TY - JOUR
T1 - Microscale trace-element distribution across the Cretaceous/Palaeogene ejecta layer at the Agost section
T2 - Constraining the recovery of pre-impact conditions
AU - Sosa-Montes de Oca, Claudia
AU - de Lange, Gert J.
AU - Martínez-Ruiz, Francisca
AU - Ortega-Huertas, Miguel
AU - Rodríguez-Tovar, Francisco J.
PY - 2020/2/5
Y1 - 2020/2/5
N2 - A high-resolution, sub-mm scale analysis of the distribution of major and trace elements across the ejecta layer marking the Cretaceous/Palaeogene boundary (KPgB) at the Agost section (SE Spain) was performed using Laser Ablation-Inductivity Coupled Plasma-Mass Spectrometry (LA-ICP-MS). A KPgB interval ≈17 mm thick, has been selected for this study. It includes gray calcareous marl from the uppermost Maastrichtian (Cretaceous), 2.02-mm-thick red clay (the ejecta layer), and blackish-gray clay (boundary clay layer) from the lowermost Danian (Palaeogene). The unconsolidated sediments were resin-embedded under O2-free conditions and analyzed by LA-ICP-MS line continuous scan measurements at 20 μm increments and a laser-beam of 120 μm. These micron-scale analyses show that the anomalous contents of trace and major elements in this boundary are restricted to the ejecta layer, which displays a relatively uniform distribution over its ≈2 mm thickness. Trace and major elemental ratios, such as Ca/Al, Ti/Al, Cr/Al, Fe/Al, Ni/Al, Cu/Al, Zn/Al, As/Al, Sb/Al and Pb/Al have similar values below and above the ejecta layer, consistent with similar palaeoenvironmental conditions prior to and after the impact event. Such element distribution points to anomalies exclusively restricted to the ejecta, thus a nearly instantaneous re-establishment of pre-impact conditions right after the impact event is observed.
AB - A high-resolution, sub-mm scale analysis of the distribution of major and trace elements across the ejecta layer marking the Cretaceous/Palaeogene boundary (KPgB) at the Agost section (SE Spain) was performed using Laser Ablation-Inductivity Coupled Plasma-Mass Spectrometry (LA-ICP-MS). A KPgB interval ≈17 mm thick, has been selected for this study. It includes gray calcareous marl from the uppermost Maastrichtian (Cretaceous), 2.02-mm-thick red clay (the ejecta layer), and blackish-gray clay (boundary clay layer) from the lowermost Danian (Palaeogene). The unconsolidated sediments were resin-embedded under O2-free conditions and analyzed by LA-ICP-MS line continuous scan measurements at 20 μm increments and a laser-beam of 120 μm. These micron-scale analyses show that the anomalous contents of trace and major elements in this boundary are restricted to the ejecta layer, which displays a relatively uniform distribution over its ≈2 mm thickness. Trace and major elemental ratios, such as Ca/Al, Ti/Al, Cr/Al, Fe/Al, Ni/Al, Cu/Al, Zn/Al, As/Al, Sb/Al and Pb/Al have similar values below and above the ejecta layer, consistent with similar palaeoenvironmental conditions prior to and after the impact event. Such element distribution points to anomalies exclusively restricted to the ejecta, thus a nearly instantaneous re-establishment of pre-impact conditions right after the impact event is observed.
KW - Ejecta layer
KW - KPgB
KW - LA-ICP-MS
KW - Microscale analyses
KW - Palaeoenvironmental reconstruction
UR - http://www.scopus.com/inward/record.url?scp=85076713746&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2019.119431
DO - 10.1016/j.chemgeo.2019.119431
M3 - Article
AN - SCOPUS:85076713746
SN - 0009-2541
VL - 533
JO - Chemical Geology
JF - Chemical Geology
M1 - 119431
ER -