Geochemical and isotopic characterization of trace fossil infillings: New insights on tracemaker activity after the K/Pg impact event

doi:10.1016/j.cretres.2015.03.003

Cretaceous Research

Volume 57, January 2016, Pages 391-401

https://doi.org/10.1016/j.cretres.2015.03.003 Get rights and content

Highlights

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The infilling of trace fossils from the K–Pg boundary transition has been analyzed.
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Geochemical proxy evidence material from the ejecta layer infilling trace fossils.
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Trace fossils distribution evidences a rapid recovery of the macrobenthic community.
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Bioturbational disturbance should be considered for the K–Pg event reconstruction.

Abstract

Geochemical and isotopic analyses of the Cretaceous–Paleogene (K/Pg) boundary deposits were conducted at the Caravaca section (External Subbetic, southeast of Spain) in order to evaluate the recovery of the macrobenthic tracemaker community and the bioturbational disturbance. Samples from the infilling material of several lower Danian dark-colored trace fossils (Chondrites, Planolites, Thalassinoides and Zoophycos) located in the uppermost 8-cm of the light upper Maastrichtian strata, as well as samples from the host sedimentary rock of these trace fossils, were analyzed and compared with data from the lower Danian deposits. The values of element ratios indicative of extraterrestrial contamination (Cr/Al, Co/Al and Ni/Al) are higher in the infilling trace fossil material than in the upper Maastrichtian and lower Danian deposits, which suggests a contribution of the ejecta layer. Regarding the isotope composition, the δ¹³C values are lower in the infilling material than in the Maastrichtian host sedimentary rocks surrounding the traces, while the δ¹⁸O are higher in the infilling material. The geochemical and isotopic compositions of the infilling material evidence the unconsolidated character of the sediment, including the red boundary layer. Softground conditions confirm a relatively rapid recovery by the macrobenthic tracemaker community, starting a few millimeters above the K/Pg boundary layer. The mixture of the infilling material of the trace fossils moreover reveals a significant macrobenthic tracemaker activity affecting K–Pg boundary transition sediments that may have significantly altered original signatures.

Introduction

The Cretaceous–Paleogene (K/Pg) boundary, recently dated as ≈ 66.04 Ma ago (Husson et al., 2014, Vandenberghe et al., 2012), is associated with the second most relevant mass extinction taking place during the Phanerozoic, with 40% of genus extinction (Bambach, 2006) and the disappearance of about 70% of the marine and continental species existing at this time (D'Hondt, 2005). Currently, the hypothesis of an extraterrestrial impact (Alvarez et al., 1980, Smit and Hertogen, 1980) causing the end-Cretaceous mass extinction is widely accepted (Molina, 2015, Schulte et al., 2010). The synchronicity of the Chicxulub impact and the mass extinction at the K/Pg boundary has also been widely demonstrated (e.g., Pälike, 2013, Renne et al., 2013 and references therein).

Over recent decades numerous literature on this topic has provided details about the impact site on the Yucatan peninsula in Mexico (Hildebrand et al., 1991); the size of the meteorite, around 10 ± 4 km in diameter (Donaldson and Hildebrand, 2001, Kyte and Wasson, 1982); its nature, of carbonaceous chondritic type CM or CO (Goderis et al., 2013, Kyte, 1998, Shukolyukov and Lugmair, 1998); and the amount and nature of debris ejected to the atmosphere that led to major environmental perturbations (Kring, 2007 and reference therein).

The impact event also resulted in geochemical anomalies worldwide, recognized both in marine and continental depositional environments. The extraterrestrial effects are particularly evident in marine distal sections, located further than 7000 km from the Chicxulub crater (Smit, 1999). In these sections, trace metals of extraterrestrial origin show higher concentrations than in proximal and intermediate sections, wherein the extraterrestrial contribution is highly diluted by target rocks (Berndt et al., 2011, Martínez-Ruiz et al., 2001).

