Search

Mountain building in the Al-Hajar Mountains (NE Oman) occurred during two major shortening stages, related to the convergence between Africa–Arabia and Eurasia, separated by nearly 30 Ma of tectonic quiescence. Most of the shortening was accommodated during the Late Cretaceous, when northward subduction of the Neo-Tethys Ocean was followed by the ophiolites obduction on top of the former Mesozoic margin. This shortening event lasted until the latest Santonian – early Campanian. Maastrichtian to Eocene carbonates unconformably overlie the eroded nappes and seal the Cretaceous foredeep. These neo-autochthonous post-nappe sedimentary rocks were deformed, along with the underlying Cretaceous tectonic pile, during the second shortening event, itself including two main exhumation stages. In this study we combine remotely sensed structural data, seismic interpretation, field-based structural investigations and apatite (U–Th)/He (AHe) cooling ages to obtain new insights into the Cenozoic deformation stage. Seismic interpretation indicates the occurrence of a late Eocene flexural basin, later deformed by an Oligocene thrusting event, during which the post-nappe succession and the underlying Cretaceous nappes of the internal foredeep were uplifted. This stage was followed by folding of the post-nappe succession during the Miocene. AHe data from detrital siliciclastic deposits in the frontal area of the mountain chain provide cooling ages spanning from 17.3 to 42 Ma, consistent with available data for the structural culminations of Oman. Our work points out how renewal of flexural subsidence in the foredeep and uplift of the mountain belt were coeval processes, followed by layer-parallel shortening preceding final fold amplification. [ABSTRACT FROM AUTHOR]

Geological and seismic data have been integrated to describe the impact of structural and sedimentological heterogeneities on fluid dynamics for one of the reservoirs (Reservoir X) of the Akpo field (deep offshore of Niger Delta). Akpo is a sinuous 4-way anticline formed because of strong deformation occurring within the over pressurized shales of the Akata Formation. Weak deformation may have started since 9 Ma; however, most of the strain associated with shortening was accumulated between ca 7 Ma and ca 3 Ma. The cumulative shortening has been estimated in the order of 4% (ca 400 m). From 3 Ma (during the latest stages of growth of the Akpo anticline) up to Present-day, the residual strain was taken up by oblique (right lateral strike-slip component) extensional faults, between 2 km and ca 15 km in length, organized into two main trends: N-dipping, ENE-WSW to NE-SW striking faults, and NNW-SSE striking faults mainly dipping to the east. These faults are segmented and have a maximum throw in the order of 70 m. Based on the architectural elements identified in this work, the Reservoir X of the Akpo field has been subdivided into three main intervals: a basal lobe (Interval 1a) and a related channel (Interval 1 b); two intermediate generations of meandering channels (Interval 2a and 2 b); and an upper and strongly erosional constructive channel (Interval 3). The 4D signal has been integrated to better understand the complex fluid flow within Reservoir X in time and space. The extensional faults play a role in baffling mainly in the central part of the field, where across-fault flow is likely to occur in correspondence with the spill points. Facies distribution and the nature of the contact between various reservoir intervals are also important because vertical and lateral communication between sand bodies can be complex. Levees or mud barriers can inhibit flow, impacting both efficiency of support between injectors and producers. On the other hand, sand-to-sand communication due to the strong erosional character of the contacts enhances dynamic connectivity between sands belonging to different reservoir intervals. As an example, even if sands belonging to Interval 3 totally erode (i.e. dynamically isolate) those of Interval 2 in the southern part of the field, in the northern sector the two reservoir intervals are in (vertical) communication as suggested by the 4D signal. A key result of this integrated work is that of documenting in detail the modes in which faults and sedimentary features impact fluid flow within and across reservoir intervals in a deep-water environment. • Multi-scale and multi-disciplinary analysis of a deep-water clastic reservoir. • Integration of wells data, seismic interpretations, production data, seismic inversion and 4D. • Better definition of the geometry and the distribution of the reservoir intervals, describing the lateral and vertical sand connectivity. • Impact of geological (structural and sedimentological) heterogeneities in dynamic condition and better understanding of the fluid flow. [ABSTRACT FROM AUTHOR]

Abstract: Field data and seismic reflection profiles of various resolutions, calibrated by deep well logs, have been used to unravel the tectonic evolution of the Crati Basin (southern Italy). The study area is located in the northern portion of the Calabrian Arc, a well-developed arc-shaped feature of the circum-Mediterranean belts, consisting of a series of ophiolite-bearing tectonic units and overlying basement nappes. NW–SE oriented left-lateral strike-slip faults exerted a major control on the tectonic evolution of northern-central Calabria, from Middle Miocene to Lower Pleistocene times. Such faults, arranged in an en-échelon geometry and dissecting the pre-existing Late Oligocene–Early Miocene orogenic belt, led to a structural setting including major N-S striking synforms – as the offshore Paola Basin and the Crati Basin are interpreted based on our results – separated by a broad antiformal ridge. Since the Middle Pleistocene, both E- and W-dipping normal faults developed in the southernmost sector of the Crati Basin, probably as a consequence of both uplift of the orogenic edifice and Tyrrhenian back-arc extension. The pre-existing regional strike-slip faults became inactive in this sector of the belt. However, working as persistent barriers, it is envisaged here that they inhibited the southern propagation of the newly formed normal faults, which therefore propagated towards the north. A minimum value of cumulative displacement of ca. 600m has been unraveled for the central sector of the Crati Basin since Middle Pleistocene times. This yields a vertical strain rate of ca. 0.9mm/y during the last 700ka. [ABSTRACT FROM AUTHOR]

