【摘要】 大别-苏鲁造山带的大理岩分布非常广泛,在三叠纪的陆-陆碰撞中,经受了不同程度的变质作用。本文对分布在大别地区北淮阳、苏家河、桐柏、宿松和苏鲁地区张八岭、五莲和坪上等地区的浅变质大理岩进行了碳氧同位素分析。结果发现,除了张八岭大理岩δ¹³C值出现明显正异常（1‰～8‰）外,其他地区大理岩的δ¹³C值均处于0±2‰（PDB）范围之内。所有地区大理岩的δ¹⁸O值都有不同程度的降低,最低的δ¹⁸O值达到4.5‰（SMOW）。与前人对大别-苏鲁超高压大理岩碳氧同位素研究结果相对比,我们发现大理岩δ¹³C值分布与岩石是否经过超高压没有联系,而主要反映了其原岩沉积的时代和环境,并且其特征可以与发生在新元古代的冰川事件相关联。区域性的δ¹⁸O值降低则说明,大部分岩石都经过了流体交换,并且流体的主要成分是水,含碳很少或者不舍碳,因此流体的来源是大气降水,可能与新元古代冰川溶融有关。更多还原

【Abstract】 Marbles are widely outcroped in the Dabie-Sulu orogenic belt, but they experienced different grades of metamorphism during the Triassic collision between Sino-Korean and Yangtze Cratons. Carbon and oxygen isotope analyses were carried out for marbles from Beihuanyang, Sujiahe, Tongbo and Susong in the Dabie region, and from Zhangbaling, Wulian and Pingshang in the Sulu region. The results show that only the samples from Zhangbaling are characterized by significantly positive δ13 C values, the other samples have δ13C values close to 0±2‰ ( PDB) . There is no correlation between δ13C value and metamorphic grade. The variations in marble δ13 C are considered to mainly reflect the features of the age and environment of protolith precipitation, in which the positive δ13C values can be related to global glaciations during the Neoproterozoic. All the marbles show decreased δ18 O values relative to marine limestones, with the lowest one at 4. 5‰ (SMOW). The regional decrease in δ18 O is consistent with hydrothermal alteration during the middle Neoproterozoic, resulting in the very low δ18 O values. The fluid involved was mainly composed of surface water without significant amounts of carbon, and thus is derived from the meteoric water relevant to deglaciation.更多还原