Deep-water Sediments Research Articles

Morphological features, ontogenetic changes and stratigraphic range of conodonts <i>Siphonodella belkai</i> Dzik (Tournaisian, Mississippian)

Research subject. Multidisciplinary characteristics of the Siphonodella belkai Dzik conodonts, which an index species in the Tournaisian (Mississippian) conodont zonation. Materials and methods. Data on conodonts collected from the North Cis-Urals and Subpolar Urals sections was used. In total, 89 specimens of Siphonodella belkai were found in the Kozhim Eiver basin sections (Subpolar Urals) and the Vangyr River section (Tchernyshev Uplift). The histology, morphology and ontogeny of platform elements of this species were studied using SEM, optic microscope and X-ray micro-CT. In total, 45 complete specimens were biometrically studied. Results. Siphonodella belkai can be reliably distinguished by having a smooth lens-like platform and bearing developed rostral ridges. The paralamellar tissue occurs in the platform and rostral ridges; distribution of the albid tissue is restricted by carina denticles in the cusp neighborhood. Sinistral and dextral P1 elements of the species compose asymmetric pairs and differ by the position and number of rostral ridges (Class III of symmetry). The element outline remains constant in ontogeny. Rostral ridges appear at early ontogeny stages, when an element is of 0.4-0.5 mm in length, thus allowing reliable taxonomic diagnostics. Conclusions. Siphonodella belkai is known from the moderately deep-water deposits of the Central and Eastern Europe and South China. The base of the S. belkai zone, marked by the first appearance of the eponimic taxon, coincides with the base of the Upper duplicata zone. Distinguishing the S. belkai zone as a standard zone seems unreasonable due to the rarity, restricted area and specific ecology of S. belkai. This zone is of low correlation potential.

Seismostratigraphic and sedimentological characterization of deepwater channel systems on the NW Borneo margin: Sediment sources and structurally-controlled routing system

• Late Miocene folding in deepwater NW Borneo influenced submarine channel development. • The Champion sediment-supply system comprised in its onshore part multiple rivers. • The paleo-Padas River was one of the primary rivers supplying lithic-rich sediment. • Variation in catchment-area geology influenced deepwater sediment composition. The northwest (NW) Borneo margin is one of the geologically most complex regions of Southeast Asia characterized by a steep slope gradient and an extensive deepwater fold and thrust belt. This area is economically important because of large-volume hydrocarbon accumulations in the deep-marine sandstones in fold and thrust anticlines. Although much attention has been paid to the distribution of deepwater reservoir rocks, the provenance of these rocks and compositional variations are yet not fully understood. In this study we present geomorphological and petrological analyses of Late Miocene deepwater channel deposits that form important reservoirs in the region. Our results reveal the presence of a northwest-trending deepwater channel system displaying morphological variations induced by syn -sedimentary structural development. Petrological analyses of core samples show a predominant lithic-rich rock composition in the reservoir sandstones, suggesting sediment supply from a lithic-rich Crocker Formation hinterland, probably through a paleo-Padas River. This rock composition differs from the quartz-rich rock composition of an adjacent contemporaneous deepwater reservoir mainly comprising reworked quartz-rich Meligan sandstones. The observed petrological differences are interpreted to reflect a Late Miocene multi-source sediment supply system that drained offshore different NW Borneo hinterland areas. Offshore, sediment transport to and across the slope was dominantly margin-perpendicular, linear or of low sinuosity, in the deepwater locally affected by faulting and folding. This study provides new insights into the complexity of sediment routing systems along continental margins, highlighting the influences of the configuration of the sediment supply system and tectonics on deepwater sedimentation.

