莓状黄铁矿:环境与生命的示踪计

莓状黄铁矿这一奇妙的微晶(0.1~1 μm)矿物集合体(5~50 μm)自科学家首次发现(1923年)和冠名(1935年)至今一直是不同学科竞相研究的热点.主要从莓状黄铁矿的形成机制、莓状黄铁矿与环境的关系等方面回顾了莓状黄铁矿的生物成因说(1923-1969年)、非生物成因说(1969-2000年)和多元成因说(2000-现今)各研究阶段取得的进展和存在的问题,指出莓状黄铁矿作为表层生物圈、深部生物圈和地外环境与生命示踪计具有巨大潜力,提出从地球科学、生命科学、材料科学、化学和纳米科技以及凝聚态物理学融合的角度加强对莓状黄铁矿研究的建议.      

Classification and origin of natural gases from Lishui Sag,the East China Sea Basin

Natural gases discovered up to now in Lishui Sag,the East China Sea Basin,differ greatly in gaseous compositions,of which hydrocarbon gases amount to 2%―94%while non-hydrocarbon gases are dominated by CO2.Their hydrocarbon gases,without exception,contain less than 90%of methane and over 10%of C2 heavier hydrocarbons,indicating a wet gas.Carbon isotopic analyses on these hydrocarbon gases showed thatδ13C 1 ,δ13C 2 andδ13C 3 are basically lighter than-44‰,-29‰and-26‰, respectively.The difference in carbon isotopic values between methane and ethane is great,suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation.δ13C CO2 values of nonhydrocarbon gases are all heavier than-10‰,indicating a typical abiogenic gas.The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit,consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter.Moreover, δ13C 1 values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit whileδ13C 2 andδ13C 3 values of the former are over 9‰heavier than those of the latter.Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag,where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter,therefore,natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks.