Stacking patterns and growth models of multiscopic structures within Cambrian Series 3 thrombolites at the Jiulongshan section, Shandong Province, northern China
Stacking patterns and growth models of multiscopic structures within Cambrian Series 3 thrombolites at the Jiulongshan section, Shandong Province, northern China
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DOI：
10.1016/j.palaeo.2016.07.009
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发表时间：
2017-05
期刊：
影响因子：
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通讯作者：
Zhen Yan;Jianbo Liu;Y. Ezaki;Natsuko Adachi;Shengxian Du
中科院分区：
文献类型：
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作者：
Zhen Yan;Jianbo Liu;Y. Ezaki;Natsuko Adachi;Shengxian Du
北方山东九龙山剖面寒武系昌下组3统凝块岩为研究钙微构造的发育提供了一个很好的范例。由calcimicrobes构建的血栓具有特定的堆积模式，这些模式受其环境控制，并反映在微观，介观和宏观结构之间的关系中，需要我们称之为“多尺度”的方法。在高能条件下，EpiphytonA（具有密集的泥晶分叉菌体）呈散生生长，并以丛状侧向生长的方式适应环境，因为丛状向上的形态更容易被波浪或水流打破，EpiphytonA在介观水平上相互融合形成斑点状框架。斑点框架的弱阻碍导致通过优先侧向加积形成低浮雕的平板状/透镜状宏观结构。在低能量、深潮下带环境中，EpiphytonA和EpiphytonB（分叉叶状体中有微晶石）与HedstroemiaA（末端宽）和B（末端窄）共存。这些calcimicrobes生长丰富的垂直和横向方向，融合在一起，形成网状框架，或树枝状框架，如果垂直融合的灌木向上calcimicrobes是占主导地位的。网状和树枝状介观结构的优先垂直堆叠突出了这些框架主动阻挡石灰渣并最终形成大圆顶宏观结构的能力。这些多尺度结构中的堆叠模式有助于为血栓岩的环境解释提供信息。我们在这里提出的血栓生长模型提供了重要的见解，在其他情况下，特别是钙质微生物为主的早，中古生代血栓的环境解释。
The Cambrian Series 3 thrombolites from the Changhia Formation, at the Jiulongshan section in Shandong Province, northern China, provide an excellent example for studying the development of calcimicrobial structures. Thrombolites constructed by calcimicrobes have particular stacking patterns, which are controlled by their environments and are reflected in the relationships between micro-, meso- and macroscopic structures, requiring an approach we term “multiscopic”. Under high-energy conditions,EpiphytonA (with dense micritic bifurcating thalli) grew sporadically and adapted to the environment by taking a bushy-lateral form, because the bushy-upward form is more likely to be broken by waves or currents.EpiphytonA was fused with each other to form spotted frameworks at the mesoscopic level. The weak baffling of spotted frameworks led to the formation of low-relief tabular/lentoid macrostructures via preferential lateral accretion. In low-energy, deep-subtidal settings,EpiphytonA andEpiphytonB (with microsparry segments in the bifurcating thalli) coexisted withHedstroemiaA (with a wide terminal) and B (with a narrow terminal). These calcimicrobes grew abundantly in both the vertical and lateral directions, fusing together to form meshed frameworks, or dendritic frameworks if vertical fusion of bushy-upward calcimicrobes was predominant. The preferential vertical stacking of meshed and dendritic mesostructures highlights the ability of these frameworks to actively baffle lime mud, and ultimately to form large-domed macrostructures. Stacking patterns in these multiscopic structures help to inform environmental interpretations of thrombolites. The thrombolitic growth model we present here provides important insights into the environmental interpretations of thrombolites in other cases, especially the calcimicrobe-dominated early and middle Palaeozoic thrombolites.