ErosiĆ³n de Yardangs en la formaciĆ³n Fossae Medusae en Marte asociada a la ocurrencia de tormentas de polvo globales
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2022
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es
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Universidad AndrƩs Bello
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La formaciĆ³n Fossae Medusae (MFF) se ubica en la regiĆ³n ecuatorial de Marte. Ćsta se reconoce por la gran cantidad de yardangs que presenta generados por la influencia eĆ³lica que ha recibido a lo largo de los aƱos. Mandt et al., (2008) consideraron que el origen mĆ”s apropiado de la MFF corresponde a un depĆ³sito de ignimbritas.
Por otro lado, las tormentas de polvo globales son eventos atmosfĆ©ricos poco comprendidos en cuanto a su dinĆ”mica, intensidad e interacciĆ³n con la superficie marciana. Actualmente, esta formaciĆ³n se considera la principal fuente de polvo a largo plazo de las tormentas de polvo globales que se producen en el planeta.
Este estudio pretende determinar nuevas evidencias de erosiĆ³n en yardangs localizados en la MFF tras la ocurrencia de las tormentas de polvo globales MY 28 y MY 34 para contribuir al conocimiento sobre de estos fenĆ³menos atmosfĆ©ricos a partir de un punto de vista geomorfolĆ³gico.
Los resultados se obtienen utilizando imĆ”genes CTX para medir las orientaciones e identificar la forma de los yardangs, y mapas de viento obtenidos a partir de los Modelos de CirculaciĆ³n General (GCM) que permiten determinar la dinĆ”mica de estas tormentas con el terreno. Las evidencias de erosiĆ³n en yardangs encontradas en las imĆ”genes tras la ocurrencia de estos dos eventos se relacionan con las caracterĆsticas geomorfolĆ³gicas generales del MFF, y con las propiedades mecĆ”nicas de las rocas asociadas a facies de ignimbritas, para determinar la intensidad relativa de las tormentas.
Este estudio ha permitido evidenciar la erosiĆ³n en los yardangs generada por estas dos tormentas de polvo globales, haciendo menciĆ³n a la gran influencia eĆ³lica que recibieron las rocas. Esta erosiĆ³n forma nuevas estructuras en los yardangs siguiendo las orientaciones del rĆ©gimen de vientos que rige la zona.
Las irregularidades topogrĆ”ficas contribuyen a una intensificaciĆ³n local de los vientos. Esta contribuciĆ³n, unida a las propiedades mecĆ”nicas de las rocas susceptibles de erosiĆ³n, disminuye de W a E, provocando que la erosiĆ³n se produzca en diferentes grados a lo largo del MFF. AdemĆ”s, la comparaciĆ³n cualitativa de estos resultados permitiĆ³ establecer que la tormenta de polvo global MY 34 fue mĆ”s intensa que la MY 28.
Dado que la MFF estarĆa compuesta por facies de ignimbrita y que tiene un alto nivel de erosiĆ³n, Ć©sta puede considerarse una fuente de polvo a largo plazo porque la superficie presenta cambios geomorfolĆ³gicos significativos despuĆ©s de cada tormenta de polvo.
The Fossae Medusae Formation (MFF) is located in the equatorial region of Mars. It is recognized by an extensive yardang formation created by the intense aeolian influence it has received over the years. Mandt et al., (2008) considered that the most appropriate origin of the MFF corresponds to a deposit of ignimbrites. On the other hand, the global dust storms are poorly understood atmospheric events in terms of their dynamic, intensity, and interaction with the martian surface. Currently, this formation is considered the main long-term dust source for global dust storms that occur on the planet. This study aims to determine new evidence of erosion in yardangs located at MFF after global dust storms MY 28 and MY 34 to contribute to the knowledge of these atmospheric phenomena from a geomorphological point of view. The results are obtained by using CTX images to measure the yardang orientations and recognize their shape. Wind maps were obtained from the General Circulation Models (GCM) developed by the LMD Planetology Team, which will determine the dynamics of these storms with the terrain. The evidence of erosion in yardangs found after these two events will be related to the general geomorphological characteristics of the MFF, and with mechanical properties of the rocks associated with ignimbrite facies to determine the relative intensity of the storms. This study has allowed evidencing the erosion in yardangs generated by these two global dust storms, mentioning the great aeolian influence that the rocks received. This erosion forms new structures in yardangs following the wind regime's orientations that govern the area. Topographic irregularities contribute to a local intensification of winds. This contribution, coupled with the mechanical properties of rocks susceptible to erosion, decreases from west to east, causing erosion to occur with different intensities along the MFF. In addition, the qualitative comparison of these results made it possible to establish that the dust storm from MY 34 was more intense than the dust storm from MY 28. As the MFF is mainly composed of ignimbrite and has a high level of erosion, it can be considered a long-term dust source because the surface presents significant geomorphological changes after each dust storm.
The Fossae Medusae Formation (MFF) is located in the equatorial region of Mars. It is recognized by an extensive yardang formation created by the intense aeolian influence it has received over the years. Mandt et al., (2008) considered that the most appropriate origin of the MFF corresponds to a deposit of ignimbrites. On the other hand, the global dust storms are poorly understood atmospheric events in terms of their dynamic, intensity, and interaction with the martian surface. Currently, this formation is considered the main long-term dust source for global dust storms that occur on the planet. This study aims to determine new evidence of erosion in yardangs located at MFF after global dust storms MY 28 and MY 34 to contribute to the knowledge of these atmospheric phenomena from a geomorphological point of view. The results are obtained by using CTX images to measure the yardang orientations and recognize their shape. Wind maps were obtained from the General Circulation Models (GCM) developed by the LMD Planetology Team, which will determine the dynamics of these storms with the terrain. The evidence of erosion in yardangs found after these two events will be related to the general geomorphological characteristics of the MFF, and with mechanical properties of the rocks associated with ignimbrite facies to determine the relative intensity of the storms. This study has allowed evidencing the erosion in yardangs generated by these two global dust storms, mentioning the great aeolian influence that the rocks received. This erosion forms new structures in yardangs following the wind regime's orientations that govern the area. Topographic irregularities contribute to a local intensification of winds. This contribution, coupled with the mechanical properties of rocks susceptible to erosion, decreases from west to east, causing erosion to occur with different intensities along the MFF. In addition, the qualitative comparison of these results made it possible to establish that the dust storm from MY 34 was more intense than the dust storm from MY 28. As the MFF is mainly composed of ignimbrite and has a high level of erosion, it can be considered a long-term dust source because the surface presents significant geomorphological changes after each dust storm.
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Tesis (GeĆ³logo)
Palabras clave
Tormentas de polvo globales, Influencia eĆ³lica, FenĆ³menos atmosfĆ©ricos, MediciĆ³n por imĆ”genes, Chile