气候变化领域集成服务门户(CCPortal): Sedimentary organic matter and early Toarcian environmental changes in the Lusitanian Basin (Portugal)

CCPortal

DOI	10.1016/j.palaeo.2020.109781
	Sedimentary organic matter and early Toarcian environmental changes in the Lusitanian Basin (Portugal)
	Rodrigues B.; Duarte L.V.; Silva R.L.; Mendonça Filho J.G.
发表日期	2020
ISSN	0031-0182
卷号	554
英文摘要	The objective of this study is to investigate the relationship between early Toarcian climatic events and the composition of kerogen assemblages in the Lusitanian Basin (Portugal). In particular, we aim to understand how the Pliensbachian–Toarcian Event (Pl–Toa Event) and Toarcian Oceanic Anoxic Event (TOAE) affected the continental areas of the western Iberian margin and how possible variations in continental sources of organic matter (OM) were expressed in marginal-marine and hemipelagic depositional environments during the early Toarcian. We present here a characterisation [total organic carbon (TOC), total sulphur (TS), δ13C in kerogen concentrate (δ13CKerogen), and palynofacies] of kerogen assemblages from several uppermost Pliensbachian (emaciatum ammonite Zone)–lower Toarcian sections in the Lusitanian Basin (western Iberian margin), including the Peniche section, which contains the Toarcian GSSP. In all sections, TOC concentration is low (average 0.4 wt.%), with the highest values reaching up to 2.1 wt.% in a discrete level located approximately 10.5 m above the base of the levisoni Zone at Peniche. The TOAE negative carbon isotope excursion is observed in kerogen concentrate at the base of the levisoni Zone throughout the basin. Palynofacies analysis demonstrates that the kerogen assemblages are mostly of terrestrial affinity, with the dominance of the Phytoclast Group and terrestrial palynomorphs, and with punctual increases in amorphous organic matter, freshwater (e.g. Botryococcus sp.) and marine microplankton (dinoflagellate cysts, acritarchs, and prasinophyte algae) in specific stratigraphic intervals. A change in palynofacies assemblages associated with the TOAE is observed around the base of levisoni Zone. Although with slight differences between sections, the TOAE interval records an increase in non-opaque, translucent, phytoclasts (NOP) and cuticle fragments, and is also associated with an increased contribution of terrestrial palynomorphs (increase in sporomorphs and Classopollis in tetrads and agglomerates) and decrease in marine palynomorphs. The increases in NOP and terrestrial palynomorphs support the postulated enhancement of the hydrological cycle and increased export of terrestrial OM into marine environments during the early Toarcian, especially during the TOAE, in the western Iberian margin. Understanding the impact of the early Toarcian climatic events on land-based ecosystems may provide important insights into current climate change. © 2020 Elsevier B.V.
英文关键词	Organic geochemistry; Palynofacies; Pliensbachian–Toarcian Event; Toarcian Oceanic Anoxic Event; Western Iberian margin
语种	英语
scopus关键词	ammonite; anoxic conditions; carbon isotope; concentration (composition); cuticle; cyst; dominance; environmental change; facies; fossil assemblage; hydrocarbon reservoir; hydrological cycle; kerogen; microplankton; Pliensbachian; sulfur; Toarcian; total organic carbon; Atlantic Ocean; Leiria [Portugal]; Lisboa [Portugal]; Lusitanian Basin; Peniche; Portugal; Portugal; Acritarcha; algae; Ammonoidea; Botryococcus; Classopollis; Dinophyceae
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150433
作者单位	University of Coimbra, MARE–Marine and Environmental Sciences Centre - Department of Earth Sciences, Faculty of Sciences and Technology, Portugal; Department of Geology and iCRAG, School of Natural Sciences, Trinity College Dublin, The University of Dublin, Ireland; Department of Geology, Institute of Earth Sciences, Centre for Mathematical Sciences and Nature, Federal University of Rio de Janeiro, Brazil
推荐引用方式 GB/T 7714	Rodrigues B.,Duarte L.V.,Silva R.L.,et al. Sedimentary organic matter and early Toarcian environmental changes in the Lusitanian Basin (Portugal)[J],2020,554.
APA	Rodrigues B.,Duarte L.V.,Silva R.L.,&Mendonça Filho J.G..(2020).Sedimentary organic matter and early Toarcian environmental changes in the Lusitanian Basin (Portugal).Palaeogeography, Palaeoclimatology, Palaeoecology,554.
MLA	Rodrigues B.,et al."Sedimentary organic matter and early Toarcian environmental changes in the Lusitanian Basin (Portugal)".Palaeogeography, Palaeoclimatology, Palaeoecology 554(2020).