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

Alliya A. Akhtar

Alliya A. Akhtar, Postdoctoral Research Associate

An appreciation of the coevolution of the Earth and its biosphere requires a focus on the integration and application of low temperature geochemistry to the paleontological and sedimentary record.  Alliya Akhtar is particularly interested in studying the chemical and climatic conditions governing times of not only proliferation, but also distress of animal life.  Employing various isotope systems can aid in establishing constraints on changes in climate and ocean chemistry.  Coupling this with isotopic studies in modern environments will aid in better understanding the information we derive from these proxies.

Department/Program(s): Geosciences
Position: Research Staff
Title: Postdoctoral Research Associate
Office: 209 Guyot Hall
Phone: 609-258-9836



Tommy Rock

Tommy Rock, Postdoctoral Research Associate

Department/Program(s): Geosciences
Position: Research Staff
Title: Postdoctoral Research Associate
Office: A15 Guyot Hall
Phone: 609-258-0896


Sarah Shackleton

Sarah Shackleton is a postdoc working with John Higgins and Michael Bender. She is interested in Earth’s climate system and how it has changed through time. Her work at Princeton is focused on extending atmospheric gas and ice records with blue ice archives. She uses measurements of air samples trapped in ice bubbles to understand the evolution of past ice, ocean, and atmosphere conditions. 

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




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