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首页> 外文期刊>Palaios: An International Journal of the Society of Economic Paleontologists & Mineralogists >PUNCTUATED GROWTH OF MICROBIAL CONES WITHIN EARLY CAMBRIAN ONCOIDS, BAYAN GOL FORMATION, WESTERN MONGOLIA
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PUNCTUATED GROWTH OF MICROBIAL CONES WITHIN EARLY CAMBRIAN ONCOIDS, BAYAN GOL FORMATION, WESTERN MONGOLIA

机译：蒙古西部巴彦G尔组早寒武世体中的锥状点状生长

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Oxygen bubbles produced during photosynthesis internally deform filamentous cyanobacterial mats, producing distinctive fenestral patterns. Similar textures preserved in ancient microbialites are useful biosignatures when filaments are no longer preserved, but have typically been observed within stromatolites. This study describes bubble-associated fenestrae within oncoids from the early Cambrian Bayan Gol Formation of Mongolia. Fenestrae appear in mm-scale micritic laminae which contain dense accumulations of large (10 x 300 mu m) filamentous Girvanella microfossils. Many laminae are not spherical, often occurring with one flat side opposite a conical peak. Up to six generations of conical geometry are present, with each cone rotated with respect to the previous peak. We hypothesize that the oncoids experienced intermittent disturbances followed by periods of stasis and vertical growth. During resting periods, we hypothesize that flat areas formed the oncoid resting base and peaked areas the top. The presence of bubble laminae within peaks implies formation in part via entrapment of microbially produced gases. Examples of resting oncoids growing into stromatolites are well known, as well as irregularly laminated oncoids with no cones; the Bayan Gol Formation samples are intermediate between typical spherical oncoids and stromatolites. The preservation of cones also provides evidence for relatively rapid mineralization in the Cambrian ocean, as antecedent microbial tufts would likely have collapsed if disturbed before calcification.
机译：光合作用过程中产生的氧气气泡会在内部使丝状蓝细菌垫变形，从而产生独特的女性特征。当不再保留细丝时，在古代微辉石岩中保留的相似质地是有用的生物特征，但通常在叠层石中观察到。这项研究描述了蒙古寒武纪巴彦G尔组的类瘤体中与气泡相关的窗孔。窗孔出现在毫米级的微片状薄片中，其中包含大量（10 x 300微米）丝状Girvanella微化石的密集堆积。许多薄层不是球形的，通常发生在与圆锥形峰相对的一侧。最多可产生六代圆锥几何形状，每个圆锥相对于先前的峰旋转。我们假设类癌经历了间歇性干扰，随后出现停滞期和垂直生长。在休息期间，我们假设平坦区域形成了类瘤体的休息基础，而顶部则形成了尖峰区域。峰内气泡层的存在意味着部分地通过截留微生物产生的气体而形成。生长到叠层石中的静止的类瘤以及无锥状不规则层压的类瘤的例子是众所周知的。 Bayan Gol地层样品介于典型的球形类瘤体和叠层石之间。视锥的保存还为寒武纪海洋中相对较快的矿化提供了证据，因为如果在钙化之前受到干扰，先前的微生物簇可能会塌陷。

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