CAJ | 학술논문

伴生碳酸盐矿物在海底与天然气水合物伴生是一种普遍现象，但在陆上冻土区中报道较少。以近两年在祁连山冻土区发现天然气水合物伴生的碳酸盐矿物为研究对象，根据对含碳酸盐样品的显微镜观察及矿物分析，确定了伴生碳酸盐的矿物种属及赋存状态。按碳酸盐矿物组成及地质产状的不同，其赋存状态分成4种类型，即白色薄层状、烟灰色菱形晶簇状、深灰色薄壳状、微细浸染状。根据不同赋存形态碳酸盐的 C、O 同位素特征，认为烟灰色菱形晶簇状方解石或呈（云烟状）微晶方解石可能与天然气水合物分解有关。碳酸盐 C、O 同位素随深度变化特征表明在一定深度处可能存在着烃类物质的活动，即天然气水合物分解，导致碳酸盐的矿物生成。
반생탄산염광물재해저여천연기수합물반생시일충보편현상，단재륙상동토구중보도교소。이근량년재기련산동토구발현천연기수합물반생적탄산염광물위연구대상，근거대함탄산염양품적현미경관찰급광물분석，학정료반생탄산염적광물충속급부존상태。안탄산염광물조성급지질산상적불동，기부존상태분성4충류형，즉백색박층상、연회색릉형정족상、심회색박각상、미세침염상。근거불동부존형태탄산염적 C、O 동위소특정，인위연회색릉형정족상방해석혹정（운연상）미정방해석가능여천연기수합물분해유관。탄산염 C、O 동위소수심도변화특정표명재일정심도처가능존재착경류물질적활동，즉천연기수합물분해，도치탄산염적광물생성。
It is a universal phenomenon for gas hydrate associated carbonates in seafloor sediments,but it is rarely reported in the permafrost.Based on microscopic observations and mineral analyses on carbonates associ-ated with gas hydrate,mineral species and occurrence modes of carbonates are determined in the Qilian Moun-tain permafrost.The results show that occurrence modes of carbonates can be divided into four types according to mineral compositions and geological features.Characteristics of C and O isotopes in different occurrence modes of carbonates indicate that the smoky gray rhombic calcite crystals or microcrystalline calcites may be re-lated to gas hydrate decomposition.The variation of C and O isotopic compositions in carbonates with depth sug-gests that there probably exist hydrocarbon seepage activities within a certain depth,namely decomposition of gas hydrate,resulting in carbonate formation.