New paleomagnetic data for Ochotsk-Chukotka volcanic belt

2020 ◽  
Author(s):  
Ivan Lebedev ◽  
Olesya Usanova ◽  
Tanya Fadeeva ◽  
Florian Lhuillier ◽  
Baha Eid ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Field Work ◽  
Magnetic Fabric ◽  
Time Interval ◽  
The North ◽  
Secular Variations ◽  
North Eastern ◽  
Chukotka Volcanic Belt ◽  
Normal Polarity

<p class="db9fe9049761426654245bb2dd862eecMsoNormal"><span lang="EN-US">The Okhotsk-Chukotka volcanic belt (OChVB),  located in the north-eastern part of Russia, is a unique volcanic structure, which has been formed over a wide time interval from Aptian (K1) to Cenomanian (K2) [Tihomirov, 2018]. Age of its formation nearly coincides with the occurrence of the Cretaceous geomagnetic superchron of normal polarity. Thus, the volcanic formations of the OChVB represent a promising object to study the characteristics of the geomagnetic field during the Cretaceous superchron (direction, paleointensity, secular variations) needed to test various models explaining superchrons’s existence .</span></p> <p class="db9fe9049761426654245bb2dd862eecMsoNormal"><span lang="EN-US">During the reconnaissance field work of the summer 2019 we have sampled volcanic rocks in 9 sections each includes from 8 to 30 sites corresponding either to lava flow or to tuff layers.</span></p> <p class="db9fe9049761426654245bb2dd862eecMsoNormal"><span lang="EN-US">Up to date we have carried out AF demagnetization, petromagnetic and AMS studies. Demagnetisations studies demonstrate that the rocks contain paleomagnetic record of the ancient (primary?) magnetization of good to excellent quality. Petromagnetic experiments indicate that the main magnetic mineral in majority of studied volcanics is titanomagnetite with pseudo-single domain grain size. We use the magnetic fabric derived from AMS studies to test either the modern attitude (slight dipping up to 10-15˚) of studied rocks is due to primary paleorelief or the rocks have experienced some tectonic deformations.</span></p>

The Chingandzha flora of the Okhotsk-Chukotka volcanic belt

Palaeobotany ◽  
2019 ◽  
Vol 10 ◽  
pp. 13-179
Author(s):  
L. B. Golovneva
Keyword(s):  
River Basin ◽  
Volcanic Belt ◽  
Flowering Plants ◽  
Sedimentary Deposits ◽  
North East ◽  
The North ◽  
Magadan Region ◽  
Chukotka Volcanic Belt ◽  
Systematic Composition ◽  
Coastal Lowlands

The Chingandzha flora comes from the volcanic-sedimentary deposits of the Chingandzha Formation (the Okhotsk-Chukotka volcanic belt, North-East of Russia). The main localities of the Chingandzha flora are situated in the Omsukchan district of the Magadan Region: on the Tap River (basin of the middle course of the Viliga River), on the Kananyga River, near the mouth of the Rond Creek, and in the middle reaches of the Chingandzha River (basin of the Tumany River). The Chingandzha flora includes 23 genera and 33 species. Two new species (Taxodium viligense Golovn. and Cupressinocladus shelikhovii Golovn.) are described, and two new combinations (Arctopteris ochotica (Samyl.) Golovn. and Dalembia kryshtofovichii (Samyl.) Golovn.) are created. The Chingandzha flora consists of liverworts, horsetails, ferns, seed ferns, ginkgoaleans, conifers, and angiosperms. The main genera are Arctop teris, Osmunda, Coniopteris, Cladophlebis, Ginkgo, Sagenoptepis, Sequoia, Taxodium, Metasequoia, Cupressinocladus, Protophyllocladus, Pseudoprotophyllum, Trochodendroides, Dalembia, Menispermites, Araliaephyllum, Quereuxia. The Chingandzha flora is distinct from other floras of the Okhotsk-Chukotka volcanic belt (OCVB) in predominance of flowering plants and in absence of the Early Cretaceous relicts such as Podozamites, Phoenicopsis and cycadophytes. According to its systematic composition and palaeoecological features, the Chingandzha flora is similar to the Coniacian Kaivayam and Tylpegyrgynay floras of the North-East of Russia, which were distributed at coastal lowlands east of the mountain ridges of the OCVB. Therefore, the age of the Chingandzha flora is determined as the Coniacian. This flora is assigned to the Kaivayam phase of the flora evolution and to the Anadyr Province of the Siberian-Canadian floristic realm. The Chingandzha flora is correlated with the Coniacian Aleeky flora from the Viliga-Tumany interfluve area and with other Coniacian floras of the OCVB: the Chaun flora of the Central Chukotka, the Kholchan flora of the Magadan Region and the Ul’ya flora of the Ul’ya Depression.

