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Rui Quartau - One of the best experts on this subject based on the ideXlab platform.

  • imprints of volcanic erosional depositional tectonic and mass wasting processes in the morphology of santa maria insular shelf azores
    Marine Geology, 2020
    Co-Authors: Alessandro Ricchi, Daniele Casalbore, Rui Quartau, Ricardo S Ramalho, Claudia Romagnoli, Zhongwei Zhao
    Abstract:

    Abstract The present-day morphology of volcanic island shelves is the result of several factors, namely the original shape and structure of the volcanic edifice, the nature and age of the materials that compose its flanks, and the erosional, volcanic, tectonic and sedimentary processes that acted to form these shelves. By combining detailed Seafloor Mapping with onshore studies it is possible to gain a unique insight onto the evolution of volcanic island edifices and the processes that helped to shape their shelves. Here we look at Santa Maria Island in the Azores Archipelago, which is a 6 Ma old ocean-island volcano surrounded by a 135 km2 shelf, characterized by an history of subsidence since its formation c. 6 Ma ago, followed by uplift from 3.5 Ma onwards. By analyzing the geomorphic parameters of the insular shelf (such as the shelf width and the erosive edge depth), the island's history of vertical movements, and by relating the morphology of the outcrops found on the shelf with those onshore, we contribute to a better knowledge of the evolutionary history of Santa Maria with particular focus on its earlier stages of growth. We infer that the outer part of the northern shelf is carved on units older than the oldest volcanic sequences exposed on land; the western and southern shelves are almost entirely carved in the products of the oldest shield volcano (Anjos Volcanic Complex), whilst the eastern shelf is the youngest in formation, being related to units of the Pico Alto volcanic complex. We also discuss the distribution of sediments on the shelf. High wave energy concomitant with sea level drops contributed to the erosion and transport of older sequences offshore, which were ultimately lost to the slopes of the island, resulting in a shelf that is sediment-stripped for the most part. Presently, wide shelves further contribute to wave-energy dissipation, resulting in a significantly diminished sediment production. The shelf edges around Santa Maria exhibit several erosive scars, interpreted as the head of a submarine drainage network carved on the slopes of the island. On the western, southern and eastern shelves, these mass-wasting features are mostly controlled by tectonics since the extension of faults can be followed from onshore to the shelf edge. On the northern shelf mass-wasting appears to be mostly correlated with presence of unstable sediments on the shelf edge that triggered landsliding. Overall, this work shows how detailed Mapping of the shelves surrounding old volcanic islands can still provide important complementary information about the evolution of these islands, which could not be acquired solely by the study of their subaerial and deeper submarine parts.

  • volcanic tectonic and mass wasting processes offshore terceira island azores revealed by high resolution Seafloor Mapping
    Bulletin of Volcanology, 2015
    Co-Authors: Daniele Casalbore, C Romagnoli, Adriano Pimentel, Rui Quartau, David Casas, Gemma Ercilla, Ana Hipolito, A Sposato, F L Chiocci
    Abstract:

    Terceira Island, in the Azores Archipelago, lies at the intersection of four submarine volcanic ridges. New high-resolution bathymetric and seismic reflection data have been used to analyze the main volcanic, tectonic and mass-wasting features of the island offshore. Volcanic features such as linear volcanic centers, and pointy and flat-topped cones are mainly concentrated on the narrow western and north-western ridges, characterized by an overall rugged morphology. Fault scarps dominate mainly the broad eastern and south-eastern ridges, which are characterized by an overall smooth and terrace-like morphology. On the eastern ridge, faults form a series of horsts and grabens related to the onshore Lajes Graben. The strikes of the fault scarps, linear volcanic centers and alignment of volcanic cones on the ridges reveal two main structural trends, WNW–ESE and NNW–SSE, consistent with the main tectonic structures observed on the Azores Plateau. In contrast, a large variability of strike was observed in inter-ridge areas, reflecting the relative importance of regional and local stresses in producing these structures. Mass-wasting features are subordinate and mostly represented by hundred meter-wide scars that indent the edge of the insular shelf surrounding the island, apart from two large, deeper scars identified on the southern steep flank of the western ridge. Finally, the remarkable morpho-structural differences between the western and eastern ridges are discussed in the framework of the evolution of the Terceira volcanic edifice and hypothesized to reflect successive stages of ridge evolution.

Daniele Casalbore - One of the best experts on this subject based on the ideXlab platform.

