Open AccessThe remanent magnetisation recorded in the Chesapeake Bay impact crater, Virginia
Author(s) -
Radchagrit Supakulopas,
Sonia M. Tikoo-Schantz
Publication year - 2021
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/2145/1/012051
Subject(s) - impact crater , geology , remanence , natural remanent magnetization , magnetization , geophysics , paleomagnetism , schist , geochemistry , mineralogy , metamorphic rock , magnetic field , astrobiology , physics , quantum mechanics
During impact events, planetary crusts experience high pressures that can impart rocks with shock remanent magnetisation (SRM) if an ambient magnetic field or demagnetise rocks if a field is absent. If rocks experience substantial impact heating or are pressurised above ~40 GPa (inducing melting and recrystallisation) they may instead record a thermo-viscous remanent magnetisation (TVRM) as they cool below their Curie temperatures. Understanding impact re-magnetisation is crucial for studying terrestrial impact craters, but also unraveling the history of long-lived core dynamo fields on other planetary bodies. In this research we studied impact-related re-magnetisation recorded in natural rock samples from the Chesapeake Bay impact crater, Virginia. As a case study, here we discuss the natural remanent magnetisation (NRM) of two samples of different rock types: a suevite (sample I9-UI, depth 1.40 km beneath the ground) and a schist (sample S32, depth 1.67 km beneath the ground) using thermal and alternating field demagnetisation. The suevite represents a sample that contains material that experience impact remelting, whereas the schist represents an unmelted rock. From the NRM spectra, we found that the sample ITH9-UI was remagnetised by TVRM due to impact-related heating, while the sample STH32 shows the indication of shock deformation of magnetic minerals.