Kevin Pedoja

Does kamchatka belong to north America? An extruding okhotsk block suggested by coastal neotectonics of the ozernoi peninsula, kamchatka, Russia

This paper addresses one part of an outstanding tectonic problem regarding the nature of the plate boundary between Eurasia and North America in northeastern Russia. In this region, the northwestern corner of the Pacific plate interacts either simply with the North American plate, or more complexly with one or more blocks independent of North America. North of this corner, evidence of uplift, tilting, and convergence contradicts the prevailing, simpler model. On the Ozernoi Peninsula, similar to 150 km north of the subducting Pacific plate, marine terraces indicate uplift rates of 0.1 to 0.3 mm/yr, with faster rates to the east. Historic and paleoseismic records provide evidence for recurring tsunamigenic, thrust earthquakes offshore of the Ozernoi Peninsula, the most recent a Mw 7.7 earthquake in 1969. A multiplate model where an eastward-moving Okhotsk block, including most of Kamchatka, is converging with a clockwise- rotating Bering block better explains these observations than does the unbroken North American plate model.

A nexus of plate interaction: Vertical deformation of Holocene wave-built terraces on the Kamchatsky Peninsula (Kamchatka, Russia)

Kamchatsky Peninsula lies within a complex meeting place of tectonic plates, in particular, the orthogonal interaction of the west-moving Komandorsky Island block with mainland Kamchatka. Examining the Holocene history of vertical deformation of marine wave-built terraces along the peninsular coast, we differentiated tectonic blocks undergoing uplift and tilting separated by zones of stable or subsided shorelines. We analyzed ∼200 excavations along >30 coastal profiles and quantified vertical deformation on single profiles as well as along the coast using paleoshorelines dated with marker tephras. For the past ∼2000 yr, the average rates of vertical deformation range from about –1 to +7 mm/yr. Uplift patterns are similar to those detected from historical leveling and from mapping of the stage 5e Quaternary marine terrace (ca. 120 ka). Average vertical deformation in the Holocene is highest for the shortest studied time period, from ca. A.D. 250 to 600, and it is several times faster than rates for marine oxygen isotope stage (MIS) 5e terraces. Vertical displacements observed along the coast are most likely coseismic and probably have included subsidence as well as uplift events. Because subsidence is generally associated with erosion, almost surely more prehistoric large earthquakes occurred than are recorded as topographic steps in these terraces. We suggest that the distribution of coastal uplift and subsidence observed along the Kamchatsky Peninsula coastline is qualitatively explained by the squeezing of the Kamchatsky Peninsula block between the Bering and Okhotsk plates, and the Komandorsky Island block.

Coastal uplift west of Algiers (Algeria): pre- and post-Messinian sequences of marine terraces and rasas and their associated drainage pattern

AbstractThe North Africa passive margin is affected by the ongoing convergence between the African and Eurasian plates. This convergence is responsible for coastal uplift, folding, and reverse faulting on new and reactivated faults on the margin. The active deformation is diffuse and thus rather difficult to locate precisely. We aim to determine how a coastal landscape evolve in this geodynamic setting and gain insights into active tectonics. More particularly, we evidence and quantify coastal uplift pattern of the Chenoua, Sahel, and Algiers reliefs (Algeria), using sequences of marine terraces and rasas and computing several morphometric indices from the drainage pattern. Upper and Middle Pleistocene uplift rates are obtained by fossil shoreline mapping and preliminary U/Th dating of associated coastal deposits. Extrapolation of these rates combined to analyses of sea-level referential data and spatial relationships between marine terraces/rasas and other geological markers lead us to tentatively propose an age for the highest coastal indicators (purported the oldest). Values of morphometric indices showing correlations with uplift rate allow us to analyze uplift variation on area devoid of coastal sequence. Geological and geomorphological data suggest that coastal uplift probably occurred since the Middle Miocene. It resulted in the emergence of the Algiers massif, followed by the Sahel ridge massif. The Sahel ridge has asymmetrically grown by folding from west to east and was affected by temporal variation of uplift. Compared to previous study, the location of the Sahel fold axis has been shifted offshore, near the coast. The Chenoua fault vertical motion does not offset significantly the coastal sequence. Mean apparent uplift rates and corrected uplift rates since 120xa0ka are globally steady all along the coast with a mean value of 0.055xa0±xa00.015xa0mm/year (apparent) and of 0.005xa0±xa00.045xa0mm/year (corrected for eustasy). Mean apparent coastal uplift rates between 120 and 400xa0ka increase eastward from 0.045xa0±xa00.025 to 0.19xa0±xa00.12xa0mm/year (without correction for eustasy) or from 0.06xa0±xa00.06 to 0.2xa0±xa00.15xa0mm/year (with correction for eustasy). In addition, the combination of structural and geomorphic data suggests a low uplift rate for the southern part of the Algiers massif.n

Reef Carbonate Productivity During Quaternary Sea Level Oscillations

Global variations in reef productivity during the Quaternary depend on external parameters that may alter the global chemical balance in the oceans and atmosphere. We designed a numerical model that simulates reef growth, erosion, and sedimentation on coastlines undergoing sea level oscillations, and uplift or subsidence. We further develop a probabilistic evaluation that accounts for variable vertical ground motion, erosion, and foundation morphologies.

Coastal staircase sequences reflecting sea-level oscillations and tectonic uplift during the Quaternary and Neogene

Absolute

Quaternary coastal uplift along the Talara Arc (Ecuador, Northern Peru) from new marine terrace data

sea level change appears primordial, as productivity must have increased by an order of magnitude since the onset of the glacial cycles, ∼2.6 Ma. But most important is

Late Holocene sea-cliff retreat recorded by 10Be profiles across a coastal platform: Theory and example from the English Channel

relative

Quaternary evolution of the Marrakech High Atlas and morphotectonic evidence of activity along the Tizi N'Test Fault, Morocco

sea level change, i.e., eustasy modulated by uplift or subsidence, that rejuvenates the accommodation space and exposes pristine domains of the shore to active reefs at each cycle. Integrated over the long‐term, vertical land motion sets the pace of reef growth: productivity in tectonically unstable domains is thus expected to be up to 10 times higher than in stable regions, if any. We quantify the global length of reef coasts and the probability density functions for slopes and uplift rates.Productivity waxes nduring transgressions to reach 2–8 Gt CaCO

Transpressional tectonics in the Marrakech High Atlas: Insight by the geomorphic evolution of drainage basins

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“Arc-continent collision” of the Aleutian-Komandorsky arc into Kamchatka: Insight into Quaternary tectonic segmentation through Pleistocene marine terraces and morphometric analysis of fluvial drainage

/yr and wanes during highstands, which may contribute to increase atmospheric