scholarly journals Marine terraces of the last interglacial period along the Pacific coast of South America (1° N–40° S)

2021 ◽  
Vol 13 (6) ◽  
pp. 2487-2513
Author(s):  
Roland Freisleben ◽  
Julius Jara-Muñoz ◽  
Daniel Melnick ◽  
José Miguel Martínez ◽  
Manfred R. Strecker
Keyword(s):  
South America ◽  
Sea Level ◽  
Short Wavelength ◽  
Tidal Range ◽  
Uplift Rate ◽  
Last Interglacial ◽  
Central Chile ◽  
Long Wavelength ◽  
South Central ◽  
Marine Terraces

Abstract. Tectonically active coasts are dynamic environments characterized by the presence of multiple marine terraces formed by the combined effects of wave erosion, tectonic uplift, and sea-level oscillations at glacial-cycle timescales. Well-preserved erosional terraces from the last interglacial sea-level highstand are ideal marker horizons for reconstructing past sea-level positions and calculating vertical displacement rates. We carried out an almost continuous mapping of the last interglacial marine terrace along ∼ 5000 km of the western coast of South America between 1∘ N and 40∘ S. We used quantitatively replicable approaches constrained by published terrace-age estimates to ultimately compare elevations and patterns of uplifted terraces with tectonic and climatic parameters in order to evaluate the controlling mechanisms for the formation and preservation of marine terraces and crustal deformation. Uncertainties were estimated on the basis of measurement errors and the distance from referencing points. Overall, our results indicate a median elevation of 30.1 m, which would imply a median uplift rate of 0.22 m kyr−1 averaged over the past ∼ 125 kyr. The patterns of terrace elevation and uplift rate display high-amplitude (∼ 100–200 m) and long-wavelength (∼ 102 km) structures at the Manta Peninsula (Ecuador), the San Juan de Marcona area (central Peru), and the Arauco Peninsula (south-central Chile). Medium-wavelength structures occur at the Mejillones Peninsula and Topocalma in Chile, while short-wavelength (< 10 km) features are for instance located near Los Vilos, Valparaíso, and Carranza, Chile. We interpret the long-wavelength deformation to be controlled by deep-seated processes at the plate interface such as the subduction of major bathymetric anomalies like the Nazca and Carnegie ridges. In contrast, short-wavelength deformation may be primarily controlled by sources in the upper plate such as crustal faulting, which, however, may also be associated with the subduction of topographically less pronounced bathymetric anomalies. Latitudinal differences in climate additionally control the formation and preservation of marine terraces. Based on our synopsis we propose that increasing wave height and tidal range result in enhanced erosion and morphologically well-defined marine terraces in south-central Chile. Our study emphasizes the importance of using systematic measurements and uniform, quantitative methodologies to characterize and correctly interpret marine terraces at regional scales, especially if they are used to unravel the tectonic and climatic forcing mechanisms of their formation. This database is an integral part of the World Atlas of Last Interglacial Shorelines (WALIS), published online at https://doi.org/10.5281/zenodo.4309748 (Freisleben et al., 2020).

Eemian marine terraces along the Pacific coast of South America (1°N-40°S) allow regional assessments of tectonic forcing from earthquake cycle to glacial-cycle timescales

2021 ◽  
Author(s):  
Roland Freisleben ◽  
Julius Jara-Muñoz ◽  
Daniel Melnick ◽  
José Miguel Martínez ◽  
Manfred Strecker
Keyword(s):  
South America ◽  
Sea Level ◽  
Earthquake Cycle ◽  
Uplift Rate ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Central Chile ◽  
Long Wavelength ◽  
South Central ◽  
Marine Terraces

