Late Quaternary deformation of marine terraces on the Cascadia Subduction Zone near Cape Blanco, Oregon

Tectonics ◽  
1990 ◽  
Vol 9 (5) ◽  
pp. 983-1014 ◽  
Author(s):  
Harvey M. Kelsey
Keyword(s):  
Subduction Zone ◽  
Late Quaternary ◽  
Cascadia Subduction Zone ◽  
Marine Terraces ◽  
Quaternary Deformation

scholarly journals Dating and morphostratigraphy of uplifted marine terraces in the Makran subduction zone (Iran)

2018 ◽  
Author(s):  
Raphaël Normand ◽  
Guy Simpson ◽  
Frédéric Herman ◽  
Rabiul Haque Biswas ◽  
Abbas Bahroudi ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Surface Deformation ◽  
Late Quaternary ◽  
Makran Subduction Zone ◽  
Megathrust Earthquakes ◽  
Surface Uplift ◽  
Marine Terraces ◽  
Uplift Rates ◽  
Tectonically Active ◽  
East West

Abstract. The western part of the Makran subduction zone (Iran) has not experienced a great megathrust earthquake in recent human history, yet, the presence of emerged marine terraces along the coast indicates that the margin has been tectonically active during at least the late Quaternary. To better understand the surface deformation of this region, we mapped the terraces sequences of seven localities along the Iranian Makran. Additionnaly, we performed radiocarbon, 230Th/U and optically stimulated luminescence (OSL) dating of the layers of marine sediments deposited on top of the terraces. This enabled us to correlate the terraces regionally and to assign them to different Quaternary sea level highstands. Our results show east-west variations in surface uplift rates mostly between 0.05 and 1.2 mm y−1. We detected a region of anomalously high uplift rate, where two MIS 3 terraces are emerged, yet we are uncertain how to insert these results in a geologically coherent context. Although it is presently not clear whether the uplift of the terraces is linked with the occurrence of large megathrust earthquakes, our results highlight heterogeneous accumulation of deformation in the overriding plate.

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.

scholarly journals Submarine Terraces reveal Late Quaternary Tectonic deformation in the Intermediate Zone between the Island Shelf and Rift Zone of the Middle Part of the Nanseishoto Islands, Southwest Japan

2021 ◽  
Author(s):  
Hideaki Goto
Keyword(s):  
Subduction Zone ◽  
Rift Zone ◽  
Late Quaternary ◽  
Middle Part ◽  
Tectonic Deformation ◽  
Southwest Japan ◽  
The West ◽  
West Side ◽  
Marine Terraces ◽  
Island Shelf

Abstract Late Quaternary tectonic deformation of coastal areas is usually examined based on the height distribution of paleo-shorelines observed on marine terraces. However, it is difficult to examine deformation along the subduction zone, in which small, isolated islands are distributed. In this paper, the author focuses on the widespread shallow submarine terraces surrounding the Iheya-Izena islands in the middle part of the Nanseishoto islands, Southwest Japan, where crustal deformation is not known. The islands are located in the intermediate zone between island shelf uplifted during the Late Quaternary and the rift zone occurred to the northwest, along the Okinawa trough. Detailed topographic anaglyph images and maps of the islands were produced using a digital elevation model (DEM) of the seafloor, which is stored by the Japan Coast Guard (JCG) and the Advanced Institute of Science and Technology (AIST). Topographic anaglyph images enabled us to identify the widespread distribution and deformation of the shallow seafloor above −200 m using red-cyan glasses. Four terrace-like features divided by small steps were found on the shallow seafloor, which are named T1, T2, T3, and T4, in descending order. Topographic expressions of paleo-shoreline depths are preserved on submarine terraces formed during the last glacial period. The paleo-shoreline depths of terraces T2 and T3 are −60 m and −70 m on the west side and −70 m and −80 m, respectively, on the east side of Iheyajima island; this indicates southeastward tilting. The tilting ratio of T2 and T3 was calculated to approximately 1‰. The tilting rate is approximately 1×10^4/kyr, assuming that the T2 was formed in 10–11 kyr. This is much more rapid than that of the last inter-glacial marine terraces in the Muroto peninsula of Shikoku, Japan, with a tilting rate of 4×10^5/kyr, which formed by steep northward tilting against the Nankai subduction zone. The author suggests that this phenomenon is not related to mega-thrusting along the subduction zone, but rather to local deformation, probably caused by the reverse faulting of nearby active submarine faults along the west side of the islands.