Application of Methane Hydrate Critical State Soil Model on Multistage Triaxial Tests of Methane Hydrate-Bearing Sediment

Natural methane hydrate, as a potential alternative energy source to fossil energy in the 21st century, is found in abundance in deep-water sediments and permafrost regions. During the production of methane gas from these sediments, the dissociation process may induce various changes to the geotechnical properties. Thus, it is important to study the geomechanical behavior of hydrate sediments and simulate the sediment deformation patterns. In this study, the effects of different sediment types on the mechanical properties of hydrate-bearing soils were investigated using multistage triaxial tests, and the methane hydrate critical state (MHCS) soil model was calibrated using an optimization-based technique. The results revealed that: (1) the strain-hardening phenomenon in methane hydrate-bearing sediments varies with the particle sizes of the host sediments; (2) the strengths of methane hydrate-bearing sediments are higher with the host sediments being pure sand, compared with those with clay-added sediments, and the strength is inversely proportional to the clay contents in these sediments; and (3) the multistage triaxial test data were fitted with the MHCS model, which illustrates the combined effects of the abovementioned factors on the model parameters and geomechanical behavior of methane hydrate-bearing sediments.

Sediment transfer from shelf to deepwater slope: How does it happen?

ABSTRACT The processes that transport sediment from the coastline to the shelf edge are key components of the sedimentary source-to-sink system, determining basin-margin building, deepwater deposition, organic-material accumulation, and the long-term carbon cycle. Research on shelf sediment transport has been aided recently by advances in modeling and marine technology. In this study we provide a much needed review of up-to-date findings on how sediment moves from the outer shelf onto the upper slope, and we summarize four dominant shelf-to-slope drivers: 1) river currents, 2) reworking storm waves and longshore currents, 3) strong tidal currents supplementing river outflow, and 4) small-scale to very large-scale gravity collapse of the shelf-edge area.

Iron-manganese mineralization in Eocene deposits of Parashka skyba (Skybov nappe, Ukrainian Carpathians)

Formulation of the problem. Modern advances in oceanographic studies of sedimentogenesis and orogenesis open up opportunities for in-depth study of rocks by fold-nappe systems, including the Carpathian region. Review of previous research. On the territory of the Carpathians in flysch complexes researchers have mainly noted the findings of carbonates of manganese and iron nodules.At the same time, flysch complexes contain iron-manganese oxide mineralization. The purpose of the work was to study the mineral and chemical composition, morphological types of aggregates and the origin of iron-manganese mineralization (IMM) among the Eocene deposits of the Parashka skyba of Skybov nappe in the middle course of the river Opir. Methods used: Sedimentological, mineralogical, petrogeochemical and X-ray diffractometric analyzes of wall rocks and ore minerals. Results: The ore mineralization is associated with the Paleocene to Eocene transition strata, which is represented by coarse-grained turbidites and grainites of the Yamna suite and variegated fine- and medium-grained turbidites and hemipelagites of the Manyava suite. IMM are deposited in a main ore bed, ore crusts and scattered in the wall rocks. It is synchronously sedimented with deep-water deposits of the lower bathyal. The оre bed is composited of concretionary, sinter, brecciated, earthy and sooty aggregates. Concretionary morphotypes have concentric-zonal structure, which is formed by shells with different mineral composition and structural features. Crystalline secretions are observed in the nucleus. The ore substance is represented by X-ray amorphous compounds of iron and manganese hydroxides, among which are minerals of hydrothermal (pyrolusite, psilomelan, todoroquite and bersenite) and hydrogenic (vernadite, buserite) origin. Shells often have columnar, dendrіtic and colomorphic structures typical of hydrothermal formations. Differentiation of mineralization by mineral composition causes significant fluctuations in metal contents in ore aggregates (from 3 to 11.5% of Fe oxides and from 2 to 10% of Mn) and host rocks (from 1.4 to 11.5% of Fe oxides and from 0.12 to 12% Mn). This confirms the endogenous origin of ore-bearing fluids. On the diagram of the ratios of the main components of iron-manganese formations of different zones of modern oceans by E. Bonatti, the geochemical composition of the ore mineralization of the Nad’yamne variegated horizon falls into the fields of both hydrothermal and hydrothermal-hydrogen origin. Mineralogical and geochemical features of ore mineralization indicate that the main source of metals on the seabed were hydrothermal vents. Direct deposition of ore mineral phases and deposition of oxide and hydroxide compounds from metal-enriched bottom waters occurred as a result of reaction of hydrothermal fluids with seawater. The formation and functioning of the hydrothermal system was likely caused by the intensification of tectonic movements of the Laramian phase on Paleocene-Eocene boundary, which also led to restructuring and deepening of the Carpathian paleobasin. An important role in these processes was played by faults in the flysch foundation, which served as channels for circulation of hot fluids. The source of heat and metals could be deep magma, according to authors. Scientific novelty. Iron-manganese mineralization in the Eocene rocks of the Nad’yamne variegated horizon was characterized for the first time, IMM morphotypes, structural-textural, mineralogical and geochemical features of ore formations and sedimentation and petrographic features of the content rocks were described. The studied features make it possible to propose a hydrothermal model of mineral formation. Practical significance. The studied features of IMM correlate well with modern and recent formations of pelagic sedimentation. The presence of iron-manganese mineralization in the Eocene Nad’yamne variegated horizon expands the cognitive aspects of the study of the Outer Carpathian basin of the Tethys Ocean and will contribute to the study of other variegated horizons and their geochemical specialization.