Ketilidian structure and the rapakivi suite between Lindenow Fjord and Kap Farvel, South-East Greenland

2000 ◽  
pp. 50-59
Author(s):  
Brian Chadwick ◽  
Adam A. Garde ◽  
John Grocott ◽  
Ken J.W. McCaffrey ◽  
Mike A. Hamilton
Keyword(s):  
Coastal Region ◽  
Field Work ◽  
Natural Environment Research Council ◽  
East Greenland ◽  
The North ◽  
Tectonic Processes ◽  
Field Investigations ◽  
North Eastern ◽  
Bad Weather ◽  
North Eastern Part

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Chadwick, B., Garde, A. A., Grocott, J., McCaffrey, K. J., & Hamilton, M. A. (2000). Ketilidian structure and the rapakivi suite between Lindenow Fjord and Kap Farvel, South-East Greenland. Geology of Greenland Survey Bulletin, 186, 50-59. https://doi.org/10.34194/ggub.v186.5215 _______________ The southern tip of Greenland is underlain by the Palaeoproterozoic Ketilidian orogen (e.g. Chadwick & Garde 1996; Garde et al. 1998a). Field investigations in the summer of 1999 were focused on the structure of migmatites (metatexites) and garnetiferous granites (diatexites) of the Pelite Zone in the coastal region of South-East Greenland between Lindenow Fjord and Kap Farvel (Figs 1, 2). Here, we first address the tectonic evolution in the Pelite Zone in that region and its correlation with that in the Psammite Zone further north. Then, the structure and intrusive relationships of the rapakivi suite in the Pelite Zone are discussed, including particular reference to the interpretation of the controversial outcrop on Qernertoq (Figs 2, 8). Studies of the structure of the north-eastern part of the Julianehåb batholith around Qulleq were continued briefly from 1998 but are not addressed here (Fig. 1; Garde et al. 1999). The field study was keyed to an interpretation of the Ketilidian orogen as a whole, including controls of rates of thermal and tectonic processes in convergent settings. Earlier Survey field work (project SUPRASYD, 1992–1996) had as its principal target an evaluation of the economic potential of the orogen (Nielsen et al. 1993). Ensuing plate-tectonic studies were mainly funded in 1997–1998 by Danish research foundations and in 1999 by the Natural Environment Research Council, UK. The five-week programme in 1999 was seriously disrupted by bad weather, common in this part of Greenland, and our objectives were only just achieved. Telestation Prins Christian Sund was the base for our operations (Fig. 2), which were flown with a small helicopter (Hughes MD-500).

scholarly journals The geology of the north-eastern corner of Greenland - photogeological studies and 1993 field work

1994 ◽  
Vol 161 ◽  
pp. 21-33
Author(s):  
H.F Jepsen ◽  
J.C Escher ◽  
J.D Friderichsen ◽  
A.K Higgins
Keyword(s):  
Field Work ◽  
Tectonic Activity ◽  
Mobile Belt ◽  
North East ◽  
The North ◽  
Upper Proterozoic ◽  
North Eastern ◽  
Field Season ◽  
Upper Boundary ◽  
Middle Proterozoic

Late Archaean and Early Proterozoic crust-forming events in North-East and eastern North Greenland were succeeded by Middle Proterozoic sedimentation and volcanic activity; Late Proterozoic through Tertiary sedimentation was interrupted by several periods of tectonic activity, including the Caledonian orogeny in East Greenland and the Mesozoic deformation of the Wandel Hav mobile belt. Photogeological studies helped pinpoint areas of special interest which were investigated during the short 1993 field season. Insights gained during field work include: the nature of the crystalline basement terrain in the Caledonian fold belt, redefinition of the upper boundary of the Upper Proterozoic Rivieradal sandstones, revision of Caledonian nappe terminology, and the northern extension of the Caledonian Storstrømmen shear zone.

