Long chain n-alkanes deposited from borehole PRGL1P (ROMESS1) in the upper slope of the Gulf of Lions

• Main Authors: Cortina, Aleix, Grimalt, Joan O, Rigual-Hernandez, Andrés S, Ballegeer, Anne-Marie, Martrat, Belén, Sierro, Francisco Javier, Flores, José-Abel
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Age model; LR04 Lisiecki & Raymo (2005); Bavenit; DEPTH; sediment/rock; DRILL; Drilling/drill rig; Gas chromatography - Mass spectrometry (GC-MS); Gulf of Lions; n-Alkane C21; n-Alkane C22; n-Alkane C23; n-Alkane C24; n-Alkane C25; n-Alkane C26; n-Alkane C27; n-Alkane C28; n-Alkane C29; n-Alkane C30; n-Alkane C31; n-Alkane C32; n-Alkane C33; PRGL1-1; PROMESS1; Rhone; Ice Sheet
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.873377; https://doi.org/10.1594/PANGAEA.873377

During the PROMESS campaign (summer 2004) a borehole (PRGL1) was drilled in the upper slope of the Gulf of Lions. Previous studies showed that the deposition of the sedimentary units at borehole PRGL1 was determined by changes in the discharge of the Rhone river, induced by sea level and climate variability with a strong 100 ka imprint. However, there are no detailed studies that focus on the glacial/interglacial transitions (i.e. Terminations) that define 100 ka Quaternary ice-age cycles. Here we present a high-resolution record of terrestrial long chain n-alkanes (C21 to C33) from MIS 3 to MIS 11 in order to monitor changes in the sediments deposited on the upper slope of the Gulf of Lions with the aim to provide new insight into the climatic events occurring during Terminations in the western Mediterranean Sea. Principal component analysis grouped n-alkane on the basis of the degree of maturation of organic matter (fresh/degraded) that allowed to monitor past variability in the source of the sediment deposited in the upper slope as a consequence of sea level and climate change. This information was used to estimate the impact that northern ice-sheet variability had on the western Mediterranean basin. As sea level started to fall, fresh terrestrial organic matter increased owing to the seaward migration of Rhone's mouth. Simultaneously, the decrease in sea level exposed old and reworked organic material from the Rhone's catchment, including the delta plain and the continental shelf, that was eroded and transported into our study site. This resulted in an increase in the proportion of degraded terrestrial organic matter together with sea level decrease. Aside from sea level changes, the proportion of fresh vs degraded organic matter seems to be affected by the amount of continental runoff, with an increasing proportion of fresh terrestrial organic matter occurring at times of reduced continental runoff. During the last glacial, the increase of fresh terrestrial organic matter was contemporaneous with Heinrich ...