scholarly journals Upper-plate deformation of Late Pleistocene marine terraces in the Trinidad, California, coastal area, southern Cascadia subduction zone

Geosphere ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 1323-1341 ◽  
Author(s):  
J. Scott Padgett ◽  
Harvey M. Kelsey ◽  
David Lamphear
Keyword(s):  
Subduction Zone ◽  
Sea Level ◽  
Coastal Area ◽  
Hanging Wall ◽  
Cascadia Subduction Zone ◽  
Marine Terrace ◽  
Plate Deformation ◽  
Marine Terraces ◽  
Sea Cliff

Abstract Forming at sea level, uplifted shore platforms serve as long-term geodetic markers. The spatial distribution and elevation of marine terrace sequences offer insight into regional tectonics. In the Trinidad coastal area (California, USA), active tectonic processes reflect upper-plate deformation above the southern extent of the Cascadia subduction megathrust. A set of five uplifted and deformed Late Pleistocene marine terraces is preserved in the Trinidad region and provides an opportunity to analyze regional uplift, folding, and faulting. Using lidar imagery embedded within a GIS, we employ a surface classification model (SCM) that identifies uplifted marine terraces on the basis of their micro-topographical characteristics, i.e., low slope and low roughness. The SCM-based identification of marine terraces both supplements and verifies existing field mapping. We demonstrate the utility of the SCM, which can be applied to a variety of surface terrain analysis investigations that seek to identify smooth and/or rough terrain features, e.g., terraces and fault scarps. Age assignments for the five marine terraces, which range from 80 ka to <500 ka, are based on paleo–sea cliff geomorphology and soil development trends. Specifically, the steepest, highest, and most prominent paleo–sea cliff, which is associated with terrace number 3, is correlated to the long-duration sea-level highstand centered at 125 ka (marine isotope stage 5e), exemplifying a novel method in relative age assignment for Pleistocene geomorphic features. Based on these age assignments, the average maximum uplift rates in the Trinidad coastal area are ∼1.0 m/k.y., and the average long-term uplift rate diminishes westward to ∼0.4 – 0.5 m/k.y. on the downthrown side of the Trinidad fault. Based on analysis of deformation using the high-resolution lidar imagery of the marine terraces, the Trinidad hanging-wall anticline represents a fault propagation fold that ceased to be active when the associated reverse fault, the Trinidad fault, daylighted to the surface ca. 80–100 ka. Based on deformation tilts of a marine terrace with an assigned age of 200 ka, the Trinidad anticline has accommodated at least 1 km of shortening in the last 200 k.y., which represents at least 2% of the convergence of the Juan de Fuca plate relative to North America over the same time period. Overall, both the hanging wall and the footwall of the Trinidad fault show long-term positive rock uplift, which implies that the Trinidad anticline and fault are contained within the hanging wall of a deeper structure. Therefore, the Trinidad fault likely splays off of the Cascadia subduction zone megathrust or off of a deeper thrust fault that splays off of the megathrust.

Development of a Late Quaternary Marine Terraced Landscape during On-Going Tectonic Contraction, Crescent City Coastal Plain, California

1999 ◽  
Vol 52 (2) ◽  
pp. 217-228 ◽  
Author(s):  
Michael Polenz ◽  
Harvey M. Kelsey
Keyword(s):  
Coastal Plain ◽  
Late Quaternary ◽  
Hanging Wall ◽  
Thrust Fault ◽  
Cascadia Subduction Zone ◽  
Marine Terrace ◽  
Crescent City ◽  
The North ◽  
Marine Terraces ◽  
Tectonically Active

The Crescent City coastal plain is a low-lying surface of negligible relief that lies on the upper plate of the Cascadia subduction zone in northernmost California. Whereas coastal reaches to the north in southern Oregon and to the south near Cape Mendocino contain flights of deformed marine terraces from which a neotectonic history can be deduced, equivalent terraces on the Crescent City coastal plain are not as pronounced. Reexamination of the coastal plain revealed three late Pleistocene marine terraces, identified on the basis of subtle geomorphic boundaries and further delineated by differentiable degrees of soil development. The youngest marine terrace is preserved in the axial valley of a broad syncline, and the two older marine terraces face each other across the axial region. An active thrust fault, previously recognized offshore, underlies the coastal plain, and folding in the hanging wall of this thrust fault has dictated, through differential uplift, the depositional limits of each successive marine terrace unit. This study demonstrates the importance of local structures in coastal landscape evolution along tectonically active coastlines and exemplifies the utility of soil relative-age determinations to identify actively growing folds in landscapes of low relief.

