Tertiary Rocks Research Articles

A New Evaluation Method for the Uniaxial Compressive Strength ahead of the Tunnel Face Based on the Driving Data and Specification Parameters of TBM

Uniaxial compressive strength (UCS) is a very important fundamental mechanical parameter for TBM construction. In this work, a predictive model of UCS was proposed according to the TBM parameters including torque, penetration, cutter number, and cutter diameter. The parameter of the new proposed model was established by fourteen existed TBM tunnels’ construction data. To describe the relationships of UCS with PLSI of the Murree tertiary hard rocks, regression analyses have been conducted and a fitting equation with high‐prediction performance was developed. Validation from the data of Neelum–Jhelum (NJ) TBM diversion tunnel were carried out. The absolute errors between predictive UCS and experimental UCS were presented. Through comparison, it can be concluded that the proposed calculation equation of UCS has a high accuracy for a certain rock type with UCS from 50 MPa to 200 MPa. For special hard rock or soft rock, a new calculation equation between UCS and TBM parameters should be studied furthermore.

Palaeocurrent Analysis of the Tertiary Rocks of Changkikong Range, Mokokchung District, Nagaland, Northeast India

Palaeocurrent Analysis of the Tertiary Rocks of Changkikong Range, Mokokchung District, Nagaland, Northeast India

Finite strain of the Tertiary rocks and their relation to tectonic deformation at Al-Tib Anticline in Missan governorate, Southeastern part of Iraq

This paper presents the finite strain results from seven oriented samples data on Tertiary sandstone of Muqdadiya Formation and (400) samples of pebbles and conglomerate of Bai –Hassan Formation at the southwestern limb of Al-Tib Anticline in the Southeastern part of Iraq. Measurement and analysis of finite strain are carried out including these rocks at fluvio- lacustrine environment. The present study followed Fry method. The computed strain was, in the form of ellipses, within three prepared perpendicular planes in a single sample and Center to Center method was used to determine the strain ratio of the these samples. The strain in the studied area is low, this is mainly due to the sampled rocks underwent brittle deformation during folding. The calculated axial ratios (Rs), (three dimensional orientations of the strain axes) of strained rocks are shown which is equivalent to the log Flinn diagram normally used for plotting strain ellipsoids and according to the stereographic projection method, the long axes of this ellipsoid are sub parallel to measured Al-Tib Anticline axis and the short axes are approximately perpendicular to the axis of Al- Tib Anticline in the study area. This orientation of these axes is related to the movement of the Arabian plate.

Regional magnetic lithologies and structures as controls on porphyry copper deposits: evidence from Iran

Tertiary magmatic activities in Iran are the main magmatic events responsible for porphyry copper deposit occurrences. The Urumieh-Dokhtar magmatic belt (UDMB), the Ahar-Arasbaran, the Taleghan-Tarom, the Kavir-Sabzevar zones, and the Lut Block contain the greatest volume of the Tertiary magmatic rocks in Iran. Many porphyry copper deposit indications have been found, especially in the south-east and north-west of the UDMB in the Kerman and the Ahar-Arasbaran zones, respectively. New porphyry copper mineralisation found in central parts of the UDMB and the East Iran magmatic belt (the Lut Block), in Tertiary rocks, have made these areas more interesting for porphyry copper prospecting, where before that they were not noteworthy. In this paper, we used the combination of upward continuation and edge enhancement filters to find and predict the pattern of distribution of porphyry copper deposits in the Tertiary magmatic belts. The results show the high correlation between magnetic lithologies/structures and porphyry copper deposits at a regional scale and new attractive areas have been proposed for prospecting based on deep geophysical features.

