Columnar Sections Research Articles

High‐frequency palaeoenvironmental changes in the mixed siliciclastic–carbonate sedimentary system from a lower Permian restricted basin (West Gondwana, southern Brazil)

ABSTRACTGlobal climatic and palaeogeographical changes generated a siliciclastic–carbonate system with high organic matter accumulations in a shallow sea during the lower Permian in Western Gondwana. The 60 m thick mixed siliciclastic–carbonate succession (Irati Formation and the base of the Serra Alta Formation) from the Paraná Basin represents a singular record of the interplay between carbonate production and siliciclastic input, providing a window of opportunity to integrate large‐scale depositional architecture with facies and geochemical analyses. The detailed study of cores supported by outcrop columnar sections revealed a siliciclastic‐dominated, retrogradational to aggradational facies, and a carbonate‐dominated, mixed aggradational to progradational facies composing three depositional sequences that record an outer‐ramp and mid to upper‐ramp. An integrated approach based on the description of facies and microfacies, organic geochemistry and mineralogical composition, indicated high‐frequency palaeoenvironmental changes during the evolution of this restricted basin. Climate changes, resulting in humid and dry phases, produced ideal conditions for high organic matter production and dolomite formation. The high organic matter production (humid phases) in addition to the restricted condition was responsible for the anoxic bottom waters that were widespread due to the low angle and homoclinal platform. Nutrient‐rich freshwater inflows in the anoxic and hypersaline restricted basin created a density‐stratified water column causing low‐salinity surface and anoxic bottom water, which allowed planktonic life, typical of lakes, such Botryococcus braunii, to flourish in the photic zone and sulphur bacteria to populate below the chemocline. Microbial activity induced primary dolomite precipitation (dry phases) and widespread formation of synsedimentary dolostone. Freshwater inflow and marine incursions are reflected in the organic matter accumulation (kerogen types I and II, respectively), generating bituminous shale with high total organic carbon (5 to 27 wt.%).

Comment on Souza and Perez Filho (2019) “Late Holocene coastal dynamics, climate pulses and low terraces in the coast of the state of São Paulo, southeast Brazil”

Souza and Perez Filho (2019) inferred two transgressive events in the Late Holocene record of lower Ribeira de Iguape River and Ilha Comprida barrier, Southeastern Brazil, based on luminescence ages and paleoenvironmental interpretation of four columnar sections. In the present paper, we discuss inconsistencies on the methods applied and sample design adopted by those authors, which lead to an incorrect model of coastline evolution for the region over the time period covered by the dates obtained. The dataset presented by Souza and Perez Filho (2019) allows the reinterpretation of the deposits studied as regressive and fits into previous models of regional coastal evolution.

Rock Magnetic Signatures of Hydrothermal Mineralization in the Trans‐Atlantic Geotraverse (TAG) Hydrothermal Field

AbstractThe Ocean Drilling Program Leg 158 drill holes from the Trans‐Atlantic Geotraverse hydrothermal field are investigated to understand the rock magnetic signatures of hydrothermal mineralization. A composite columnar section has been constructed through hole correlation to understand the stratigraphic variation of magnetomineralogy within the stockwork. Isothermal remanent magnetization components unmixing, first‐order reversal curve diagrams, low‐temperature magnetic signatures, and electron microscopic analyses disclose magnetic minerals of disparate occurrences related to predominating hydrothermal mineralization reactions in three broad zones: For basaltic basements, serpentinization of olivine phenocrysts during preliminary hydrothermal alteration produces magnetite, in addition to primary titanomagnetite; Chloritized and silicified zone samples contain relict titanomagnetite and exsolved magnetite that survived hydrothermal dissolution; Anhydrite and sulfide zone samples are dominated by magnetite and hematite, likely from oxidation of polymetallic sulfides due to exposure in oxidative seafloor environments during drilling. Our findings suggest that seafloor oxidation potentially modifies the magnetic properties of polymetallic sulfides in hydrothermal deposits, which applies to magnetic tomography of sophisticated subseafloor vent structures and prospecting seafloor massive sulfides (SMS) deposits therein. Meanwhile, we alert future deep‐sea mining that drilling may promote physicochemical alteration of SMS deposits, causing environmental risks. The established magnetic signatures ultimately contribute to understanding the in situ geological preservation of SMS deposits and optimizing exploitation procedures in the future.