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 Barra de Tabatinga and Touros Formations: evidence of pleistocene hich sea-level stillstands of the Rio Grande do Norte coast

2001 ◽  
Vol 28 (2) ◽  
pp. 5 ◽  
Author(s):  
KENITIRO SUGUIO ◽  
ALCINA MAGNÓLIA FRANCA BARRETO ◽  
FRANCISCO HILÁRIO REGO BEZERRA
Keyword(s):  
Sea Level ◽  
Rio Grande ◽  
Trace Fossils ◽  
Coarse Grained ◽  
Marine Terrace ◽  
Upper Pleistocene ◽  
Sedimentary Structures ◽  
Partial Dissolution ◽  
Marine Terraces ◽  
Stratigraphic Nomenclature

The Barra de Tabatinga Formation corresponds to the previous informally named Barra de Tabatinga unit, after a homonymous beach name. These marine terrace deposits occur along the present shoreline in patches between Natal and Barra de Sagi (ca. 80km). The summit of those deposits is about 7.5m above m.s.l. at Natal. They are composed of very friable clayey sandstones and conglomerates, exhibiting more-or-less conspicuous hydrodynamic sedimentary structures. The Touros Formation, after a homonymous town name, corresponds to the previous Tertiary Guamaré Formation, found by Petrobras only in subsurface. These marine terrace deposits extend, frequently as steep sea-cliffs along the present shoreline, between São Bento and Zumbi (ca. 120 km). The summit of these deposits reaches to a maximum of 20m above m.s.l., 2km to the N of Zumbi. Deposits are made-up of medium to coarse-grained sanstones, frequently well-cemented due to partial dissolution of biodetrital components. Hydrodynamic sedimentary structures, and trace fossils of Ophiomorpha nodosa, are very conspicuous. Both marine terraces, recently dated by TL and/or OSL methods, indicated Upper Pleistocene ages, and overlie unconformably the Neogene Barreiras Formation. Finally, as they fulfill all the requirements of the Brazilian Stratigraphic Nomenclature Code, as demonstrated in this paper, two new formations are formally proposed here.  

Marine terrace evolution of windward Barbados

2021 ◽  
Author(s):  
Robert C. Speed ◽  
Hai Cheng
Keyword(s):  
Sea Level ◽  
Overland Flow ◽  
Breaking Waves ◽  
Marine Terrace ◽  
Wave Impact ◽  
Oxygen Isotope Stage ◽  
Marine Terraces ◽  
The Face ◽  
Reefal Facies ◽  
Island Slope

ABSTRACT The geomorphic evolution of southeastern windward Barbados is embodied in the development of a terraced seaward island slope on a tectonically rising scarp. The island slope is wholly erosional and a product of marine and subaerial processes. Modulation of the slope by terraces has occurred fundamentally by marine erosion at eustatic stillstands but includes morphologic additions by limestone deposition. The ongoing phase of morphologic development and island emergence began at or before ca. 700 ka. Emergence has proceeded at an increasing rate northwestward along the island’s southeastern coastline. The terraced island slope is markedly affected by post-terrace denudation. As many as eight marine terraces are preserved on the windward island slope below the planed surface of the Central Highlands, which is counted as terrace 1. Relics of an upper set of terraces are perched on the face of Second High Cliff, the ancient erosional margin of the oldest limestone capping Barbados. Second High Cliff developed by successive marine incisions over a probably long duration preceding oxygen isotope stage 9. A lower terrace set was excised in stages 9 through 5a in the siliciclastic island foundation or (and) in limestone cover of preceding terraces. Marine terrace floors extend seaward from an erosional backcliff and shoreline angle to a younger erosional cutoff. The most broadly preserved terrace floors indicate the following systematic succession of seaward profile elements: narrow upper ramp; broad upper flat; lower ramp; and on one, a lower flat. Carbonate cover is chiefly clastic on the upper ramp and flat, and chiefly reefal on the lower ramp. Most shoal-water reefal facies appear to be in fringe reef blankets. Terrace profile geometries are explained by a simple theory of wave abrasion in proportion to duration of sea level at a shoreline. At stillstands, the wave impact caused large shoreline recession and development of flats, whereas in transgression and regression, rapid sea-level change permitted only minor recession. Corresponding differences in cover facies are explained as functions of duration of breaking waves and seabed stability. Widespread post-terrace denudation is attributed to floods of upland provenance, local overland flow, and marine flooding. Riverine processes have produced channelization and a high degree of terrace preservation on the interfluves in the steeper, foundation-based northern windward region. This differs markedly from the more diffuse, shallow gullying and stripping of the limestone-covered shallow slopes of the southern region. An intensely stormy spell is suggested between stages 5e and 5c.

