sea communities in the aftermath of the extinction.

For further information about this project please contact Dr. Julio Sepúlveda ( and Prof. Roger E. Summons (

Video credit: Helen Hill.

All photos courtesy J. Sepúlveda.

Recent Update: New fieldwork to Tunisia is scheduled for September 2013. This time, Julio will be leading a drilling campaign as part of a collaboration with Prof. Tim Bralower (Penn State University) and colleagues from Yale University, Utrech University, University of Zaragoza, and Southampton. Look out for more about this later in the year.


Julio Sepúlveda is a research scientist working in Roger Summons' geobiology group.

The Summons Group (Geobiology at MIT)



Cretaceous Impact

Sixty five million years ago, a 10 km meteorite crashed into what is now Mexico’s Yucatan Peninsula, creating a 177 km crater and causing mass extinctions across the globe. In this video (geared to a K-12 audience) Sepúlveda explains what happened and the evidence scientists see in the rock record. 


Sepúlveda wins Infinite K Award EAPS News

A New Day Dawned Fast MIT News