Search

Non-invasive estimation of right atrial pressure from the inspiratory collapse of the inferior vena cava using ultrasound machines is nowadays promising with the increasing availability of these machines in emergency departments, critical care units and in operating theaters. The learning curve of these tools is steep and they are becoming less expensive and give quick, non-invasive, dynamic clue to the preload status. The aim of this study is to evaluate the transhepatic inferior vena cava (IVC) diameter by non-invasive sonographic imaging and compare it with that measured by subxiphoid approach to reveal the degree of agreement between them. This is a prospective study, done in a tertiary care referral hospital at intensive care unit in Al-Sadr Teaching Hospital over a period of four months from 1st February 2017 to 5th of June 2017. Eighty shocked patients were included for assessment of volume status. Bedside ultrasound images were obtained with the patient in supine position to determine the dimensions and collapsibility of IVC. Evaluation of each patient included the standard anterior subxiphoid IVC assessment and lateral transhepatic assessment of IVC by ultrasound using liver as an acoustic window in mid-axillary line. The IVC diameter was measured 2 cm caudal to the hepatic vein-IVC junction, or approximately 3-4 cm caudal to the junction of IVC and the right atrium. Then IVC maximal diameter, IVC minimal diameter and collapsibility index were calculated for both approaches. A comparison between these data was made. A total of eighty patients were included, 31 (37.5%) were females and 49 (62.5%) were males. Mean age was 45.81±14.89 years. The results showed that there is no statistically significant difference between transhepatic and subxiphoid approaches in regard to IVC diameter and its collapsibility. In conclusion, transhepatic lateral view of IVC provides a good alternative when subxiphoid anterior view cannot be obtained to guide fluid management in shocked patients.

The formation and distribution of natural fractures in Cretaceous–Paleogene strata in Jordan are strongly tied to diagenetic processes, which in turn reflect the lithology of the host material. Observations collected from subsurface cores show that widespread fracturing began before compaction of the host sediment was complete, based on ptygmatic folding of one set of mineral-filled fractures (veins). Non-folded veins are preferentially developed within heavily cemented layers. Calcium carbonate is the greatest volumetric component of the host sediment, and most fractures are at least partially filled by calcite. Dolomite- and silica-bearing fractures are present in dolomitized and silicified host beds, respectively. Horizontal veins are filled by cone-in-cone calcite or, rarely, silica or dolomite. The stratigraphic arrangement and degree of compaction around ptygmatically folded calcite veins and chert nodules suggest that silica diagenesis was an important driver of early fractures. Nevertheless, those fractures were filled with carbonate cements as they opened, based on crack-seal texture of the vein fill. The volume loss associated with silica diagenesis created fracture porosity, which was filled coevally by carbonate cements. The distribution of later veins reflects embrittlement of host layers by cementation and is consistent with crustal deformation as the primary fracture driver.

Large distance correlation of sedimentary organic rich facies units in Jordan has been established by means of calcareous nannofossil biostratigraphy. Based on a biostratigraphic framework, a better understanding of the deposition and distribution of Maastrichtian to Eocene oil shales is obtained. A total of 812 samples representing 29 wells located across Jordan were studied for calcareous nannofossil biostratigraphy. The results reveal major regional changes in paleogeography leading to a change in oil shales distribution in time. The tectonic settings have been determined for four different oil shale sequences of Maastrichtian, Paleocene, Early Eocene and Middle Eocene age. Large variations in thickness over short distances indicate syndepositional subsidence control in several fault bound sedimentary sub-basins. During the Early Maastrichtian transgression, a thick oil shale dominated succession was accumulated in the south of Jordan. This transgression continued into the Paleocene as represented by a thick sequence of oil shales in nannofossil Zone NP 3. In the Late Paleocene, the gradual progradation of the oil shale facies from south to north coincided with an uplift of the Sirhan Sub-basin in east Jordan. Accordingly, the oil shale distribution varies locally and shows a scattered geographic distribution in the Late Paleocene. An up to 60 m thick succession of Early Eocene oil shales was found in central Jordan. Localized restricted conditions, which prevailed during the Ypresian–Lutetian transition (nannofossil Zone NP 14), were caused by the subsidence of the Azraq-Hamza and Sirhan sub-basins. These movements resulted in thick oil shale accumulation in the southeastern and central parts of Jordan. A gradual relative sea level fall during the Bartonian resulted in a prograding and thinning of the oil shale facies from west to east in central Jordan.

Oil-shale beds formed under anoxic conditions that were controlled by various local, regional and global factors. The Jordanian oil shales, which were deposited during the Late Cretaceous to Eocene, are considered as an example for the interplay of these factors. Two cores of organic-rich marls were investigated and analyzed with respect to their lithology, ichnofabrics and carbonate microfacies. The first core (OS-01, 183.3 m; South Jordan) is of Late Cretaceous age, the second one (OS-23, 256.3 m; Central Jordan) is of Eocene age. Our studies revealed that the Upper Cretaceous oil shales were deposited in a shallow-water carbonate shelf. Oyster bioherms acted as physical barriers that reduced the water circulation with the open shelf, thereby causing anoxic conditions. The Eocene oil shales also accumulated on a shallow-water carbonate shelf. In this case, however, synsedimentary tectonics caused subsiding grabens and half grabens, which in turn gave way to anoxic conditions. Both deposition and richness of the Jordanian oil shales were affected by regional sea-level fluctuations and global climatic changes.