Abstract: The Crati basin is a tectonic depression developed between the Coastal Range and the Sila Massif and is characterised by a sedimentary succession ranging between Late Miocene to Holocene age. Basin cover can be subdivided into a series of stratigraphic intervals bounded by angular unconformities. The general basin architecture is mainly controlled by N–S striking normal faults (the Crati Fault System) cropping out along both basin margins. These faults formed since the Middle Pliocene in the southern part of the basin and propagated northwards, where they developed during Middle–Late Pleistocene. The occurrence of several earthquakes along N–S striking faults, suggest their still ongoing activity. The northernmost part of the Crati basin, bordered by the 30 km long Pollino fault, is thought to be characterised by an important seismic gap; this contrasts with the geological evidences of Quaternary fault activation of both the central part of the Pollino fault and some NNW–SSE striking normal faults. We propose that the NNW–SSE striking faults represent the northernmost prolongation of the Crati Fault System, a large scale active crustal rift related to the Tyrrhenian spreading. These faults mechanically interacted with the Neogene Pollino fault and determined the almost contemporary activation of the central part of this structure, because of stress triggering phenomena, as suggested by the Coulomb failure stress changes. [Copyright &y& Elsevier]

Abstract: The main structural characteristics of the Caggiano and Polla faults, exposed in the epicentral area of the 1561 earthquake (Mw = 6.4), southern Italy, have been investigated in detail to assess their spatial and temporal properties, and to evaluate their seismogenic potential. These right stepping normal faults show an overlap of about 7 km and an across strike separation of about 4 km. The geometric relationships between the Caggiano and Polla faults, but also the displacement distribution along each fault, demonstrate that they have been strongly interacting throughout the Pleistocene. Nevertheless, geological evidence of Holocene tectonic activity was mainly recognized along the Caggiano Fault (faulted late glacial deposits) and in the southernmost part of the Polla Fault (faulted deposits of probably Late Pleistocene age). This suggests that the Caggiano Fault can be considered as the most tectonically active fault in the Vallo di Diano Fault System. By calculating Coulomb stress changes, we have constrained modes of mechanical interactions between the two faults in a scenario compatible with the 1561 earthquake. This approach allows us to argue that both the Caggiano and the Polla Faults are probably linked at depth, and part of the same seismogenic structure which may be potentially responsible for composite ruptures with magnitude ≥ 6.5. [Copyright &y& Elsevier]

Based on the interpretation of geological maps, seismic reflection and well data complemented with a bibliographic compilation and field work in the Rif, we investigate the factors that control the rift initiation, its development and the formation of oceanic crust in NW Africa. From SE to NW, we examine the Western Sahara Atlas, the Tendrara, the Guercif, and the Rif basins, to establish their geodynamic evolution in relation with the Mesozoic formation of the Central Atlantic and Maghrebian Tethys oceans, respectively. The Triassic extension was diffuse and developed over Lower Carboniferous horst-and-graben structures formed in the NW passive margin of Gondwana and involved in the subsequent late Carboniferous – early Permian Variscan orogenic system; suggesting that, at the onset of the Triassic rifting, the lithosphere was thermally re-equilibrated and replaced by more fertile lithospheric mantle. Afterwards, extension resumed in the Atlas system during middle to late Pliensbachian and finished during Toarcian. In the Rif and Guercif basins, the extension began later, mainly during the Toarcian, climaxing during Middle Jurassic times with the exhumation along low-angle extensional faults of CAMP gabbroic bodies and the final mantle exhumation during Upper Jurassic in the Rif. The study evidences the prominent role of the Variscan structural and thermal inheritance on the subsequent deformation events. Accordingly, the Paleozoic inverted basins and horsts localized the Triassic extension. From that, the opening of the Central Atlantic and Maghrebian Tethys oceans activated, respectively, the SE (Atlas) and NW (Tethys) rifted segments of the weakened continental crust where the Jurassic extension was gradually distributed. This led to the final formation of an oceanic domain in the NW paleomargin of Africa. • The tectonic/thermal features, inherited from Paleozoic events, were reactivated and controlled the subsequent Mesozoic extension in NW Africa. • Triassic extension was diffuse and developed over both former lower Paleozoic horsts and Lower Carboniferous basins in a thermally re-equilibrated lithosphere. • Jurassic far-field extensional deformations and their orientations were recorded by the NW African basins during the gradual opening of both the Central Atlantic and Maghrebian Tethys oceanic domains. [ABSTRACT FROM AUTHOR]

The article presents the study on the Krüppel-like factor 2 transcription factor gene in splenic marginal zone lymphoma (SMZL). It discusses how the study was conducted which involved mutation analysis of Krüppel-like factor 2 transcription factor gene and of genes that regulate MZ B-cell differentiation. The results reportedly revealed that Krüppel-like factor 2 transcription factor gene is mutated in SMZL.

