The Argentina Continental Margin: A Potential Paleoclimatic-Paleoceanographic Archive for the Southern Ocean

129 Pages·2017·2.647 MB·English

by  Roberto A. Violante, Cecilia Laprida, Natalia L. García Chapori (auth.)

SPRINGER BRIEFS IN EARTH SYSTEM SCIENCES
Roberto A. Violante
Cecilia Laprida
Natalia L. García Chapori
The Argentina
Continental Margin
A Potential
Paleoclimatic-
Paleoceanographic
Archive for the
Southern Ocean
123
SpringerBriefs in Earth System Sciences
Series editors
Gerrit Lohmann, Bremen, Germany
Lawrence A. Mysak, Montreal, Canada
Justus Notholt, Bremen, Germany
Jorge Rabassa, Ushuaia, Argentina
Vikram Unnithan, Bremen, Germany
More information about this series at http://www.springer.com/series/10032
Roberto A. Violante Cecilia Laprida
(cid:129)
í
Natalia L. Garc a Chapori
The Argentina Continental
Margin
A Potential Paleoclimatic-Paleoceanographic
Archive for the Southern Ocean
123
RobertoA.Violante Natalia L. GarcíaChapori
Division of Marine Geologyand NationalCouncilofScientificandTechnical
Geophysics,DepartmentofOceanography Research,InstituteofAndeanStudiesDon
Argentina Hydrographic Survey PabloGroeber,Department of Geology
BuenosAires University of BuenosAires
Argentina BuenosAires
Argentina
Cecilia Laprida
NationalCouncilofScientificandTechnical
Research,InstituteofAndeanStudiesDon
PabloGroeber,Department of Geology
University of BuenosAires
BuenosAires
Argentina
ISSN 2191-589X ISSN 2191-5903 (electronic)
SpringerBriefs inEarth System Sciences
ISBN978-3-319-04195-7 ISBN978-3-319-04196-4 (eBook)
DOI 10.1007/978-3-319-04196-4
LibraryofCongressControlNumber:2017932421
©TheAuthor(s)2017
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Contents
1 Introduction.... .... .... ..... .... .... .... .... .... ..... .... 1
2 Continental Margins in the Global Context ... .... .... ..... .... 3
References.. .... .... .... ..... .... .... .... .... .... ..... .... 8
3 The Argentina Continental Margin:
Location and Significance. ..... .... .... .... .... .... ..... .... 11
3.1 Geotectonic Considerations, Types of Margins
and Stratigraphy. .... ..... .... .... .... .... .... ..... .... 15
3.1.1 Brief History of the Margin Evolution
in the Context of the Southern Hemisphere.... ..... .... 15
3.1.2 Margin Types and Geotectonic Configuration.. ..... .... 18
3.1.3 Stratigraphic Evidences of the Margin Evolution .... .... 21
References.. .... .... .... ..... .... .... .... .... .... ..... .... 27
4 Morphosedimentary Configuration of the Argentina
Continental Margin.. .... ..... .... .... .... .... .... ..... .... 33
4.1 Coastal Plains... .... ..... .... .... .... .... .... ..... .... 34
4.2 Continental Shelf .... ..... .... .... .... .... .... ..... .... 36
4.3 Shelf Break. .... .... ..... .... .... .... .... .... ..... .... 42
4.4 Slope . .... .... .... ..... .... .... .... .... .... ..... .... 42
4.5 Rise .. .... .... .... ..... .... .... .... .... .... ..... .... 47
4.6 Submarine Canyons .. ..... .... .... .... .... .... ..... .... 48
4.7 Argentine Basin . .... ..... .... .... .... .... .... ..... .... 48
References.. .... .... .... ..... .... .... .... .... .... ..... .... 49
5 Climate and Oceanographic Background . .... .... .... ..... .... 55
5.1 Regional Climate Background ... .... .... .... .... ..... .... 55
5.1.1 Intertropical Convergence Zone .... .... .... ..... .... 56
5.1.2 South American Monsoon System .. .... .... ..... .... 57
5.1.3 Southern Hemisphere Westerlies.... .... .... ..... .... 58
v
vi Contents
5.1.4 South Atlantic Convergence Zone... .... .... ..... .... 58
5.2 Oceanographic Background . .... .... .... .... .... ..... .... 59
5.2.1 The Western South Atlantic and the Meridional
Overturning Circulation... .... .... .... .... ..... .... 59
5.2.2 Western South Atlantic Main Currents ... .... ..... .... 61
5.2.3 Western South Atlantic Hydrographic Structure ..... .... 64
References.. .... .... .... ..... .... .... .... .... .... ..... .... 65
6 Principles of Paleoceanographic Reconstruction.... .... ..... .... 71
6.1 Paleoceanography and Proxy Data .... .... .... .... ..... .... 72
6.2 Climate Proxies . .... ..... .... .... .... .... .... ..... .... 77
6.3 Biological Proxies: Fossils as Paleoceanographic Proxies.... .... 78
6.3.1 Foraminiferida. ..... .... .... .... .... .... ..... .... 79
6.3.2 Coccolithophorids... .... .... .... .... .... ..... .... 79
6.3.3 Dinoflagellates. ..... .... .... .... .... .... ..... .... 80
6.3.4 Diatoms.. .... ..... .... .... .... .... .... ..... .... 80
6.3.5 Radiolarians .. ..... .... .... .... .... .... ..... .... 81