Clay Minerals And Their Implications For Late Quaternary Palaeoclimate Investigation: A Case Study In Pontian, Johor

Paleoclimate during Quaternary can be inferred from clay minerals composition in the coastal deposit acquired from the west coast of Johor, wherein this particular region has been linked with the few scholarly efforts delineating the field. This present study examined several core materials sourced from Pontian, Johor, mainly due to their almost entirely fine-grained sedimentary sequence suitable for high-resolution clay mineral assessment. Accordingly, semi-quantitative clay minerals assemblages were obtained by employing a series of measurement repetitions of air-drying, glycolation, and heating up to 350 °C and 550 °C on the sample conditions via X-ray diffraction (XRD) method. These assemblages were found to be predominantly kaolinite and illite in nature, apart from the presence of minor chlorite and smectite possibly sourced from the tuffaceous deep water deposit and granitic intrusive rock in central Johor. In line with this, stratigraphic clay mineral records revealed that the Late Quaternary experienced climatic changes between warm and humid conditions, whereas drier conditions were correlated to Greenlandian and Northgrippian sub-epoch of Holocene.

Discovery of Late Triassic bivalves from Jurassic deep-water deposits in Riganpeicuo area, Tibet and their geological significance

The Jurassic sequences in the South Qiangtang Basin of Tibet are essential for understanding the paleogeography and tectonic evolution of this basin and the Bangong-Nujiang Meso-Tethys Ocean (BNMO). However, the partial absence of fossils hinders the study of the stratigraphic distribution and tectonic paleogeography of the basin. Late Triassic bivalves, including nine species in nine genera, were identified for the first time in olistostromes from the Sêwa Formation in the Riganpeicuo area. Based on detailed geological field surveys and sedimentary facies analysis, the lower-middle part of the Rigenco section is a deep-water turbidite fan deposit and the upper part is a shallow sea mixed shelf deposit, which differs distinctively from the carbonate platform facies of the Jiebuqu Formation. Therefore, the strata formerly assigned to the Jiebuqu Formation (Rigenco section) is formally reassigned to the Lower-Middle Jurassic Sêwa Formation and Middle Jurassic Shaqiaomu Formation. These results not only provide further understanding of the sedimentary infill history of the South Qiangtang Basin, but also further support that the BNMO was already open in the Late Triassic and formed a mature ocean in the Early-Middle Jurassic, with subsequent rapid subduction. Both the opening and subduction processes were completed in a relatively short time interval with a large number of attendant olistostromes.

Efficient back analysis of multiphysics processes of gas hydrate production through artificial intelligence

Natural gas hydrate, a crystalline solid existing under high-pressure and low-temperature conditions, has been regarded as a potential alternative energy resource. It is globally widespread and occurs mainly inside the pores of deepwater sediments and sediments under permafrost area. Hydrate production via well depressurization is deemed well-suited to existing technology, in which the pore pressure is lowered, the natural gas hydrate is dissociated into water and gas, and the water and gas are produced from well. This method triggers multiphysics processes such as fluid flow, heat transfer, energy adsorption, chemical reaction and sediment deformation, all of which are dependent on the amount of gas hydrates remaining in the pores. Therefore, modeling of hydrate production is computationally intensive and expensive. While back-analysis through observed production history is essential for better understanding of the reservoir characteristics and reliable prediction for future gas hydrate production, a large number of required simulations makes it impractical. This study employs Artificial Intelligence (AI) to achieve an efficient back-analysis of the gas hydrate production conducted at the offshore Nankai site, Japan, in 2013. The results show that the AI-based metamodel is capable of reproducing outputs of heavy computation of the multiphysics processes and thus performs back-analysis greatly efficiently. The efficient AI-based metamodel also makes it possible to carry out sensitivity analysis and it is found that the permeability and the preyield plasticity parameter are most influential to reservoir responses. The approach of this study can be applicable to other reservoirs and will reveal the ground truth in-situ properties and the most influential properties, contributing to better understanding of reservoir behavior for future gas hydrate production.