A review of biostratigraphic studies in the olistostrome deposits of Karangsambung Formation

Planktonic foraminifera is widely used for marine sediment biostratigraphy. Foraminiferal biostratigraphy of Karangsambung Formation is relatively rare to be investigated by previous researchers. A review of foraminiferal biostratigraphy is expected to be early work to perform a research about the ages of Tertiary rock formations in Karangsambung. The research area is formed by olistostrome process; a sedimentary slide deposit characterized by bodies of harder rock mixed and dispersed in a matrix. Biostratigraphic studies based on foraminifera and nannoplankton in Karangsambung Formation are still qualitative analysis using fossils biomarker. However, the age of this formation is still debatable based on foraminifera and nannofossil analysis. Two explanations of debatable ages in Karangsambung Formation that is possibly developed in Karangsambung area: firstly, Karangsambung Formation is characterized by normal sedimentation in some places and other regions such Kali Welaran and Clebok, Village as a product of olistostrome, and secondly, Karangsambung Formation is olistostrome deposit. However, micropaleontology sampling and analysis in matrix clays from olistostrome were ignored causing biostratigraphical results in those matrix clays occurred in normal sedimentation process and achieving the age of middle Eocene to Oligocene. We suppose previous authors picked samples in matrix of Karangsambung Formation from several river sections, which will make misinterpretation of the age of Karangsambung Formation. The age of middle to late Eocene probably is the dates of the older sediment that was reworked by sliding and sampling process and accumulated in Karangsambung Formation. The date of Karangsambung Fm is in Oligocene period based on a finding of several calcareous nannofossils. Detailed micropaleontological analysis of olistostrome deposits in Karangsambung Formation should be reevaluated for new finding of the accurate dating. Re-evaluation should start from detailed sedimentological mapping of Karangsambung Fm transects based on previous authors especially Kali Welaran, Jatibungkus transect and Clebok section followed by systematic sampling of normal sedimentation process from olistostrome products and matrix clays of olistostrome Karangsambung Formation. Finally, quantitative method of micropaleontological analysis can be applied to identify the age of Karangsambung Formation.

Geophysical investigation using gravity data in Kinigi geothermal field, northwest Rwanda

A land gravity survey was carried out in the Kinigi geothermal field, Northwest Rwanda using 184 gravity stations during August and September, 2015. The aim of the gravity survey was to understand the subsurface structure and its relation to the observed surface manifestations in the study area.The complete Bouguer Gravity anomaly was produced with a reduction density of 2.4 g/cm3. Bouguer anomalies ranging from −52 to −35 mGals were observed in the study area with relatively high anomalies in the east and northwest zones while low anomalies are observed in the southwest side of the studied area. A decrease of 17 mGals is observed in the southwestern part of the study area and caused by the low-density of the Tertiary rocks. Horizontal gradient, tilt angle and analytical signal methods were applied to the observed gravity data and showed that Mubona, Mpenge and Cyabararika surface springs are structurally controlled while Rubindi spring is not. The integrated results of gravity gradient interpretation methods delineated a dominant geological structure trending in the NW-SE, which is in agreement with the regional geological trend. The results of this gravity study will help aid future geothermal exploration and development in the Kinigi geothermal field.

Petrophysical Properties of the Upper Qamchuqa Carbonate Reservoir through Well Log Evaluation in the Khabbaz Oilfield

Khabbaz oilfield has a symmetrical subsurface anticline with a length of 20 km and a width of 4 km. Despite the fact that Khabbaz oilfield has a small size structure, it is known as one of the massive Oilfields in Iraq. The reservoirs of Khabbaz oilfield are produced by both Cretaceous and Tertiary rocks. The Upper Qamchuqa reservoir is the most productive reservoir of the Khabbaz oilfield with thickness ranges between 138 to 170 m. This formation is subdivided into two units, from the top is Unit A with a thickness of 67 m and from the bottom is Unit B with a thickness of 84.5 m. From a full set of log data of three wells (Kz-1, Kz-13 and Kz-14), the petrophysical properties of Khabbaz oilfield has been evaluated. The wireline log data includes gamma-ray log, sonic log, neutron log, density log and resistivity logs, both Rxo and Rt logs. This study revealed that Unit A represents the best reservoir characteristics where Unit A is subdivided into six reservoir subunits named (1-A, 2-A, 3-A, 4-A, 5-A and 6-A). They are separated by five non-reservoir subunits named 1-N, 2-N, 3-N, 4-N and 5-N. In addition to a less porous reservoir unit that is called Unit B, which has been divided into four reservoir subunits named 1-B, 2-B, 3-B and 4-B. These are separated by five non-reservoir units named 1-N, 2-N, 3-N, 4-N and 5-N. It has been recognized that both reservoir units A and B are clean formations and have minimum shale volume with high porosity in limestone and dolomite to dolomitic limestone lithology with high oil saturation and low water saturation. Based on the above reservoir characteristics it can be concluded that the reservoir units of the Khabbaz oilfield contain a massive commercial hydrocarbon accumulation.

