Nutman Allen P
Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia.
Science. 2006 Feb 10;311(5762):779; author reply 779. doi: 10.1126/science.1120977.
Watson and Harrison (Reports, 6 May 2005, p. 841) interpreted low temperatures (approximately 700 degrees C) for Hadean zircons as evidence of the existence of wet, minimum-melting conditions within 200 million years of solar system formation. However, high-temperature melts (approximately 900 degrees C) are zircon-undersaturated and crystallize zircon only after substantial temperature drop during fractional crystallization. Zircon thermometry cannot distinguish between low- and high-temperature Hadean igneous sources.
沃森和哈里森（《报告》，2005年5月6日，第841页）将冥古宙锆石的低温（约700摄氏度）解释为太阳系形成2亿年内存在潮湿的最低熔融条件的证据。然而，高温熔体（约900摄氏度）是锆石不饱和的，并且仅在分离结晶过程中温度大幅下降后才结晶出锆石。锆石测温法无法区分低温和高温的冥古宙火成岩源。
