Planktonic versus benthic foraminifera response to Milankovitch forcing (Late Jurassic,Betic Cordillera): testing methods for cyclostratigraphic analysis |
| |
Authors: | Francisco J Rodríguez-Tovar Matías Reolid Eulogio Pardo-Igúzquiza |
| |
Institution: | 1.Departamento de Estratigrafía y Paleontología, Facultad de Ciencias,Universidad de Granada,Granada,Spain;2.Departamento de Geología,Universidad de Jaén,Jaén,Spain;3.Departamento de Geodinámica, Facultad de Ciencias,Universidad de Granada,Granada,Spain |
| |
Abstract: | Foraminiferal assemblages from the Bifurcatus Zone (Oxfordian, Upper Jurassic) are studied in the Navalperal section (Betic
Cordillera, southern Spain). A total of 24 sampling stations and around 5,700 specimens of foraminifera were recognized on
thin-section analysis and classified into two major categories: planktonic and benthic. The abundance of foraminifera (number
of specimens/cm2) was calculated for both categories and the cyclic pattern was studied by spectral analysis, considering the autochthonous
and para-autochthonous character of the studied assemblages. The Lomb-Scargle periodogram together with a permutation test
were tested for performing the high-resolution spectral analysis, being particularly well suited for working with short time
series and uneven sampling. Spectral analysis reveals the influence of orbital-scale Milankovitch cyclicity at the eccentricity,
obliquity, and precession bands. Moreover, this incidence is significantly different depending on the analyzed group (benthic
versus planktonic). Whereas the long-range eccentricity band is not distinguishable from a trend and the short-range eccentricity
band is not statistically significant (at 90% confidence level), the obliquity band is better represented in the planktonic
component and the precession band is better developed in the benthic group. Variations in temperature affecting upper waters,
determined by obliquity-scale fluctuations, could be responsible for changes in the planktonic foraminiferal assemblage, while
changes in nutrient availability and substrate oxygenation, as a consequence of input variations from source areas at the
precession-scale cycles, could affect the benthic foraminiferal assemblage. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|