Tectonic geomorphology and neotectonic setting of the seismically active South Wagad Fault (SWF), Western India, using field and GPR data

The South Wagad Fault (SWF) is an E–W trending fault that delimits the Wagad uplift comprising Mesozoic rocks in its northern upthrown block and Neogene–Quaternary sediments in the southern downthrown block. Detailed GPR investigations were carried out at seven sites selected after field studies. All profiles clearly showed the lithological contrast across the fault. The sharp amplitude contrast of the radar waves along a vertical to sub-vertical line is interpreted as the near surface trace of the SWF. As the Quaternary sediments are not displaced, we infer that no large magnitude earthquake has occurred along the SWF in late Quaternary. We attribute the low magnitude of neotectonic activity along the SWF to gentle warping of the Tertiary rocks in the southern downthrown block and greater accumulation of compressive stresses along the nearby KMF with an opposite structural setting. This is consistent with the observed variable levels of ongoing seismicity in the region around the SWF.

Gravity models as tool for basin boundary demarcation: A case study of Anambra Basin, Southeastern Nigeria

This work analyzed gravity data over the Anambra Basin, Southeastern, Nigeria, with the aim of inferring the boundaries of the basin from gravity models. Method of study involved data acquisition and reduction, generation of Bouguer gravity map and separation of regional and residual anomalies. Data processing was enhanced by the use Oasis Montaj software. The interpretation of the Bouguer gravity anomalies ranged from visual inspection of figures to more complex methods that involved modelling of the subsurface layers. Sediment thickness in the study area ranged approximately from 0.4km to 6km. The highest gravity values (≥30mGal) are associated with igneous rocks; the intermediate gravity values (11–29mGal) are associated with Cretaceous sedimentary rocks, while the lower gravity values (<11mGal) are associated with Tertiary rocks. Boundary of the Anambra Basin from the western–Southwestern–southern portion of the study area is inferred around and along Adeigba–Umuezeanam–Nnewi–Akokwa areas, its boundary in the north-western part is beyond Igga and exists somewhere outside the study area, around Ogurugu, while its boundary in the southeastern side is around Umulokpa community. In the northern part of the study area the basin went beyond Obolafor in Enugu State and extended up to Orokam in Benue State. Afikpo Basin has been defined as a distinct inland basin different from the Anambra Basin. The present work has indicated that basin boundaries do not always coincide with surface lithologic boundaries; hence, field relationship alone is not enough for basin boundary demarcations.

Rock-Eval Pyrolysis Results from the Bijeel 1 Well, Kurdistan Region, Iraq

We used Rock-Eval pyrolysis to examine the petroleum source potential of rock samples from the Bijeel 1 Well in Kurdistan Region of northern Iraq. The results show that Sargelu and Sehkaniyan marine Type IIS kerogen are potential sources of hydrocarbons and are thermally mature with respect to the oil window. In the samples that we studied, carbonate are more organic-rich and more oil-prone than carbonaceous shales and silty mudstones, which appear to be potential sources of natural gas. The Paleocene rocks from Bijeel 1 Well are thermally immature. Lithologically similar rocks may be present in the deeper parts of the subsurface of Iraqi Kurdistan located south of the Bijeel 1 Well, where they may have been buried deeply enough to generate oil and (or) gas. The Tertiary rocks are sparsely examined and mostly unexplored and no commercial production of hydrocarbons has been obtained. However, the existence of potential source rocks of oil and gas, as shown by our Rock-Eval results, suggests that undiscovered petroleum accumulations may be present in the area.

