Paleoecology of Early Ladinian low-diversity radiolarian fauna from Mt. Svilaja (External Dinarides, Croatia)

IF 0.7 Q4 PALEONTOLOGY

REVUE DE MICROPALEONTOLOGIE Pub Date : 2025-04-03 DOI:10.1016/j.revmic.2025.100841

Špela Goričan , Tea Kolar-Jurkovšek , Dunja Aljinović , Tamara Troskot-Čorbić , Bogdan Jurkovšek

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引用次数: 0

Abstract

Dark-grey cherty limestone from Mt. Svilaja contains moderately well-preserved radiolarians of unusually low diversity. Nineteen genera were encountered, namely, only one fourth of genera known from the time equivalent Buchenstein Formation. Based on conodonts, the studied interval is assigned to the Lower Ladinian Budurovignathus hungaricus Zone. Ammonoids and allochthonous fossil elements (calcareous algae, corals, brachiopods, bivalves, benthic foraminifera, terrestrial-plant remains) from the same interval were previously reported. Facies and organic-matter analyses support the interpretation of depositional setting in a semi-enclosed basin with oxygen-deficient bottom waters. The radiolarian assemblage consists of spherical Entactinaria (Pentactinocarpidae, Heptacladidae, Hindeosphaeridae) and Spumellaria (Archaeocenosphaera, Paurinella, Triassospongosphaera, Spongopallium), and monocyrtid Nassellaria (mostly Hozmadia). Among Pentactinocarpidae, Lobactinocapsa ellipsoconcha Dumitrica is abundant and characterized by considerable variability of the cortical shell regarding its shape (ovoid to spherical), wall thickness (single-layered to spongy), and number of external spines. Eptingiidae, Oertlispongidae, Relindellidae, and all multicyrtid Nassellaria, common in the Buchenstein Formation as well as in radiolarian cherts associated with ophiolites, are missing. Similar, although less drastically reduced radiolarian fauna is known from the coeval San Giorgio Dolomite, which was also deposited in an oxygen-deficient intra-platform basin. The San Giorgio fauna lacks multicyrtid Nassellaria but still contains abundant Eptingiidae, Oertlispongidae, and Relindellidae. The likely factor reducing the diversity in the intra-platform basins was the vertical extent of the oxygen-deficient lower water column. Only surface-dwelling radiolarians were successful in stratified basins with expanded deep-water hypoxia.

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克罗地亚Svilaja山早拉丹世低多样性放射虫动物群的古生态学研究

来自斯维拉加山的深灰色樱桃状石灰岩含有保存较好的放射虫，其多样性异常低。他们发现了19个属，也就是说，只有四分之一的属是在同等时间的布亨斯坦地层中发现的。根据牙形刺，将研究区间划分为下拉底统Budurovignathus hungaricus带。来自同一区间的氨类和异域化石元素（钙质藻类、珊瑚、腕足类、双壳类、底栖有孔虫、陆生植物残骸）已被报道过。相和有机质分析支持对底水缺氧的半封闭盆地沉积背景的解释。放射虫群主要由球形盘虫属（Pentactinocarpidae, Heptacladidae, hinindeosphaidae）和Spumellaria （Archaeocenosphaera, Paurinella, Triassospongosphaera, sponopallium）和单圆虫属（moncytid Nassellaria，主要为Hozmadia）组成。在Pentactinocarpidae中，Lobactinocapsa ellipsoconcha Dumitrica数量丰富，其特征是皮质壳的形状（卵形到球形）、壁厚（单层到海绵状）和外棘的数量具有相当大的可变性。在Buchenstein组以及与蛇绿岩相关的放射虫岩中常见的Eptingiidae， Oertlispongidae， Relindellidae和所有多圆柱Nassellaria都缺失。类似的，虽然减少较少的放射虫动物群在同时期的圣乔治白云岩中也被发现，它也沉积在一个缺氧的台地内盆地中。圣乔治区系缺乏多圆柱鼻虫科，但仍有丰富的Eptingiidae、Oertlispongidae和Relindellidae。台内盆地多样性降低的可能因素是缺氧下水柱的垂直程度。只有表层放射虫在深水缺氧扩大的层状盆地中存活。

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来源期刊

REVUE DE MICROPALEONTOLOGIE PALEONTOLOGY-

CiteScore

2.50

自引率

0.00%

发文量

期刊介绍： La Revue de micropaléontologie publie 4 fois par an des articles de intérêt international, consacrés à tous les aspects de la micropaléontologie. Les textes, en anglais ou en français, sont des articles originaux, des résultats de recherche, des synthèses et mises au point, des comptes rendus de réunions scientifiques et des analyses de ouvrages. La revue se veut résolument ouverte à tous les aspects de la micropaléontologie en accueillant des travaux traitant de la systématique des microfossiles (et de leurs équivalents actuels), des bactéries aux microrestes de vertébrés, et de toutes leurs applications en sciences biologiques et géologiques.