Impact-related Indicator of Grains with Akaganeite Composition Found at Takamatsu, Kuga, Nio (japan) and Carancas (peru)

Introduction: Grains of composition with Fe, Ni and Cl are reported as relicts of awaruite (in mafic minerals of olivine and serpentine from the interior of the Earth) [1] or meteoritic mixture found originally at the fusion crust melted in atmosphere [2, 3, 4]. Recently author (YM) discusses that carbon contents of these phases are significant to discuss the sources of Fe, Ni and Cl [2, 3, 4, 5]. The purpose of this paper is to elucidate chlorine (Cl)-bearing Fe and Ni phases originated from impact projectiles of meteoroids (Takamatsu, Nio, Kuga and Carancas) compared with awaruite (Dumont, Canada) by the FE-SEM with EDX analyzer (JEOL7000F), Yamaguchi, Japan [2, 3, 4, 5]. Carbon-bearing Fe and Ni grains in veins of terrestrial mafic rocks in Canada: Ni-rich Dumont dunite sample [1] contains Fe and Ni grains (as awaruite composition) “without chlorine contents” (i.e. not akaganeite composition in this study for comparison), though serpentine vein has significant chlorine contents, whereas significant carbon content are found in Ni, Fe, Mg-rich grains [5]. Chlorine-bearing Fe and Ni akaganeite grains from Takamatsu, Kagawa, Japan: Sample from Takamatsu is buried crater at Busshozan-Cho, Takamatsu City, Kagawa Prefecture (in center site) which are reported by (a) geophysical data, (b) shocked data and (c) broken by tectonic movement during the Japan islands formation [6, 7, 8, 9], where sample used in this study is mixed sample of impacted and volcanic later-uplifted from the crater bottom (Fig.1). Significant Cl-contents (ca.2wt%Cl) of Fe and Ni-rich grains (with akaganeite composition, Fig. 2) on melted glasses with granitic composition are found at the southern rim of the buried crater structure, where crystalline shape with 2x3x4 micrometers (Fig.3). The texture and composition of sample are melted of basement rocks of granite and found at mountain rim side lifted from deeper crater bottom, which are estimated from relict composition of grain with Na, Ca, K, Si and Al contents. Table 1 shows that crystalline grain with akaganeite composition (shown in Fig.3) is secondary mineral formed at melting condition to form granitic grasses after impact event which is lifted masses during Japan islands formation [7, 8, 9]. It is found in the FE-SEM analyses with in-site sample observation (to avoid mixture from sample preparation) that significant carbon-contents can be obtained in the melted samples,