Magma source feature and eruption age of volcanic rocks in the Tram Tau district, Tu Le Basin

Magma source feature and eruption age of volcanic rocks in the Tram Tau district, Tu Le Basin

현장 초기응력 측정과 시추공 이미지 스캐닝 자료의 통합 분석을 통한 포항분지 제 3기 지층 내 수평응력 분포 특성 연구

현장 초기응력 측정과 시추공 이미지 스캐닝 자료의 통합 분석을 통한 포항분지 제 3기 지층 내 수평응력 분포 특성 연구

The Effect of Differences Leachate Concentration and Material Properties on Electrical Conductivity of Volcanic Deposits – Case Studies Piyungan Landfill Bantul Yogyakarta

Monitoring at the contaminated subsurface soil, have been conducted by using the geophysical surface method, especially for geoelectrical resistivity method. Monitoring is commonly conducted by using geoelectrical resistivity through measuring the value of Electrical Resistivity (ER) or Electrical Conductivity (EC) of leachate contaminated soil layer. EC measurement value of soil is affected by many factors, among others, particle conduction of soil materials, surface conduction, fluid conduction in the pores as well as the effect of particle shape and soil materials. Piyungan landfill is the main disposal site of Yogyakarta municipal solid waste. This landfill located mainly on the tertiary rocks of volcanic rocks and its weathering products. In order to improve the accuracy of geoelectrical measurements on resistivity in monitoring soil layers from contaminated leachate on this area, this research conducted several measurements on physical properties of soil sample and electrical properties of leachate in the saturated soil samples. The measurement of physical properties includes: porosity, clay content, particle content, and cation exchange capacity (CEC) value. The soil samples were collected from 3 locations around Piyungan Landfill. Type of soils are taken from the alluvial deposits (Sample B), weathered tuffaceous sandstone-claystone (Sample D), and weathered andesitic breccia (Sample F). Samples were made in containers, saturated with aquades-leachate solution with 12 different concentration levels. Electrical conductivity (EC) was measured by using Soil Box Miller and Geoelectric Resistivity Oyo McOhm. According to results of physical properties analysis, the grain size of soils are dominantly sandy clayey silt in grain size distribution, with clay content ranging from 33.0--38.4 %, the CEC values ranging from 26.8--52.7 meq/100 gr, and the porosity of samples B, D and F is 58.85 %, 55.30 %, 59.24 %, respectively. Based on the experiments with 12 different leachate concentrations, there is a linear increase in EC of 0.718mS/cm for every increase in electrical conductivity pore fluid (ECf ) 1 mg/l in samples B, while in samples D and F are 0.492 mS/cm and 0.284 mS/cm respectively. Plotting the data of EC vs ECf for each samples and ER vs ECf , it can be concluded the slope ofDEC/DECf differ for each samples and the electrical conductivity value of different concentration of leachate is very sensitive for alluvial deposits compare to the weathered tuffaceous sandstone-claystone and weathered volcanic breccia deposits.

Field Occurrence and Petrographic Characteristics of Tertiary Volcanic Rocks and Associated Intrusions in and around Taiz City, Yemen

Geologic and petrographic studies of Tertiary volcanic rocks and their intrusive bodies such as plutons, dykes and sills were carried out in and around Taiz city, Yemen with an aim to document their field occurrence and distribution as well as to study their mineralogical composition. This has an important bearing on the town planning in the city of Taiz as the existing buildings are collapsing due to the foundation problems. Studies on 110 exposures, carefully selected after field traverses revealed that the Tertiary rocks in the study region are mainly represented by typical bimodal mafic-felsic associations in the form of flows, plutons and dykes. Tertiary volcanic flows are characterized by alternating sequences of basic and felsic rocks and varicoloured volcaniclastic deposits which were all extruded and fed from fracturing and fissuring in the old rocks through which magma emerged in successive pulses, flooding the surrounding region. The basic flows (Tb1, Tb2 and Tb3) consist of jointed/massive basaltic rocks and volcaniclastic deposits while the felsic flows (Tr1 and Tr2) are comprised of jointed/massive rhyolite/dacite rocks and also varicoloured felsic volcaniclastic deposits. All these rocks show wide variations in their geological and petrographical characteristics such as colour, texture, heterogeneity, macro/microfractures, weathering/alteration, thickness, horizontal attitude, and intercalation with volcaniclastic deposits, repetition with depth in both vertical and horizontal directions. Volcaniclastic deposits are also characterized with great diversity in their types, colours, textural features, thicknesses, grain sizes, matrices, and degree of roundness of rock fragments and alternating and/or interlocking as well as intercalation laterally and vertically with basalt/rhyolite lava rocks. Volcaniclastic rocks were classified for the first time in the study area based on their particle sizes into different types. They range from strong, compact, welded rocks to weak, altered soils. The younger Sabir granitic pluton is represented by alkaline or peralkaline granites that are white to greyish white coloured massive, medium to coarse-grained, grading up to granite porphyry. Petrographic examinations of 52 thin sections representing the samples of basaltic lava flows, rhyolitic/dacite lava flows and younger intrusives under polarizing microscope have been carried to study their mineralogy. The dominant minerals in basaltic rocks are plagioclase, augite and olivine whereas rhyolitic rocks contain quartz, orthoclase and biotite. The main mineral constituents of younger granitic rocks are k-feldspar, quartz, hornblende and biotite. The mafic and felsic dykes almost resemble basalts and rhyolites/dacites respectively in their petrographical characteristics. XRD technique used for characterizing the minerals of volcanic soils revealed the presence of clay minerals namely montmorillonite and kaolinite as the major mineral phase in most of the samples whereas mica group of minerals such as muscovite, vermiculite and chlorite are present in minor amounts, in addition to talc, feldspar, calcite and halloysite.