&lt;p&gt;&lt;strong&gt;Abstract. &lt;/strong&gt;Tectonically active coasts are dynamic environments characterized by the presence of multiple marine terraces formed by the combined effects of wave-erosion, tectonic uplift, and sea-level oscillations at glacial-cycle timescales. Well-preserved erosional terraces from the last interglacial sea-level highstand are ideal marker horizons for reconstructing past sea-level positions and calculating vertical displacement rates, which can be subsequently compared to short-term coastal deformation patterns associated with the earthquake cycle. We carried out an almost continuous mapping of the last interglacial marine terrace along ~5,000 km of the western coast of South America between 1&amp;#176;N and 40&amp;#176;S. We used quantitatively replicable approaches constrained by published terrace-age estimates to ultimately compare elevations and patterns of uplifted terraces with tectonic and climatic parameters in order to evaluate the controlling mechanisms for the formation and preservation of marine terraces, and crustal deformation. Uncertainties were estimated on the basis of measurement errors and the distance from referencing points. Overall, our results indicate a median elevation of 30.1 m, which would imply a median uplift rate of 0.22 m/ka averaged over the past ~125 ka. The patterns of terrace elevation and uplift rate display high-amplitude (~100&amp;#8211;200 m) and long-wavelength (~10&lt;sup&gt;2&lt;/sup&gt; km) structures at the Manta Peninsula (Ecuador), the San Juan de Marcona area (central Peru), and the Arauco Peninsula (south-central Chile). Medium-wavelength structures occur at the Mejillones Peninsula and Topocalma in Chile, while short-wavelength (&lt; 10 km) features are for instance located near Los Vilos, Valpara&amp;#237;so, and Carranza, Chile. We interpret the long-wavelength deformation to be controlled by deep-seated processes at the plate interface such as the subduction of major bathymetric anomalies like the Nazca and Carnegie ridges. In contrast, short-wavelength deformation may be primarily controlled by sources in the upper plate such as crustal faulting, which, however, may also be associated with the subduction of topographically less pronounced bathymetric anomalies and varying distances to the trench. Latitudinal differences in climate additionally control the formation and preservation of marine terraces. Based on our synopsis we propose that increasing wave height and tidal range result in enhanced erosion and morphologically well-defined marine terraces in south-central Chile. Conversely, river incision and lateral scouring in areas with high precipitation may degrade marine terraces. Our study emphasizes the importance of using systematic measurements and uniform, quantitative methodologies to characterize and correctly interpret marine terraces at regional scales, especially if they are used to unravel tectonic and climatic forcing mechanisms of their formation.&lt;/p&gt;

scholarly journals Marine terraces of the last interglacial period along the Pacific coast of South America (1° N–40° S)

2020 ◽  
Author(s):  
Roland Freisleben ◽  
Julius Jara-Muñoz ◽  
Daniel Melnick ◽  
José Miguel Martínez ◽  
Manfred R. Strecker
Keyword(s):  
South America ◽  
Sea Level ◽  
Measurement Errors ◽  
Continuous Mapping ◽  
Interglacial Period ◽  
Western Coast ◽  
Uplift Rate ◽  
Last Interglacial ◽  
South Central ◽  
Marine Terraces

Abstract. Tectonically active coasts are dynamic environments characterized by the presence of multiple marine terraces formed by the combined effects of wave-erosion, tectonic uplift, and sea-level oscillations at glacial-cycle timescales. Well-preserved erosional terraces from the last interglacial sea-level highstand are ideal marker horizons for reconstructing past sea-level positions and calculating vertical displacement rates. We carried out an almost continuous mapping of the last interglacial marine terrace along ~5,000 km of the western coast of South America between 1° N and 40° S. We used quantitatively replicable approaches constrained by published terrace-age estimates to ultimately compare elevations and patterns of uplifted terraces with tectonic and climatic parameters in order to evaluate the controlling mechanisms for the formation and preservation of marine terraces, and crustal deformation. Uncertainties were estimated on the basis of measurement errors and the distance from referencing points. Overall, our results indicate a median elevation of 30.1 m, which would imply a median uplift rate of 0.22 m/ka averaged over the past ~125 ka. The patterns of terrace elevation and uplift rate display high-amplitude (~100–200 m) and long-wavelength (~102 km) structures at the Manta Peninsula (Ecuador), the San Juan de Marcona area (central Peru), and the Arauco Peninsula (south-central Chile). Medium-wavelength structures occur at the Mejillones Peninsula and Topocalma in Chile, while short-wavelength (

Formation and preservation of marine terraces during multiple sea level stands

2021 ◽  
Author(s):  
Luca C Malatesta ◽  
Noah J. Finnegan ◽  
Kimberly Huppert ◽  
Emily Carreño
Keyword(s):  
Sea Level ◽  
Basic Assumption ◽  
Cumulative Exposure ◽  
Marine Terrace ◽  
Uplift Rate ◽  
Marine Terraces ◽  
Uplift Rates ◽  
Ca 50 ◽  
Wave Erosion ◽  
Mis 5E

