scholarly journals Detrital Zircon U-Pb Data for Jurassic–Cretaceous Strata from the South-Eastern Verkhoyansk-Kolyma Orogen—Correlations to Magmatic Arcs of the North-East Asia Active Margin

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 291
Author(s):  
Andrei V. Prokopiev ◽  
Victoria B. Ershova ◽  
Daniel F. Stockli

We performed U-Pb dating of detrital zircons collected from Middle–Upper Jurassic strata of the Sugoi synclinorium and Cretaceous rocks of the Omsukchan (Balygychan-Sugoi) basin, in order to identify their provenance and correlate Jurassic–Cretaceous sedimentation of the south-eastern Verkhoyansk-Kolyma orogenic belt with various magmatic belts of the north-east Asia active margins. In the Middle–Late Jurassic, the Uda-Murgal magmatic arc represented the main source area of clastics, suggesting that the Sugoi basin is a back-arc basin. A major shift in the provenance signature occurred during the Aptian, when granitoids of the Main (Kolyma) batholith belt, along with volcanic rocks of the Uyandina-Yasachnaya and Uda-Murgal arcs, became the main sources of clastics deposited in the Omsukchan basin. In a final Mesozoic provenance shift, granitoids of the Main (Kolyma) batholith belt, along with volcanic and plutonic rocks of the Uyandina-Yasachnaya and Okhotsk-Chukotka arcs, became the dominant sources for clastics in the Omsukchan basin in the latest Cretaceous. A broader comparison of detrital zircon age distributions in Jurassic–Cretaceous deposits across the south-eastern Verkhoyansk-Kolyma orogen illustrates that the Sugoi and Omsukchan basins did not form along the distal eastern portion of the Verkhoyansk passive margin, but in the Late Mesozoic back-arc basins.

1916 ◽  
Vol 3 (10) ◽  
pp. 435-441 ◽  
Author(s):  
G. W. Tyrrell

The new material on which this paper is based has lately been received through Mr. D. Ferguson, who recently investigated the geology of the island, and collected the rocks described in an earlier paper. It consists of twenty-seven rock specimens from the south-eastern end of the island, between Cape Disappointment and Cooper Island, and nine specimens from Gold Harbour on the north-east coast between Cooper Island and Royal Bay. All these were collected by the staff of the South Georgia Co., Ltd., under the instructions of Mr. Th. E. Salvesen, managing director, of Leith.


Africa ◽  
1977 ◽  
Vol 47 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Fremont E. Besmer

IntroductionThe town of Ningi is located on the western edge of the North East State of Nigeria, about 25 km from the south-eastern corner of Kano State. Old Ningi town (about 50 km from the town's present site) was founded by a Kano Qur'anic teacher-scholar, Malam Hamza, and his followers in the middle of the nineteenth century. Malam Hamza is said to have fled Kano because of political and religious disputes with the Emir of Kano which resulted in a purge of the Malam class. Moving away from the centre of Kano power to the comparative safety of the Kabara hills and the non-Hausa people who lived in them, Malam Hamza was able to establish the separatism he and his followers desired. During this period the Kabara hills were the scene of slave-raiding and warfare, constantly threatened by the Hausa-Fulani emirates which surrounded them. Fighting from the hills, the people of Old Ningi, loosely allied with their neighbours, the Butawa, Warjawa, and others, were able to maintain their independence from Bauchi, Zaria, and Kano.


2021 ◽  
Author(s):  
Vlad-Alexandru Amihăesei ◽  
Lucian Sfîcă ◽  
Alexandru Dumitrescu

<p>The south-eastern part of the European continent is known as a region where the types of climate are hard to be delimited, being indicated by Trewartha since 1961 among the so-called Earth's Climate Problem regions of the world. This is given especially by its position at the merges of arid and cold climate of the temperate zone in Europe. Taking to account this aspect, it is not surprisingly that after almost 100 years of climate classification attempts, there is still no agreement regarding the climate type of Romania and its corresponding subdivisions. Even if a weak majority of the Romanian climatologists plead for a temperate continental climate, some others consider that Romania has a typically temperate transitional climate specific for central Europe. However, most of previous regionalizations are highly subjective with no proper quantitative assessment of climate conditions. </p><p>In our study a climate regionalization of Romania’s territory is proposed, based on an objective approach. For this purpose, 9 monthly climate parameters extracted from interpolation gridded data sets (ERA-5 land and ROCADA) were used.</p><p>The regionalization was performed by mixing two objective methods. Firstly, all the 108 input variables were reduced at 8 major factors using factor analysis. Secondly, those factors were used in a k-means clustering method and a new scheme of climate regionalization of Romanian territory was obtained. Through this, we succeed to delimitate 8 different climate subtypes within Romania's territory which we aggregated firstly in 2 major zonal climate types: (i) temperate transitional climate (TTC) from maritime to continental type, extended in the north-east part of Romania and (ii) temperate orographically sheltered climate (TOSC) with 2 major subtypes. The first sub-type of TOSC is extended within the Carpathian mountain arch (an extension of pannonian climate) and the second one covers the romanian part of the region between Carpathian and Balkan Mountain (lower danubian climate). Besides these two zonal types the major landforms of Romania impose specific climate conditions: (iii) the Carpathian mountains and sub-mountains area have their own climate features (CMSC) with 3 climate subtypes (precarpathian, eastern Carpathian and alpine climates), while the (iv) Black Sea shapes the main climate conditions of the south-eastern side of the country especially along the coast with 2 climate subtypes (ponto-deltaic and western pontic type). The main features of these climate types/subtypes are presented in detailed in the study.</p><p>In the meantime, the proposed climate regionalization covers partially the neighbor countries in an attempt to homogenize the different national perspectives on the climate types along the states boundaries in central and south-eastern Europe.</p>