Magnetic Fabric Studies of Xiong'er Volcanic Rocks in Southern Margin of the North China Craton and its Implications

2016 ◽  
Vol 90 (s1) ◽  
pp. 167-167
Author(s):  
Huiru XU ◽  
Zhenyu YANG ◽  
Peng PENG ◽  
Kunpeng GE ◽  
Rixiang ZHU
Keyword(s):  
North China Craton ◽  
North China ◽  
Volcanic Rocks ◽  
Magnetic Fabric ◽  
The North ◽  
Southern Margin

scholarly journals Reconnaissance work in the Triassic of the Wandel Sea Basin, eastern North Greenland

1977 ◽  
Vol 85 ◽  
pp. 11-15
Author(s):  
E Håkansson ◽  
C Heinberg
Keyword(s):  
Air Force ◽  
Field Work ◽  
Regional Mapping ◽  
Structural Detail ◽  
The North ◽  
Single Section ◽  
North Eastern ◽  
Logistic Support ◽  
North Eastern Part ◽  
North Greenland

The North-eastern part is one of the geologically least known areas in Greenland and although late Palaeozoic, Mesozoic and Tertiary strata are known to comprise the Wandel Sea basin, litlIe stratigraphical and structural detail is available (for summaries see Peel et al., 1974; Dawes, 1976). As a forerunner to GGU's forthcoming regional mapping project in northern Greenland, a reconnaissance tour to the Wandel Sea basin was attempted through the courtesy of the Royal Danish Air Force. However, due to partial failure in logistic support the field work was severely restricted and only part of the eastern Peary Land sequence was visited. Here only a single section was measured.

scholarly journals Petrogenesis and geochronology of the Arkasani Granophyre and felsic Dalma volcanic rocks: implications for the evolution of the Proterozoic North Singhbhum Mobile Belt, east India

2014 ◽  
Vol 152 (3) ◽  
pp. 492-503 ◽  
Author(s):  
H.N. BHATTACHARYA ◽  
D.R. NELSON ◽  
E.R. THERN ◽  
W. ALTERMANN
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Tectonic Activity ◽  
Mobile Belt ◽  
Northern Margin ◽  
The North ◽  
Ne India ◽  
New Findings ◽  
Minimum Age ◽  
Felsic Volcanic

AbstractThe North Singhbhum Mobile Belt (NSMB) is a 200 km long, curved Proterozoic fold–thrust belt that skirts the northern margin of the Archean Singhbhum Craton of NE India. The Singhbhum Shear Zone (SSZ) developed between the Dhanjori and Chaibasa formations near the southern margin of the NSMB and represents an important Cu-U-P metallotect. A SHRIMP U–Pb zircon date of 1861±6 Ma, obtained for the syn- to post-kinematic Arkasani Granophyre that has intruded the SSZ, provides a minimum age for the prolonged tectonic activity and mineralization along the SSZ and for the time of closure of the Chaibasa and Dhanjori sub-basins. The Dalma Volcanic Belt, a submarine rift-related bimodal mafic-felsic volcanic suite, forms the spine of the NSMB. A SHRIMP U–Pb zircon igneous crystallization date of 1631±6 Ma was obtained for an unfoliated felsic volcanic rock from the base of the Dalma volcanic sequence. These new findings suggest that the different sub-basins in the NSMB evolved diachronously under contrasting tectonic environments and were juxtaposed during a later orogenic movement.

scholarly journals New research in the sacred zone of the Fabrika Hill in Nea Paphos, Cyprus

2020 ◽  
Vol 24 ◽  
pp. 59-76
Author(s):  
Jolanta Młynarczyk
Keyword(s):  
Building Material ◽  
Field Work ◽  
Town Planning ◽  
Joint Project ◽  
Site Development ◽  
The North ◽  
North Eastern ◽  
New Research ◽  
The Hill ◽  
The Town

New research in the sacred zone of the Fabrika Hill in Nea Paphos, Cyprus The rocky hillock of Fabrika in the north-eastern most part of ancient Nea Paphos, founded during the late 4th century BC, is of key importance for understanding the early phase of the town planning, but at the same time very difficult to be methodically explored. Both its eminent location and geology made it a natural source of building material throughout the ages, greatly hindering any accurate reconstruction of the site development. However, the data collected so far strongly suggest that the arrangement of the southern part of the hill was of a cultic nature. Therefore, on undertaking a joint project with Université d’Avignon, we decided to focus the research on the southern part of the hill where, near the top of an Early Hellenistic theatre, there are rock-cut outlines of atemple possibly devoted to Aphrodite Paphia. During two seasons of field work (2018-2019), we retrieved some important information regarding both an original Hellenistic arrangement of the sacred area and its later (Late Roman/Byzantine and Medieval) use. Some new observations were also made regarding the topographical details of the area.