&lt;p&gt;Marine terraces are a cornerstone for the study of paleo sea level and crustal deformation. Commonly, individual erosive marine terraces are attributed to unique sea level high-stands. This stems from early reasoning that marine platforms could only be significantly widened under moderate rates of sea level rise as at the beginning of an interglacial and preserved onshore by subsequent sea level fall. However, if marine terraces are only created during brief windows at the start of interglacials, this implies that terraces are unchanged over the vast majority of their evolution, despite an often complex submergence history during which waves are constantly acting on the coastline, regardless of the sea level stand.&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Here, we question the basic assumption that individual marine terraces are uniquely linked to distinct sea level high stands and highlight how a single marine terrace can be created By reoccupation of the same uplifting platform by successive sea level stands. We then identify the biases that such polygenetic terraces can introduce into relative sea level reconstructions and inferences of rock uplift rates from marine terrace chronostratigraphy.&lt;/p&gt;&lt;p&gt;Over time, a terrace&amp;#8217;s cumulative exposure to wave erosion depends on the local rock uplift rate. Faster rock uplift rates lead to less frequent (fewer reoccupations) or even single episodes of wave erosion of an uplifting terrace and the generation and preservation of numerous terraces. Whereas slower rock uplift rates lead to repeated erosion of a smaller number of polygenetic terraces. The frequency and duration of terrace exposure to wave erosion at sea level depend strongly on rock uplift rate.&lt;/p&gt;&lt;p&gt;Certain rock uplift rates may therefore promote the generation and preservation of particular terraces (e.g. those eroded during recent interglacials). For example, under a rock uplift rate of ca. 1.2 mm/yr, Marine Isotope Stage (MIS) 5e (ca. 120 ka) would resubmerge a terrace eroded ca. 50 kyr earlier for tens of kyr during MIS 6d&amp;#8211;e stages (ca. 190&amp;#8211;170 ka) and expose it to further wave erosion at sea level. This reoccupation could accordingly promote the formation of a particularly wide or well planed terrace associated with MIS 5e with a greater chance of being preserved and identified. This effect is potentially illustrated by a global compilation of rock uplift rates derived from MIS 5e terraces. It shows an unusual abundance of marine terraces documenting uplift rates between 0.8 and 1.2 mm/yr, supporting the hypothesis that these uplift rates promote exposure of the same terrace to wave erosion during multiple sea level stands.&lt;/p&gt;&lt;p&gt;Hence, the elevations and widths of terraces eroded during specific sea level stands vary widely from site-to-site and depend on local rock uplift rate. Terraces do not necessarily correspond to an elevation close to that of the latest sea level high-stand but may reflect the elevation of an older, longer-lived, occupation. This leads to potential misidentification of terraces if each terrace in a sequence is assumed to form uniquely at successive interglacial high stands and to reflect their elevations.&lt;/p&gt;

scholarly journals Last interglacial (MIS 5e) sea-level proxies in southeastern South America

2021 ◽  
Vol 13 (1) ◽  
pp. 171-197
Author(s):  
Evan J. Gowan ◽  
Alessio Rovere ◽  
Deirdre D. Ryan ◽  
Sebastian Richiano ◽  
Alejandro Montes ◽  
...  
Keyword(s):  
South America ◽  
Sea Level ◽  
Last Interglacial ◽  
Amino Acid Racemization ◽  
Exceptional Preservation ◽  
Infrared Stimulated Luminescence ◽  
Spin Resonance ◽  
Coastal Deposits ◽  
Mis 5E ◽  
Terrace Level

Abstract. Coastal southeast South America is one of the classic locations where there are robust, spatially extensive records of past high sea level. Sea-level proxies interpreted as last interglacial (Marine Isotope Stage 5e, MIS 5e) exist along the length of the Uruguayan and Argentinian coast with exceptional preservation especially in Patagonia. Many coastal deposits are correlated to MIS 5e solely because they form the next-highest terrace level above the Holocene highstand; however, dating control exists for some landforms from amino acid racemization, U∕Th (on molluscs), electron spin resonance (ESR), optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and radiocarbon dating (which provides minimum ages). As part of the World Atlas of Last Interglacial Shorelines (WALIS) database, we have compiled a total of 60 MIS 5 proxies attributed, with various degrees of precision, to MIS 5e. Of these, 48 are sea-level indicators, 11 are marine-limiting indicators (sea level above the elevation of the indicator), and 1 is terrestrial limiting (sea level below the elevation of the indicator). Limitations on the precision and accuracy of chronological controls and elevation measurements mean that most of these indicators are considered to be low quality. The database is available at https://doi.org/10.5281/zenodo.3991596 (Gowan et al., 2020).