6.3.6 Corals... .... ..... .... .... .... .... .... ..... .... 81
6.3.7 Ostracods .... ..... .... .... .... .... .... ..... .... 82
6.3.8 Mollusks. .... ..... .... .... .... .... .... ..... .... 82
6.4 Biomarkers as Paleoceanographic Proxies .. .... .... ..... .... 83
6.4.1 Alkenones.... ..... .... .... .... .... .... ..... .... 83
6.4.2 N-Alkyl-Lipids ..... .... .... .... .... .... ..... .... 84
6.5 Geological Proxies ... ..... .... .... .... .... .... ..... .... 84
6.5.1 Geomorphology..... .... .... .... .... .... ..... .... 85
6.5.2 Sedimentary Architecture and Structures.. .... ..... .... 86
6.5.3 Physical Properties .. .... .... .... .... .... ..... .... 87
6.5.4 Geochemical Properties... .... .... .... .... ..... .... 87
References.. .... .... .... ..... .... .... .... .... .... ..... .... 88
7 State of the Art in the Paleoceanographic Reconstructions
at the Argentina Continental Margin. .... .... .... .... ..... .... 91
7.1 Reconstructions in the Continental Shelf ... .... .... ..... .... 91
7.2 Reconstructions in the Slope and Rise . .... .... .... ..... .... 97
7.2.1 Paleoceanographic and Biostratigraphic Background
Offshore the Argentina Continental Margin.... ..... .... 97
7.2.2 Geomorphological Records.... .... .... .... ..... .... 99
7.2.3 Sedimentary Architecture and Structures as Records.. .... 100
7.2.4 Physical Proxies .... .... .... .... .... .... ..... .... 100
7.2.5 Geochemical Proxies. .... .... .... .... .... ..... .... 101
References.. .... .... .... ..... .... .... .... .... .... ..... .... 103
8 Conclusions .... .... .... ..... .... .... .... .... .... ..... .... 111
Further Readings. .... .... ..... .... .... .... .... .... ..... .... 112
Abbreviations
AABW Antarctic Bottom Water
AAIW Antarctic Intermediate Water
AAO Antarctic Oscillation
ACC Antarctic Circumpolar Current
ACM Argentina Continental Margin
AM Active Margin
AMOC Atlantic Meridional Overturning Circulation
BMC Brazil–Malvinas Confluence
BP Before Present (14C age)
CDW Circumpolar Deep Water
DIC Oceanic Dissolved Organic Carbon Reservoir
DSDP Deep Sea Drilling Program
ENSO El Niño Southern Oscillation
GDGT Glycerol Dialkyl Glycerol Tetraethers
ITCZ Intertropical Convergence Zone
LDEO Lamont–Doherty Earth Observatory
LGM Last Glacial Maximum
MCM Mixed (convergent + sheared) Continental Margin
MOC Meridional Overturning Circulation
Mwd Meters water-depth
Myr Millions of years
NADW North Atlantic Deep Water
NAO North Atlantic Oscillation
PMS Passive Margin Slope
SACW South Atlantic Central Water
SACZ South Atlantic Convergence Zone
SAMS South American Monsoon
SAMW Subantarctic Mode Water
SHWW Southern Hemisphere Westerlies
SSS Sea-Surface Salinity
vii
viii Abbreviations
SST Sea-Surface Temperature
STSF Subtropical Shelf Front
TEX86 TetraEther Index of Tetraethers
TMS Transcurrent and Transpressive Margin Slope
T-SCM Transcurrent (Sheared) Continental Margin
TW Tropical Water
VRCM Volcanic Rifted Continental Margin
WSA Western South Atlantic Ocean
List of Figures
Figure 2.1 Global map with details of the ocean floor features.
The region of the Argentina Continental Margin
is indicated by the red square. Observe the “lighter”
colors around the continents, indicating the shallowest
environments (shelf and part of the slope) in the continental
margins. Compare the extension of the Argentine margin
respect to other continental margins .. .... .... .... ..... .. 4
Figure 2.2 Schematic section of a typical passive margin
with its component environments .... .... .... .... ..... .. 5
Figure 2.3 Schematic diagram of the Source-to-Sink system
(modified after Curray 1975).... .... .... .... .... ..... .. 7
Figure 2.4 Basic scheme of the main branches of the Ocean Meridional
Overturning Circulation.... .... .... .... .... .... ..... .. 8
Figure 3.1 Location of the Argentina Continental Margin in the context
of South America. Note the extension of the margin
(light blue color) in relation to the extension of the
Argentine Republic .. ..... .... .... .... .... .... ..... .. 12
Figure 3.2 Main surface currents that compound the basic circulation
in the Western South Atlantic Ocean (modified after Matano
et al. 2010). Note the region (in front of the Río de la Plata)
where north-sourced and south-sourced water-masses meet
(Brazil–Malvinas Confluence)... .... .... .... .... ..... .. 13
Figure 3.3 Bathymetric map of the Argentina Continental Margin.
Source Bathymetric Chart of the Western South Atlantic,
Argentina Hydrographic Survey (1976). Geographic
references mentioned in the text . .... .... .... .... ..... .. 15
ix