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The Ghana margin displays one of the best-known transform margins. Studies of the margin have provided the framework for a number of conceptual models aimed at understanding transform margin development worldwide. However, the deep structure of the margin is poorly known as knowledge is based only on wide-angle refraction measurements obtained from two separate localities on the margin. Consequently, complexities in the rift–shear margin architecture have been overlooked by current interpretations of margin development. Based on combined analysis of a detailed grid of ∼2710 km multichannel (MCS) lines and potential field data, we provide new insights into the structural architecture and tectonic development of the Ghana margin. In particular, we outline the deep structure of the entire margin using a series of 2D gravity modelled transects constrained by MCS and published wide-angle data. Our study reveals more complex rift–shear margin architecture than previously envisaged. We demonstrate that the main transform boundary representing the continental extension of the Romanche Fracture Zone, is actually composed of two distinct margin segments, i.e., the ENE–WSW trending sheared margin segment of the Cote d’Ivoire-Ghana Ridge and the NE–SW trending rift-influenced sheared margin segment of the Ghana Platform. These segments evolved under varying stress regimes, and during different time intervals. West of the transform margin, divergent rifting during the Early Cretaceous initiated the development of the Deep Ivorian Basin, essentially, as a single major pull-apart structure. However, east of the shear zone, oblique rifting resulted in the development of the Eastern Ghana Slope Basin as a composite of at least two coalescing pull-apart basins displaced along strike-slip faults. Our structural interpretation of the transform boundary geometry shows that the ridge and platform margin segments were each subjected to separate thermal influences from two different migrating spreading centres. Tectonic uplift of the ridge began through transpression during mid-Albian time following a change in relative direction of plate motion from NE–SW to ENE–WSW. However, the ridge uplift was amplified by thermal heating from a previously undocumented spreading centre whose progressive westward migration along the ridge followed closely after the Albian transpressional phase. The structural architecture of the Ghana margin resulted from a combination of factors, notably, pre-existing basement structure, plate boundary geometry, the relative direction of plate motion and thermal heating. 相似文献
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Asimina Kanta Pantelis Soupios Pavel Barsukov Maria Kouli Filippos Vallianatos 《Environmental Earth Sciences》2013,70(5):2153-2165
Effective management of groundwater resources is a well-known problem in several areas around the world. It is especially important to areas suffering from an intrinsic lack of fresh water, such as islands. Detailed study of available aquifers is of particular interest in the highly touristic Greek island of Crete. The increasing water demand makes water resources management extremely important for sustainable development. This is the case in the prefecture of Chania in Western Crete, where there has been a lack of success of many different groundwater management plans that have been produced over the years and submitted for application to water management authority. The inefficiency of the management plans is verified by the continuous water shortage reported every year which forces the public authorities to transfer water from far away sources and wells. Until today there are only geological data as well as information from the borehole logs; therefore, the current work is focused to study in detail the tectonic and hydrogeological characteristics of the Keritis watershed to make a correlation of the available geoenvironmental information with the geophysical data of the study aquifer. Transient electromagnetic soundings were conducted to obtain detailed information about: the tectonic, hydrogeological, hydrolithological, and geometrical characteristics of the aquifer under investigation. In addition, optimum areas of water well drilling were identified to minimize the uncertainty and the total cost (economical, managerial, etc.) of future groundwater surveys. 相似文献
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Katsanos Dimitrios Retalis Adrianos Tymvios Filippos Michaelides Silas 《Natural Hazards》2016,83(1):53-74
A study of a daily precipitation database for the island of Cyprus is performed for a period of 30 years. A number of climatic indices for precipitation are calculated using the recently available CHIRPS dataset, on high spatial (0.05°) and temporal (daily) resolution. The same parameters for the same time period (1981–2010) are then calculated using the dense network of rain gauges of the Cyprus Department of Meteorology. The results show a quite promising performance regarding indices related to daily precipitation thresholds, resulting in high correlation scores. In the case of indices referring to number of days, it seems that the results are ambiguous, with medium or no correlation, probably related to the criteria used for the identification of a wet (rainy) day on the CHIRPS dataset. 相似文献
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In earthquake occurrence studies, the so-called q value can be considered both as one of the parameters describing the distribution of interevent times and as an index of
non-extensivity. Using simulated datasets, we compare four kinds of estimators, based on principle of maximum entropy (POME),
method of moments (MOM), maximum likelihood (MLE), and probability weighted moments (PWM) of the parameters (q and τ
0) of the distribution of inter-events times, assumed to be a generalized Pareto distribution (GPD), as defined by Tsallis
(1988) in the frame of non-extensive statistical physics. We then propose to use the unbiased version of PWM estimators to
compute the q value for the distribution of inter-event times in a realistic earthquake catalogue simulated according to the epidemic type
aftershock sequence (ETAS) model. Finally, we use these findings to build a statistical emulator of the q values of ETAS model. We employ treed Gaussian processes to obtain partitions of the parameter space so that the resulting
model respects sharp changes in physical behaviour. The emulator is used to understand the joint effects of input parameters
on the q value, exploring the relationship between ETAS model formulation and distribution of inter-event times. 相似文献
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