How to Draw a Graph of Flow Velocity Changes from Columnar Section DataUsing the Hjulström Diagram

How to Draw a Graph of Flow Velocity Changes from Columnar Section DataUsing the Hjulström Diagram

On the Use of Geostatistical Cross-Association Method for Lithostratigraphical Correlation

The aim of this paper is to determine the effectiveness of cross association in detecting the similarity between correlated geological columnar sections. For this purpose, cross association is used to compare several geological columnar sections which are arbitrarily selected from different localities in central and north Jordan. It turns out, for most of the study cases, that the sections which consist of the same rock units (formations) are statistically classified as similar (p-value .05), while sections of different rock units (formations) are statistically classified as dissimilar (p-value .05).

On the Use of Geostatistical Cross-Association Method for Lithostratigraphical Correlation

The aim of this paper is to determine the effectiveness of cross association in detecting the similarity between correlated geological colum- nar sections. For this purpose, cross association is used to compare several geological columnar sections which are arbitrarily selected from different lo- calities in central and north Jordan. It turns out, for most of the study cases, that the sections which consist of the same rock units (formations) are statistically classified as similar (p-value � .05), while sections of differ- ent rock units (formations) are statistically classified as dissimilar (p-value � .05). Geologists get used to study rocks in outcrops or in drill cores. A sequence of sedimentary rocks may be divided up into a number of lithostratigraphical units usually of various sizes. Superimposed lithostratigraphical units are frequently distinguished from each other based on lithological properties and stratigraphical position. The formation is the fundamental unit of stratigraphy with definite lithological composition or a distinctive interbedded or intergraded succession of rock types that must be differ from the adjacent units above and below. The for- mations in a rock sequence named for some geographical localities that show typ- ical exposures of these formations (known as type sections), are usually traceable or mappable from one exposure to another or from well to well in the subsurface (Krumbein and Sloss, 1963; Doyle et al., 1994). Geologists can draw stratigraphi- cal sections for several outcrops (or cores) in an area, and trace beds from section to section that finally leads to what is known as lithological correlation. This type of correlation basically demonstrates the equivalency of rock units across an area. The matter of correlation between different geological sections is relatively easier if the formation in the vertical rock sequence is not so greatly different in its lithology and thickness from one place to another. However, in many cases

Grid mapping revealed hidden geochemical lens and its chemostratigraphic bias in the middle‐upper Permian marine carbonate sequence in Laibin, South China

Deep‐time chemostratigraphy provides important data for stratigraphy and palaeoenvironmental reconstruction. Geochemical analysis for the same proxy from the same outcrop section, however, often results in different data among various researchers. The dispute was ascribed to inappropriate screening of samples weathering, pre‐treatment, and analytical methods. An outstanding example is that a great variation of 1–3‰ in δ13CVPDB values from the same horizons at Auxiliary Global Stratotype of Section and Point for the Guadalupian–Lopingian (G‐L) boundary in Tieqiao, Laibin, South China was obtained by various research groups. The Walther's Law of Facies suggests that such differences in analytical results may be due to the diachronism of samples measured in high‐resolution stratigraphy. Although lithology and broad sedimentary facies are the same in a lithostratigraphic unit, heterogeneous distribution of bioclastics, δ13Corg, provenances, trace elements, and age‐controlling geochemical signals might have printed on sediments within the same bed. Here, we verified the variations by grid mapping and sampling, a new method for high‐resolution chemostratigraphy, and this practice is applied to the auxiliary GSSP at the Tieqiao section. A total of nine parallel columnar sections from the upper Guadalupian to lowest Lopingian were measured and sampled. In addition, four lateral profiles along four beds were also sampled, and two of them are close to the lower part of the section (upper Guadalupian) and near the G‐L boundary, respectively. These analytical results are plotted along the coordinate of X–Y axis and form the grid mapping on the outcrop. Contour maps of various proxies (i.e., CaO%, total Fe%, and δ13Ccarb) based on the grid mapping were constructed on the outcrop, instead of single excursions of various geochemical proxies throughout the upper Guadalupian to lowest Lopingian. The results show different negative excursions of δ13Ccarb coinciding with biotic extinction near the G‐L boundary and answered the differences of proxy reported in previous studies. Grid mapping of various proxies shows general trends of the proxies on the outcrop; however, there are invisible beddings across lenses in dozens meters size of geochemical abnormal. Analytical data of the same proxy from the same horizons at different columnar sections may present different excursions if sampling on the abnormal lenses or not. This is why the data are different among various studies when different columnar sections were sampled. Various lenses of geochemical abnormal which may be linked tectonic controlled diagenesis, and microhabitat et al., and resulted in the bias from different columnar sections were sampled.