Sediment petrographic studies combined with carbon and oxygen stable-isotope analyses are considered to be powerful tools in deciphering the depositional and diagenetic history of carbonate rocks. These studies have been found valuable for understanding the environmental controls and global changes of climate and oceanography. Two cores of Eocene bituminous marls (OS-22 and OS-23) from central Jordan with thicknesses of 222.4 m and 256.3 m, respectively, were logged. A total of 103 thin sections were analyzed for sediment petrographic investigations. Another 295 bulk rock samples from Core OS-23 were selected for stable-isotope analysis (δ13C, δ18O). The two cores show similar lithologic variations that correspond to third-order sea-level changes. The sediment petrographic study reveals the presence of six major microfacies that range from mudstones to grainstones. The distribution of these six types of microfacies in the two cores indicates an overall shallow-marine environment in an interior carbonate-platform setting. Within this environment, conditions fluctuated between open and restricted marine. The stratigraphic variability of the carbon-isotope data of Core OS-23 reflects a highly dynamic depositional system that exhibits a variable rate of organic matter accumulation in the sediments, which can be directly linked to the interaction between primary organic-matter burial and oxidative weathering of reworked organic matter. Within the overall diagenetically controlled δ18Ocarb profile an excursion is observed for a specifically enriched organic matter interval. This excursion is believed to coincide with the Middle Eocene Climatic Optimum (MECO), suggesting that next to seawater, porewaters were influenced by this event and making it the first record of this event in the region.

Reworked microfossils, common in Paleogene sediments in Jordan, are here used to reconstruct the depositional environment. The reworked taxa, which include both calcareous nannofossils and foraminifera of Cretaceous and Paleocene age, were found in Eocene oil shales. The potential provenance of the reworked material and the underlying processes of the reworking are discussed. We differentiate between a subaerial erosion of exposed hinterland strata and a submarine abrasion of sediments. A total of 73 smear slides have been prepared to identify calcareous nannofossils, another fifteen samples were analyzed for foraminifera. The allochthonous calcareous nannofossil and foraminifera taxa can be linked to a lithified source, which was eroded and transported with both calcitic lithic fragments and organic matter. Multiple factors controlling the transport of the reworked taxa during the time of deposition have been investigated for the Jordanian oil shales. Climate changes are thought to be the cause for changes in the abundance patterns and in the composition of the reworked taxa. The input of common autochthonous components during arid phases and more allochthonous sediment particles during humid periods filled the Eocene sink. A fall in relative sea level, perhaps in combination with increased storm activity, caused a transport of reworked material to deeper parts of the Azraq Hamza Sub-basin. The relative sea level changes in turn were related to syndepositional movements, redefining the shape of the Azraq Hamza Sub-basin and its internal fault-block architecture.

The study of trace fossils is widely used in facies interpretation. It provides a crucial tool for reconstructing depositional paleoenvironments when used in combination with other sedimentological and paleontological proxies. Here we present the first detailed study of Eocene trace fossils from Jordan. Two sections of Early to Middle Eocene age, with a total thickness of 478.7 m, from central Jordan were cored and investigated. The results of individually occurring (isolated) or co-occurring (combined) ichnofabrics and bioturbation levels, in combination with results from biostratigraphic and geochemical studies, were used for stratigraphic and paleoenvironmental reconstructions. The bioturbation index (BI) was used to classify the burrowing density versus the preservation of the original sedimentary structures. The two cores show highly variable grades of bioturbation with BI ranging from 0 to 6. Four ichnogenera were identified: Thalassinoides, Chondrites, Teichichnus and Zoophycos. Both the ichnofabrics and the variations of the BI suggest a shallow, highly dynamic depositional system with rapid changes of water depth and degree of bottom-water oxygenation.

Cretaceous and Paleogene marls, rich in total organic carbon, are widespread throughout Jordan and adjoining areas. Based on planktonic foraminifera these oil shales have been assigned a late Campanian–Paleocene age in previous studies. For the current analysis a total of 283 smear slides from five wells in central Jordan have been investigated for calcareous nannofossil biostratigraphy. Findings suggest a much more differentiated age model of the oil shales than previously proposed. The oil shales studied contain abundant calcareous nannofossil taxa of Eocene age along with varying abundances of Maastrichtian and Paleocene taxa. The encountered marker species Rhomboaster cuspis, Tribrachiatus bramlettei, Tribrachiatus orthostylus, Discoaster lodoensis, Coccolithus crassus, Discoaster sublodoensis, Nannotetrina quadrata, Reticulofenestra umbilicus and Chiasmolithus solitus, indicate an Early to Middle Eocene age, while the presence of Maastrichtian and Paleocene forms suggests major reworking. The presence of Cretaceous taxa reflects either subaerial erosive input from the hinterland or submarine reworking of Cretaceous strata within the basin. The highly variable amount of reworked material and associated deposition rates in the basin may represent changes in the tectonic setting during the Eocene. We propose that the high abundances of Cretaceous and Paleocene taxa reflect an increase in accommodation space by active graben flank movements. A dominance of Eocene taxa, on the other hand, indicates either periods of little accommodation space due to graben infill or inversion-type movements of the graben itself. In any case, the youngest Eocene and autochthonous taxa represent shallower or low topography graben phases.