Evolution of Pleistocene travertine depositional system from terraced slope to fissure-ridge in a mixed travertine-alluvial succession (Jebel El Mida,Gafsa, southern Tunisia)     

Mohsen Henchiri  Walid Ben Ahmed  Andrea Brogi  Mehmet Cihat Alçiçek  Ramdhane Benassi 《Geodinamica Acta》2017,29(1):20-41

The Quaternary stratigraphic record of Jebel El Mida, composed of continental deposits, is a useful example of concomitant travertines and alluvial deposition in an extensional setting. Travertine deposition occurred in a faulted Pleistocene alluvial fan giving rise to seven (recognised) facies interfingering with five other alluvial ones. The travertine depositional events indicate a tectonically driven evolution from terraced slope (facies group FC1–FC6) to a travertine fissure ridge-type depositing phase (facies group of FC1–FC7). Interfingering between travertine and alluvial facies indicates the co-existence of adjacent and time-equivalent depositional environments. The travertine deposition resulted from deep origin hydrothermal fluids channelled along damaged rocks volumes associated to a regional fault system, named as the Gafsa Fault (GF). The travertine–terrigenous succession in Jebel El Mida highlights the major role played by the GF in controlling: (i) the hydrothermal fluid flow, still active as also indicated by the numerous thermal springs aligned along the fault zone; (ii) paleoflow directions, discharge locations, volume, rate and fluctuations of the water supply. The paleoclimatic correlation with adjacent localities reveals that, at that time, humid episodes could have contributed to the recharge of the hydrothermal system and to the deposition of alluvial sediments.  相似文献   

Correlation between Cerchar abrasivity index,rock properties,and drill bit lifetime     

Mehmet Capik  Ali Osman Yilmaz 《Arabian Journal of Geosciences》2017,10(1):15

The Cerchar abrasivity index (CAI) is one of the most widely known index method for identification of rock abrasivity. It is a simple and fast testing method providing reliable information on rock abrasiveness. In this study, the relationships between the CAI and some rock properties such as uniaxial compressive strength (UCS), point load strength, Brazilian tensile strength and Schmidt rebound hardness, and equivalent quartz content (EQC) are examined. The relationships between the CAI and drill bit lifetime is also investigated and the type of drill bit wear observed is mentioned. Additionally, the CAI is modeled using simple and multiple linear regression analysis based on the rock properties. Drill bit lifetime is also modeled based on the CAI. The results show that the CAI increases with the increase of the UCS, point load strength, Brazilian tensile strength, L-type and N-type Schmidt rebound hardness, and the EQC. It is concluded that the higher and the lower bit lifetime are obtained for marl and andesitic-basaltic formation, respectively. Moreover, flushing holes, inserted button, button removal, and failures of button on the bits are determined as the type of drill bit wear. The modeling results show that the models based on the UCS and the EQC give the better forecasting performances for the CAI.  相似文献   

Wave sloshing in corrugated bottom tanks with two-dimensional flow     

Abdi Kükner  Mehmet A. Baykal 《Ocean Engineering》1999,26(8):93

The boundary integral element method based on Green's formula is applied to the analysis of transient flow problem in corrugated bottom tanks. The problem is formulated as a two-dimensional linear, initial boundary value problem in terms of a velocity potential. The Laplace equation and the boundary conditions, except the dynamic boundary condition on the free surface, are transformed into an integral equation by the application of Green's formula. Finite Difference discretization is applied timewise. Initially a triangular wave on the free surface is assumed to be formed. The height of the triangular corrugated bottom is varied between 1/10 and 1/5 of the tank depth. The form of the free surface and the equipotential lines for the flow in the tank are presented at different time steps. An accuracy analysis is performed and distortion in time is considered. Proper coefficients for solutions are derived and presented. The results show that utilization of triangular corrugated bottoms may help to regulate the flow in tanks.  相似文献   

Local site effects evaluation by surface wave and H/V survey methods in Senirkent (Isparta) region,southwestern Turkey     

Kanbur  Mehmet Zakir  Silahtar  Ali  Aktan  Gökhan 《地震工程与工程振动(英文版)》2020,19(2):321-333

This study aimed to investigate the site characterization of the Senirkent Basin(Isparta) by using the microtremor(H/V) and surface wave analysis(ReMi) methods. Senirkent district, which is located on the foothill of the Kap? Mountain, are prone to seismic and landslide hazards. After the last landslip disaster(1995), the city has continued to develop on the alluvial basin. The microtremor data collected at 41 stations were analyzed. The predominant frequency and the amplification of the soil were found to be in the range of 1.8–6.6 Hz and 0.8–6.8, respectively. These are 4.0-6.8 Hz and 1-2.5 around the slope of the Kap? Mountain and 0.8-3.6 Hz and 3.0-6.6 at alluvium deposits of the valley. The ReMi data collected along 41 profiles were analyzed to obtain a V_(s30) map. The soil classifications were done by using V_(s30) values according to NEHRP soil classification criteria. The results showed that the southern area of the study had better soil conditions with V_(s30) between 360-1160 m/s and soil class between C and B. The alluvium deposits on the north are relatively low with V_(s30) in the range of 260-360 m/s and soil class D.  相似文献