Major environmental perturbations (i.e., nitric and sulfuric acid rain, widespread dust and blackout, destruction of the stratospheric ozone layer, greenhouse effect, temperature increase), followed the K/Pg event (Alegret and Thomas, 2005, Peryt et al., 2002). Diverse geochemical redox proxies, commonly used to reconstruct paleo-oxygen conditions (e.g., Calvert and Pedersen, 2007, Tribovillard et al., 2006), indicate anoxic conditions across the K/Pg boundary transition, mostly promoted by the enhanced contribution of metals to the basins (extraterrestrial contamination and terrestrial elements derived from increasing chemical alteration in emerged areas), as well as a higher input of both terrestrial and marine organic material. An abrupt spike in biomarkers such as dibenzofuran, biphenyl and cadalene evidences the increasing input of terrestrial organic material (Mizukami, Kaiho, & Oba, 2014).

The biotic response to the K/Pg impact event, including the post-event recovery, is still a matter of debate. Several contradictory hypotheses postulate the effects on planktonic vs. benthic organisms, K- vs. r-strategists, or deposit vs. suspension feeders (Labandeira et al., 2015, Molina, 2015, Powell and MacGregor, 2011, Schulte et al., 2010). In the past decade, relevant information has been provided by ichnological data. The trace fossil analysis of K/Pg boundary sections reveals a minor impact of K/Pg environmental changes on the deep-sea macrobenthic tracemaker community, as well as its rapid recovery (Monaco et al., 2015, Rodríguez Tovar et al., 2004, Rodríguez Tovar et al., 2006, Rodríguez-Tovar et al., 2011, Rodríguez-Tovar, 2005, Rodríguez-Tovar and Uchman, 2006, Rodríguez-Tovar and Uchman, 2008). As pointed out by Sosa-Montes de Oca, Martínez-Ruiz, and Rodríguez-Tovar (2013), this unusual biotic recovery could be explained by a rapid response (some few hundred years) of bottom water oxygenation that reestablished shortly after the K/Pg event. Ichnological analyses furthermore revealed the importance of the bioturbational redistribution by tracemakers, which may have affected original signatures and therefore should be considered so as to prevent possible misinterpretations (Kędzierski et al., 2011, Rodríguez-Tovar et al., 2010).

In order to evaluate and corroborate the hypothesis of the rapid recovery of the macrobenthic tracemaker community and the bioturbational disturbance, further analyses have been performed. In particular, geochemical and isotopic analyses of the K/Pg boundary deposits at the Caravaca section (southeast of Spain) included the infilling material of trace fossils as well as the upper Maastrichtian and lower Danian host rocks.

Section snippets

Geological setting and the study section

The K/Pg boundary section at Caravaca (38°04′36.39″N, 1°52′41.45″W) is located on the NW side of road C-336, in the Barranco del Gredero, about 4 km southwest of the town of Caravaca (Murcia, Spain) (Fig. 1). It belongs to the Jorquera Formation (lower Maastrichtian-lower Eocene), around 225 m-thick, which consists of intercalated marls, marly limestones and occasional turbidites. Geologically, this outcrop belongs to the External Subbetic of the Betic Cordillera, corresponding to a

Materials and methods

For this study we selected a 11-cm-thick interval, involving Maastrichtian materials from 8.0-cm below the K/Pg boundary, and Danian rocks to 3.0-cm above the boundary. According to the sedimentation rate of 3.1 cm kyr⁻¹ estimated for the Maastrichtian deposits, and of 0.8 cm kyr⁻¹ calculated for the boundary clay layer (Kaiho et al., 1999), the studied transition would span a time interval of around 6330 years —from 2580 years prior to the K/Pg boundary to 3750 years afterward. Deposition of

Geochemical analysis

Geochemical data are presented in Table 1. The normalized concentrations of Cr, Co and Ni are plotted in Fig. 2, in which the diverse sedimentary intervals are marked: i) the ejecta layer (CA K–Pg) (data from Sosa-Montes de Oca et al., 2013), ii) the host rock from the lower Paleogene, at 2.8–3.0-cm above the K/Pg boundary (previous data from Sosa-Montes de Oca et al., 2013), iii) the infilling material of several trace fossils analyzed, and iv) the Cretaceous deposits hosting trace fossils (

Discussion

As previously indicated, numerous paleontolological studies have been conducted on the K/Pg boundary at the Caravaca section in order to evaluate the effect of the K/Pg boundary event on the biota, in particular on the micropaleontological assemblages. Micropaleontological studies involving planktonic (i.e., Arenillas and Molina, 1997, Arz et al., 2000, Canudo et al., 1991, Kaiho and Lamolda, 1999, Molina et al., 1998, Molina et al., 2001, Smit, 1990) and benthic foraminifera (Coccioni et al.,

Conclusions

Geochemical and isotopic analyses conducted on the Cretaceous–Paleogene boundary transition at the Caravaca section have provided significant information on the macrobenthic tracemaker activity after the K/Pg boundary event.

