Tracking Cosmic Dust with Extraterrestrial Helium and Neon in Deep-Sea Sediments

Author: Deng, Ruolin

Year: 2026

Degree: Dissertation (Ph.D.)

Advisor: Farley, Kenneth A.

Committee Members: Asimow, Paul David; Batygin, Konstantin; Eiler, John M.; Farley, Kenneth A.; Kirschvink, Joseph L.; Tissot, Francois L. H.

Option: Geology

DOI: 10.7907/51e1-q145

Abstract

Cosmic dust represents the dominant form of extraterrestrial material currently accreted by Earth, yet many fundamental aspects of its origin, composition, and impact remain poorly constrained. The past cosmic dust flux can be reconstructed by measuring extraterrestrial helium-3 in deep-sea sediments, which is retained in cosmic dust for millions of years, even through diagenetic processes. While cosmic dust flux through most of the times in the last 100 Myr is relatively constant, several short-lived helium-3 enhancement events have been identified and linked to asteroid disruptions in the asteroid belt. The cosmic dust sources of other similar events, however, remain uncertain. Moreover, the mineralogical carrier of solar wind helium and neon in marine sediments is still debated, and the broader influence of cosmic dust on terrestrial systems remains an open question. This thesis addresses these outstanding issues using noble gas geochemistry, trace metal analysis, paleomagnetism, stable isotope geochemistry, and dust dynamics modeling. Chapter II investigates the cosmic dust source and consequences of the K1 helium-3 enhancement event in the Late Cretaceous. Chapter III explores the source of cosmic dust through time, including the potential role of the Moon. Chapter IV evaluates the climatic significance of enhanced cosmic dust flux during the Late Eocene. Together, these studies provide new insight into the source, dynamic evolution, composition, and terrestrial impact of cosmic dust.