Simple three-dimensional display method for cross sections and columnar sections

Simple three-dimensional display method for cross sections and columnar sections

GEOLOGIA DA ÁREA NORDESTE DA FOLHA POÇO DA CRUZ, BACIA DE JATOBÁ, NORDESTE DO BRASIL

A Bacia de Jatobá está localizada na porção centro-sul do estado de Pernambuco e no norte da Bahia e Alagoas, possui uma área com cerca de 5000 km², direção preferencial NE-SW e registro sedimentar com aproximadamente 3 km. Esta bacia do tipo rifte foi desenvolvida a partir dos eventos distensivos da ruptura do supercontinente Gondwana e marca o limite norte do sistema rifte abortado Recôncavo-Tucano-Jatobá. A sucessão estratigráfica da área de estudo, localizada no distrito Campos, Ibimirim (PE), compõe as sequências Sinéclise, Início de Rifte e Clímax de Rifte da bacia. A partir da utilização de seções colunares e identificação de fácies sedimentares foram reconhecidas seis unidades estratigráficas, além de uma cobertura quaternária. As duas unidades flúvio-marinhas inferiores estão relacionadas aos registros sedimentares siluro-devonianos da sequência Sinéclise, enquanto os sedimentitos lacustres e fluvio-eólicos das unidades superiores marcam a sequência de Início de Rifte e Clímax de Rifte. A Formação Aliança, discutida de forma particular neste trabalho, representa os primeiros registros sedimentares da sequência de Início de Rifte de idade Neojurássica (andar Dom João). Essa unidade foi depositada sob um sistema lacustre, com níveis carbonáticos decimétricos altamente fossilíferos dispostos em espessos pacotes pelíticos, sugerindo deposição em momentos de variações energéticas de um lago raso. O detalhamento estratigráfico desses depósitos, associado a estudos petrográficos e paleontológicos, traz uma nova compreensão acerca do sistema deposicional que atuou nesse ambiente e os primeiros processos que deram início à abertura do rifte durante o Jurássico Superior.

Molecular Dynamics Study of the Effect of l-Alanine Chiral Dopants on Diluted Chromonic Solutions.

Atomistic molecular dynamics simulations have been performed for disodium cromoglycate (DSCG) chromonic solutions mixed with l-alanine chiral dopants. We study the fundamental molecular mechanisms induced by low concentrations of l-alanine on diluted DSCG solutions, including their effect on the chromonic aggregates, the solvent, and sodium counterions. Simulations reveal that l-alanine molecules primarily interact with DSCG stacks establishing salt bridges between their respective ammonium and carboxylate groups. Our results demonstrate that l-alanine and sodium counterions jointly establish an intricate network of noncovalent interactions around DSCG aggregates that decreases the global electrostatic repulsion of the chromonic system. Two possible structural effects in DSCG aggregates arise from this electronic stabilization: the increment of the total number of consecutively stacked aromatic planes per DSCG aggregate (intracolumnar effect) or the partial separation reduction between neighboring DSCG columnar sections due to the simultaneous bridging of intercolumnar DSCG carboxylate sites by sodium counterions, forming sodium bridges (intercolumnar effect). Sodium bridges may be responsible for the formation of stacking faults in DSCG aggregates in the form of lateral overlap junctions. This mechanism would explain the difference between lower X-ray correlation lengths with the expected persistence length in chromonics.