Disconformity between the El Abra Formation underlying the “Temazcal unit” in Cerro Quemado locality, Temazcal, San Luis Potosí, Mexico: Biostratigraphy and microfacies analysis

On the western part of the Valles–San Luis Potosí Platform located in Cerro Quemado near Temazcal, municipality of Armadillo de Los Infante, two sequences crop out. The lower one is the shallow-water El Abra Formation of the mid–upper Cenomanian, unconformably covered by a deep-water deposit of the upper Maastrichtian informally called here the “Temazcal unit.” The succession presents a nonconforming contact between these two sedimentary units, displaying a hiatus as the result of a time of non-deposition in the sedimentary record, showing a subaerial exposure with erosion yielding topographic relief. Based on the lithological changes from the underlying limestone toward the overlying silty limestone, as well as a detailed biostratigraphic study based on foraminiferal associations that provide an accurate dating, it has been possible to estimate the magnitude of the hiatus, which spans from the lower part of the Turonian, including the Coniacian, the Santonian, and possibly the lower part of the Maastrichtian.

THE APPLICATION OF SCANNING ELECTRON MICROSCOPY USING ENERGY- AND WAVELENGTH DISPERSIVE SPECTROMETERS FOR CHEMICAL DATING OF URANIUM MINERALIZATION ON THE EXAMPLE OF CARBONACEOUS SHALES OF THE DABANZHALGA SUITE (EAST SAYAN)

On the one hand, the widespread use of electron microprobe analysis in the version of a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) and, on the other hand, the comparability of the metrological characteristics of the EDS and wavelength dispersive spectrometry (WDS) in the case of determining the major components of minerals are a favourable background for investigating the possibility of using SEM-EDS for chemical dating of uranium mineralization. Carbonaceous-siliceous formations of the Dabanzhalga suite are widespread in carbonate deposits of the Lower Paleozoic in the Oka structural-formational zone of the East Sayan and represent deep-water deposits of the back-arc basin. All varieties of carbonaceous-siliceous rocks of the Dabanzhalga suite are characterized by increased U, Au, Ag, Pt, Pd, Mo, V, P, Cu. Their amounts are 5–10 times higher than those for other black shale deposits of the Eastern Sayan. Uranium forms its minerals – uraninite and brannerite, in association with carbonaceous matter and sulfides, and is also part of anhydrous phosphates – xenotime, monazite. The paper presents data on the composition and dating of brannerite and uraninite in samples of carbonaceous-siliceous shale sampled at three sites: Uber-Zhadoy, Deed-Khara-Zhalga and Erye-Khara-Zhalga. The obtained estimates of the isochronous dates of uraninite and brannerite grains for these areas are 523±26, 506±10, and 511±17 Ma, respectively. It was shown that these dates could be compared with the age of metamorphism at the Sukhoi Log deposit, estimated using modern methods of isotope geochronology. It should be noted that the average estimates of the dates of uraninite and brannerite in all studied areas of the Dabanzhalga suite are lower than the corresponding estimates of the isochronous date, which is probably due to the partial loss of radiogenic lead. For the Uber-Zhadoy site, a comparison of the EDS and WDS data was carried out, and it was shown that when using the EDS data, there is an underestimation of the Pb content in uraninite, and, as a consequence, an underestimation of the age of uraninite.

