Spatial distribution of isotopic compositions of Globigerina bulloides and Neogloboquadrina pachyderma (dex.) and the faunal assemblages of planktic foraminifera in surface sediment samples along the Chilean continental slope between 23°S and 44°S

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Autori principali: Mohtadi, Mahyar, Hebbeln, Dierk, Marchant, Margarita
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Lingua:en
Pubblicazione: PANGAEA 2005
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author Mohtadi, Mahyar
Hebbeln, Dierk
Marchant, Margarita
author_facet Mohtadi, Mahyar
Hebbeln, Dierk
Marchant, Margarita
collection Datos científicos de ciencias marinas y ambientales
contents We report on the spatial distribution of isotopic compositions of the two planktic foraminifera species Globigerina bulloides and Neogloboquadrina pachyderma (dex.), and the faunal assemblages of planktic foraminifera in 91 surface sediment samples along the Chilean continental slope between 23°S and 44°S. Both d13C and d18O data of N. pachyderma (dex.) show little variability in the study area. North of 39°S, the isotopic values of N. pachyderma (dex.) are heavier than those of G. bulloides, whereas south of 39°S, this relation inverses. This is indicative for a change from a well-mixed, deep thermocline caused by coastal upwelling north of 39°S to well-stratified water masses in a non-upwelling environment south of 39°S. In addition, the faunal composition of planktic foraminifera marks this change by transition from an upwelling assemblage north of 39°S to a high-nutrient-non-upwelling assemblage south of 39°S, which is characterized by decreased contributions of upwelling indicators such as G. bulloides, N. pachyderma (sin.), and Globigerinita glutinata. In general, we can conclude that food and light rather than temperature are the primary control of the planktic foraminiferal assemblage between 23°S and 44°S off Chile. Our data point to higher marine productivity at upwelling centers north of 25°S and at 30-33°S. South of 39°S, significant supply of nutrients by fluvial input most likely boosts the productivity.
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spellingShingle Spatial distribution of isotopic compositions of Globigerina bulloides and Neogloboquadrina pachyderma (dex.) and the faunal assemblages of planktic foraminifera in surface sediment samples along the Chilean continental slope between 23°S and 44°S
Mohtadi, Mahyar
Hebbeln, Dierk
Marchant, Margarita
Center for Marine Environmental Sciences; GeoB; GeoB7103-4; GeoB7104-5; GeoB7106-1; GeoB7108-3; GeoB7112-1; GeoB7114-1; GeoB7115-1; GeoB7116-1; GeoB7118-1; GeoB7119-1; GeoB7120-1; GeoB7121-1; GeoB7122-2; GeoB7123-1; GeoB7127-1; GeoB7129-1; GeoB7130-1; GeoB7131-1; GeoB7132-1; GeoB7133-1; GeoB7134-1; GeoB7135-1; GeoB7136-1; GeoB7137-2; GeoB7138-1; GeoB7139-1; GeoB7140-1; GeoB7141-1; GeoB7142-2; GeoB7143-1; GeoB7144-1; GeoB7145-1; GeoB7146-1; GeoB7147-1; GeoB7148-1; GeoB7149-1; GeoB7150-1; GeoB7152-1; GeoB7153-1; GeoB7154-2; GeoB7156-1; GeoB7157-1; GeoB7158-1; GeoB7159-1; GeoB7160-3; GeoB7162-3; GeoB7163-4; GeoB7166-2; GeoB7167-3; GeoB7171-2; GeoB7172-3; GeoB7173-4; GeoB7174-2; GeoB7175-4; GeoB7177-2; GeoB7179-1; GeoB7180-1; GeoB7181-1; GeoB7182-1; GeoB7183-1; GeoB7186-1; GeoB7187-1; GeoB7189-1; GeoB7190-1; GeoB7191-1; GeoB7192-1; GeoB7193-1; GeoB7194-1; GeoB7195-1; GeoB7197-1; GeoB7198-1; GeoB7199-2; GeoB7200-1; GeoB7201-1; GeoB7202-1; GeoB7203-1; GeoB7204-1; GeoB7205-1; GeoB7207-1; GeoB7208-1; GeoB7209-2; GeoB7211-1; GeoB7212-1; GeoB7213-1; GeoB7214-1; GeoB7215-1; GeoB7216-1; GeoB7217-1; GeoB7218-1; GeoB7219-1; GeoB7220-1; Geosciences, University of Bremen; MARUM; MUC; MultiCorer; off Chile; PUCK; SO156/1; SO156/2; SO156/3; Sonne