Evolution of the gravel-bedded anastomosing river within the Qihama reach of the First Great Bend of the Yellow River

The anastomosing river that is present within the First Great Bend of the Yellow River is different from other sand-bedded rivers of this type because it contains gravel-bedded materials. It is therefore important to determine whether, or not, the specific characteristics of this anastomosing river are similar to those seen in sand-bedded forms, including the characteristics of erosion and deposition, and the stability of channel and interchannel wetlands. Four Landsat images from 1990, 2001, 2013, and 2016 alongside two Google Earth (GE) images from 2011 and 2013 were utilized in this study in tandem with field sampling and observations to select a 12 km main channel length section of the Qihama reach anastomosing river. This section was then used to determine variations in channel planform and sedimentary characteristics over a 26 year period. The results of this study show that this gravel-bedded anastomosing river has exhibited a high degree of stability overall, and that there has been no obvious channel and wetland bank erosion and deposition. Data also show that over the 26 years of this study, anastomosing belt area increased by 2.43%, while the ratio of land to water area remained almost equal. The number of wetlands has also increased along this river section at a rate as high as 62.16% because of the fragmentation of some small interchannel examples, while the talweg has alternately migrated to either the left or right over long periods of time at a relatively stable rate. Indeed, as a result of the migration of this line, there has been significant turnover in the number of islands within the main channel while bank shift has occurred at a rate of about 5 m/yr. The numerous anastomosing channels within this river section remained very stable over the course of this study, characterized by a mean annual migration rate of just 1 m/yr, while the sediments in bank columnar sections are mainly composed of fine sands or silts with a relatively high clay content. The sediment grain-size distribution curve for this river section contains multiple peaks, distinct from the muddy sediments within bank columnar sections from sand-bedded anastomosing rivers. The dense vegetation within riparian and interchannel wetlands alongside this river reach has also protected anastomosing channels from erosion and maintained their stability, a key feature of this gravel-bedded system.

Geochemical assessment of Paleocene limestones of Sinn El-Kaddab Plateau, South Western Desert of Egypt, for industrial uses

The present work assesses the potential industrial uses of Paleocene limestone deposits, Garra Formation in Sinn El-Kaddab Plateau, South Western Desert of Egypt, based on their mineralogy and geochemical characteristics. Eighty-six limestone samples collected from ten stratigraphic columnar sections were analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. Petrographically, Garra limestone deposits consist dominantly of benthic foraminiferal wackestone and packstone microfacies. The XRD data revealed dominance of low-Mg calcite as essential carbonate mineral in the studied limestone. The bulk rock XRF results revealed CaO (29.28–55.75%) with an average of 52.74%. The CaO exhibits a strong negative correlation with MgO, SiO2, TiO2, Al2O3, and moderate negative correlation with Fe2O3 which indicates that the contribution of these elements is mainly due to detrital input. On the other hand, Al2O3 and Na2O contents exhibit significant negative correlation with loss of ignition (LOI) wt% indicating their incorporation within terrigenous matrix. The average Sr content attains 1297 ppm indicating deposition in temperate marine environment. The average molar CaCO3% values of bulk samples have been computed for individual columnar sections to determine the purity status of Garra limestone deposits. They range from impure (CaCO3% = 79.92%) to high-pure (CaCO3% = 97.76%) limestone. Therefore, Garra limestone deposits have extremely valuable uses in a wide spectrum of industrial applications including Portland cement, steel, ceramics, whiting, chemical uses, paper, and feed stuff.

