Displacement history of a limestone normal fault scarp, northern Israel, from cosmogenic Cl-36

Citation
Sg. Mitchell et al., Displacement history of a limestone normal fault scarp, northern Israel, from cosmogenic Cl-36, J GEO R-SOL, 106(B3), 2001, pp. 4247-4264
Citations number
50
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
ISSN journal
2169-9313 → ACNP
Volume
106
Issue
B3
Year of publication
2001
Pages
4247 - 4264
Database
ISI
SICI code
0148-0227(20010310)106:B3<4247:DHOALN>2.0.ZU;2-U
Abstract
The abundance of cosmogenic Cl-36, measured in 41 limestone samples from a 9 m high bedrock fault scarp, allows us to construct the 14 kyr fault displ acement history of the Nahef East normal fault, northern Israel (300 m abov e sea level, N33 degrees latitude). The Nahef East fault is one of a series of fault scarps located along the 700 m high Zurim Escarpment, a major geo morphic feature. Samples at the top of the scarp have the highest nuclide c oncentrations (79 x 10(4) atoms (g rock)(-1)); samples at the base have the lowest (11 x 10(4) atoms (g rock)(-1)). Using chemical data from the sampl es, Nahef East fault scarp geometry, and surface and subsurface production rates for the Cl-36-producing reactions, we have constructed a numerical mo del that calculates Cl-36 accumulation on a scarp through time, given a ser ies of unique displacement scenarios. The resulting model Cl-36 concentrati ons are compared to those measured in the scarp samples. Faulting histories that result in a good match between measured and modeled Cl-36 abundances show three distinct periods of fault activity during the past 14 kyr with o ver 6 vertical meters of motion occurring during a 3 kyr time period in the middle Holocene, Smaller amounts of displacement occurred before and after the period of most rapid motion. The episodic behavior of the Nahef East f ault indicates that the average displacement rate of this fault system has varied through time.