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81.
82.
Evolution of an early Eocene pull‐apart basin in the Central Pontides (Northern Turkey): New insights into the origin of the North Anatolian Shear Zone 下载免费PDF全文
Giuseppe Ottria Luca Pandolfi Rita Catanzariti Simone Da Prato Alessandro Ellero Chiara Frassi Mehmet Cemal Göncüoğlu Michele Marroni Leonardo Ruffini Kaan Sayit 《地学学报》2017,29(6):392-400
Although the North Anatolian Shear Zone is one of the main lithospheric‐scale strike‐slip deformation zone in the world, playing a prominent role in the complex geodynamic interaction among the Eurasian, Anatolian and Arabian plates, the onset time of its activity remains highly controversial. Here, we tackle this issue by utilizing nannofossil biostratigraphy on deposits from the Ta?cilar basin, a pull‐apart basin that we have identified inside the North Anatolian Shear Zone overprinting the Intra‐Pontide suture zone. The syn‐tectonic sedimentary succession of the Ta?cilar basin developed completely during the early Eocene (Ypresian; CNE4–CNE5 Zones). The strike‐slip faulting related to the initial onset of the North Anatolian Shear Zone can likely be constrained within the Ypresian, suggesting that the westward escape of the Anatolian plate along the North Anatolian Shear Zone started in the early Eocene. 相似文献
83.
Chiara Origliasso Marilena Cardu Vladislav Kecojevic 《Rock Mechanics and Rock Engineering》2014,47(2):757-770
The purpose of this research was to evaluate the production rate (PR) and cutting performance of surface miners (SM) based on rock properties and specific energy (SE). We use data from equipment manufacturers and experimental data in this study and propose a new method and equations to determine both the PR and the cutting speed of SM. The unconfined compressive strength (UCS) of the rock, its abrasivity, and the machine’s engine power are the three most important factors influencing the PR. Moreover, the cutting depth, UCS, and engine power have a significant impact on the cutting speed. We propose a new method and equations to determine the energy required to cut a volume unit and a surface unit, i.e., specific energy, and establish the relationship between SE, UCS, and PR. The results of this study can be used by surface miner operators to evaluate the applicability of the machines to a specific mine site. 相似文献
84.
Validation of theoretical footprint models using experimental measurements of turbulent fluxes over maize fields in Po Valley 总被引:1,自引:0,他引:1
Representative source area of turbulent fluxes measured by eddy covariance stations is an important issue which has not yet been fully investigated. In particular, the validation of the analytical footprint models is generally based on the comparison with Lagrangian model predictions, while experimental results are not largely diffused in literature. In this work, spatial distribution of carbon dioxide, latent and sensible heat fluxes across two different maize fields in Po Valley, is used to validate two theoretical footprint models. Experiments are performed in two totally different scenarios at bare and vegetated soils using two eddy covariance systems: one fixed station which is located about in the middle of the field and a mobile station which is placed at various distances from the field edge to investigate the horizontal variation of the vertical scalar fluxes. The first objective of this work is to provide detailed information about the spatial distribution of turbulent fluxes across Po Valley characteristic fields at bare and vegetated soils, highlighting peculiarities and uniqueness. The second objective consists in the comparison between mobile measurements of carbon dioxide, latent and sensible heat fluxes and the predictions of two analytical footprint models widely used in literature. Contemporaneously, the latter objective will permit to understand what is the best footprint model which, under typical Po Valley atmospheric turbulent conditions, describes a representative source area compatible with the field dimensions and the turbulent flux distributions. The results show that both models are in good agreement with experimental measurements. The results also show that the spatial distribution of turbulent fluxes is strongly influenced by the presence of vegetation in the field. Moreover, the representative source area is different for different scalar fluxes. Another result is about 10:1 fetch-to-height obtained for both field situations. 相似文献
85.
Orogens and rift zones have a finite number of regional faults. The accretionary prisms analysed here have a number of thrusts < 50, whereas extensional areas have a number of normal faults ranging between six and 44. The average spacing of thrusts is between 5 and 25 km; spacing of normal faults is more restricted into two peaks, at 25–29 km and 4–6 km, in which the latter is the most common. The number and spacing of faults appear to be mainly controlled by the depth of the decollement plane, which seems to be more variable in compressive settings with respect to rift zones. Basement‐involved orogens present fewer and more spaced thrusts; by contrast, a greater number of thrusts with shorter spacing characterize thin‐skinned thrust belts. The shallower the decollement is, the stronger it appears to control the palaeogeography, in the sense of rheological lateral variations in the sedimentary cover. 相似文献
86.
