In the terrestrial planet zone, Comets start outgassing due to solar radiation. This can make comet composition fragile enough to break under the gravitational gradient. Examples like those of Comet Shoemaker-Levy 9 [...In the terrestrial planet zone, Comets start outgassing due to solar radiation. This can make comet composition fragile enough to break under the gravitational gradient. Examples like those of Comet Shoemaker-Levy 9 [1] show that it is not unusual for comets to disintegrate due to gravitational gradients. In the event of an impact of such a disintegrated comet on earth, multiple coherent impact craters will be distributed over a large area. The low-density porous composition of the comet will result in the formation of “large flat-floored craters” spread over a large area with a network of faults and fractures as described by Roddy and co-workers (Roddy, 1976;Roddy et al., 1977) [2] [3]. Due to its unusual appearance these impacts patterns are different than rock/metal asteroid impact craters. As a result, these sites are difficult to identify. There are multiple such sites on the planet earth which are under study for impact but due to complex nature of comet impact craters, they have been a conundrum for some time. One such possible site matching the comet impact features can be observed in the southern Tibet between the latitudes of 82°30'E and 90°30'E and 29°N and 33°N. This study indicates that the lakes in this region were formed by the impact of a single disintegrating comet that hit the region. Observation indicates that the lakes are unusually closely aligned and have a steep slope facing circular feature on the eastern side. Fractures and faults connecting these lakes can be observed over entire subject site hinting towards the multiple impact craters. These craters are large flat-floored and spread over a large area. Gravitational anomaly in the lake region along with the presence of Ultra High Pressure (UHP) minerals like cubic Born Nitride, micro-diamond with the inclusion of Platinum Group Elements (PGE), coesite, Stishovite, osbornite and other complex finds in the region support the possibility of impact.展开更多
文摘In the terrestrial planet zone, Comets start outgassing due to solar radiation. This can make comet composition fragile enough to break under the gravitational gradient. Examples like those of Comet Shoemaker-Levy 9 [1] show that it is not unusual for comets to disintegrate due to gravitational gradients. In the event of an impact of such a disintegrated comet on earth, multiple coherent impact craters will be distributed over a large area. The low-density porous composition of the comet will result in the formation of “large flat-floored craters” spread over a large area with a network of faults and fractures as described by Roddy and co-workers (Roddy, 1976;Roddy et al., 1977) [2] [3]. Due to its unusual appearance these impacts patterns are different than rock/metal asteroid impact craters. As a result, these sites are difficult to identify. There are multiple such sites on the planet earth which are under study for impact but due to complex nature of comet impact craters, they have been a conundrum for some time. One such possible site matching the comet impact features can be observed in the southern Tibet between the latitudes of 82°30'E and 90°30'E and 29°N and 33°N. This study indicates that the lakes in this region were formed by the impact of a single disintegrating comet that hit the region. Observation indicates that the lakes are unusually closely aligned and have a steep slope facing circular feature on the eastern side. Fractures and faults connecting these lakes can be observed over entire subject site hinting towards the multiple impact craters. These craters are large flat-floored and spread over a large area. Gravitational anomaly in the lake region along with the presence of Ultra High Pressure (UHP) minerals like cubic Born Nitride, micro-diamond with the inclusion of Platinum Group Elements (PGE), coesite, Stishovite, osbornite and other complex finds in the region support the possibility of impact.