scholarly journals Studies on the moss flora of the Bío-Bío region of Chile

2006 ◽  
Vol 28 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Robert R. Ireland ◽  
Gilda Bellolio ◽  
Roberto Rodríguez ◽  
Juan Larraín
Keyword(s):  
South America ◽  
New Taxa ◽  
New Records ◽  
Recent Literature ◽  
Extensive Study ◽  
Central Chile ◽  
Number Of Species ◽  
South Central ◽  
Made In

An extensive study was made on the moss flora of the Bío-Bío Region (VIII Región) in south-central Chile in 2001-2003. Collections were made in all four provinces of the region: Arauco, Bío-Bío, Concepción and Ñuble. Approximately 265 localities in the region were explored with over 6,000 mosses collected in the four provinces. The mosses of this region had not previously been studied to any great extent and with part of the region’s environment being destroyed by the construction of several dams on one of the major rivers, the Bío-Bío, the study of this area seemed of utmost importance. Thus far, a total of 20 taxa were found which are new to Chile, making a total of 877 known for the country, with four new taxa known for South America. An additional 87 taxa are reported new only to the Bío-Bío Region. That number, together with some new records from the recent literature, increases the total for the Region from 190 to 300. It was determined from the 87 new taxa for the Bío-Bío Region that the majority (41) represent northern extensions of taxa, while a much smaller number (10) represent southern extensions. The remainder (36) fill in a gap in the distribution of the taxa between the northern and southern parts of the country. Many difficult species still remain to be identified and the number of species new to science, to Chile and to the Bío-Bío Region, is certain to increase when the remaining specimens are identified.

Quest for the Origins and Implications for Social Rights of the Mapuche in the Southern Cone of South America

2013 ◽  
Vol 24 (2) ◽  
pp. 149-163 ◽  
Author(s):  
Tom D. Dillehay ◽  
Francisco Rothhammer
Keyword(s):  
South America ◽  
Cultural Influences ◽  
Southern Cone ◽  
Social Rights ◽  
Indigenous Status ◽  
Central Chile ◽  
High Profile ◽  
South Central ◽  
Indigenous Groups ◽  
First Time

Debates over the cultural and biological origins of some indigenous groups in the Americas have fueled discussions about cultural identity, political justice, and resource rights. A historically high-profile case of rights and origins has involved the Araucanians or Mapuche of the southern cone of South America. This article examines, for the first time, the recent interdisciplinary archaeological and other anthropological evidence for the Mapuche of Chile and Argentina. It suggests that the ethnic and territorial origin of the Mapuche is in central and south-central Chile, although biological and cultural influences from north Chile and western Argentina also are present. It briefly discusses the implication of this study in relation to the indigenous status of the Mapuche in present-day Chile and Argentina.

Rocky shores and development of the Pliocene-Pleistocene Arroyo Blanco Basin on Isla Carmen in the Gulf of California, Mexico

2006 ◽  
Vol 43 (8) ◽  
pp. 1149-1164 ◽  
Author(s):  
James M Eros ◽  
Markes E Johnson ◽  
David H Backus
Keyword(s):  
Sea Level ◽  
Gulf Of California ◽  
Rocky Shore ◽  
Normal Faults ◽  
Rocky Shores ◽  
Last Interglacial ◽  
Marine Terraces ◽  
Shell Beds ◽  
History Of ◽  
Cap Rock

