淡水硅藻的实验分离:区分破碎的化学和物理原因

IF 1.5 4区地球科学 Q2 GEOLOGY

Palaios Pub Date : 2023-03-31 DOI:10.2110/palo.2021.047

G. Hassan, M. Díaz

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引用次数: 1

摘要

摘要:湖盆破碎是影响潘潘亚浅水湖泊硅藻保存的主要地理因素之一。尽管对现存和化石材料进行的埋藏学研究已经证明了这一点，但人们对断裂的原因及其环境意义知之甚少。沿着现代环境梯度的野外研究表明，溶蚀与破碎的相关性虽低，但显著。风作用对沉积物的再加工也被认为是对野外观测到的破碎模式的合理解释。为了评估硅藻破碎的化学和物理原因的相对重要性，进行了三个实验室实验来测试(1)物理搅拌的影响;(2)化学溶解的效果;(3)两个变量对硅藻破碎度的共同影响。硅藻样品在250 rpm的往复振动筛上进行物理搅拌20天。将硅藻组合物与不同浓度的NaCl和NaHCO3、pH值为10的溶液混合20 d，测试其化学溶解性。通过将硅藻组合溶解在盐溶液中并同时在250 rpm下搅拌20天来测试这两种过程的联合效应。在所有情况下，每个组合的等分在初始和最终实验时间取样，并通过应用破碎和溶解指数分析其保存情况。在单独溶解实验和联合实验中，破碎指数都有显著的相似的差异，但在单独搅拌的样品中没有发现差异。在所有情况下，溶蚀和破碎指数均呈相关关系，表明两者之间存在因果关系。综上所述，我们的研究结果表明，化学溶解对硅藻壳的削弱可能是潘潘亚浅水湖泊表层沉积物破碎模式的主要原因。

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EXPERIMENTAL TAPHONOMY OF FRESHWATER DIATOMS: DISCRIMINATING BETWEEN CHEMICAL AND PHYSICAL CAUSES OF FRUSTULE FRAGMENTATION

Abstract: Frustule fragmentation is one of the major taphonomic factors affecting diatom preservation in Pampean shallow lakes. Although this has been demonstrated by taphonomic studies conducted on extant and fossil material, little is known about the causes of frustule breakage and its environmental significance. Field studies along modern environmental gradients showed a low but significant correlation between dissolution and fragmentation. Reworking of sediments by wind action has also been suggested as a plausible explanation for the fragmentation patterns observed in the field. To evaluate the relative importance of chemical and physical causes of diatom fragmentation, three laboratory experiments were conducted to test for (1) the effect of physical agitation; (2) the effect of chemical dissolution; and (3) the joint effect of both variables on diatom fragmentation. Diatom samples were subjected to physical agitation with a reciprocating shaker at 250 rpm for 20 days. Chemical dissolution was tested by mixing diatom assemblages with solutions of different concentrations of NaCl and NaHCO3, and pH 10 for 20 days. The joint effect of both processes was tested by dissolving diatom assemblages in salt solutions and subjecting them simultaneously to agitation for 20 days at 250 rpm. In all cases, aliquots of each assemblage were sampled at initial and final experimental times and their preservation analyzed via the application of fragmentation and dissolution indices. Significant and similar differences in fragmentation indices were observed in both dissolution alone and combined experiments, but no differences were found in samples subjected to agitation alone. In all cases, dissolution and fragmentation indices were correlated, suggesting a causal relationship between them. Overall, our results suggest that the debilitation of the diatom frustule by chemical dissolution may be the main cause of the fragmentation patterns observed in surface sediments of Pampean shallow lakes.

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来源期刊

Palaios 地学-地质学

CiteScore

2.80

自引率

12.50%

发文量

审稿时长

6 months

期刊介绍： PALAIOS is a monthly journal, founded in 1986, dedicated to emphasizing the impact of life on Earth''s history as recorded in the paleontological and sedimentological records. PALAIOS disseminates information to an international spectrum of geologists and biologists interested in a broad range of topics, including, but not limited to, biogeochemistry, ichnology, paleoclimatology, paleoecology, paleoceanography, sedimentology, stratigraphy, geomicrobiology, paleobiogeochemistry, and astrobiology. PALAIOS publishes original papers that emphasize using paleontology to answer important geological and biological questions that further our understanding of Earth history. Accordingly, manuscripts whose subject matter and conclusions have broader geologic implications are much more likely to be selected for publication. Given that the purpose of PALAIOS is to generate enthusiasm for paleontology among a broad spectrum of readers, the editors request the following: titles that generate immediate interest; abstracts that emphasize important conclusions; illustrations of professional caliber used in place of words; and lively, yet scholarly, text.