The rediscovery of Stachys virgata (Lamiaceae), a rare endemic of Peloponnisos, Greece: taxonomy, distribution, karyology and conservation

Phytotaxa ◽  
2015 ◽  
Vol 218 (3) ◽  
pp. 241 ◽  
Author(s):  
Theophanis Constantinidis ◽  
Eleftherios Kalpoutzakis ◽  
Konstantinos Kougioumoutzis
Keyword(s):  
Conservation Status ◽  
Field Work ◽  
History Museum ◽  
Historical Collections ◽  
The North ◽  
North Eastern ◽  
Rare Endemic ◽  
First Time ◽  
Made In ◽  
Specific Conservation

Stachys virgata, a rare Greek member of S. subsect. Rectae, was hitherto known from historical collections made in the north-eastern and southern parts of Peloponnisos, the last one dated in 1844. Its only recent record, on Poros Island in 1940, is not supported by a herbarium specimen. The species was rediscovered in 2005, 161 years after its last collection, and subsequently documented in 18 populations (1 of them now extinct) distributed along the eastern slopes of Mt. Parnonas and Mt. Madara in east Peloponnisos. We review the species’ description and distribution based on both historical records and recent collections, select a specimen deposited in the Natural History Museum, Paris (P) as a lectotype, and count its chromosome number, 2n = 34, for the first time. We evaluate the species’ taxonomic relationships and consider its threats and conservation status based on our own field work and several years of monitoring. S. virgata totals 355 mature plants and 12 out of its 18 populations comprise 20 plants or fewer. Based on the IUCN criteria, S. virgata falls under the Endangered (EN) category and specific conservation measures are proposed. Finally, we provide a key distinguishing S. virgata from the other Greek members of S. subsect. Rectae.

scholarly journals Geochronology and thermochronology of Cretaceous plutons and metamorphic country rocks, Anyui-Chukotka fold belt, North East Arctic Russia

2009 ◽  
Vol 4 ◽  
pp. 157-175 ◽  
Author(s):  
E. L. Miller ◽  
S. M. Katkov ◽  
A. Strickland ◽  
J. Toro ◽  
V. V. Akinin ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
High Heat ◽  
White Mica ◽  
The Arctic ◽  
Second Phase ◽  
Quartz Veins ◽  
North East ◽  
Chukotka Volcanic Belt ◽  
Uplift And Erosion

Abstract. U-Pb isotopic dating of seven granitoid plutons and associated intrusions from the Bilibino region (Arctic Chukotka, Russia) was carried out using the SHRIMP-RG. The crystallization ages of these granitoids, which range from approximately 116.9±2.5 to 108.5±2.7 Ma, bracket two regionally significant deformational events. The plutons cut folds, steep foliations and thrust-related structures related to sub-horizontal shortening at lower greenschist facies conditions (D1), believed to be the result of the collision of the Arctic Alaska-Chukotka microplate with Eurasia along the South Anyui Zone (SAZ). Deformation began in the Late Jurassic, based on fossil ages of syn-orogenic clastic strata, and involves strata as young as early Cretaceous (Valanginian) north of Bilibino and as young as Hauterivian-Barremian, in the SAZ. The second phase of deformation (D2) is developed across a broad region around and to the east of the Lupveem batholith of the Alarmaut massif and is interpreted to be coeval with magmatism. D2 formed gently-dipping, high-strain foliations (S2). Growth of biotite, muscovite and actinolite define S2 adjacent to the batholith, while chlorite and white mica define S2 away from the batholith. Sillimanite (± andalusite) at the southeastern edge the Lupveem batholith represent the highest grade metamorphic minerals associated with D2. D2 is interpreted to have developed during regional extension and crustal thinning. Extension directions as measured by stretching lineations, quartz veins, boudinaged quartz veins is NE-SW to NW-SE. Mapped dikes associated with the plutons trend mostly NW-SE and indicate NE-SW directed extension. 40Ar/39Ar ages from S2 micas range from 109.3±1.2 to 103.0±1.8 Ma and are interpreted as post-crystallization cooling ages following a protracted period of magmatism and high heat flow. Regional uplift and erosion of many kilometers of cover produced a subdued erosional surface prior to the eruption of volcanic rocks of the Okhotsk-Chukotka volcanic belt (OCVB) whose basal units (~87 Ma) overlie this profound regional unconformity. A single fission track age on apatite from granite in the Alarmaut massif yielded an age of 90±11 Ma, in good agreement with this inference.

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