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Viscous magnetization, archaeology and Bayesian statistics of small samples from Israel and England
Author(s) -
Borradaile Graham J.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl016977
Subject(s) - geology , power law , pelagic zone , exponent , bayesian probability , statistics , archaeology , paleontology , mathematics , geography , oceanography , linguistics , philosophy
Certain limestones remagnetize viscously and noticeably over archaeological time‐intervals, after their reorientation into monuments. The laboratory demagnetization temperatures (T UB ) for the VRM increase with the installation age; with rates of ∼0.07 C 0 /year for Israel chalk and ∼0.1C 0 /year for English chalk. The empirical relationship may be used to date enigmatic buildings or geomorphological features (e.g., land slips). Such correlations also give some insight into the viscous remagnetization process over time intervals τ ≤ 4000 years, which are unobtainable in laboratory studies. The T UB ‐age relationship for the viscous remagnetization appears to follow a power law, linearized as log 10 (τ) ≈ b log 10 (T UB ). Different pelagic limestones follow different curves and, whereas conventional regression estimates the power law exponent b , the small sample size recommends a Bayesian statistical approach. From sites constructed with pelagic chalk from eastern England, precise prior information ( b = 0.761) is compared with less precise information for much more ancient sites in northern Israel ( b = 0.873). The collective posterior correlation shows a generalized power law exponent b = 0.849. That regression explains 84.9% of the collective variance in age (r 2 = 0.849). Of course, site‐specific calibration is required for archaeological age determinations.