Mysterious abrupt carbon-14 increase in coral contributed by a comet
By:Liu, Y (Liu, Yi)[ 1 ] ; Zhang, ZF (Zhang, Zhao-feng)[ 2 ] ; Peng, ZC (Peng, Zi-cheng)[ 1 ] ; Ling, MX (Ling, Ming-xing)[ 2 ] ; Shen, CC(Shen, Chuan-chou)[ 3 ] ; Liu, WG (Liu, Wei-guo)[ 4 ] ; Sun, XC (Sun, Xiao-chun)[ 5 ] ; Shen, CD (Shen, Cheng-de)[ 2 ] ; Liu, KX (Liu, Ke-xin)[ 6,7 ] ; Sun, WD (Sun, Weidong)[ 8 ]
Article Number: 3728
Published: JAN 16 2014
A large and sudden increase in radiocarbon (C-14) around AD773 are documented in coral skeletons from the South China Sea. The C-14 increased by similar to 15 parts per thousand during winter, and remain elevated for more than 4 months, then increased and dropped down within two months, forming a spike of 45 parts per thousand high in late spring, followed by two smaller spikes. The C-14 anomalies coincide with an historic comet collision with the Earth's atmosphere on 17 January AD 773. Comas are known to have percent-levels of nitrogen by weight, and are exposed to cosmic radiation in space. Hence they may be expected to contain highly elevated C-14/C-12 ratios, as compared to the Earth's atmosphere. The significant input of C-14 by comets may have contributed to the fluctuation of C-14 in the atmosphere throughout the Earth's history, which should be considered carefully to better constrain the cosmic ray fluctuation.