Holocene floodplain evolution in the Shiribeshi-Toshibetsu River lowland, northern Japan

The influence of sea-level and climate changes on the evolution of coastal floodplains is an important problem in fluvial geomorphology and geology. However, few studies have constructed detailed chronologies of floodplain evolution, and the influence of sea-level and climate changes at submillennial time scales is not clear. This study investigated the Holocene evolution of the floodplain in the Shiribeshi-Toshibetsu River lowland, Hokkaido, northern Japan, based on 13 auger cores, 15 radiocarbon ages, and 2 cross sections made using existing columnar sections. In the study area, peat beds 3–6m thick in the uppermost Holocene sediments are underlain by fluvial sediment that mainly consists of sand beds resulting from crevassing or progradational avulsion. Age–elevation plots of the bases of these peat beds suggest that fluvial aggradation was continuous until peat formation began, which in turn suggests that peat beds began to form with the cessation of fluvial deposition. The chronology of floodplain sediments based on radiocarbon ages indicates that peatlands began to develop locally before ca. 6500calBP and became moderately widespread before 5600calBP. Peatlands then became more extensive after two periods of rapid expansion during ca. 5300–5000 and 4100–3900calBP. Comparison with sea-level and regional climate changes suggests that the initiation of these peat beds before 5600calBP was associated with the deceleration of sea-level rise at ca. 7000calBP. The two later periods of peatland expansion may have been strongly influenced by reduced fluvial activity due to decreased precipitation from a weakened East Asian summer monsoon. This interpretation suggests that floodplain evolution was controlled by sea-level and climate changes and that the response to climate change occurred at submillennial time scales. A comparison with the Ishikari lowland on Hokkaido showed that the two floodplains have slightly different histories, possibly because of differences in internal characteristics of the fluvial systems such as the number and size of tributary rivers, water discharge, and sediment supply, although their responses to sea-level and climate changes were similar. The fluvial response to sea-level and climate changes revealed in this study has implications for studies of the Holocene evolution of other coastal floodplains.

Análise de fácies e petrografia de uma seção do Membro Crato em Nova Olinda (CE): contribuições à história deposicional e diagenética do neoaptiano na Bacia do Araripe

Na Bacia do Araripe, o Membro Crato é uma das mais importantes unidades estratigráficas por seu conteúdo fossilífero, seu contexto análogo ao das “Camadas Pré-Sal” e seu aproveitamento econômico como material de revestimento. Neste trabalho, análises de fácies e petrográficas foram combinadas no estudo de uma seção do Membro Crato em Nova Olinda (CE), com o intuito de investigar sua história deposicional e diagenética. Para tanto, a faciologia de uma seção colunar contínua de cerca de 70 m de espessura foi analisada com a coleta de 13 amostras de rochas carbonáticas, siliciclásticas e evaporíticas. As amostras foram analisadas por petrografia ótica. Foram descritas cinco fácies deposicionais: lamito margoso (Lm), calcilutito laminado (Cl), arenito maciço (Am), siltito com laminação cruzada cavalgante (Scc) e evaporito colunar (Ec). As fácies mais espessas e recorrentes foram interpretadas como lacustres (Lm, Cl), seguidas de sucessões aluviais (Am, Scc) em meio aos intervalos lacustres. A sucessão termina com indícios faciológicos de que condições de extrema aridez (Ec) foram atingidas ao final do intervalo descrito. A petrografia, aqui focada em rochas das fácies Cl, Am e Scc, reforça a ideia de que o intervalo do Aptiano local correspondia a um sistema lacustre árido, eventualmente alimentado por fluxos aluviais imaturos a partir de áreas-fontes próximas. Em particular, o baixíssimo grau de compactação mecânica e cimentação incipiente das rochas terrígenas sugere que a sucessão foi pouco afetada por diagênese após seu soterramento, que foi, por essa razão, pouco profundo. A semelhança dos intervalos terrígenos do Membro Crato com aqueles descritos para a porção final da sotoposta Formação Barbalha sugere contemporaneidade com passagem transicional retrogradante entre as duas unidades.