Characteristics of Cambrian tectonic-lithofacies paleogeography in China and the controls on hydrocarbons

In early Cambrian, the earth was in a state of active super-continental disintegration, ocean basin expansion, and seawater transgression. It was a critical period for hydrocarbons source rocks development on a global scale. In China for example, hydrocarbons reservoirs, including conventional and unconventional, have been discovered in the Cambrian rocks. By using regional tectonic analysis, stratigraphic correlation, and lithofacies comparison, we compiled a tectonic-lithofacies paleogeographic map and determined the lithofacies paleogeographic characteristics of the main plates of the early Cambrian period in China. Our results show that although the North China Plate was deposited in shallow-water shore facies, it was later uplifted and exposed to long-term denudation; and thus, lacked the depositional conditions necessary to form hydrocarbon source rocks. In contrast, both the South China and the Tarim Plates contain the complete platform-slope-basin facies sequence, which is the required depositional conditions to promote the formation of hydrocarbon source rocks. Furthermore, our results demonstrate that, during the period of Meishucun and Qiongzhusi formations, South China Plate was composed of deep-water sediments. Correspondingly, during the sedimentation of the Yuertusi Formation, several areas such as the Kalpin, Tabei, and Taxinan in the Tarim Basin, formed a gentle-sloping continental shelf sedimentary sequence of phosphorous siliceous rocks, muddy shales, marlstones, and doloarenite. In addition, we demonstrate that (1) abundant nutrients provided by the hydrothermal and coastal upwelling events, combined with the “periodic anoxic” bottom water conditions, resulted in the formation of high-quality hydrocarbon source rocks in the Yuertus Formation in the Tarim Basin; and (2) the intracratonic sag and continental shelf edge slope settings controlled the deposition of hydrocarbon source rocks in the Sichuan Basin.

Segmented evolution of Deyang–Anyue erosion rift trough in Sichuan Basin and its significance for oil and gas exploration, SW China

Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang–Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluated. The results show that: (1) Dengying Formation in and around Deyang–Anyue erosion rift trough varies widely in sedimentary characteristics. The Dengying Formation in the northern part of the erosion rift trough developed deep-water sediments, the Dengying Formation in the northern part of the basin varied gradually from basin to slope, platform margin, and restricted platform, and the Dengying Formation in the middle and southern parts of the trough developed carbonate platform facies. (2) Deyang–Anyue erosion rift trough is formed by extensional rift and karst erosion jointly, the north section of the erosion rift trough is mainly the product of tensile rift, while the middle and south sections are formed by erosion in multi-episodes of Tongwan period. (3) Based on the segmented origins of the erosion rift trough, Dengying Formation in and around it is divided into three exploration fields: lithologic mound and beach bodies at the northern platform margin of the basin, karst mound and beach bodies in the central platform, and karst residual mounds in the central southern trough of the basin, among them, the karst residual mounds in the central southern trough of the basin are a new frontier for natural gas exploration in the basin, and the lithologic mound and beach bodies at the northern platform margin are a new position for increasing the reserves of trillions of cubic meters of natural gas resources in the basin.

Distinct sources of bacterial branched GMGTs in the Godavari River basin (India) and Bay of Bengal sediments

Branched glycerol monoalkyl glycerol tetraethers (brGMGTs) are a group of membrane-spanning lipids produced by (yet) unidentified bacteria. They are characterized by a C-C bond connecting the two alkyl chains, which is thought to enhance membrane stability at higher temperatures. So far, they have been found in peats, lakes, and marine sediments, where their abundance relative to that of branched glycerol dialkyl glycerol tetraethers (brGDGTs) increases with temperature. However, the preferred niche(s) for production and the origin of brGMGTs in the terrestrial and marine realm remain unknown. Here we explore the occurrence of brGMGTs in soils, suspended particulate matter (SPM) and riverbed sediments in the Godavari River basin, and compare these with brGMGTs in a Holocene sediment core from the Bay of Bengal close to the Godavari River mouth. BrGMGTs are mostly detected in agricultural and/or regularly inundated soils, and in the river at sites with standing water and/or agricultural/wastewater effluents, as well as in the delta, where low oxygen conditions and/or high nutrient levels prevail. In contrast, brGMGTs are continuously present in the marine sediment core, but with a different isomeric composition than in the terrestrial realm, indicating a primarily marine source. The stable brGMGT distribution downcore and brGMGT-inferred temperature estimates which resemble the bottom water temperature, may suggest marine brGMGT production in the deep water column and/or sediments. However, to establish the proxy potential of brGMGTs for paleoreconstructions in the terrestrial and marine realm, brGMGT sources and environmental controls require further study.