We report on the spatial distribution of isotopic compositions of the two planktic foraminifera species Globigerina bulloides and Neogloboquadrina pachyderma (dex.), and the faunal assemblages of planktic foraminifera in 91 surface sediment samples along the Chilean continental slope between 23°S and 44°S. Both d13C and d18O data of N. pachyderma (dex.) show little variability in the study area. North of 39°S, the isotopic values of N. pachyderma (dex.) are heavier than those of G. bulloides, whereas south of 39°S, this relation inverses. This is indicative for a change from a well-mixed, deep thermocline caused by coastal upwelling north of 39°S to well-stratified water masses in a non-upwelling environment south of 39°S. In addition, the faunal composition of planktic foraminifera marks this change by transition from an upwelling assemblage north of 39°S to a high-nutrient-non-upwelling assemblage south of 39°S, which is characterized by decreased contributions of upwelling indicators such as G. bulloides, N. pachyderma (sin.), and Globigerinita glutinata. In general, we can conclude that food and light rather than temperature are the primary control of the planktic foraminiferal assemblage between 23°S and 44°S off Chile. Our data point to higher marine productivity at upwelling centers north of 25°S and at 30-33°S. South of 39°S, significant supply of nutrients by fluvial input most likely boosts the productivity.
title Spatial distribution of isotopic compositions of Globigerina bulloides and Neogloboquadrina pachyderma (dex.) and the faunal assemblages of planktic foraminifera in surface sediment samples along the Chilean continental slope between 23°S and 44°S
topic Center for Marine Environmental Sciences; GeoB; GeoB7103-4; GeoB7104-5; GeoB7106-1; GeoB7108-3; GeoB7112-1; GeoB7114-1; GeoB7115-1; GeoB7116-1; GeoB7118-1; GeoB7119-1; GeoB7120-1; GeoB7121-1; GeoB7122-2; GeoB7123-1; GeoB7127-1; GeoB7129-1; GeoB7130-1; GeoB7131-1; GeoB7132-1; GeoB7133-1; GeoB7134-1; GeoB7135-1; GeoB7136-1; GeoB7137-2; GeoB7138-1; GeoB7139-1; GeoB7140-1; GeoB7141-1; GeoB7142-2; GeoB7143-1; GeoB7144-1; GeoB7145-1; GeoB7146-1; GeoB7147-1; GeoB7148-1; GeoB7149-1; GeoB7150-1; GeoB7152-1; GeoB7153-1; GeoB7154-2; GeoB7156-1; GeoB7157-1; GeoB7158-1; GeoB7159-1; GeoB7160-3; GeoB7162-3; GeoB7163-4; GeoB7166-2; GeoB7167-3; GeoB7171-2; GeoB7172-3; GeoB7173-4; GeoB7174-2; GeoB7175-4; GeoB7177-2; GeoB7179-1; GeoB7180-1; GeoB7181-1; GeoB7182-1; GeoB7183-1; GeoB7186-1; GeoB7187-1; GeoB7189-1; GeoB7190-1; GeoB7191-1; GeoB7192-1; GeoB7193-1; GeoB7194-1; GeoB7195-1; GeoB7197-1; GeoB7198-1; GeoB7199-2; GeoB7200-1; GeoB7201-1; GeoB7202-1; GeoB7203-1; GeoB7204-1; GeoB7205-1; GeoB7207-1; GeoB7208-1; GeoB7209-2; GeoB7211-1; GeoB7212-1; GeoB7213-1; GeoB7214-1; GeoB7215-1; GeoB7216-1; GeoB7217-1; GeoB7218-1; GeoB7219-1; GeoB7220-1; Geosciences, University of Bremen; MARUM; MUC; MultiCorer; off Chile; PUCK; SO156/1; SO156/2; SO156/3; Sonne
url https://doi.org/10.1594/PANGAEA.726861