The Upper Cretaceous carbonates cropping out in the Murge Plateau are good analogues of the fractured and faulted carbonate oil reservoirs of southern Italy. For this reason, a detailed field analysis focused on structural architecture of fault and fracture networks has been carried out in the Murge Plateau. The well-bedded carbonates exposed there are crosscut by a set of bed-parallel stylolites and two sets of bed-perpendicular cross-orthogonal joints/veins. These structural elements were likely formed under vertical loading during burial diagenesis and flexure of the Apulian foreland of the Southern Apennines fold-and-thrust belt. Bed-parallel stylolites and bed-perpendicular cross-orthogonal joints/veins represent the background deformation that was overprinted by the fault-related localized deformation. The fault sets documented in the study area are arranged in two kinematically-compatible fault networks. The first one is made up of WNW-ESE and NNW-SSE oriented strike-slip faults, right- and left-lateral, respectively, and NW–SE oriented normal faults. The second fault network consists of WNW-ESE oriented left-lateral strike-slip faults, and NE–SW oriented normal faults. First, both architecture and dimensional parameters of the fault and fracture networks have been characterized and computed by means of statistical analysis. Then, the permeability structures associated to the aforementioned networks have been assessed in order to determine the role exerted by fault architecture and dissolution/cementation processes on the fluid storage and migration pathways within the studied platform carbonates. Network 1 faults show a quite variable fluid behavior, in which the fluid flow is strongly affected by inherited structural elements and karst dissolution, whereas network 2 faults show a more uniform, fluid conduit behavior. [ABSTRACT FROM AUTHOR]

Abstract: This contribution focuses on the controls exerted by sedimentological, petrographic and mechanical rock properties on the distribution of bed-perpendicular joints throughout layered carbonates. The study was conducted on Tortonian, shallow-marine skeletal grainstones and rudstones cropping out in the Granada Basin, southern Spain. The results of combined field and laboratory analyses are consistent with the rock grain size of the studied carbonates exerting a key control on distribution of the bed-perpendicular joints. A positive correlation between joint spacing and mechanical unit thickness is computed for the grainstones, whereas joints are almost absent in rudstones. The rock grain size affected the diagenetic processes, such as cementation and dissolution, and therefore the resulting porosity and uniaxial compressive strength (UCS) values. Quantitative data show that higher UCS values are commonly associated with greater calcite amounts, lower values of porosity and finer grain sizes and, hence, denser bed-perpendicular joint sets. In conclusion, this study documents that it is possible to infer the density of bed-perpendicular joints in layered carbonates based on the sedimentological, petrographic and mechanical parameters. Considering the impact that this type of joints has on subsurface fluid flow, the acquired knowledge can help the management of geofluids as well as the overall prediction of carbonate reservoir quality. [Copyright &y& Elsevier]

Unlabelled: Cystic adenomatoid malformation of the lung (CAML) is a rare pulmonary maldevelopment resulting from an abnormal growth of the terminal bronchial structures. This study proposes a possible management of prenatally diagnosed CAML. A group of nine cases of CAML diagnosed prenatally between January 1990 and December 1995 was studied retrospectively. The evolution of lesions was followed in utero by serial ultrasound monitoring. Chest X-ray was performed at birth in all neonates and CT only in the symptomatic ones. CAML was macrocystic in three cases and microcystic in six. No polyhydramnios, hydrops or associated malformations were seen. In four cases, CAML was confirmed at birth and required surgery. The lesion decreased in size prenatally in five fetuses, of whom only one underwent surgery. In two further cases a prenatal diagnosis of CAML was changed to diaphragmatic hernia.Conclusion: Given the possible clinical disappearance or resolution of cystic adenomatoid malformation of the lung, we believe that surgery is justified at birth only in symptomatic and radiologically positive neonates. It could be safely delayed in those asymptomatic patients with either positive or negative chest X-ray. The former need computed tomography at birth, whereas, in the latter, it should be performed at 6 months of age for a more definitive assessment of the patient. [ABSTRACT FROM AUTHOR]

We report a rare case of a subdiaphragmatic cyst, diagnosed prenatally during routine ultrasound screening at 25 weeks’ gestation. Serial ultrasonographic evaluation demonstrated a slight increase in the size of the cyst during pregnancy. On the basis of the anatomic site and the sonographic features of the lesion, four diagnosic hypotheses were postulated: cystic neuroblastoma, adrenal hemorrhage, duplication of the inferior third of the esophagus and retroperitoneal cystic lymphangioma. A healthy baby, weighing 3300 g and with Apgar scores of 8 and 9, was delivered vaginally at term. He underwent successful surgery at the age of 3 months. The postoperative course was uneventful and the baby is currently doing well. Histology revealed a bronchogenic cyst. [ABSTRACT FROM AUTHOR]