Implications for carbonate mass-wasting complexes induced by volcanism from Upper Cretaceous Austin Chalk strata in the Maverick Basin and San Marcos Arch areas of south-central Texas, USA

The upper part of the Austin Chalk (AC-B1 subunit), as seen in a series of cores in areas of the Maverick Basin and San Marcos Arch in south-central Texas, contains a stratigraphic section of mass-wasting complexes resulting from penecontemporaneous volcanic-induced gravity-flow deposition. The types of gravity flows are variable in composition depending on sources of volcanic or carbonate sediments available and position of initiation of the flow on the volcanic mounds.The gravity flows occurred in a deeper-water drowned-shelf setting where argillaceous chalk-rich sediments were being deposited. The mafic volcanoes are part of the Balcones Igneous Province that was active during very Late Santonian to Early Campanian time. Some of the volcanoes formed mounds that created elevated areas in the photic zone or above sea level. In the shallow-water photic zones, carbonate factories formed as atolls and shoals. These carbonate factories were a source for shallow-water allochems, and along with the volcanic debris, constituted gravity flows that were likely triggered by volcanic-associated earthquakes. As gravity flows moved downslope, they eroded deeper-water, bottom sediments, which were incorporated into the flows. The two major transport mechanisms were debris flows and hyperconcentrated-density flows.The debrites appear as two types: those dominated by mud clasts and those dominated by cm-scale skeletal fragments such as inoceramid or disarticulated oyster shells. The clasts in the mud-clast-dominant debrites range in rigidity from very soft (i.e., easily deformed) to firm (i.e., resist deformation and preserved burrows). Since the mud clasts are composed of planktic foraminifers and calcispheres in a coccolith-hash matrix, they are assumed to have originated from the deeper flanks of the volcanic mounds. The rigidity of the mud clasts are likely related to initial (i.e., early) depth of burial of the unlithified mud.The skeletal-dominated debrites with disarticulated oyster shells appear to have been sourced from the upper slopes of the volcanic mounds and underwent little abrasion during debris-flow transportation. The inoceramid-fragment-dominated debrites may have been initiated lower on the volcanic mounds where these low-oxygen-tolerating bivalves would dominate the macrofauna.The hyperconcentrated-density-flow deposits are grain-rich in skeletal fragments with a mixture of shallow- and deep-water biota, suggesting some direct sourcing from shallow-water shoals and later incorporation of deeper-water sediments from the flanks of the volcanic mounds. These hyperconcentrated-density-flow deposits are positioned close to the base of the mounds.This distinct stratigraphic interval varies greatly from the rest of the Austin Chalk section in the Maverick Basin and San Marcos Arch areas. Deeper-water chalk deposition was the general background environmental setting, but it was disrupted by this period of volcanism that initiated numerous mass-wasting complexes punctuating the deeper-water chalk deposits. Within the gravity-flow deposits, volcanic components such as lapilli, ash, and glauconite-altered volcanic grains occurred along with both shallow- and deep-water carbonate allochems. Investigation of this stratigraphic unit within the Austin Chalk provides an analog for mass-wasting complexes associated with active volcanism and explains the variations in composition of the gravity-flow deposits.

Deep-water sedimentation processes on a glaciated margin: The Foula Wedge trough mouth fan, West of Shetland

