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1 In sti tute of Geo log i cal Sci ences, Jagiellonian Uni ver sity, Oleandry 2a, 30-063 Kraków, Po land Kania M. (2014) Microfabric di ver sity and grain shape anal y sis of fault rocks from the se lected ar eas of the West ern Tatra Moun tains. Geo log i cal Quar terly, 58 (1): 3-18, doi: 10.7306/gq.1129 Fault rocks in brit tle and brit tle-duc tile shear zones played a key role in the evo lu tion of the West ern Tatra Moun tains crys tal-line rocks (Po land-Slovakia). Microfabrics of these rocks, in clud ing grain shape anal y ses, were in ves ti gated in the six ar eas of the West ern Tatra Moun tains. Based on stud ies of thin sec tions, 14 types of fault rock microfabric are dis tin guished, accord ing to the fol low ing cri te ria: (a) the pres ence and abun dance lev els of a cataclastic ma trix and (b) the pres ence and form of a pre ferred ori en ta tion fea tures. Gen eral ten den cies ob served in these ar eas in di cate south wards in creas ing non-co ax ial de for ma tion as well as the dom i na tion of ultracataclasites or ultramylonites to phyllonites in ar eas with neg a tive re lief (e.g., sedlo Zabrat’ Pass, Dziurawa Prze³êcz Pass). A model of shear zone evo lu tion em brac ing fol low ing three stages is proposed: (1) de for ma tion par ti tion ing and block-con trolled cataclastic flow, (2) ma trix-con trolled cataclastic flow, (3) se lec tive leach ing and de po si tion of sil ica, lead ing to the for ma tion of soft ened and hard ened de for ma tion do mains re spec tively. These microstructural ob ser va tions were sup ported by sta tis ti cal anal y ses of the grain shape in di ca tors (com pact ness, isometry, el lip tici ty, so lid ity, con vex ity). Two trends of re la tion ships be tween com pact ness and con vex ity were noted: the first, hor i zon tal on the cor re la tion di a grams, was in ter preted as an ef fect of rapid cataclasis and then sericitization, the second , with a strongly neg a tive cor re la tion co ef fi cient, was con sid ered as an ef fect of long-term cataclastic flow. The dif fer ent microfabric data and microstructural in ter pre ta tions de scribed in this pa per are con sis tent with a new model of the tec tonic his tory of the West ern Tatra Moun tains evo lu tion, with an im por tant role for a non-co ax ial de for ma tion dur ing Al pine orog eny in brit tle and brit tle-duc tile con di tions.

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Reservoir formation damage is a major problem that the oil and gas industry has to mitigate in order to maintain the oil and gas supply. A case study is presented that identifies the impacts of formation damage and their causes in the Nubian ‘C’ hydrocarbon reservoir within Sidki field located in the Southern Gulf of Suez, Egypt. In addition, a formation damage mitigation program was designed and implemented involving an effective stimulation treatment for each well experiencing reservoir damage. The data available for this study include core analysis to provide rock mineralogy and lithology; analysis of production fluid data; water chemistry; drilling fluid composition; perforations and well completion details; workover operations; and stimulation history. The diagnosis of formation damage based on the integrated assessment of the available data is associated with several benefits, (1) The integration of the data available helps provide a robust analysis of formation damage causes and in establishing suitable remediation actions, (2) Workover fluid is confirmed as the primary cause of reservoir damage in the studied well, (3) Several reservoir damage mechanisms were identified including water blockage, solids and filtrate invasion, fluid/rock interaction (deflocculation of kaolinite clay), salinity shock and/or high-sulfate content of the invaded fluid, (4) Irrespective of the potential causes of formation damage, the primary objective of a gas production company is to mitigate its effects and the integrated dataset helps to design appropriate and effective stimulation treatments to overcome formation damage, and (5) In gas reservoirs, especially low permeability ones, extra precautions are necessary to avoid potential reservoir damage due to workover fluid invasion.

<p>Granulometry, shape, and chemical composition analyses of the sediments studied by the Opportunity rover along its entire 45-km-long traverse have been used to classify sediments and provide information about their origin and depositional processes.</p><p>We have conducted granulometry and shape analyses of 179 sediment targets visible in MI images [1]. To facilitate the analyses, we have used the PADM algorithm - a semi-automatic tool for particle detection, measurement, and analysis [2]. This allowed identification of more than 70000 individual grains. For chemical composition analysis we used APXS data of 62 sediment targets [3]. The normative mineral composition was calculated from APXS according to the CIPW procedure to calculate the estimated density of the material and to classify in QAPF system.</p><p>The analyses show five deposit classes: i) dust with very fine sand enriched in sulphur, ii) fine basaltic sand, iii) coarse sand enriched in iron, found only on the plains, iv) gravel enriched in iron, also found on the plains, and iv) gravel with a typical for basalts amount of iron, found at the Endeavour crater rim. These classes occur in the following geomorphological settings: i) dust mixed with very fine sand is common on the leeward side of topographical obstacles, ii) fine sand is present in depressions, iii) coarse sand is related to coarse-grained ripples fields, iv) gravel occur as a lag deposit, especially in coarse-grained ripple troughs and at crater rims and outcrops.</p><p>The typical diameter of grains for the fine sand is 0.13 mm, and for the coarse sand - 1.20 mm. The best sorted coarse sands were found on the slopes and the crests of coarse-grained ripples. In most cases, the normative mineral composition of deposits fits in the basalt/andesite field of the QAPF classification. The coarse sand found in coarse-grained ripples was characterized by the highest content of iron and shows the most mafic composition in the QAPF diagram. This deviation from the basalt composition is related to iron-rich spherules (a frequent component of the gravel) than to a more mafic type of rock. On the other hand, the coarse sand grains found in ripple fields were characterized by lower roundness than the iron-rich spherules. Therefore, many of the transported by wind coarse sand grains had their origin in partial fragmentation of iron-rich spherules.</p><p>The work was funded by the Anthropocene Priority Research Area budget under the program "Excellence Initiative – Research University" at the Jagiellonian University.</p><p>[1] Herkenhoff, K. E. (2003) MER1 Microscopic Imager Science Calibrated Data Bundle. PDS Geosciences Node. DOI: 10.17189/1519006</p><p>[2] Kozakiewicz, J. (2018). Image Analysis Algorithm for Detection and Measurement of Martian Sand Grains. <em>Earth Science Informatics</em>, 11, 257-272. DOI: 10.1007/s12145-018-0333-y<em> </em></p><p>[3] Gellert, R. (2009). MER APXS Derived Oxide Data Bundle. PDS Geosciences (GEO) Node. DOI: 10.17189/1518973</p>

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Abstract. The Polish part of the Western Outer Carpathians lineament network was analysed based on the GMTED2010 digital elevation model. Lineaments were identified in the visual screening of the hillshade model. To the best of our knowledge, no one has studied the geometrical properties of the network with relation to the topological ones. The NetworkGT QGIS toolbox was applied to identify the nodes and branches of the network, as well as to calculate the topology parameters. Our aim was to find differences between the western and eastern parts of the Western Outer Carpathians; therefore, the analyses were carried out in six sectors chosen based on the geographical subdivision in the geological context: three in the north, mainly the Silesian unit; and three in the south, mainly the Magura unit. We found general agreement of the identified network with the photolineament map; however, some of the photolineaments are not confirmed by digital elevation model (DEM). We found that the topological parameters of the networks change from west to east, but not from north to south. There are areas of increased interconnectivity, especially the Nowy Sącz Basin, where the lineament network may reflect a complicated system of cross-cutting deep-rooted fault zones in the basement.