Geochemical evidence for the genesis of the Sarical-Yavu hematite mineralizations (Sivas, Central Turkey)

The hematite mineralization under investigation is located 11 km NE of Sarical (Yavu) village of the Yildizeli town (Sivas Province) in central Turkey. The region is within the Central Anatolian Thrust Zone and is comprised of metamorphic units, ophiolitic rocks and overlying Tertiary volcanic and volcanosedimentary rocks in addition to Neogene terrestrial deposits. The mineralization occurs as lenticular or bedded bodies and is composed chiefly of hematite and a lesser amount of goethite. Quartz, calcite, and dolomite are the gangue minerals. Kaolinite and zeolite are the common alteration products. In this study, geochemical and mineralogical investigations were carried out using an X-ray diffractometer analysis (XRD), Raman spectroscopy, and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX). The V/(V + Ni) ratio increases in parallel to the detritic contribution, and when this ratio is less than 0.60, deposition conditions are said to be anoxic. Considering the V/(V + Ni) ratio and Ceanom values of the studied samples, we suggest that the environment is both oxic and anoxic in character. The overall assessment of the field observations, mineral paragenesis, major, trace, and rare earth element (REE) data indicates that the Sarical hematite mineralization is of a hydrothermal-sedimentary type.

Dismembered Porphyry Systems near Wickenburg, Arizona: District-Scale Reconstruction with an Arc-Scale Context

This study combines results from reconnaissance-scale mapping of hydrothermal alteration, rock types, and structures to provide a district-scale cross section and associated palinspastic reconstruction of an area with two previously undescribed Laramide (~70 Ma) porphyry systems at Sheep Mountain and Copper Basin (Crown King). Extension at the district scale is placed in an arc-scale context using an original compilation of strike and dip measurements on Tertiary rocks to reconstruct the Laramide porphyry belt prior to extension. The study area contains five sequential, partially superimposed sets of normal faults that are nearly planar where exposed. Dips of all normal faults initiated at 60° to 70° and rotated during slip to angles as gentle as 20°. A palinspastic reconstruction reveals that two, spatially distinct hydrothermal systems overlie different cupolas of a Late Cretaceous pluton. Hydrothermal alteration is zoned from greisen to potassic to transitional greisen-potassic assemblages from deep to shallow structural levels. The reconstruction is used to identify two covered exploration targets. The prospects may be porphyry molybdenum systems of the quartz monzonitic-granitic porphyry Mo-Cu subclass, joining others in an arc that is best known for porphyry copper deposits. The Laramide porphyry belt prior to extension displays a variably well-defined axis, ~100 km wide, with gaps and clusters of deposits along its 700-km strike length. The majority of deposits lie along the axis, but others lie in fore- or rear-arc positions. The interpreted preextensional geometry of the Laramide porphyry belt resembles other porphyry belts and the distribution of active volcanoes at convergent margins.

