Biomarkers reveal the role of photic zone euxinia in exceptional fossil preservation: An organic geochemical perspective

Melendez, Ines; Grice, Kliti; Trinajstic, Kate; Ladjavardi, Mojgan; Greenwood, Paul F.; Thompson, Katherine Jenny

doi:10.1130/g33492.1

Cited by 86 publications

(105 citation statements)

References 28 publications

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“…A high algal contribution to the n-alkanes is also supported by the similarity of δ 13 C signatures to predominantly algal-derived steranes, whereas the bacterial-derived ββ-20R-homohopane was slightly more 13 C-enriched. The decreased CPI in the lower interval (Table 1), despite a presumably higher terrigenous input in this core-section (Section 4.7), was possibly caused by an increased contribution from SRB which are known to produce longchain n-alkanes without an odd-over-even predominance (Davis, 1968;Melendez et al, 2013b). The differences in several of the described n-alkane parameters in the OM-lean middle interval are presumably the result of biodegradation after the uplift that followed burial or of diagenesis, with the effects of these magnified in OM-lean horizons.…”

Section: Variations In Pristane Phytane and N-alkanesmentioning

confidence: 92%

Changes of palaeoenvironmental conditions recorded in Late Devonian reef systems from the Canning Basin, Western Australia: A biomarker and stable isotope approach

et al. 2015

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Although the Late Devonian extinctions were amongst the largest mass extinction events in the Phanerozoic, the causes, nature and timing of these events remain poorly restrained. In addition to the most pronounced biodiversity loss at the Frasnian-Famennian (F-F) boundary and the end Famennian, there were also less extensively studied extinction pulses in the Middle to Late Givetian and the Frasnian. Here we used a combination of palynological, elemental, molecular and stable isotope analyses to investigate a sedimentary record of reef-systems from this time period in the Canning Basin, Western Australia. The acquired data generally showed distinct variations between sediments from (i) the time around the Givetian-Frasnian (G-F) boundary and (ii) later in the Frasnian and indicated a distinct interval of biotic stress, particularly for reef-builders, in the older sediments. Alterations of pristane/phytane ratios, gammacerane indices, Chlorobi biomarkers, δD kerogen and chroman ratios describe the change from a restricted marine palaeoenvironment with an anoxic/euxinic hypolimnion towards a presumably open marine setting with a vertically mixed oxic to suboxic water column. Simultaneous excursions in δ 13 C profiles of carbonates, organic matter (OM) and hydrocarbons in the older sediments reflect the stratification-induced enhancement of OMrecycling by sulfate reducing bacteria. Alterations in sterane distributions and elevated abundances of methyltrimethyltridecylchromans (MTTCs) and perylene indicate an increased terrigenous nutrient input via riverine influx, which would have promoted stratification, phytoplankton blooms and the development of lower water column anoxia. The detected palaeoenvironmental conditions around the G-F boundary may reflect a local or global extinction event. Our data furthermore suggest a contribution of the higher plant-expansion and photic zone euxinia to the Late Devonian extinctions, consistent with previous hypotheses. Furthermore, this work might contribute to the understanding of variations in Devonian reef margin and platform-top architecture, relevant for petroleum exploration and development in the global Devonian hydrocarbon resources.

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Section: Variations In Pristane Phytane and N-alkanesmentioning

confidence: 92%

Changes of palaeoenvironmental conditions recorded in Late Devonian reef systems from the Canning Basin, Western Australia: A biomarker and stable isotope approach

et al. 2015

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“…For more details on acquisition parameters used for GC (e.g. injector, carrier gas), MS/irMS, interface (for GC-irMS) and instrument softwares see Melendez et al (2013b).…”

Section: Methodsmentioning

confidence: 99%

“…biomarkers) (Melendez et al, 2013a(Melendez et al, , 2013b. The samples for the present study originate from a core (MR-1) collected at the location of McWhae Ridge (18.72796°S, 126.0682°E) and comprise interfingering marginal slope and basin facies (Sadler and Gogo formations, respectively).…”

Section: Geological Settingmentioning

confidence: 99%

Molecular proxies as indicators of freshwater incursion-driven salinity stratification

et al. 2015

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Salinity-related stratification in marine environments is one of the main drivers for the development of persistent anoxia and euxinia. It therefore plays a vital role in the sedimentary preservation of organic matter and has also been associated with Oceanic Anoxic Events during several mass extinctions in Earth's history.Here we present a novel molecular proxy using relative abundances of methyltrimethyltridecylchromans (MTTCs) as indicators of riverine freshwater incursions into Middle to Late Devonian paleoreefs exposed to conditions of prevailing anoxia, photic zone euxinia and water column stratification. This paper aims at re-instigating a discussion about the origin of these compounds to potentially broaden their utilization as paleoproxies, adding freshwater stratification to the general salinity reconstructions. The co-variation of MTTC abundance profiles and δ 13 C values with other biomarker parameters in the sediments studied here indicate a link of MTTCs to terrigenous input, pointing towards a previously suggested early diagenetic formation of these compounds from phytol with higher plant-derived alkylphenols.

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“…Further, recent research shows that PZE played a pivotal role in the exceptional preservation of soft tissue and biomarkers (Melendez et al 2013a). Most importantly, it was demonstrated that the oldest intact sterols in a crustacean had been preserved for some 380 Myr within a Devonian concretion (Melendez et al 2013b). This exceptional preservation of original biomass is attributed to microbially induced carbonate encapsulation, which suppressed decomposition and transformation and thereby extended sterol occurrences in the geological record by 250 Myr.…”

Section: The Late Devonian Extinctionmentioning

confidence: 97%

Biomarker Records Associated with Mass Extinction Events

Whiteside

Grice

2016

Annu. Rev. Earth Planet. Sci.

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The history of life on Earth is punctuated by a series of mass extinction episodes that vary widely in their magnitude, duration, and cause. Biomarkers are a powerful tool for the reconstruction of historical environmental conditions and can therefore provide insights into the cause and responses to ancient extinction events. In examining the five largest mass extinctions in the geological record, investigators have used biomarkers to elucidate key processes such as eutrophy, euxinia, ocean acidification, changes in hydrological balance, and changes in atmospheric CO 2 . By using these molecular fossils to understand how Earth and its ecosystems have responded to unusual environmental activity during these extinctions, models can be made to predict how Earth will respond to future changes in its climate.

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Biomarkers reveal the role of photic zone euxinia in exceptional fossil preservation: An organic geochemical perspective

Cited by 86 publications

References 28 publications

Changes of palaeoenvironmental conditions recorded in Late Devonian reef systems from the Canning Basin, Western Australia: A biomarker and stable isotope approach

Changes of palaeoenvironmental conditions recorded in Late Devonian reef systems from the Canning Basin, Western Australia: A biomarker and stable isotope approach

Molecular proxies as indicators of freshwater incursion-driven salinity stratification

Biomarker Records Associated with Mass Extinction Events

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