Benthic habitat mapping: Concerns using a combined approach (acoustic, sediment and biological data)     

Rosa Freitas  Fernando Ricardo  Fbio Pereira  Leandro Sampaio  Susana Carvalho  Miguel Gaspar  Victor Quintino  Ana Maria Rodrigues 《Estuarine, Coastal and Shelf Science》2011,92(4):72

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Correction to: Solar Temperature Variations Computed from SORCE SIM Irradiances Observed During 2003 – 2020     

Cahalan  Robert F.  Ajiquichí  Paulino  Yatáz  Gaspar 《Solar physics》2022,297(2):1-17

Forbush decreases (FDs) are sharp reductions of the cosmic-ray (CR) intensity, following intense solar activity such as coronal mass ejections (CMEs) and their corresponding interplanetary shocks. In some cases, shocks create sudden storm commencements (SSCs) at the Earth’s magnetosphere with significant interest for space-weather studies. Preincreases and/or predecreases of CR intensity before the onset of FDs, known as precursory signals, have been widely examined by many authors. In this work, an attempt to define precursory signals that are not related to SSCs is presented. For the present analysis, CR data recorded by the ground-based Neutron Monitor Network as well as data on solar flares, CMEs, solar-wind speed, interplanetary magnetic field, and geomagnetic indices for the years 1969?–?2019 are used. To identify FDs that present precursors, the adopted criteria are mainly the FD amplitude (> 2%) and the equatorial CR anisotropy before the onset time (> 0.8%). The analysis of FDs and the study of their asymptotic-longitude CR distribution for precursors are based on the Global Survey Method and the Ring of Stations Method, respectively. Precursory signals are identified in 17 out of 27 events without SSCs.

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How Large Was the Earth in the Sixteenth Century? The Length of the Degree of Latitude in the Iberian Cartography of the Renaissance     

Joaquim Alves Gaspar 《The Cartographic journal》2013,50(4):318-324

In this paper, the results of a cartometric analysis of a number of Portuguese and Spanish charts of the sixteenth and seventeenth centuries are presented and conclusions are drawn concerning the length of the degree of latitude adopted in the Iberian nautical cartography of the Renaissance. Under the light of what we know about the navigational and charting methods of the time, a new interpretation of the textual and cartographic sources is proposed. Rather than being the result of technical considerations or precise measurements, the adoption of the various standards during this long period appears to be no more than the echoes of the traditional models of the Earth and of the political disputes between Portugal and Spain.  相似文献   

Economic restructuring, social re-composition and recent urban changes in Portugal     

Jorge Gaspar  Eduardo Brito Henriques  Mário Vale 《GeoJournal》1998,46(1):63-76

The productive restructuring process has affected more than just the economic field, because its effects have been felt on urbanisation processes, on social relations, and on the spatial organisation of society. Starting from the ‘metapolis’ concept, developed by Ascher (1995), we analyse the evolution of new forms of urban space in Portugal, arguing that new urban forms generate new social inequalities and, in extreme cases, social exclusion. Portugal is a semi-peripheral country that combines certain of the trends in social and economic organisation common to core countries, with certain trends more common in the developing world. Thus the understanding of urban change in Portugal is a complex task, made more difficult by the rapidity of processes since the mid 1970s. The Lisbon Metropolitan Area has been deeply affected by the productive restructuring process. The role of economic and urban policies in the Lisbon region is discussed, and an assessment is made of certain measures aimed at solving economic and social problems. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

A comparison of direct macrofaunal mortality using three types of clam dredges     

Gaspar  M.B; Leitao  F; Santos  M.N; Chicharo  L; Dias  M.D; Chicharo  A; Monteiro  C.C 《ICES Journal of Marine Science》2003,60(4):733-742

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Regional provenance from southwestern Colombia fore‐arc and intra‐arc basins: implications for Middle to Late Miocene orogeny in the Northern Andes          下载免费PDF全文

Sebastián Echeverri  Agustín Cardona  Andrés Pardo  Gaspar Monsalve  Victor A. Valencia  Carlos Borrero  Sebastián Rosero  Sergio López 《地学学报》2015,27(5):356-363

Andean orogenic processes controlled the spatial and temporal distribution of the magmatic and sedimentary record. This contribution integrates new U/Pb zircon ages, heavy mineral analyses and biostratigraphic constraints from the Neogene sedimentary record of the fore‐arc and intra‐arc basins and volcano‐plutonic rocks of southwestern Colombia, to reconstruct these orogenic processes. The results reveal continuous arc magmatism since the Late Oligocene, with a major post‐Middle Miocene magmatic peak and exhumation. When integrated with other geological constraints, the tectonic evolution of the margin includes Eocene‐Oligocene oblique convergence with limited magmatic activity, followed by the initiation of a Late Oligocene‐Early Miocene arc that migrated to the east in the Middle Miocene, when it experienced a major increase in magmatic activity, crustal deformation, exhumation and thickening. This orogenic evolution is related to the shallowing of the slab dip due to the subduction of the Neogene Nazca Plate.  相似文献   

Depositional sequences in a foreland basin (north-western domain of the continental Duero basin,Spain)     

Antonio Herrero  Gaspar Alonso-Gavilán  Juan Ramón Colmenero 《Sedimentary Geology》2010,223(3-4):235-264