Arroyo Blanco Basin on Isla Carmen preserves a 157 m thick, nearly complete record of Pliocene–Pleistocene history in the Gulf of California. Examples of rocky-shore geomorphology occur on all margins of this trapezoidal-shaped, 3.3 km2 basin. A shoreline is developed in low relief on Miocene andesite from the Comondú Group at the rear of the basin parallel to the long axis of the island. Two end walls trace normal faults that stayed active during the life of the basin and maintained steep rocky shores. The basin is 64% filled by calcarudite and calcarenite derived from crushed rhodolith debris. Other facies include shell beds and stringers of andesite conglomerate that define a 4°–6° ramp. The ramp expanded onshore through Pliocene time, based on a succession of overlapping range zones for 22 macrofossils typical of Lower through Upper Pliocene strata in the Gulf of California. The unconformity exposed 1 km inland at the rear of the basin is between Miocene volcanics and Pleistocene cap rock at an elevation of 170 m above sea level. Whole rhodoliths encrusted on andesite pebbles occur above this unconformity. Presumably, the older Miocene-Pliocene unconformity is buried beneath the ramp. Four marine terraces with sea cliffs notched in Pliocene limestone occur at elevations of 68, 58, 37, and 12 m. The 12 m terrace is associated regionally with the last interglacial epoch between 120 000 and 135 000 years ago. Juxtaposition of ramp and terrace features in the same exhumed basin supports a long history of gradual Pliocene subsidence followed by episodic Pleistocene uplift.

Darwin the geologist in southern South America

2016 ◽  
Vol 35 (2) ◽  
pp. 303-345 ◽  
Author(s):  
Robert H. Dott ◽  
Ian W. D. Dalziel
Keyword(s):  
South America ◽  
Charles Darwin ◽  
Lateral Compression ◽  
Central Chile ◽  
Southern South America ◽  
The Andes ◽  
Andean Cordillera ◽  
Marine Terraces ◽  
Four Books ◽  
Geological Map

Charles Darwin was a reputable geologist before he achieved biological fame. Most of his geological research was accomplished in southern South America during the voyage of H.M.S. Beagle (1831–1836). Afterward he published four books and several articles about geology and coral atolls and became active in the Geological Society of London. We have followed Darwin's footsteps during our own researches and have been very impressed with his keen observations and inferences. He made some mistakes, however, such as appealing to iceberg rafting to explain erratic boulders and to inundations of the sea to carve valleys. Darwin prepared an important hand-colored geological map of southern South America, which for unknown reasons he did not publish. The distributions of seven map units are shown. These were described in his books wherein he also documented multiple elevated marine terraces on both coasts of South America. While exploring the Andean Cordillera in central Chile and Argentina, he discovered two fossil forests. Darwin developed a tectonic theory involving vertical uplift of the entire continent, which was greatest in the Andes where magma leaked up from a hypothetical subterranean sea of magma to form volcanoes and earthquakes. The theory had little impact and was soon eclipsed by theories involving lateral compression of strata. His and other contemporary theories suffered from a lack of knowledge about the earth's interior. Finally with modern plate tectonic theory involving intense lateral compression across the Andean Cordillera we can explain satisfactorily the geology so carefully documented by Darwin.

scholarly journals A review of MIS 5e sea-level proxies around Japan

2021 ◽  
Vol 13 (4) ◽  
pp. 1477-1497
Author(s):  
Evan Tam ◽  
Yusuke Yokoyama
Keyword(s):  
Sea Level ◽  
Age Dating ◽  
Stratigraphic Correlation ◽  
Last Interglacial ◽  
14C Dating ◽  
Carbon 14 ◽  
Marine Terraces ◽  
Uplift Rates ◽  
Tephra Layers ◽  
Mis 5E

Abstract. Sea-level proxies for Marine Isotopic Stage 5e (MIS 5e, ca. 124 ka) are abundant along the Japanese shoreline and have been documented for over at least the past 60 years. The bulk of these sea-level proxies are identified in Japan as marine terraces, often correlated by stratigraphic relationships to identified tephra layers, or other chronologically interpreted strata. Use of stratigraphic correlation in conjunction with other techniques such as paleontological analysis, tectonic uplift rates, tephra (volcanic ash), uranium–thorium (U–Th), and carbon-14 (14C) dating have connected Japan's landforms to global patterns of sea-level change. This paper reviews over 60 years of publications containing sea-level proxies correlated with MIS 5e in Japan. Data collected for this review have been added to the World Atlas of Last Interglacial Shorelines (WALIS), following their standardizations on the elements necessary to analyze paleosea-levels. This paper reviewed over 70 studies, assembling data points for over 300 locations and examining related papers denoting sea-level indicators for MIS 5e. The database compiled for this review (Tam and Yokoyama, 2020) is available at https://doi.org/10.5281/zenodo.4294326. Sea-level proxy studies in Japan rely heavily on chronostratigraphic techniques and are recognized as reliable, though opportunities exist for further constraining through the further use of numerical age dating techniques.

Sign in / Sign up

Export Citation Format

Share Document