The Dar al Gani meteorite field (Libyan Sahara): Geological setting, pairing of meteorites, and recovery density

Abstract

Abstract-As of July 2001, 1238 Libyan meteorites have been reported. Most were found in two areas called Dar al Gani and Hamadah al Hamra. Dar al Gani is located on a plateau of marine carbonate rocks with marly components. Eight-hundred and sixty-nine meteorites between 6 g and 95 kg totalling 687 kg have been found here but the calculated mean recovery density is comparatively low with one meteorite on 6.5 km-.Dar al Gani is a perfect site for the recognition and preservation of meteorites. The existence of meteorites is the result of a combination of specific geological and geomorphological conditions: there is a bright-colored, old limestone plateau «2 Ma), under arid weather conditions over long periods of time, with rapid elimination of surface water if present and low erosion rates. The preservation of meteorites is guaranteed through the absence of quartz sand on the plateau, strongly reducing wind erosion and a basic environment emerging from the carbonate ground retards rusting ofmetallic meteorite components. A supposed soil cover during pluvial times has probably protected older meteorites and led to a concentration of meteorites of different periods.An evaluation of Dar al Gani meteorites suggests the existence of at least 26 strewnfields and 26 meteorite pairs reducing the number of falls to, at most, 534. Shock and weathering grades as a tool for the recognition of pairings turned out to be problematic, as several strewnfields showed paired meteorites which had been classified to different shock and weathering grades.

Weathering of meteorites from Oman: Correlation of chemical and mineralogical weathering proxies with14C terrestrial ages and the influence of soil chemistry

“…Rocks and meteorites lying on the surface of a flat desert plain are subject to mechanical erosion by aeolian abrasion, an effect also observed in other desert areas (Schl¸ter et al 2002). Desert rocks are more eroded on the sides facing the direction of prevailing wind (Fig.…”

Exposure history and terrestrial ages of ordinary chondrites from the Dar al Gani region, Libya

“…One exception to this sampling strategy is the selection of four L6 chondrites (DaG 328,457,458,757) that were identified to be part of a large pairing group. We also selected two L6 chondrites (DaG 341 and 906) that may be part of a small pairing group (Schlüter et al 2002). The selected samples include 19 H, 10 L, 1 L/LL, and 2 LL chondrites, ranging from petrologic type 3 to type 6 ( Table 1).…”

“…Schlüter et al (2002) suggested that meteorites may have been protected from wet periods in the Sahara, such as the one between 11,000 and 3000 years ago, by soil coverage. This soil was removed by deflation during the current arid period, exhuming the meteorites.…”

“…In the past decade, more than 1000 meteorites have been recovered from this region. The geological setting, pairing of meteorites, and recovery density of the DaG field are described in Schlüter et al (2002).…”

The Jiddat al Harasis 073 strewn field, Sultanate of Oman

“…Although large meteorite strewn fields are relatively rare, data for several such strewn fields were reported in the last two centuries. Examples are Holbrook (Foote 1912), Mbale (Jenniskens et al 1994), Norton County (LaPaz 1965), Mócs (Koch 1882), Tenham (Brooks et al 1964), Allende (Clarke et al 1970), Camel Donga (Bevan et al 1986;Cleverly et al 1986), Murchison (Fuchs et al 1973), Gold Basin (Kring et al 2001), an L6 and CO3 strewn field in the Libyan desert (Schlüter et al 2002) and Park Forest (Simon et al 2004). Large showers with many stones were also recognized in Antarctica in the Allan Hills (Nishiizumi et al 1989), the Elephant Moraine (Grossman 1994), and the Frontier Mountains (Welten et al 2006a) regions.…”