Abstract The lower Paleozoic marine siliciclastic succession of the Central Andean Basin, northwestern Argentina, provides a valuable record of the onset of the Great Ordovician Biodiversification Event in western Gondwana. A new ichnospecies of rosette trace fossil, Gyrophyllites cristinae, is documented from lower and upper Tremadocian (Tr1 and Tr2) deposits of this basin. It is characterized by five to six non-overlapping petaloid lobes and can be easily differentiated from the other four formally defined ichnospecies. Gyrophyllites cristinae occurs at the top of hummocky cross-stratified sandstone regularly interbedded with mudstone. These deposits are interpreted as reflecting the alternation of high-energy storm events and low-energy fair-weather conditions immediately below the fair-weather wave base, representing deposition in offshore transition environments. Gyrophyllites has been traditionally interpreted as the product of worms of uncertain taxonomic affinity that mined the sediment in search for food (fodinichnia). The occurrence of Gyrophyllites cristinae in these Ordovician deposits records post-storm colonization. Storms may have increased oxygenation and supplied fresh organic detritus that were exploited by worm-like, surface detritus- or shallow deposit-feeders exploring the uppermost silt-rich fine-grained sediments.

中文翻译：

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Grophyllites cristinae isp。十一月 阿根廷西北部下奥陶统浅海沉积

摘要 阿根廷西北部中安第斯盆地的下古生界海相硅质碎屑岩序列为冈瓦纳西部大奥陶纪生物多样性事件的发生提供了有价值的记录。在该盆地的下部和上部 Tremadocian（Tr1 和 Tr2）沉积物中记录了一种新的玫瑰花环化石物种，Gyrophyllites cristinae。它的特点是五到六个不重叠的花瓣状裂片，可以很容易地与其他四种正式定义的鱼类物种区分开来。Gryrophyllites cristinae 产于丘状交错层理砂岩顶部，有规律地与泥岩互层。这些沉积物被解释为反映了紧接在晴朗天气波基下方的高能量风暴事件和低能量晴朗天气条件的交替，代表海上过渡环境中的沉积。传统上，叶蜡石被解释为具有不确定分类亲和性的蠕虫的产物，这些蠕虫挖掘沉积物以寻找食物（fodinichnia）。在这些奥陶纪沉积物中出现的 Gyrophylites cristinae 记录了风暴后的殖民化。风暴可能增加了氧化作用并提供了新鲜的有机碎屑，这些碎屑被蠕虫状、地表碎屑或浅层沉积物捕食者利用，探索最上层富含淤泥的细粒沉积物。