Surface Morphology of Meteorites in Lut Desert (Iran) Environment
Received Date: Jan 05, 2018 / Accepted Date: Jan 17, 2018 / Published Date: Jan 22, 2018
It is believed that low chemical weathering in the desert has made it suitable for preservation and concentration of meteorites. The dry and warm climate causes low chemical weathering in the Lut Desert. But the effects of salt and temperature fluctuations, however, are the main culprits for physical fragmentation and reshaping the meteorites. The present study aims to illustrate surface morphology of meteorites in various erosion conditions in Lut Desert. To reach the purpose authors have studied surface morphology of the meteorite typed H5 which was fragmented by physical weathering in southwestern Lut Desert (yardangs region). Each piece of this meteor placed in different environment; Sandy land, salty land and lag gravel surface. The results show that meteorites are best preserved in sandy land and its outer crust remnant and that sandy land keeps more stable condition of humidity and temperature for protection meteorite from weathering so outer crust may keep thousands of years. But the most weathered part was exposed to salt and groundwater in salty land Meteorite on lag gavel surface are well developed under wind sculpture and show polished surface with bombardment porosity.
Keywords: Surface morphology; Meteorite; Lut Desert
Given the special geographical conditions, Lut Desert has a convenient place for preservation and seeking for meteorites. Recently a number of meteorites were found in Lut Desert and over 230 of them were recorded in Meteoritical bulletin database are accordance with the point of view . The majority of the recovered meteorites were found in the western part of Lut Desert (yardangs region) and all the recovered meteorites are ordinary chondrites (mostly typed H and L) and the majority show high weathering degrees (W3 to W4) . It seems that the meteorites of similar composition must depict similar weathering but exposure histories, weathering processes and terrestrial environment have a major role. Terrestrial environment like climate, topography, and geomorphology act a major role over Earth’s entire surface and rock weathering, so for studying meteorite weathering the terrestrial microenvironment condition must be considered. The present study aims to illustrate various surface morphology of meteorite due to various erosion conditions in Lut Desert. Reaching this goal, authors have been studied several parts of (H5) meteorite that placed on different microenvironment; Sandy land, salty land and lag gravel surface.
Lut Desert geography
The Lut Desert is now considered one of the best areas in the world for finding meteorites . Climate and surface conditions in this desert make it a high-potential region to preserve meteorites . This desert is one of the largest playa situated in southeastern Iran and includes a great diversity of arid land landforms and aeolian processes. It has the form of asymmetrical depression with a total area of about 80, 000 Km2. From topographical view it can be divided into three different regions: northern, central and southern . According to Alavipanah study  the Lut Desert, particularly the yardangs region, is characterized by an extremely arid climate with excessive summer heat and an annual rainfall less than 50 mm. Some researchers believe that the Lut Desert was determined to be the hottest point on Earth in two of three years previously evaluated with the Aqua/Modis satellite LST data .
Method to study Surface Morphology of Meteorite
In terrestrial environments, meteorites are subject to weathering processes that lead to the formation of secondary surface morphology and show external weathering of exposure meteorite to climate. The rate and form of meteorite reshaping in continents is governed by the environmental condition such as climate, soil, and geomorphology.
H chondrites have high metal concentration which subsequently makes them prone to fragment during weathering. In this work, for studying surface morphology and surface alteration processes of meteorite, several parts of H5 should be considered that found in different environment such as sandy land (or lee side), salty land and lag gravel surface in southwestern Lut Desert in Kalut, these samples previously classified and described by some researchers .
Surface Morphology of Meteorite (H5)
Some pieces of meteorite were buried in the sand during aeolian processes and we were finding them after emerging by wind blowing sediments above them, they are the best preserved ones and show less exposure time to the air. Some of these samples were placed in lee side and thus keep away from wind and water alternation. Most of the meteorites found in sandy land (H5a) keep their outer crust (Figure 1), but the most weathered parts were exposed to salt and groundwater in salty land (H5c). Soil salts dissolved by water infiltrate into meteorite by capillary forces triggered by temperature fluctuations. So the most weathered meteorite as observed in salty land that expose to atmosphere and soil characteristics. Salt weathering and input of sand into the cracks enhance fragmentation, as it is visible on the “H5c” meteorite (Figure 2).
Meteorites on lag gavel surface don’t have any protection against wind abrasion and lose their outer crust under sandblasting, so they show well developed polished surface. Wind ablation can modify the surface of these meteorites. Most of these meteorites become ventifacts with flat, wind-abraded surfaces (H5b) (Figure 3). Grooving, fluting, scalloping, boring, and/or faceting are indicative signs of interaction with wind-blown particles on them . These meteorites have a variety of wind-abraded surfaces ranging from surficial polishing to deep incision from late Pleistocene and Holocene sand grain saltation.
Results, Discussion and Conclusion
Surface morphology of meteorites reveals physical surface alteration processes in the Lut Desert. Most meteorites reveal their terrestrial environment on their surface. Surface morphology of meteorite depicts the effect of environmental condition on physical weathering of meteorite of Lut Desert. Major physical processes in desert depend on dry and hot climate and soil characteristics. In this article 3 main environments illustrate wind, salt and sand condition on physical surface of meteorite.
Results of studying surface morphology of H5 meteorite in these three environments reveals meteorite has been very weakly altered and outer crust retained in sandy land. It means meteorites were best preserved in sandy land (H5a), particularly the one hidden in sand as meteorites are more stable in humid conditions and temperature condition have custody of meteorite from weathering so their outer crust may preserve thousands of years in sands. Meteorite on lag gavel surface exposed to wind and well developed under wind abrasion so they often found with grooved, etched, or polished surfaces. They were shaped into a ventifact over thousands of years, similar to the surrounding stones. The most surface altered meteorites were exposed to salt and groundwater in Salty land with low to high salt content with wind and water erosion. This highly-weathered chondrite is fragmented into several pieces, some of them in so fine and transferred downwind in yardangs corridors.
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Citation: Kamali H, Zahabnazouri S (2018) Surface Morphology of Meteorites in Lut Desert (Iran) Environment. Astrobiol Outreach 6: 163. Doi: 10.4172/2332-2519.1000163
Copyright: © 2018 Kamali H, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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