Trough Mouth Fans (TMF) are sedimentary depocenters located at glaciated continental margins and consist predominantly of glacigenic debris flow deposits. The Foula wedge is a Pleistocene TMF accumulated offshore West of Shetland over the Northeast Atlantic margin. This study presents an analysis of a 3D seismic reflection dataset imaging the distal Foula wedge basin fan deposits between 1010 and 1100 m water depth, directly downslope from a gully system which was active untill the end of the last deglaciation. Results reveal, in unprecedented detail, the basal surface of this fan system and its internal complex architecture. Features typical of both debris flow deposits and turbidites are identified, including a basin channel network with linear and diverging erosional features forming distinctive terminal lobes, stacked and backstepping. The study links the seafloor morphology of the basin fan with its subsurface geomorphology, showing connection with the downslope gully system to the east. It presents evidence for a complex distal depositional system on glaciated margins, characterised by heterogeneous sediment delivery processes and deposits. A conceptual evolution model is proposed, with a glacigenic debris flow-dominated TMF at the LGM, subsequently influenced by meltwater discharges, with deposition occurring as a function of the shelf margin and slope paleo-morphology, slope substrate composition, interaction of downslope and along slope processes and ice-margin dynamics.

Predicting marine organic-rich deposits using forward stratigraphic modelling: The Jurassic Najmah source rock – Case study

Predicting the distribution and heterogeneity of marine Mesozoic organic-rich rocks is a challenging task that requires multi-disciplinary data integration supported by innovative numerical modelling. This study aims at investigating the factors controlling marine organic matter production, accumulation, and preservation along the eastern Arabian intrashelf basins. Such types of basins exhibit an enhanced lateral and vertical facies variability caused by the interplay between shallow and deeper water sedimentation. The work focuses on characterizing the Mid-Upper Jurassic Najmah Formation that presents source rock, reservoir, as well as seal characteristics along Kuwait. It comprises high maturity levels (>0.6% Ro) and TOC values ranging between 2 and 30%. Forward stratigraphic modelling that includes organic matter production, transport, and preservation (i.e., degradation and dilution) was utilized. Models corresponding to two end-member basin types (restricted and fully open marine) have been simulated to mimic the organic matter deposition within a 3rd-order sequence stratigraphic framework. Simulation outputs provide a qualitative and quantitative assessment of organic matter characteristics (TOC, HI, and OI) at the time of deposition. Results show that (1) a combined variable eustatic sea level change and tectonic subsidence are the main driving mechanisms for sediment accommodation during the Mid-Upper Jurassic time, (2) strong anoxic conditions in the restricted basin simulations promote the preservation of organic-rich deposits in the distal northern sectors while (3) the influence of open marine bottom current oxygenation is not expected to impact the relatively shallower conditions affecting the intrashelf basin (<200 m depth), (4) organic matter dilution can be observed along the southernmost sectors of Kuwait due to high sedimentation rates related to the development of gravity driven deposits. Sensitivity analysis on input parameters (i.e., primary productivity vs water depth) supports the partially restricted basin conditions with occasional connection to the open ocean during eustatic sea level rise. This study contributes to the improvement of basin models in conventional as well as unconventional petroleum system exploration.

Nearshore Pelagic Influence at the SW Margin of the Paratethys Sea—Examples from the Miocene of Croatia

(1) The ancient Paratethys Sea was a spacious inland salt-water basin, extending from the Alps, over Central Europe, to Central Asia. The southwestern part of its central area, the Croatian part of the Pannonian Basin System (CPBS), is generally known for shallow-water deposition and biota. The main purpose of this paper is to emphasize the significance of its less widespread deeper-water deposits in environmental and applied geology. (2) The authors consulted the previously published data, combined with their own results, obtained from the paleontological and sedimentological research, seismic stratigraphy and well-log analyses. (3) During our research in the CPBS, we noticed the connection between the tectonic structures and deep marine canyons and depressions within the Paratethyan shallows. Such structures can be recognized on well-logs and seismic or surface outcrops. They are situated along the faults, and deposits are characterized by the domination of pelagic over the benthic biota, sometimes with visible selective dissolution of aragonite/calcite tests. (4) Studied sedimentary sequences from these structures proved to be a precious source of data on the transgressive-regressive cycles, ancient migrations, modes of deposition and hydrocarbon formation during the Miocene Epoch in the CPBS.

