Fourier Transform Infrared Spectroscopy Studies of Cretaceous Gymnosperms from the Santa Cruz Province, Patagonia, Argentina
Fourier Transform Infrared Spectroscopy Studies of Cretaceous Gymnosperms from the Santa Cruz Province, Patagonia, Argentina
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DOI：
10.1086/714283
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发表时间：
2021-03
影响因子：
2.3
通讯作者：
Maiten A. Lafuente Diaz;Georgina M. Del Fueyo;J. D'Angelo;Martín A. Carrizo
中科院分区：
文献类型：
--
作者：
Maiten A. Lafuente Diaz;Georgina M. Del Fueyo;J. D'Angelo;Martín A. Carrizo
研究的前提。本文介绍了出露于阿根廷圣克鲁斯省的Anfiteatro de Ticó和Punta del Barco组(Baquerógroup；Aptian)和SpringHill(Hauteriian-Barremian)以及Piedra Clavada/Kachaike(Albian)组的裸子植物化石遗骸的光谱特征，这些化石属于蕨类植物门、苏铁藻门、银杏门和松柏藻门。从这些岩石地层单位中，选择了几个化石类群的标本，这些标本表明在巴塔哥尼亚下白垩统存在着多样化的植物组合。方法论。这些化石由叶面挤压而成，角质层保存完好，用傅里叶变换红外光谱对其化学特征进行了表征。叶片残留物以两种样本形式进行分析：(1)压榨(CPS；包括结合的叶肉和角质层)和(2)角质层(CTS)。此外，通过主成分分析对半定量数据进行了评估，揭示了所有分析的化石分类群在叶肉和角质层水平上保存的功能基团。关键成果。总体而言，Baqueró群的物种在Cp和Ct样品形式之间显示出相似的化学成分，而SpringHill和Piedra Clavada/Kachaike组的叶压化学表明，组成角质层的芳香结构具有很高的比例。结论。在成岩过程中和成岩后，龙须草、银杏和虎鳞鱼的挤压作用可能经历了一次自然氧化过程，很可能是由巴克罗群阿普提安沉积期间反复发生的火山活动引起的。与之相反，红景天、小乳突银杏和银杏的角质层可能也含有芳香结构(如苯丙烷和芳香域)，这是由于其他酚类化合物的存在。本文提出了一个新的术语--玻璃化压缩，并将Ornata、G.tigrensis、S.tigrensis、P.microPapillosum和R.orlandoi称为脂质压缩。
Premise of research. In this contribution, the spectroscopic characterization of gymnosperm fossil remains belonging to Pteridospermophyta, Cycadophyta, Ginkgophyta, and Coniferophyta collected from the Anfiteatro de Ticó and Punta del Barco Formations (Baqueró Group; Aptian) and Springhill (Hauterivian-Barremian) and Piedra Clavada/Kachaike (Albian) Formations, outcropping in the Santa Cruz Province, Argentina, is presented. From these lithostratigraphic units, specimens of several fossil taxa showing the existence of a diverse plant assemblage during the Lower Cretaceous in Patagonia were selected. Methodology. The fossils consist of foliar compressions with very well-preserved cuticles, which are chemically characterized by Fourier transform infrared spectroscopy. Foliar remains are analyzed in two sample forms: (1) compressions (Cps; including coalified mesophyll and cuticles) and (2) cuticles (Cts). Additionally, semiquantitative data are evaluated through principal component analysis, revealing the functional groups preserved at the mesophyll and cuticle levels for all analyzed fossil taxa. Pivotal results. In general, the species from the Baqueró Group show similar chemical compositions between the Cp and Ct sample forms, whereas the chemistry of the foliar compressions from the Springhill and Piedra Clavada/Kachaike Formations reveals the presence of a high contribution of aromatic structures making up the cuticles. Conclusions. The compressions of Pseudoctenis ornata, Ginkgoites tigrensis, and Squamastrobus tigrensis probably underwent, during and after diagenesis, a natural oxidation process most likely caused by the recurrent volcanic activity that occurred during the Aptian sedimentation of the Baqueró Group. In contrast, Ruflorinia orlandoi, Ptilophyllum micropapillosum, and Ginkgoites skottsbergii have cuticles presumably composed of highly aromatic structures (such as phenylpropanoids and aromatic domains) in cutins and cutans as well due to the presence of other phenolic compounds. A new term, vitrinitic compression, is proposed here for G. skottsbergii, while P. ornata, G. tigrensis, S. tigrensis, P. micropapillosum, and R. orlandoi are called liptinitic compressions.