The Cenozoic record of the north-western domain of the Duero basin is articulated at the surface through a set of continental depositional sequences called, from base to top, the Vegaquemada sequence, the Candanedo sequence, and the Barrillos sequence. These depositional sequences were deposited in continental sedimentary environments. The deposition of the first sequence occurred through a fluvial system with floodplains cut by low-sinuosity channels. The Vegaquemada sequence was developed between the Middle Eocene and the Early Agenian. The second sequence was formed by a set of highly efficient transport alluvial fans that evolved laterally towards fluvial systems with low-sinuosity fluvial channels and an extensive floodplain, where several types of palaeosols were formed. This sequence developed between the Early Agenian and the Late Vallesian. The third unit–the Barrillos sequence (between the Late Vallesian and the Turolian/Ruscinian transition), was generated by a set of highly efficient transport alluvial fans dominated by low-sinuosity fluvial channels.In subsurface geology, seismic and well data are used to rebuild the stratigraphic architecture. The two basal depositional sequences can be identified with two seismic units: the Palaeogene Seismic Unit (PgSU) and the Neogene Seismic Unit (NgSU), respectively. In the present work, we obtained the isovelocity, isochron, and isobath maps for the top and base of the two Cenozoic units. The Palaeozoic (PzSU) and Mesozoic (MzSU) seismic units are found under these two units. Through study of the logs of the various boreholes, it was only possible to analyse the upper 700 m of the Candanedo Sequence (NgSU), without encompassing the total thickness of the unit. Several middle-order sequences were differentiated, in general showing a sequential fining-upwards evolutionary character. Additionally, for the boreholes analysed two main types of electrofacies were identified, both representing fluvial channels and floodplain deposits.The north-western domain of the Duero basin is interpreted to have been formed in response to the tectonic uplifting of the Cantabrian Mountains since Middle-Eocene times. Integration of the data concerning the surface and subsurface geology in this domain reveals that this basin edge behaved as a foreland basin during Cenozoic stages. The foredeep, with a depth of 2800 m, is oriented east–west and has a sediment thickness of up to 3500 m. The forebulge is located in the southwestern zone and represents an area of basement uplifting in which a minimum thickness of materials from the Cenozoic depositional sequences has accumulated.  相似文献   

Theories for the interaction of electromagnetic and oceanic waves — A review     

Gaspar R. Valenzuela 《Boundary-Layer Meteorology》1978,13(1-4):61-85

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Stone-line formation processes documented by in situ-produced Be distribution, Jardim River basin, DF, Brazil     

R. Braucher  C.V. Lima  D.L. Bourlès  J.C. Gaspar  M.L.L. Assad 《Earth and Planetary Science Letters》2004,222(2):645-651

Concentrations of in situ-produced cosmogenic ¹⁰Be (T_1/2=1.5 Myr) were measured in quartz samples from a quartz vein and its connected stone line from the Jardim River basin, Distrito Federal, Brazil, in order to quantify the processes involved in the landscape evolution of that region. The exponential decrease of the ¹⁰Be concentrations along the quartz vein, as well as their systematic increase along the stone-line away from the quartz vein, suggests an autochthonous development. Two models allow to estimate the lateral displacement rate. A plugs model assuming that the sample depth, and hence the production rate, is constant, and a burial model assuming that the sample depth, and hence the production rate, varies through time, yield lateral displacement rate of 37±5 and 68±6 m Myr⁻¹, respectively.  相似文献   

Paleomagnetic and gravimetrical reconnaissance of Cretaceous volcanic rocks from the Western Colombian Andes: paleogeographic connections with the Caribbean Plate     

Santiago Hincapié-Gómez  Agustín Cardona  Giovanny Jiménez  Gaspar Monsalve  León Ramírez-Hoyos  Germán Bayona 《Studia Geophysica et Geodaetica》2018,62(3):485-511

The reconstruction of the tectonic evolution of the oceanic crust, including the recognition of ancient oceanic plumes and the differentiation between multiple and single oceanic arcs, relies on the paleogeographic analysis of accreted oceanic fragments found in orogenic belts. Here we present paleomagnetic and gravity data from Cretaceous oceanic basaltic and gabbroic rocks, the continental metamorphic basement, and their associated cover from northwestern Colombia. Based on regional scale tectonic reconstructions and geochemical constraints, such rocks have been interpreted as remnants of an oceanic large igneous province formed in southern latitudes, which was accreted to the sialic continental margin during the Late Cretaceous. Gravity analyses suggest the existence of a coherent high density segment separated by major suture zones from a lower density material related to the continental crust and/or thick sedimentary sequences trapped during collision. A characteristic paleomagnetic direction in Early and Late Cretaceous oceanic volcano-plutonic rocks, revealing a southeastern declination (D) and a negative inclination (I), may be interpreted in two different ways: (1a primary magnetization (tilt-corrected direction D = 130.3°, I = -23.3°, k = 23.4, α₉₅ = 26.4°), suggesting clockwise rotation around 130°, and magnetization acquired in southern latitudes (range of 4°S to 21°S); or (2) a remagnetization event during a reverse interval of the Earth’s magnetic field in the Cenozoic (in situ direction D = 128.7°, I = -6.2°, k = 23.1, α₉₅ = 26.1°), suggesting a counter-clockwise rotation around 50°. The first scenario seems more plausible, as it is consistent with previous paleomagnetic studies at other localities; it is compatible with a southern paleogeography for this block, and when integrated with other regional geological and paleomagnetic studies, supports a southern Pacific origin of a major oceanic block, formed as a part of a broader Cretaceous plateau that may have extended south or southwest of Galapagos. After its initial accretion, this block was subsequently fragmented due to the oblique SW-NE approach to the continental margin during the Late Cretaceous.  相似文献