Geochemistry and Petrogenesis of Tertiary Volcanic Rocks of the Eastern Roodbar, Alborz Mountain, North of Iran

In the Alborz Mountains of the eastern Roodbar (north of Iran), Tertiary volcanic rocks have a variety of composition between olivine basalt, basaltic andesite, pyroxene andesite and andesite. The presence of different xenoliths and xenocrysts is among the evidence of crustal contamination of these rocks. The positive correlations of CaO/Al2O3 vs to MgO and Al2O3 vs. SiO2 are of signs of the olivine and clinopyroxene fractionation in the variation trend of the area rocks. Positive correlations K2O/P2O5 vs with SiO2 and La/Sm vs. K2O/P2O5 demonstrate contamination of magma with the continental crust. The incompatible trace element patterns and their comparison with crustal contents indicate contamination of the rocks of the area with the lower and upper continental crust. Linear trends in the variation diagram of Nb/Y vs. Zr/Y, introduce two different source regions: a MORB source and the other continental crust for the rocks which are the genesis. The variations of Y/Nb vs. Zr/Nb and Rb/Y vs. Nb/Y reveal a crustal contamination of the magma originated from the MORB source. Geochemical studies represent that the area’s rocks were derived from the 15% melting of a mantle source of MORB type with spinel facies within a continental environment, which was contaminated by varying degrees of continental crustal rocks.

A Preliminary Documentation of the Coral Reefs from Libya

Corals studies in Libya are very limited, although they play an important role in the oil exploration as they form excellent reservoirs of coral reef buildups at some oil fields of Sirt Basin (e.g. Intisar “Idris” and Sahabi Fields). Both fields are produced from Paleocene coral reefs. Meanwhile, in Cyrenaica, corals are of less importance as they are not reported in subsurface tertiary rocks, which probably in the environmental settings of these sediments out of the core of reef as occurred in the surface. Meanwhile, corals are reported from older (Jurassic) subsurface successions as in Concession NC-152, but the cementation diagenesis leads to blocking and destroying the porosity. This study presents the first surface documentation work of eight scleractinian coral species from the exposed sediments in northern Libya, where sixtaxa is reported from Al Jabal al Akhdar region, these include a) an association of huge colonies of Caulastrea sp. and Stylophora sp., from the Middle Eocene Darnah Formation at West Darnah road cut section. Theco-existence of the fastCaulastrea sp. with the slow Stylophora sp. is due to the competition strategy; b) Antiguastrea sp. which is reported from the Oligocene Algal Limestone of Al Bayda Formation at Daryanah-Abyar Roadcut section; c) Cyphastrea sp. andAleveopora sp. from Oligo-Miocene Al Faidiyah Formation at Al Fatayah cement quarry and d) Tarbellastraea sp. From Middle Miocene Benghazi Formation at Benghazi Cement Quarry. In addition, two species Astraeaopora sp. and Actinacis paroraiare reported from the Upper Miocene sediments of formation “M” in As Sahabi area.

Letter from the editor

Letter from the editor

JATIBARANG LANDFILL OF SEMARANG CITY: IS IT POTENTIAL AS THE WATER CONTAMINATION SOURCE?

Like other million inhabitants Cities, Semarang which is the capital city of Central Java Province in Indonesia has a problem in solid waste management. One biggest landfill in the City is the Jatibarang Landfill. The landfill operated since 1992 and currently receives the domestic waste of about 337 ton/day with total volume of about 5.2 million m3 of solid waste. It located on the hill slope of sandstone tertiary rocks and relatively closed to the river of Kreo (which is the main source of drinking water for Semarang City). In order to evaluate the potentiality of landfill as the contamination source to groundwater and surface water, the quality of leachates were analyzed and the hydrogeology of the area was re-studied. Result of the study show that the leachates contain high chloride concentration of about 2600 mg/L however low concentration of heavymetals. Hydrogeology study show evidence that this leachate is already enters the groundwater system. However its load to the river can be neglected due to the fact that the chloride mass flux derived from the study area was significantly low comparing to the net river loads. &#x0D; &#x0D; Key Word: landfill, water contamination, chloride, groundwater and surface water interaction