1910 ◽  
Vol 7 (4) ◽  
pp. 159-171 ◽  
Author(s):  
Arthur R. Andrew

The town of Dolgelley lies slightly outside the main tract of gold-bearing country of Merionethshire, but it forms a convenient headquarters from which to visit the various gold-mines and auriferous lodes. The Dolgelley Gold-belt lies within the area covered by the quarter-sheets 27 N.E., 27 S.E., 32 S.E., 33 N.W., 33 N.E., 33 S.W., 36 N.W., 36 N.E. of the 6 inch Ordnance Survey maps of Merionethshire. It is on the north side of the estuary of the Mawddach, extending from the sea at Barmouth to the locality of Gwynfynydd on the north-east. The belt forms the south-eastern flank of a range of high ground sloping down to the south and south-east from the mountains of Rhinog, Diphwys, and Garn. It is drained by several tributaries of the Mawddach, of which the principal are the Afons Hirgwm, Cwm-llechen, Cwm-mynach, Wnion, Las, Gamlan, Eden, and Gain.


1966 ◽  
Vol 6 (1) ◽  
pp. 7
Author(s):  
T. J. Brady ◽  
W. Jauncey ◽  
C. Stein

An estimated total of over 20,000 feet of Palaeozoic sediments accumulated in the Bonaparte Gulf Basin. The thickest known continuous section is that in Bonaparte No. 1 Well, abandoned at 10,530 feet in Upper Devonian sandstone and shale. Rocks of the Basin margins are mainly sandstones and limestones (in part reef), whereas a thick shale section has been discovered in the deeper parts. Data from recent seismic surveys indicate that the seaward extension of the Basin is considerable and that a thick pile of sediments is preserved there.The Bonaparte Gulf Basin formed as a result of subsidence of the north-eastern part of the Kimberley Block along fault lines associated with the Halls Creek Mobile Zone. This zone borders the south-eastern margin of the Basin and trends north-east. One basement block, represented by the presentday Pincombe Range, remained relatively high. The Bonaparte Gulf Basin can be divided into two subsidiary basins, the Carlton Basin to the west and north-west and the Burt Range Basin in the east and south-east. The Pincombe Range separates the two.Marine sediments were deposited in the Carlton Basin during the Middle and Upper Cambrian, Lower Ordovician, Upper Devonian and Lower Carboniferous epochs. Angular unconformities have been mapped between the Lower Ordovician and Upper Devonian rocks, and between Upper Devonian and Lower Carboniferous rocks. In the Burt Range Basin, deposition began in the Upper Devonian and continued with minor breaks through the Lower Carboniferous. Faults along the south-eastern margin were active through this period and affected the character of the sediments.Permian sediments are widely distributed and lie with unconformity on older units.


