Original paper
Orbital forcing of carbonate versus siliceous productivity in the late Albian–late Cenomanian (Umbria-Marche Basin, central Italy)
Gambacorta, Gabriele; Malinverno, Alberto; Erba, Elisabetta
Newsletters on Stratigraphy Volume 52 Number 2 (2019), p. 197 - 220
published: Mar 15, 2019
published online: Oct 18, 2018
manuscript accepted: Jul 20, 2018
manuscript revision received: Jul 19, 2018
manuscript revision requested: May 22, 2018
manuscript received: Jan 14, 2018
ArtNo. ESP026005202002, Price: 29.00 €
Abstract
We applied a cyclostratigraphic analysis to a late Albian – late Cenomanian Tethyan section (Monte Petrano) from the Umbria-Marche Basin. Starting from a high-resolution (mm-scale) lithological log, estimated calcium carbonate contents were used as input data for cyclostratigraphy. The orbital tuning was based on long and short eccentricity, obliquity and precessional components and was tied to a radiometric age of 93.9 ± 0.15 Ma (2σ) of the Cenomanian/Turonian boundary. The estimated variations in sedimentation rates allowed for constructing an anchored astrochronology of the composite Albian – Cenomanian δ13C record. Our estimates of the total duration of the Albian and Cenomanian stages are about 14.20 ± 0.86 Myr and about 4.94 ± 0.35 Myr, respectively. The Aptian/Albian boundary lies at 113.04 ± 0.94 Ma and the Albian/Cenomanian boundary at 98.84 ± 0.35 Ma. Moreover, according to our results, OAE1d lasted about 1.21 ± 0.17 Myr (from 100.11 ± 0.41 Ma to 98.90 ± 0.35 Ma). We obtained an astronomical tuned age of 96.28 ± 0.28 Ma to 96.12 ± 0.27 Ma for the MCE I with a total duration of the event of about 166 ± 20 kyr. Astronomical cyclicities and climatic conditions exerted a direct influence on the depositional style of the studied geological record. Orbitally-paced variation in insolation controlled the variability in monsoon intensity, with maximum in monsoon strength during insolation maxima. Under humid climatic conditions, the orbitally-paced variations in summer monsoon precipitation controlled the amount of runoff and transportation of fine-grained detrital sediments in the basin, thus modulating the alternate deposition of marls and carbonate-rich sediments. During arid climate periods, the fluctuations in winter monsoon intensity controlled the variations in wind-blown dust availability and the fluctuations in ocean fertilization with times of enhanced siliceous productivity under eutrophic conditions and carbonate productivity under oligotrophic conditions.