  • imprints of volcanic erosional depositional tectonic and mass wasting processes in the morphology of santa maria insular shelf azores
    Marine Geology, 2020
    Co-Authors: Alessandro Ricchi, Daniele Casalbore, Rui Quartau, Ricardo S Ramalho, Claudia Romagnoli, Zhongwei Zhao
    Abstract:

    Abstract The present-day morphology of volcanic island shelves is the result of several factors, namely the original shape and structure of the volcanic edifice, the nature and age of the materials that compose its flanks, and the erosional, volcanic, tectonic and sedimentary processes that acted to form these shelves. By combining detailed Seafloor Mapping with onshore studies it is possible to gain a unique insight onto the evolution of volcanic island edifices and the processes that helped to shape their shelves. Here we look at Santa Maria Island in the Azores Archipelago, which is a 6 Ma old ocean-island volcano surrounded by a 135 km2 shelf, characterized by an history of subsidence since its formation c. 6 Ma ago, followed by uplift from 3.5 Ma onwards. By analyzing the geomorphic parameters of the insular shelf (such as the shelf width and the erosive edge depth), the island's history of vertical movements, and by relating the morphology of the outcrops found on the shelf with those onshore, we contribute to a better knowledge of the evolutionary history of Santa Maria with particular focus on its earlier stages of growth. We infer that the outer part of the northern shelf is carved on units older than the oldest volcanic sequences exposed on land; the western and southern shelves are almost entirely carved in the products of the oldest shield volcano (Anjos Volcanic Complex), whilst the eastern shelf is the youngest in formation, being related to units of the Pico Alto volcanic complex. We also discuss the distribution of sediments on the shelf. High wave energy concomitant with sea level drops contributed to the erosion and transport of older sequences offshore, which were ultimately lost to the slopes of the island, resulting in a shelf that is sediment-stripped for the most part. Presently, wide shelves further contribute to wave-energy dissipation, resulting in a significantly diminished sediment production. The shelf edges around Santa Maria exhibit several erosive scars, interpreted as the head of a submarine drainage network carved on the slopes of the island. On the western, southern and eastern shelves, these mass-wasting features are mostly controlled by tectonics since the extension of faults can be followed from onshore to the shelf edge. On the northern shelf mass-wasting appears to be mostly correlated with presence of unstable sediments on the shelf edge that triggered landsliding. Overall, this work shows how detailed Mapping of the shelves surrounding old volcanic islands can still provide important complementary information about the evolution of these islands, which could not be acquired solely by the study of their subaerial and deeper submarine parts.

  • volcanic tectonic and mass wasting processes offshore terceira island azores revealed by high resolution Seafloor Mapping
    Bulletin of Volcanology, 2015
    Co-Authors: Daniele Casalbore, C Romagnoli, Adriano Pimentel, Rui Quartau, David Casas, Gemma Ercilla, Ana Hipolito, A Sposato, F L Chiocci
    Abstract:

    Terceira Island, in the Azores Archipelago, lies at the intersection of four submarine volcanic ridges. New high-resolution bathymetric and seismic reflection data have been used to analyze the main volcanic, tectonic and mass-wasting features of the island offshore. Volcanic features such as linear volcanic centers, and pointy and flat-topped cones are mainly concentrated on the narrow western and north-western ridges, characterized by an overall rugged morphology. Fault scarps dominate mainly the broad eastern and south-eastern ridges, which are characterized by an overall smooth and terrace-like morphology. On the eastern ridge, faults form a series of horsts and grabens related to the onshore Lajes Graben. The strikes of the fault scarps, linear volcanic centers and alignment of volcanic cones on the ridges reveal two main structural trends, WNW–ESE and NNW–SSE, consistent with the main tectonic structures observed on the Azores Plateau. In contrast, a large variability of strike was observed in inter-ridge areas, reflecting the relative importance of regional and local stresses in producing these structures. Mass-wasting features are subordinate and mostly represented by hundred meter-wide scars that indent the edge of the insular shelf surrounding the island, apart from two large, deeper scars identified on the southern steep flank of the western ridge. Finally, the remarkable morpho-structural differences between the western and eastern ridges are discussed in the framework of the evolution of the Terceira volcanic edifice and hypothesized to reflect successive stages of ridge evolution.

Zhongwei Zhao - One of the best experts on this subject based on the ideXlab platform.

  • imprints of volcanic erosional depositional tectonic and mass wasting processes in the morphology of santa maria insular shelf azores
    Marine Geology, 2020
    Co-Authors: Alessandro Ricchi, Daniele Casalbore, Rui Quartau, Ricardo S Ramalho, Claudia Romagnoli, Zhongwei Zhao
    Abstract:

    Abstract The present-day morphology of volcanic island shelves is the result of several factors, namely the original shape and structure of the volcanic edifice, the nature and age of the materials that compose its flanks, and the erosional, volcanic, tectonic and sedimentary processes that acted to form these shelves. By combining detailed Seafloor Mapping with onshore studies it is possible to gain a unique insight onto the evolution of volcanic island edifices and the processes that helped to shape their shelves. Here we look at Santa Maria Island in the Azores Archipelago, which is a 6 Ma old ocean-island volcano surrounded by a 135 km2 shelf, characterized by an history of subsidence since its formation c. 6 Ma ago, followed by uplift from 3.5 Ma onwards. By analyzing the geomorphic parameters of the insular shelf (such as the shelf width and the erosive edge depth), the island's history of vertical movements, and by relating the morphology of the outcrops found on the shelf with those onshore, we contribute to a better knowledge of the evolutionary history of Santa Maria with particular focus on its earlier stages of growth. We infer that the outer part of the northern shelf is carved on units older than the oldest volcanic sequences exposed on land; the western and southern shelves are almost entirely carved in the products of the oldest shield volcano (Anjos Volcanic Complex), whilst the eastern shelf is the youngest in formation, being related to units of the Pico Alto volcanic complex. We also discuss the distribution of sediments on the shelf. High wave energy concomitant with sea level drops contributed to the erosion and transport of older sequences offshore, which were ultimately lost to the slopes of the island, resulting in a shelf that is sediment-stripped for the most part. Presently, wide shelves further contribute to wave-energy dissipation, resulting in a significantly diminished sediment production. The shelf edges around Santa Maria exhibit several erosive scars, interpreted as the head of a submarine drainage network carved on the slopes of the island. On the western, southern and eastern shelves, these mass-wasting features are mostly controlled by tectonics since the extension of faults can be followed from onshore to the shelf edge. On the northern shelf mass-wasting appears to be mostly correlated with presence of unstable sediments on the shelf edge that triggered landsliding. Overall, this work shows how detailed Mapping of the shelves surrounding old volcanic islands can still provide important complementary information about the evolution of these islands, which could not be acquired solely by the study of their subaerial and deeper submarine parts.

Polina Lemenkova - One of the best experts on this subject based on the ideXlab platform.

  • Seafloor Mapping of the Atlantic Ocean by GMT: Visualizing Mid-Atlantic Ridge Spreading, Sediment Distribution and Tectonic Development
    Acta Geobalcanica, 2020
    Co-Authors: Polina Lemenkova
    Abstract:

    The study presents the insights of the tectonic development and geological settings of the Atlantic Ocean supported by cartographic visualization in Generic Mapping Tools (GMT). The aim is to study geologic situation and trends in the tectonic development of the Mid-Atlantic Ridge and Atlantic Ocean Seafloor. The objective is to find out impact of various factors (such as volcanic, tectonic, hydrothermal and sedimentary processes) that sculpt Seafloor geomorphology, and correlation between early history of crust formation, geological processes and present submarine landforms. Other assignments in this work refer to mutual comparison of raster grids on sedimentation, topography, geology, Seafloor fabric and highlighting similarities among the landforms and sediment thickness. Asymmetry in crustal accretion is explained by the tectonic history of the lithosphere formation. Correlation between plate subduction and development of the submarine landforms is explained by the Earth's crust extension resulting in formation of cracks, elongations, faults, rifts. Ocean Seafloor geomorphology is shaped by a variety of factors that impact its form at different scales. These drivers (tectonic evolution, oceanic currents, hydrology, sedimentation) have effects on geomorphic landforms of the Seafloor in context of historic geological development and during Quaternary. Technical part of this work was performed by GMT scripting toolset with all maps plotted in American polyconic projection. The results are received by overlay, cartographic analysis and synthesis of the multi-source geodata through Mapping and interpreting grids (ETOPO1, EGM96, GlobSed, crustal age). This work contributes to expand the knowledge on geological and tectonic development of the Atlantic Ocean seabed in order to complete the view of its submarine geomorphology

  • технология получения данных глубин при съемке морского дна с использованием программного обеспечения caris hips gmt и arcgis data capture for Seafloor bathymetric Mapping using software caris hips gmt and arcgis
    Social Science Research Network, 2015
    Co-Authors: Polina Lemenkova
    Abstract:

    Russian Abstract: Проведение батиметрической съемки с использованием высокоточных сонарных измерений на основе современных приборов (ультразвуковой гидролокатор) обеспечивает детальной информацией о глубинах и рельефе дна океанов, облегчает точное позиционирование и навигации судна и вносит существенный вклад в изучение интерпретаций движений литосферных плит. Последнее особенно важно для ключевых тектонических регионов в области границ литосферных плит. ПО Caris Hips - наиболее профессиональная и признанная во всем мире программа, предназначенная для составления лоцманских карт на основе данных промера. Это многофункциональный инструмент для обработки батиметрических данных, обеспечиващий также создание векторных карт на базе отснятых измерений. Caris Hips обрабатывает исходные данные, полученные на борту корабля, доводя их до уровня лоцманских и батиметрических карт. Программа поддерживает более 40 рабочих стандартов и форматов сонарных данных, чем облегчается их установка на борту практически любого НИС. Его используют организации по составлению лоцманских карт. Caris Hips Professional обеспечивает осуществление полной последовательности батиметрической обработки данных, включая визуализацию, просмотр, корректировку эходанных и изготовление карт на их основе, а также обработку эходанных различных типов акустических гидролокаторов. В программе Caris Hips проводится редактирование измеренных глубин, а также чистка профилей рельефа дна от пиков, т.е. значений глубин, резко и во много раз отличающихся по абсолютному значению от всех соседних, т.е. неточных измерений. Работа представляет собой технический пример использования ПО Caris Hips в целях батиметрического картографирования. English Abstract: Current paper reports experience of the successful usage of Caris HIPS bathymetric software for Seafloor Mapping and marine geology survey. Performing bathymetric surveys using high-precision sonar measurements based by modern instruments (ultrasonic sonar) provides detailed information on depths and topography of the ocean floor. It furthermore facilitates accurate positioning and navigation of the vessel and makes a significant contribution to the study of the movements of lithospheric plates. The latter is especially important for the key tectonic regions in the region of the boundaries of the lithospheric plates. Caris HIPS software is the most professional and globally recognized program for compiling navigation charts based on measurement data. This is a multifunctional tool for processing bathymetric data, which also provides for the creation of vector maps based on captured measurements. Caris HIPS processes the raw data obtained aboard the ship, bringing it to the level of navigation and bathymetric charts. The program supports more than 40 working standards and formats of sonar data, which facilitates their installation on the board of almost any research vessels. It is used by the organization for compiling navigation and bathymetric charts. Caris HIPS Professional provides complete consistency of bathymetric data processing, including visualization, review, correction of e-data, Mapping, as well as processing of various types of the acoustic sonar data. In the Caris HIPS program, the measured depths are edited, and the bottom relief profiles are cleaned from the peaks, i.e. depth values, sharply and many times different in absolute value from all neighbouring ones, i.e. inaccurate measurements. Current paper provides a technical report on the usage of the Caris HIPS for bathymetric survey.

Alessandro Ricchi - One of the best experts on this subject based on the ideXlab platform.

  • imprints of volcanic erosional depositional tectonic and mass wasting processes in the morphology of santa maria insular shelf azores
    Marine Geology, 2020
    Co-Authors: Alessandro Ricchi, Daniele Casalbore, Rui Quartau, Ricardo S Ramalho, Claudia Romagnoli, Zhongwei Zhao
    Abstract:

    Abstract The present-day morphology of volcanic island shelves is the result of several factors, namely the original shape and structure of the volcanic edifice, the nature and age of the materials that compose its flanks, and the erosional, volcanic, tectonic and sedimentary processes that acted to form these shelves. By combining detailed Seafloor Mapping with onshore studies it is possible to gain a unique insight onto the evolution of volcanic island edifices and the processes that helped to shape their shelves. Here we look at Santa Maria Island in the Azores Archipelago, which is a 6 Ma old ocean-island volcano surrounded by a 135 km2 shelf, characterized by an history of subsidence since its formation c. 6 Ma ago, followed by uplift from 3.5 Ma onwards. By analyzing the geomorphic parameters of the insular shelf (such as the shelf width and the erosive edge depth), the island's history of vertical movements, and by relating the morphology of the outcrops found on the shelf with those onshore, we contribute to a better knowledge of the evolutionary history of Santa Maria with particular focus on its earlier stages of growth. We infer that the outer part of the northern shelf is carved on units older than the oldest volcanic sequences exposed on land; the western and southern shelves are almost entirely carved in the products of the oldest shield volcano (Anjos Volcanic Complex), whilst the eastern shelf is the youngest in formation, being related to units of the Pico Alto volcanic complex. We also discuss the distribution of sediments on the shelf. High wave energy concomitant with sea level drops contributed to the erosion and transport of older sequences offshore, which were ultimately lost to the slopes of the island, resulting in a shelf that is sediment-stripped for the most part. Presently, wide shelves further contribute to wave-energy dissipation, resulting in a significantly diminished sediment production. The shelf edges around Santa Maria exhibit several erosive scars, interpreted as the head of a submarine drainage network carved on the slopes of the island. On the western, southern and eastern shelves, these mass-wasting features are mostly controlled by tectonics since the extension of faults can be followed from onshore to the shelf edge. On the northern shelf mass-wasting appears to be mostly correlated with presence of unstable sediments on the shelf edge that triggered landsliding. Overall, this work shows how detailed Mapping of the shelves surrounding old volcanic islands can still provide important complementary information about the evolution of these islands, which could not be acquired solely by the study of their subaerial and deeper submarine parts.