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.

scholarly journals Submarine terraces reveal Late Quaternary tectonic deformation in the intermediate zone between the island shelf and rift zone of the middle part of the Nanseishoto Islands, southwest Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hideaki Goto
Keyword(s):  
Subduction Zone ◽  
Rift Zone ◽  
Late Quaternary ◽  
Middle Part ◽  
Tectonic Deformation ◽  
Southwest Japan ◽  
The West ◽  
West Side ◽  
Marine Terraces ◽  
Island Shelf

AbstractLate Quaternary tectonic deformation of coastal areas is usually examined based on the height distribution of paleo-shorelines observed on marine terraces. However, it is difficult to examine deformation along the subduction zone, in which small, isolated islands are distributed. In this paper, the author focuses on the widespread shallow submarine terraces surrounding the Iheya–Izena islands in the middle part of the Nanseishoto Islands, Southwest Japan, where crustal deformation is not known. The islands are located in the intermediate zone between island shelf uplifted during the Late Quaternary and the rift zone occurred to the northwest, along the Okinawa trough. Detailed topographic anaglyph images and maps of the islands were produced using a digital elevation model (DEM) of the seafloor, which is stored by the Japan Coast Guard (JCG) and the Advanced Institute of Science and Technology (AIST). Topographic anaglyph images enabled us to identify the widespread distribution and deformation of the shallow seafloor above − 200 m using red–cyan glasses. Four terrace-like features divided by small steps were found on the shallow seafloor, which are named T1, T2, T3, and T4, in descending order. Topographic expressions of paleo-shoreline depths are preserved on submarine terraces formed during the last glacial period. The paleo-shoreline depths of terraces T2 and T3 are − 60 m and − 70 m on the west side and − 70 m and − 80 m, respectively, on the east side of Iheyajima Island; this indicates southeastward tilting. The tilting ratio of T2 and T3 was calculated to approximately 1‰. The tilting rate is approximately 1 × 10–4/kyr, assuming that the T2 was formed in 10–11 kyr. This is much more rapid than that of the last inter-glacial marine terraces in the Muroto peninsula of Shikoku, Japan, with a tilting rate of 4 × 10–5/kyr, which formed by steep northward tilting against the Nankai subduction zone. The author suggests that this phenomenon is not related to mega-thrusting along the subduction zone, but rather to local deformation, probably caused by the reverse faulting of nearby active submarine faults along the west side of the islands.

scholarly journals Submarine Terraces Reveal Late Quaternary Tectonic Deformation in the Intermediate Zone Between the Island Shelf and Rift Zone of the Middle Part of the Nanseishoto Islands

2020 ◽  
Author(s):  
Hideaki Goto
Keyword(s):  
Subduction Zone ◽  
Rift Zone ◽  
Late Quaternary ◽  
Middle Part ◽  
Intermediate Zone ◽  
Tectonic Deformation ◽  
The West ◽  
West Side ◽  
Marine Terraces ◽  
Island Shelf

Abstract Late Quaternary tectonic deformation of coastal areas is usually examined based on the height distribution of paleo-shorelines observed on marine terraces. However, it is difficult to examine deformation along the subduction zone, in which small, isolated islands are distributed. In this paper, we focus on the widespread shallow submarine terraces surrounding the Iheya-Izena islands in the middle part of the Nanseishoto islands, where crustal deformation is not known. The islands are located in the intermediate zone between island shelf uplifted during the Late Quaternary and the rift zone occurred to the northwest, along the Okinawa trough.Detailed topographic anaglyph images and maps of the islands were produced using a digital elevation model (DEM) of the seafloor, which is stored by the Japan Coast Gard (JCG) and the Advanced Institute of Science and Technology (AIST). Topographic anaglyph images enabled us to identify the widespread distribution and deformation of the shallow seafloor above −200 m using red-cyan glasses.Four terrace-like features divided by small steps were found on the shallow seafloor, which are named T1, T2, T3, and T4, in descending order. Topographic expressions of paleo-shoreline depths are preserved on submarine terraces formed during the last glacial period. The paleo-shoreline depths of terraces T2 and T3 are −60 m and −70 m on the west side and −70 m and −80 m, respectively, on the east side of Iheyajima island; this indicates southeastward tilting. The tilting ratio of T2 and T3 was calculated to approximately 1‰. The tilting rate is approximately 1×10^4/kyr, assuming that the T2 was formed in 10–11 kyr. This is much more rapid than that of the last inter-glacial marine terraces in the Muroto peninsula, with a tilting rate of 4×10^5/kyr, which formed by steep northward tilting against the Nankai subduction zone. We suggest that this phenomenon is not related to mega-thrusting along the subduction zone, but rather to local deformation, probably caused by the reverse faulting of nearby active submarine faults along the west side of the islands.

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