Micro-remnants of carbon- and calcium-bearing impact breccias of buried crater broken at Takamatsu, Japan

Introduction: Impact evidences are discussed by 30 extraterrestrial-rich elements and shocked minerals in microscopic sizes. Micro-remnants during impact reactions can be obtained by impact breccias. Impact evidences at buried and broken impact crater structure in Takamatsu, Shikoku, Japan have been reported mainly by gravity anomaly and shocked-related materials on the Cretaceous Ryoke granite [1-10]. Anomalous materials with carbon-bearing materials and impact-related materials which are not usually included in the Japanese granitic rocks are found at the drilled materials. Main purposes of the paper are to elucidate carbon- and calcium-bearing micro-particles at the drilled samples of Takamatsu, Shikoku, Japan [9-10]. Anomalous carbon and calcium-bearing micro-grains: The Ryoke granitic rock at Takamatsu, Japan has few carbon and calcium contents in bulk XRF analyses from surface to 1,500m in depth. However, drilled sample at 950 m in depth contains nano-grains with high carbon and CaSiCO3 (in 100nm size) in composition. Carbon-rich grains in Takamatsu show very weak nano-diamond-like peak in the Raman spectra which are formed at impact reaction on carbon-rich target rock. Formation of remained carbon-bearing grains: Main sources of carbon and calcium which cannot be found in the granitic rock are sedimentary rocks as follows: 1) Carbon sources mainly found near at crater bottom (ca. 950m in depth) are considered to be impact target rocks of sedimentary limestone (from sea-sediments) with carbon dioxides gas during impact reaction on sea-water impact. 2) Calcium sources to form nano-grains of CaSiCO3 in composition are also considered to be sedimentary limestone and silicate-bearing rocks stored in the shallow sea-bottom. Summary: The present study is summarized as follows: a) Carbon-rich frilled sample of 950m in depth at buried crater in Takamatsu, Japan are indicates the main sources from shallow sea-limestone during impact reaction on shallow sea-impact. b) Calcium-rich sources to form micro-grains of CaSiCO3 in composition are considered to be shallow sea- limestone during sea-impact reaction.