The accumulation rate of meteorite falls at the Earth's surface: The view from Roosevelt County, New Mexico

Abstract

Abstract— The discovery of 154 meteorite fragments within an 11 km2 area of wind‐excavated basins in Roosevelt County, New Mexico, permits a new calculation of the accumulation rate of meteorite falls at the Earth's surface. Thermoluminescence dating of the coversand unit comprising the prime recovery surface suggests the maximum terrestrial age of the meteorites to be about 16.0 ka. The 68 meteorite fragments subjected to petrological analyses represent a minimum of 49 individual falls. Collection bias has largely excluded carbonaceous chondrites and achondrites, requiring the accumulation rate derived from the recovered samples to be increased by a factor of 1.25. Terrestrial weathering destroying ordinary chondrites can be modelled as a first‐order decay process with an estimated half‐life of 3.5 ± 1.9 ka on the semiarid American High Plains. Having accounted for the age of the recovery surface, area of field searches, pairing of finds, collection bias and weathering half‐life, we calculate an accumulation rate of 9.4 × 102 falls/a per 106 km2 for falls > 10 g total mass. This figure exceeds the best‐constrained previous estimate by more than an order of magnitude. One possible reason for this disparity may be the extraordinary length of the fall record preserved in the surficial geology of Roosevelt County. The high accumulation rate determined for the past 16 ka may point to the existence of periods when the meteorite fall rate was significantly greater than at present.

Numerous unpaired meteorites exposed on a deflating playa lake at Lucerne Valley, California

“…difficulty in distinguishing achondrites from terrestrial rocks (Zolensky et al, 1990). CONCLUSIONS Unpaired meteorites have been found on more than a dozen dry lakes in the southwestern United States and meteorite hunters are searching additional dry lakes.…”

The 410,000 year terrestrial age of eucrite Río Cuarto 001

“…Second, it was discovered in a deflation hollow in sandy soil (Bland et al 2002), and probably had resided beneath the surface for much of its time on Earth. Evidently, sediment cover protects meteorites from weathering, as meteorites are found preferentially in deflation basins in, for example, Roosevelt County, New Mexico (Huss and Wilson 1973;Zolensky et al 1990).…”

“…They have been used to estimate the meteorite accretion rate (e.g., Bland et al 1996a), identify multiple fragments of single preatmospheric bodies (Benoit et al 2000), assess the role and rate of weathering processes (Bland et al 1996b), understand meteorite concentration mechanisms (e.g., Zolensky et al 1990), and constrain the environmental and geological history of the locations where they are found Folco et al 2006). A recent review of meteorite terrestrial ages and their significance is given by Jull (2006).…”

Memorial for Glenn I Huss

“…Zolensky et al (1990), acknowledging discussions with Glenn and Gary Huss, estimated that the flux of meteorites falling to Earth over the past 16 ka was an order of magnitude greater than the best estimate oftoday's flux. This impinges on current debate on whether Antarctic and non-Antarctic meteorites differ, and whether some meteoroids travel in co-orbital streams.…”