Uranium-Series Ages of Marine Terrace Corals from the Pacific Coast of North America and Implications for Last-Interglacial Sea Level History

1994 ◽  
Vol 42 (1) ◽  
pp. 72-87 ◽  
Author(s):  
Daniel R. Muhs ◽  
George L. Kennedy ◽  
Thomas K. Rockwell
Keyword(s):  
North America ◽  
Sea Level ◽  
Baja California ◽  
Pacific Coast ◽  
Baja California Sur ◽  
Marine Terrace ◽  
San Nicolas Island ◽  
Uranium Series ◽  
Marine Terraces ◽  
The Pacific

AbstractFew of the marine terraces along the Pacific coast of North America have been dated using uranium-series techniques. Ten terrace sequences from southern Oregon to southern Baja California Sur have yielded fossil corals in quantities suitable for U-series dating by alpha spectrometry. U-series-dated terraces representing the ∼80,000 yr sea-level high stand are identified in five areas (Bandon, Oregon; Point Arena, San Nicolas Island, and Point Loma, California; and Punta Banda, Baja California); terraces representing the ∼125,000 yr sea-level high stand are identified in eight areas (Cayucos, San Luis Obispo Bay, San Nicolas Island, San Clemente Island, and Point Loma, California; Punta Bands and Isla Guadalupe, Baja California; and Cabo Pulmo, Baja California Sur). On San Nicolas Island, Point Loma, and Punta Bands, both the ∼80,000 and the ∼125,000 yr terraces are dated. Terraces that may represent the ∼105,000 sea-level high stand are rarely preserved and none has yielded corals for U-series dating. Similarity of coral ages from midlatitude, erosional marine terraces with coral ages from emergent, constructional reefs on tropical coastlines suggests a common forcing mechanism, namely glacioeustatically controlled fluctuations in sea level superimposed on steady tectonic uplift. The low marine terrace dated at ∼125,000 yr on Isla Guadalupe, Baja California, presumed to be tectonically stable, supports evidence from other localities for a +6-m sea level at that time. Data from the Pacific Coast and a compilation of data from other coasts indicate that sea levels at ∼80,000 and ∼105,000 yr may have been closer to present sea level (within a few meters) than previous studies have suggested.

Nonstationary Bi-Variate Frequency Analysis of Extreme Sea Level and Rainfall Under Climate Change Impacts: South Carolina Coastal Area

2020 ◽  
Author(s):  
Saeed Golian ◽  
Ali Razmi ◽  
Heydar Ali Mardani ◽  
Zahra Zahmatkesh
Keyword(s):  
Climate Change ◽  
South Carolina ◽  
Sea Level ◽  
Frequency Analysis ◽  
Coastal Area ◽  
Goodness Of Fit ◽  
Extreme Values ◽  
Systems Design ◽  
And Sea Level

&lt;p&gt;Statistical analysis of hydrologic variables is of great importance for water resources systems. Design and operation of these systems is often based on the assumption of data stationarity. However, long-term average of variables such as rainfall as well as sea level is observed to shift over time, mostly attributed to the climate change. These changes, in turn, affect flood volume, peak value and frequency. In this study, a framework was proposed for bi- variate frequency analysis of extreme sea level and rainfall. The analysis was performed on rainfall for the coastal area of Charleston and Savannah, and sea level for the coastal area of Charleston and Fort Pulaski, South Carolina, USA. Extreme values were selected based on the peak over threshold method. To determine the most appropriate distribution, AIC and BIC goodness of fit tests were used. Frequency analysis was then carried out using nonstationary Generalized Extreme Value probability distribution function. Results showed an increase in the sea level long term average, significant trends and outliers (specifically in recent decades), while although the analysis of rainfall data confirms the presence of outliers in the time series, it does not indicate significant trends or heterogeneity. Therefore, in performing bi-variate frequency analysis of extreme rainfall and sea level, non-stationary approaches should be used to provide a more reliable prediction of the joint probability of these variables.&lt;/p&gt;

scholarly journals Late Quaternary Marine Terraces and Tectonic Uplift Rates of the Broader Neapolis Area (SE Peloponnese, Greece)

