John A. Higgins

Professor John Higgins

Professor John Higgins' primary research interest is the evolution of the carbon cycle and the global climate system over Earth history.  One focus has been on processes that control the chemical composition of seawater, and how those processes have changed on geologic timescales.  Another is how on the chemistry of carbonate sediments is affected by processes that occur post-deposition.  These include early diagenetic recrystallization, dolomitization and hydrothermal alteration.  The tools Prof. Higgins has employed to study these include numerical models of chemical and isotopic biogeochemical cycles, as well as analysis of traditional stable isotopes of oxygen and carbon, and new isotope systems such as magnesium, calcium, and potassium.

Department/Program(s): Geosciences
Position: Active Faculty
Title: Associate Professor of Geosciences.
Area(s): Geology and Paleoclimate
Office: 212 Guyot Hall
Phone: 609-258-7024

Anne-Sofie Crüger Ahm

Anne-Sofie C. Ahm

Anne-Sofie C. Ahm is a Simons Foundation Postdoctoral Fellow working on numerical models of carbonate diagenesis and measurements of Ca, Mg, and Sr isotopes. She is intrigued by the fundamental processes that transform lithified sediments into rocks and how these processes affect the geochemical signature stored in the rock record of Earth history. In particular, she is interested in what the record of marine carbonate diagenesis - as revealed through the geochemical signature of Ca, Mg, and Sr isotopes - can tell us about ancient seawater chemistry and the origins of life on Earth.

Department/Program(s): Geosciences
Position: Research Staff
Title:Postdoctoral Research Fellow
Office: 210 Guyot Hall
Phone: 609-216-6060
Curriculum Vitae


Sarah Shackleton

Department/Program(s): Geosciences
Position: Research Staff
Title: Postdoctoral Research Fellow







Stefania Gili

Stefania Gili, Associate Professional Specialist

Department/Program(s): Geosciences
Position: Associate Professional Specialist
Office: 208 Guyot Hall
Phone: 732-924-0099


Jack Murphy

Jack Murphy, Graduate Student

Jack Murphy came to Princeton after studying physics and philosophy at Bates College, volunteering with the Peace Corps in Southern Africa, and teaching high school for several years.  Murphy's research is motivated by a fascination with the complexity and the long-term stability of Earth's climate system.  Using isotope geochemistry and a range of numerical Earth system models, he studies the processes that regulate climate throughout Earth's History – in particular the silicate weathering feedback, often called “Earth's CO2-thermostat."

Department/Program(s): Geosciences
Position: Graduate Student
Office: 208 Guyot Hall
Phone: 609-937-9817



Matthew Nadeau

Matthew Nadeau, Graduate Student

Research Summary: Development and employment of alkali earth metals (Mg, Ca, Sr) as a proxy for reconstructing diagenetic effects and its influence on geochemical (trace and isotope) signatures of marine carbonates. Keywords: magnesium isotopes, dolomitization

Department/Program(s): Geosciences
Position: Graduate Student
Curriculum Vitae