Sedimentary depocenters on Snowball Earth: Case studies from the Sturtian Chuos Formation in northern Namibia

Cryogenian synglacial deposits are regionally thin but locally thick, considering glacial duration, but the reasons for local thickening are poorly known. We studied three local thickenings of the Sturtian Chuos Formation in northern Namibia by measuring closely spaced columnar sections, not only of the synglacial deposits but also of the bounding pre- and post-glacial strata. This enabled incised paleovalleys filled by glacial debris to be distinguished from morainal buildups. In case 1, a U-shaped paleovalley, ∼450 m deep by ∼3.0 km wide, is incised into pre-glacial strata and 10% overfilled by ice-contact and subglacial meltwater deposits. In case 2, a wedge of glacial diamictite, ~220 m thick by 2.0 km wide, overlies a disconformity that is demonstrably not incised into underlying pre-glacial strata. The wedge, draped by a post-glacial cap carbonate and argillaceous strata, is erosionally truncated at its apex by Marinoan glacial deposits and their basal Ediacaran cap dolomite. The wedge was a positive topographic feature, either a terminal moraine or an erosional outlier of formerly more extensive glacial deposits. In case 3, a wedge of conglomerate, glacial diamictite, and subglacial lake deposits thickens to >2000 m where it abuts against granitoid basement rock uplifted along a border fault. Fault movement ceased before the Sturtian cap carbonate was deposited. The locus of maximum deposition shifted over time from proximal to distal with respect to the border fault, similar to Mesozoic half grabens developed above listric detachments imaged seismically on offshore North Atlantic margins.

제주도 성산유역의 저투수층 구조에 따른 지하수 흐름 분석

The depth of low permeable layer in Jeju Island was analyzed using the geologic columnar section data. The highest low permeable layer was found in center of Mt. Halla and the deepest area was in eastern part of Jeju Island. The study area, Seongsan watershed, is located in the eastern part of Jeju where the low permeable layer showing deep in a northward direction. Based on this analysis, the MODFLOW modeling was performed for groundwater flow of Seongsan watershed. The boundary of Seongsan watershed was set up as a no-flow and the modeling result showed the difference -0.26~0.62 m compared to the observed groundwater level. Meanwhile, MODFLOW model results considering low permeable layer showed -0.26~0.36 m differences compared to groundwater level and indicated more accurate than no-flow method result. Therefore, to interpret the groundwater flow over Seongsan watershed, comprehensive consideration including the low permeable layer distribution below the basalt layer is needed.

A Formação Serra Alta, Permiano, no centro-leste do Estado de São Paulo, Bacia do Paraná, Brasil

A individualização e o mapeamento da Formação Serra Alta no Estado de São Paulo sempre foi motivo de controvérsia na comunidade geológica. Apesar de apresentar extensão comparável à Formação Irati em subsuperfície, a unidade ainda carece de estudos mais acurados acerca de seu posicionamento estratigráfico, conteúdo fossilífero, sistema deposicional e idade. Na região centro-leste do Estado de São Paulo, a Formação Serra Alta sucede estratigraficamente a Formação Irati, sendo constituída por depósitos pelíticos cinza escuros. A unidade é mapeada desde o limite sul do estado até o Domo de Gibóia, no Município de Rio das Pedras. Neste local, as formações Serra Alta e Teresina são substituídas pelos depósitos pelíticos da Formação Corumbataí, que se estende para norte, além do limite do Estado de São Paulo, e pode ser considerada unidade correlata a estas. Neste estudo, são apresentadas seções colunares e caracterizados os contatos da Formação Serra Alta com as formações permianas verticalmente contíguas. É apresentada também detalhada análise de fácies, com a finalidade de caracterizar o sistema deposicional. A análise de perfis de sondagem possibilitou também melhor compreensão dos padrões arquiteturais da Formação Serra Alta, auxiliando na determinação de sua real distribuição e posição estratigráfica na porção centro-sul do estado. A integração das informações obtidas permitiu identificar tendências de empilhamento transgressivo particulares, contribuindo para o detalhamento da sucessão predominantemente regressiva em que se depositaram as unidades permianas da Bacia do Paraná.