Crustacea experience periods of starvation during moulting or when limited food availability occurs. The effects of starvation on Crustacea physiological responses have been demonstrated, whereas the effects of starvation on Crustacea immune parameters remain to be more fully studied. In the present study the effects of starvation on immune parameters and antioxidant enzyme activities of the crab Carcinus aestuarii were evaluated for the first time. Treated crabs were starved for 7 days, whereas control crabs were fed daily with mussels. Total haemocyte count (THC), haemocyte diameter and volume, haemocyte proliferation, cell-free haemolymph (CFH) glucose and total protein levels, and phenoloxidase (PO) activity in both haemocyte lysate (HL) and CFH were measured in crabs. In addition, superoxide dismutase (SOD) and catalase (CAT) activities were evaluated in both gills and digestive gland from crabs, in order to evaluate whether starvation induced oxidative stress in C. aestuarii. THC increased significantly in starved crabs, with respect to controls, whereas no significant variations were observed in haemocyte diameter, volume and proliferation. In CFH of starved animals glucose concentration significantly increased, whereas total protein concentration significantly reduced. A significantly higher PO activity was recorded in HL from starved crabs, than in control crabs. Conversely, PO activity did not vary significantly in CFH. Starvation did not cause significant alterations in antioxidant enzyme activities in both gills and digestive gland. Results obtained demonstrated that starvation influenced crab immune parameters, but did not induce oxidative stress. Results also indicated that C. aestuarii can modulate its cellular and biochemical parameters in order to cope with starvation. 相似文献
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88.
Marco Bonini Giacomo Corti Chiara Del Ventisette Piero Manetti Genene Mulugeta Dimitrios Sokoutis 《地学学报》2007,19(5):360-366
Small‐scale analogue models were used to investigate the process of Cretaceous orthogonal extension in the West Antarctic Rift System. The models considered the transition from the East Antarctic Craton to a weaker lithosphere, and the results support previous hypotheses about the strong control exerted by lateral variations in lithospheric structures on the process of extension. Strain was mostly accommodated at the boundary between the two types of lithosphere, with a relative uplift of the cratonic block which remained essentially undeformed. Conversely, the weaker lithosphere showed wide‐rifting style geometry, locally associated with core complex‐like structures. In agreement with the natural prototype, this tectonic scenario led to a long‐lasting extension without continental break‐up, and to the absence of relevant surface magmatism. 相似文献
89.
Ray A. F. Cas Heather M. N. Wright Christopher B. Folkes Chiara Lesti Massimiliano Porreca Guido Giordano Jose G. Viramonte 《Bulletin of Volcanology》2011,73(10):1583-1609
The 2.08-Ma Cerro Galán Ignimbrite (CGI) represents a >630-km3 dense rock equivalent (VEI 8) eruption from the long-lived Cerro Galán magma system (∼6 Ma). It is a crystal-rich (35–60%),
pumice (<10% generally) and lithic-poor (<5% generally) rhyodacitic ignimbrite, lacking a preceding plinian fallout deposit.
The CGI is preserved up to 80 km from the structural margins of the caldera, but almost certainly was deposited up to 100 km
from the caldera in some places. Only one emplacement unit is preserved in proximal to medial settings and in most distal
settings, suggesting constant flow conditions, but where the pyroclastic flow moved into a palaeotopography of substantial
valleys and ridges, it interacted with valley walls, resulting in flow instabilities that generated multiple depositional
units, often separated by pyroclastic surge deposits. The CGI preserves a widespread sub-horizontal fabric, defined by aligned
elongate pumice and lithic clasts, and minerals (e.g. biotite). A sub-horizontal anisotropy of magnetic susceptibility fabric
is defined by minute magnetic minerals in all localities where it has been analysed. The CGI is poor in both vent-derived
(‘accessory’) lithics and locally derived lithics from the ground surface (‘accidental’) lithics. Locally derived lithics
are small (<20 cm) and were not transported far from source points. All data suggest that the pyroclastic flow system producing
the CGI was characterised throughout by high sedimentation rates, resulting from high particle concentration and suppressed
turbulence at the depositional boundary layer, despite being a low aspect ratio ignimbrite. Based on these features, we question
whether high velocity and momentum are necessary to account for extensive flow mobility. It is proposed that the CGI was deposited
by a pyroclastic flow system that developed a substantial, high particle concentration granular under-flow, which flowed with
suppressed turbulence. High particle concentration and fine-ash content hindered gas loss and maintained flow mobility. In
order to explain the contemporaneous maintenance of high particle concentration, high sedimentation rate at the depositional
boundary layer and a high level of mobility, it is also proposed that the flow(s) was continuously supplied at a high mass
feeding rate. It is also proposed that internal gas pressure within the flow, directed downwards onto the substrate over which
the flow was passing, reduced the friction between the flow and the substrate and also enhanced its mobility. The pervasive
sub-horizontal fabric of aligned pumice, lithic and even biotite crystals indicates a consistent horizontal shear force existed
during transport and deposition in the basal granular flow, consistent with the existence of a laminar, shearing, granular
flow regime during the final stages of transport and deposition. 相似文献
90.