2022 ◽  
Vol 10 (1) ◽  
pp. 99
Author(s):  
Efthimios Karymbalis ◽  
Konstantinos Tsanakas ◽  
Ioannis Tsodoulos ◽  
Kalliopi Gaki-Papanastassiou ◽  
Dimitrios Papanastassiou ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Osl Dating ◽  
Aerial Photographs ◽  
Uplift Rate ◽  
Eurasian Plate ◽  
Tectonic Processes ◽  
Marine Terraces ◽  
Coastal Uplift

Marine terraces are geomorphic markers largely used to estimate past sea-level positions and surface deformation rates in studies focused on climate and tectonic processes worldwide. This paper aims to investigate the role of tectonic processes in the late Quaternary evolution of the coastal landscape of the broader Neapolis area by assessing long-term vertical deformation rates. To document and estimate coastal uplift, marine terraces are used in conjunction with Optically Stimulated Luminescence (OSL) dating and correlation to late Quaternary eustatic sea-level variations. The study area is located in SE Peloponnese in a tectonically active region. Geodynamic processes in the area are related to the active subduction of the African lithosphere beneath the Eurasian plate. A series of 10 well preserved uplifted marine terraces with inner edges ranging in elevation from 8 ± 2 m to 192 ± 2 m above m.s.l. have been documented, indicating a significant coastal uplift of the study area. Marine terraces have been identified and mapped using topographic maps (at a scale of 1:5000), aerial photographs, and a 2 m resolution Digital Elevation Model (DEM), supported by extensive field observations. OSL dating of selected samples from two of the terraces allowed us to correlate them with late Pleistocene Marine Isotope Stage (MIS) sea-level highstands and to estimate the long-term uplift rate. Based on the findings of the above approach, a long-term uplift rate of 0.36 ± 0.11 mm a−1 over the last 401 ± 10 ka has been suggested for the study area. The spatially uniform uplift of the broader Neapolis area is driven by the active subduction of the African lithosphere beneath the Eurasian plate since the study area is situated very close (~90 km) to the active margin of the Hellenic subduction zone.

scholarly journals QUATERNARY CALCARENITE ("POROS") OF MYKONOS, DELOS AND RHENIA, CYCLADES ISLANDS, GREECE

2018 ◽  
Vol 36 (2) ◽  
pp. 725
Author(s):  
M. Varti-Mataranga ◽  
D. W.J. Piper
Keyword(s):  
Debris Flow ◽  
Sea Level ◽  
Thin Section ◽  
Vadose Zone ◽  
Late Quaternary ◽  
Sea Spray ◽  
The Past ◽  
Marine Terraces

Outcrops of friable calc-arenite of late Quaternary age, known as Poros rock, from Mykonos, Rhenia and Delos, are characterized sedimentologically and their cements are studied in thin section. Calcarenites of beach, coastal eolian dune, and pedogenic alluvium origin are distinguished sedimentologically. Beach calcarenite shows marine cementation by a uniform rim of micrite and bladed Mg-calcite. Some eolian dunes show precipitation of needle aragonite, probably from sea spray, but the dominant cements are sparry calcite from groundwater and vadose zone deposition of irregular micrite with meniscus and gravitational textures. Pedogenically cemented alluvium shows the characteristics of caliche, such as rhizoliths with clots and globules of micrite and circumgranular cracking. One outcrop of calcarenite from Panormos Bay in Mykonos shows beach fades at +2.5 to +4.0 m above present sea level, overlying cemented debris flow deposits. This occurrence is interpreted as Tyrrhenian in age (isotopie stage 5e) and implies regional long-term subsidence of 2 cm/ka, consistent with the lack of marine terraces in the area. Archeological sites on Delos show irregular variations of sea level of about 1 m in the past 2.5 ka, probably related to movement on faults.

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