Cretaceous lacustrine stromatolites in the Gyeongsang Basin (Korea): Records of cyclic change in paleohydrological condition
Cretaceous lacustrine stromatolites in the Gyeongsang Basin (Korea): Records of cyclic change in paleohydrological condition
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庆尚盆地（韩国）白垩纪湖相叠层石：古水文条件循环变化的记录
DOI：
10.1007/bf02910193
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发表时间：
2004
影响因子：
1.2
通讯作者：
K. Lee
中科院分区：
文献类型：
--
作者：
K. Woo;B. Khim;H. Yoon;K. Lee
韩国庆尚超群新阳洞组中白垩世湖相叠层石的结构观察和稳定同位素分析表明，交替纹层保存了受局部古气候影响的古水文条件的旋回变化。这些交替的片层是重复的，由下层纤维状方解石和上层微生物微晶层组成，形成对联，分别约2-5毫米厚。从下到上的边界总是层次分明的，但从上到下的边界是尖锐和陡峭的，这不仅反映了生长的停止，也反映了地面上的溶解。从纤维状方解石到微生物泥晶的δ~(18)O的富集度是一致的，表明叠层石生长的干燥阶段由于强烈的蒸发作用而降低了古湖面。δ~(13)C从纤维状方解石到微生物微晶的同时和共生亏损表明，由于古生产力的下降和湖泊水位的降低，有机质的衰变提供了更多的有效碳原子。这些结构和同位素组成的系统趋势可能与当地的古气候变化有内在联系。
Textural observation and stable isotope analyses of middle Cretaceous lacustrine stromatolites of the Sinyangdong Formation, Gyeongsang Supergroup (Korea) reveal that the alternating laminations preserve the cyclic change of paleohydrological conditions influenced by local paleoclimate. These alternating laminations are repetitive, consisting of a lower fibrous calcite and an upper microbial micrite layer forming a couplet, which is individually about 2–5 mm thick. The lower-to-upper boundaries are always gradational, but upper-to-lower boundaries are sharp and abrupt, reflecting not only cessation of growth but also subaerial dissolution. A δ18O enrichment from fibrous calcite to microbial micrite is consistent, indicating lowering of paleolake level mainly due to strong evaporation during the dry period when the stromatolite grew. Simultaneous and coeval depletion in δ13C from fibrous calcite to microbial micrite suggests that more available are12C atoms provided by the decay of organic matter due to the decreasing paleoproductivity and lowering lake level. These systematic trends of texture and isotopic composition may be intrinsically linked to local paleoclimate change.