New sites of Australasian microtektites in the central Indian Ocean: Implications for the location and size of source crater
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Fifteen new Australasian microtektite sites have been identified along a transect roughly N-S in the central Indian Ocean. These locations, in addition to the existing 46 sites, total to 61 microtektite sites in the oceans. We carried out regression analysis of a selected area between 12-26 degrees N and 98-112 degrees E, at 0.5 degrees intervals using three microtektite data sets separately: 41 sites, 46 sites (number of sites known up to the years 1994 and 2006, respectively), and the entire data set of 61 sites. This area was chosen because, on the basis of various lines of evidence, several investigators suggested impact craters for the strewn field within this broad area. The 41 site data set defines an impact site at about 12 degrees N and 106 degrees E. Whereas the contours joining the highest values of the square of the correlation coefficient by using 46 site and 61 site data sets define an area located in NE Thailand–central Laos, the center of this site is at 18 degrees N and 104 degrees E. Therefore with progressive increase in microtektite data the location of the impact site seems to get defined more rigorously. On the basis of the equations for the concentration of the ejecta and the distance from the source region, the calculated crater size has a diameter range between 33 and 120 km. Interestingly, the lower size limit of 33 km has been found closer to ground truth by verification from the microtektite data of the Ivory Coast strewn field.
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