Author(s):  
Т.В. Гиоргобиани

В статье рассмотрены условия формирования складчатой системы Большого Кавказа в альпийскую эпоху. Показано, что главная зональная линейная складчатая структура региона была сформирована на ранне- и среднеальпийской стадиях развития в результате проявления батской и пиренейской фаз складчатости. Установлено, что причиной складкообразования было активное столкновение Черноморско-Закавказского микроконтинента на юго-западе с пассивной окраиной Большого Кавказа. Определено, что позднеальпийская стадия в регионе проходила в условиях субмеридионального тангенциального давления, во время проявления плиоцен-четвертичных фаз складчатости. В это время на Большой Кавказ воздействовал не целостный Черноморско-Закавказский микроконтинент, а слагающие его мелкие плиты и блоки-шоли. Выяснено, что они в процессе тектогенеза перемещались и косо вдвигались в складчатую систему Большого Кавказа, вызывая преобразование первичной структуры и возникновение интерференционной складчатости. В результате повторного деформирования отдельных участков региона в его пределах образовалась неоднородная складчатая структура. Изучена основная особенность складчатой системы Большого Кавказа, выраженная структурной неоднородностью складчатости в поперечном и продольном направлениях. Установлено, что она отражает поэтапную и разноплановую деформацию отдельных участков, возникающую в результате последовательного проявления в регионе локальной и региональной геодинамики микроконтинента, а также связанных с ними общих и частных механизмов его формирования. Структурный анализ морфологии складчатости БК действительно показал неравномерную дислоцированность его – С-З и Ю-В сегментов, сложенных в основном ранне- и среднеальпийскими структурами, выраженную в разной степени осложненности коллизионными деформациями. Так, в пределах мальм-эоценового структурного этажа С-З Кавказа, раннеальпийская структура которого меньше всех остальных сегментов усложнена коллизионными деформациями, четко проявлена латеральная асимметричная зональность его складчатой структуры.  Она выражена в последовательной смене с юго-запада на северо-восток интенсивной линейной сильно сжатой складчатости линейными гребневидными, а затем слабо вытянутыми типичными брахиморфными складками, переходящими, в свою очередь, в полого наклонную на северо-восток моноклиналь The article considers the conditions of formation of folded system of the Greater Caucasus in the Alpine Epoch. It is shown that main zonal linear folded structure of the region was formed at the early and middle Alpine stages of the evolution in the result of manifestation of Bathonian and Pyrenean stages of folding. It was established that the cause of the folding was an active collision of the Black Sea-Transcaucasian microcontinent in the south-west with the passive margin of the Greater Caucasus. It was also determined that the Late Alpine stage in the region took place under the conditions ofsubmeridional tangential stress, during the Pliocene-Quarternary folding phases. During this period the Greater Caucasus was affected not by the whole Black Sea-Transcaucasian microcontinent, but by its smaller plates and blocks. It was found out that during the process of tectogenesis they drifted and obliquely moved into the folded system of the Greater Caucasus, causing the transformation of the initial structure and the occurrence of interferential folding. In the result of repeated deformation of separate areas of the region the heterogeneous folded structure was formed. The main feature of the folded structures of the Greater Caucasus (expressed by a structural heterogeny in transversal and longitudinal directions) was studied. It was determined that it reflects the gradual and diverse deformation of individual sections, resulting from the consistent manifestation of the local and regional geodynamics of the microcontinent, as well as the common and specific mechanisms of its formation associated with them. The structural analysis of the morphology of folding of the Great Caucasus really showed its uneven dislocation, i.e. the N-W and S-E of the segments, composed mainly of early and middle Alpine structures, expressed in varying degrees of complication by collisional deformations. So, within the Malm-Eocene structural floor of the northwestern Caucasus, the Early Alpine structure of which is less than all the other segments, is complicated by collimated deformations, the lateral asymmetric zonality of its folded structure is clearly manifested. It is expressed in a successive change from the south-west to the north-east of intensive linear highly compressed folding with linear ridge-like, and then slightly elongated typical brachymorphic folds, which turn into a hollow sloping to the north-east monocline


1965 ◽  
Vol 5 (1) ◽  
pp. 179
Author(s):  
Edward F. Durkee

The north-east margin of the basin as described herein comprises some 40,000 square miles situated regionally between the Bowen basin and the Drummond Range on the east and north-east respectively and the towns of Longreach, Charleville, and Mitchell on the west and south. The limit of the present-day Great Artesian basin in this area is marked by south-east striking outcrops of the Jurassic Precipice Sandstone.The stratigraphy of the area can be grossly subdivided into three time-rock units as follows:Pre-PermianPermian-TriassicLate Mesozoic and Tertiary.Pre-Permian rocks of importance include thick Devonian and Carboniferous units. Marine and evaporite facies are present in the Devonian in the south-west (Adavale basin), changing to more continental facies with volcanic and some marine incursions to the north-east (Drummond basin). Carboniferous units are dominantly paralic to continental types. The Devonian and Carboniferous systems were subjected to various degrees of pre-Permian tectonism and removal and, because of this, the existing occurrences of these systems are only fragments of their original extent. Permian and Triassic, marine to continental units were deposited across the area, thinning from east to west in possible cycles of transgression and regression. In addition to thinning regionally, these systems show marked variation in thickness due to transgression and drape and compaction over major, pre-Permian structural trends.Subsequent to deposition of the Triassic, a pronounced tectonic change was introduced. Previously negative areas to the north-east (Drummond basin—Springsure Shelf) began to rise and the Middle to Late Mesozoic subsidence and filling of the Great Artesian basin to the south-west commenced. Therefore, Triassic and Permian strata thicken regionally to the north-east under the Great Artesian basin margin, while post-Triassic strata thicken south-westward, in the opposite direction, into the basin.Three dominant structural trends are reflected in the sedimentary rocks of the area. These are:North-east trends under much of the Great Artesian basin margin.North-westerly trends of the Drummond basin to the north-east of the Great Artesian basin margin.Northern trends of the Denison trough east of the Great Artesian basin margin.


Author(s):  
Esraa Aladdin Noori ◽  
Nasser Zain AlAbidine Ahmed

The Russian-American relations have undergone many stages of conflict and competition over cooperation that have left their mark on the international balance of power in the Middle East. The Iraqi and Syrian crises are a detailed development in the Middle East region. The Middle East region has allowed some regional and international conflicts to intensify, with the expansion of the geopolitical circle, which, if applied strategically to the Middle East region, covers the area between Afghanistan and East Asia, From the north to the Maghreb to the west and to the Sudan and the Greater Sahara to the south, its strategic importance will seem clear. It is the main lifeline of the Western world.


2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.


Sign in / Sign up

Export Citation Format

Share Document