The effect of subaerial exposure on the morphology and microstructure of stromatolites in the Cretaceous Sinyangdong Formation, Gyeongsang Supergroup, Korea 1
The effect of subaerial exposure on the morphology and microstructure of stromatolites in the Cretaceous Sinyangdong Formation, Gyeongsang Supergroup, Korea 1
复制标题
空中暴露对韩国庆尚超群白垩系新阳洞组叠层石形态和微观结构的影响 1
DOI：
10.1111/j.1365-3091.2006.00804.x
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发表时间：
2006
期刊：
影响因子：
3.5
通讯作者：
K. Woo
中科院分区：
文献类型：
--
作者：
O. Nehza;K. Woo
叠层石的形态通常受多种生物和环境因素的控制。本文研究了朝鲜半岛东南部白垩纪新洋洞组三个叠层石单元的成岩作用对其形态的影响。文中提出，陆上暴露和大气成岩作用是白垩纪新阳洞组叠层石形成的重要因素。以往对叠层石的古生物和沉积学研究主要集中在环境和生物对叠层石形态的控制上。这些因素包括沉积速率或当前速度等外在因素。明显的瞬变陆上暴露和与之相关的大气成岩作用是新阳洞组叠层石形态的主要控制因素。3个地层层位叠层石样品的结构分析表明，叠层石具有从纤维方解石逐渐过渡到泥晶层的特征的重复旋回模式，反映了叠层石生长的湖泊水文循环的变化。叠层石的生长被腐蚀的表面终止，这表明与湖泊水位下降有关的空中暴露。叠层石的生长模式主要由大气暴露过程中腐蚀衬底的形态决定。此外，浸出过程还对叠层石内部结构进行了强烈的改性。结果表明，生长形态主要由层状向柱状转变。这项研究强烈表明，成岩作用对地质历史时期湖相叠层石的形态形成有非常重要的影响。
Stromatolite morphology is usually controlled by a number of biological and environmental factors. In the south‐eastern part of the Korean Peninsula, three stromatolite units of the Cretaceous Sinyangdong Formation have been studied with regard to the effect of diagenesis on their morphology. Here, it is proposed that subaerial exposure and meteoric diagenesis are the most significant factors in shaping the stromatolites of the Cretaceous Sinyangdong Formation. Most previous palaeontological and sedimentological studies on stromatolites have concentrated on the environmental and biogenic controls on stromatolite morphology. These include extrinsic factors such as sedimentation rates or current velocities. The main controlling factor on the morphology of the stromatolites in the Sinyangdong Formation is apparently transient subaerial exposure and related meteoric diagenesis. Textural examination of stromatolite samples from three stratigraphic horizons shows a characteristic repetitive pattern of cycles with gradual transition from fibrous calcite to micrite layers, reflecting changes in the hydrological cycle of the lake in which the stromatolites grew. Stromatolite growth was terminated by corroded surfaces indicative of subaerial exposure related to a fall in lake level. The growth pattern of the stromatolites was mostly determined by the morphology of the corroded substrates during subaerial exposure. Furthermore, the internal stromatolite structure was strongly modified by the process of leaching. As a result, growth forms mostly changed from stratiform to columnar mesostructure. This study strongly implies that diagenesis could make a very significant influence on the morphogenesis of lacustrine stromatolites in the geological past.