In particular, the Cr/Al, Co/Al and Ni/Al ratios from the infilling of trace fossils are higher than those of the upper Maastrichtian and lower Danian deposits, but lower than those corresponding to the ejecta layer, indicating a mixture of the sedimentary material due to

Acknowledgments

This research was funded through Project CGL2012-33281 and CGL2012-32659 (Secretaría de Estado de I + D + I, Spain), Project RNM-05212 and Research Group RNM-178 and RNM-179 (Junta de Andalucía) and FEDER funds. The research of Sosa-Montes de Oca was supported by a pre-doctoral grant (BES-2013-064406) by MINECO. We are likewise grateful to E. Holanda for laboratory assistance. Analyses were performed at the Centre for Scientific Instrumentation (CIC), University of Granada (Spain).

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Geochemical and isotopic characterization of trace fossil infillings: New insights on tracemaker activity after the K/Pg impact event

Highlights

Abstract

Introduction

Section snippets

Geological setting and the study section

Materials and methods

Geochemical analysis

Discussion

Conclusions

Acknowledgments

Icarus

Developments in Marine Geology

Marine Micropaleontology

Geochimica et Cosmochimica Acta

Palaeogeography, Palaeoclimatology, Palaeoecology

Chemical Geology

Palaeogeography, Palaeoclimatology, Palaeoecology

Earth-Science Reviews

Revue de Micropaleontologie

Sedimentary Geology

Palaeogeography, Palaeoclimatology, Palaeoecology

Palaeogeography, Palaeoclimatology, Palaeoecology

Palaeogeography, Palaeoclimatology, Palaeoecology

Geobios

Geobios

Sedimentary Geology

Cretaceous Research

Chemical Geology

Marine Micropaleontology

Cretaceous/Paleogene boundary bathyal paleo-environments in the central North Pacific (DSDP Site 465), the Northwestern Atlantic (ODP Site 1049), the Gulf of Mexico and the Tethys: the benthic foraminiferal record

Palaeogeography, Palaeoclimatology, Palaeoecology

Extraterrestrial cause for the Cretaceous–Tertiary extinction

Science

A new high-resolution planktic foraminiferal zonation and subzonation for the lower Danian

Lethaia

Análisis cuantitativo de los foraminíferos planctónicos del Paleoceno de Caravaca (Cordillera Bética); bioestratigrafia y evolución de las asociaciones

Revista Española de Paleontología

Spike of pyrosynthetic polycyclic aromatic hydrocarbons associated with an abrupt decrease in δ13C of a terrestrial biomarker at the Cretaceous-Tertiary boundary at Caravaca, Spain

Geology

La estabilidad evolutiva de los foraminíferos planctónicos en el Maastrichtiense Superior y su extinción en el límite Cretácico/Terciario de Caravaca, España

Revista geológica de Chile

Phanerozoic biodiversity mass extinction

Annual Review of Earth and Planetary Science

The Chicxulub ejecta deposit at Demerara Rise (western Atlantic): dissecting the geochemical anomaly using laser ablation–mass spectrometry

Geology

Trace fossils: Biology, taphonomy and application

Terminal Cretaceous deep-water benthic foraminiferal decimation, survivorship and recovery at Caravaca (SE Spain)

Paleopelagos

K/T boundary extinction: Geologically instantaneous or gradual event? Evidence from deep-sea benthic foraminifera

Geology

Consequences of the Cretaceous/Paleocene mass extinction for marine ecosystems

Annual Review of Ecology and Systematics

The global fluence of iridium at the Cretaceous-Tertiary Boundary

Meteorics & Planetary Science

Palaeoecological change in middle to low latitude calcareous nannoplankton at the Cretaceous/Tertiary boundary

Bulletin de la Societe Geologique de France

Spike of pyrosynthetic polycyclic aromatic hydrocarbons associated with an abrupt decrease in δ¹³C of a terrestrial biomarker at the Cretaceous-Tertiary boundary at Caravaca, Spain