Investigation of the organic matter properties and hydrocarbon potential of the Sivas Basin, Central Eastern Anatolia, Turkey, using Rock-Eval data and organic petrography

Abstract The main goal of this study is to assess the organic geochemical properties and hydrocarbon generation potential of the Tertiary units in the Sivas Basin which is one of the largest sedimentary basins in the Central Anatolia, Turkey. In this investigation, 200 representative samples were collected from the Tertiary sedimentary rock outcrops. In addition, 15 scaled columnar sections were measured and 187 samples were also collected from these sections. Hydrocarbon generating potential and the maturity levels of the Tertiary units along with the geological history in this basin were determined by means of the total organic carbon (TOC) analysis, Rock-Eval pyrolysis, vitrinite reflectance (Ro) and the organic petrographical observations. Kerogen slides of 96 samples containing high TOCs were prepared to determine the organic matter types. Information about maturity degrees were also obtained using the spore fluorescence colours and the vitrinite reflection (Ro). According to the results of analyses, TOC values of the Hafik (0.05–0.17%), Kalekoy (0.01–0.12%), Yagmurluseki (0.01–0.54%) and Selimiye (0.01–017%) Formations are very low and other geochemical parameters are not encouraging to perform further investigations for these formations. Because of these reasons, they may not be accepted as source rocks. However, the Bozbel (0–1.43%) and Karayun (0.07–7.5%) Formations display high TOC values indicating poor to moderate source rock characteristics with S1+S2 values up to 1.03 mg HC/g rock for the Bozbel and up to 23.45 mg HC/g rock for the Karayun Formation. Organic matter types of the Bozbel and Karayun Formations are mainly Type-III and Type-II/III in the HI–OI and HI–Tmax diagrams, respectively. Samples of the other formations include only Type-III kerogen, in general. The maturation degree of the Bozbel Formation varies in a broad range, from immature to mature levels in the majority of samples. The Karayun Formation is generally in the early mature interval. Consequently, both formations have a limited gas generation potential. However, the Sivas Basin is still worth to explore for hydrocarbons, because all samples were collected from outcrops and type sections close to the basin margins, not from boreholes or from the deeper parts of the basin. Thickness of the sedimentary units is found as 8–10 km in average in the previous studies. On the other hand, the deepest parts of the basin containing such a thick sedimentary deposits have not been drilled, yet. It is possible to find out more encouraging results in case of drilling deep exploration wells.

The Application in Calculation of the Horizontal Wells’ True Thicknesses – An Example of Penglaiba Formation in the Northern Tarim Basin

Horizontal oil and gas drilling has become one of the most valuable technologies ever introduced in the unconventional drilling especially. Nevertheless, it is complex to calculate the horizontal wells’ true formation thicknesses in the dipping strata. Combined with the actual geological conditions and mathematical methods, a complete set of new formula was derived from the basic data of the strata dips, dip directions and individual layer data to calculate the true formation thicknesses, which could obtain the horizontal wells’ true thicknesses of Penglaiba Formation of Lower Ordovician in the northern Tarim Basin. And the calculation results were accurate. Calculated with this formula, the Penglaiba Formation’s true thickness was given, wells’ relative distributions were located, and the columnar section of Penglaiba Formation was spliced to discover the geological situation subsurface accurately. The columnar section of Penglaiba Formation in the northern Tarim Basin could provide a theoretical basis for reservoir prediction and the distributions in the low permeable beds. This is the key technical method to descript the palaeogeologic map.

Research and Development on Geological Core Drilling Computer Aided Design System

On the request of the current level of the geological core drilling design, refer to oil drilling design software, a geological core drilling computer aided design system was developed by means of advanced web design technology. The system covers all procedures of geological core drilling design, and presets reference value according to system database information, and automatically draws geological column and borehole columnar section according to the user design information, and finally produces overall and standard design report. The development technology is based on ZK and Hibernate framework with MVC and MVVM model. Consequently, the system will be easy to be used and maintained, and will contribute to the geological core drilling design information exchange and share online.