Terahertz Dating of Sedimentary Rocks

The depositional products of sedimentary rocks provide vital references for investigating the paleoenvironment, paleogeography, and tectonic evolution history. However, the detection methods of geological evolution are still relatively complicated, and how to combine geological age and geological evolution is confusing. Based on the sensitivity of terahertz waves to organic matter, a THz dating method was introduced for characterizing the geological age of sedimentary rocks. In this study, the geological evolution of Liujiang Basin was analyzed by using terahertz time domain spectroscopy (THz-TDS). According to the close relation between organic matter content and sedimentary environment, it can be inferred that the geological deposition in this area is affected by Marine cover. In addition, the refractive index of Ordovician sedimentary rocks is significantly higher than that of other sedimentary rocks. Based on these results, it is inferred that the sedimentary environment of the Liujiang Basin gradually changed from continental deposition to deep-water marine deposition from the Neoproterozoic to the Ordovician, and the sea water gradually retreated due to the crustal movement, resulting in a transition from deep-water deposition to continental inshore ocean facies deposition. These findings are highly consistent with the geological history of the study area. Combined with principal component analysis (PCA) technology, the relative geological age of sedimentary rocks can be divided. Our study con-firmed the reliability of this THz dating technique, which provides an effective way to study the geological evolution history of sedimentary rocks.

Conduction of a Laboratory Experiment with the Goal of Researching Submerged Flow Peculiarities

In connection with the decreasing hydrocarbon reserves on land, the interest of researchers in new alternative methods of hydrocarbon production is growing. One of the actively developing areas is the production of hydrocarbons from deep-water deposits, in connection with which the share of developed deposits in the water area of the World Ocean is growing every year. However, this production method is not completely safe, since any damage to the production structure can lead to leakage of hydrocarbons. In this case, hydrocarbons are distributed in the form of a submerged jet. Predicting the behavior of submerged jets, calculating their trajectories and thermophysical parameters is important in the elimination of leakage. The article discusses an experimental study of a submerged jet. The results of the experiment will make it possible to verify the mathematical model describing the propagation of a submerged jet. The experiment was carried out to study the trajectory of the jet and its temperature. This paper presents the results on the analysis of the jet trajectory. In the experiment, gasoline or diesel fuel was used as a liquid, air was used as a gas. The work shows a diagram of the experimental setup, describes the process of the experiment, and also shows a photograph of the experiment and a comparison with the results of calculations.

Multiphase deformation of an inverted Permian deepwater rift basin: The Nong Pong Formation, Khao Khwang Fold and Thrust Belt, Thailand

• Khao Khwang Fold and Thrust Belt (KKFTB) is mixture of thrusted carbonate platforms over inverted deepwater rifts. • Nong Pong Formation affected by multiphase folding, whose structural style changes with sedimentary facies . • Estimated shortening of the KKFTB (300 km), supportive of E-W suture bisecting Indochina Terrane . The bathyal Permian Nong Pong Formation is crucial for understanding the deformation style, and amount of shortening in the E-W trending, Triassic (Indosinian Orogeny) Khao Khwang Fold and Thrust Belt. The formation was deposited in a series of marine rift basins, with carbonates forming on intervening highs. The platform carbonates are shortened by a series of dominantly north-directed thrusts. The Nong Pong Formation is extensively affected by tight to isoclinal, predominantly chevron style folding. Five major variations in stratigraphy (ranging between carbonate-dominated and shale-dominated) affect the deformation styles within the formation. Shortening locally is estimated to be up to 60% in sections up to 300 m long and is concentrated into short-wavelength (10 s m) structures. The absence of proximal slope depo-belts, and juxtaposition of carbonate platform facies with deepwater deposits suggest thrusts (some initiated as inverted normal faults) located on the basin margins have displacements of c. 10–25 km. Estimates of shortening from outcrops, and analogy with Zealandia, suggest the Nong Pong Formation was deposited in a basin up to 100 km wide. Such estimates point to a significant E-W trending seaway that bisected the Indochina Terrane. Multiple fold orientations and phases are present in the Nong Pong Formation, which are related to early mass transport events, multiple tectonic phases (Indosinian and Palaeogene), the influence of inherited trends (e.g. Permian rift basin morphology), and 3D deformation during a single tectonic phase. Deformation of the Nong Pong Formation demonstrates significant differences in structural style between ribbon continents and major continents, particularly, the Indochina ribbon continent shows the widespread inversion of rift basins across a submarine continent (similar to Zealandia) 100 s kms wide.