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Permian versus Jurassic geotectonic position of the Lhasa block – facts and controversies

Krobicki Michał, Golonka Jan, Starzec Krzysztof, Iwańczuk Joanna

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

38--38

EN

The Cimmerian Continent (or Cimmeria, Cimmerian terrane, Cimmerian blocks) was detached from eastern Gondwana in the Late Paleozoic as a sliver/ribbon of continental strip rifting elements. Recently, these elements belong to an almost continuous long belt (ca. 13,800 km) from central Italy trough Greece, Turkey, Iran, Afghanistan, Tibet, SW China, Myanmar, Thailand up to Indonesia (Sumatra). The palaeogeographic position and relationship of some elements during Permian-Mesozoic times is still matter of discussion. The Qiangtang and Lhasa blocks (present-day Tibet) belong to these elements and their location in space and time and their relationship causes a lot of controversies. Their position alongside eastern Gondwana in the mid-Early Permian (ca. 290–285 Ma) are suggested both by palaeomagnetic and facies studies. Palaeomagnetic studies indicated this position one decade ago, which has been confirmed by recent studies. The Cimmerian Continent [Iran (Alborz)-Qiangtang-Baoshan-Tengchong-Sibumasu] was separated from the Gondwanian part of Pangea during mid-Early Permian time by rifting and drifting. Northwards migration of it took place during Permian-Triassic times caused wide opening of the Bangong‐Nujiang Tethyan Ocean and closing of the Paleotethys Ocean but the Lhasa block was still southern margin of the Bangong‐Nujiang Ocean. The Triassic Indosinian Orogeny has been one of the most spectacular geotectonic event reflecting collision of this continent with Indochina block and closure of the Paleotethys Ocean. The separation of the Lhasa block from Gondwana is enigmatic but most probably took place during earliest Jurassic times. This separation was followed by quick shift northward. Intensive sedimentological studies of the Late Triassic (Carnian-Norian) several flysch-type turbidites in the eastern Tethyan Himalaya (e.g. Qulonggongba, Pane Chaung, Langjiexue, Quehala, Duoburi formations/groups) indicate that their provenance was connected with Lhasa block, which has been their source area during early-stage evolution of the Neotethys. The late Early Permian rift-related basaltic magmatism in northern Baoshan (in SW China) and sourrounding regions was connected with first step of separation from Gondwana margin of this block (together with South Qiangtang and Sibumasu blocks and simultaneously with opening of the Bangong‐Nujiang Ocean before the Middle Permian) – independently of Lhasa block which was separated later, the most probably during Late Triassic or Triassic/Jurassic transition time with very wide space of the Bangong‐Nujiang Tethyan Ocean between Qiangtang and Lhasa blocks (2,600 km ±710 km – 23.4° ±6.4° during the Middle Jurassic with its maximum width in the Late Triassic). From the palaeobiogeographic point of view, the worldwide distribution of Pliensbachian-Early Toarcian large bivalves of the so-called Lithiotis-facies, dominated by Lithiotis, Cochlearites, Litioperna genera revealed by the authors’ studies, indicates very rapid expansion of such type of bivalves alongside southern margin of Neotethys, and could be good evidence of palaeogeographic position of the Lhasa block in this time. Himalayan and Tibetan (Nyalam area) occurrences of Lithiotis and/or Cochlearites bivalves could help to place the Lhasa block nearby the Gondwana during Early Jurassic times. This palaeobiogeographic research contradict another interpretation based on different fossils (Permian fusulinids and brachiopods) interpreted as subtropical fauna, which could occur in low subtropical latitudes together with other parts of the Cimmerian Continent.

2

Geological origin of the Permian bedded chert succession distributed in Central Plain of Thailand

Kamata Yoshihito, Phromsuwan Waraphorn, Ueno Katsumi, Charoentitirat Thasinee, Sardsud Apsorn

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

33

EN

The geotectonic divisions, which are distributed as narrow zones in the north-south direction, are clear in the northern Thailand, but not clearly recognized in the Central Thailand. The Chao Phraya Plain, which occupies the central part of Thailand, is broadly covered with Quaternary sediments. Therefore, the basement rocks of the Paleozoic and Mesozoic are scattered in the form of residual mounds, and due to the lack of stratigraphic and age-determination data, the geological origin of these rocks have been not sufficiently discussed. In this presentation, we will report the results of a study on the geological belongings of bedded chert sporadically exposed in the Chao Phraya Plain, Central Thailand by the microfossil age and geochemical characteristics. The study areas are Thung Saliam (TS) (50 km northwest of Sukhothai) in the northern part of the plain and the Nakorn Sawan–Uthai Thani (NS-UT) area in the central part of the plain. About 20 outcrops of chert were surveyed in both areas. The cherts are distributed in scattered, and most of the cherts are recrystallized and are considered to have undergone contact metamorphism. Chert of the TS is well-bedded with red and the direct contact relationship is unknown, but tuff and limestone (marble) are exposed around it. Chert of the NSUT is also well-bedded with red, black, gray and milky white in color. Altered slatey shale and sandstone accompany the chert and form monadnocks. These cherts might be categorized into typical pelagic cherts because they contain radiolarian tests and sponge spicules in a matrix consisting of very fine clay minerals and microcrystalline quartz, and do not contain coarse-grained terrigenous materials. Sashida & Nakornsuri (1999) reported the occurrence of Pseudoalbaillella simplex, Ruzencevispongus sp., and so on from the TS chert and they assigned their age to Wolfcampian. Whereas, Saesaengseerung et al. (2007) report radiolarian occurrence of the Ps. loemntaria Assemblage (Artinskian) and Follicucullus scholasticus Assemblage (Capitanian-Wuchiapingian) from the NS-UT chert. Whole-rock chemical analysis was performed on three sections their ages were determined by radiolarians. In the Chondrite-normalized REE pattern, TS chert indicates negative anomaly of Ce, and NS-UT chert shows relatively flat and profile of the downward-sloping in the LREE. The geological age of the study sections and their REE patterns are similar to those observed in the Sa Kaeo area in southeastern Thailand. The Permian bedded cherts exposed in TS and NS-UT areas are often accompanied by thin layers of fine-grained siliciclastics and tuff, which are weakly metamorphosed and foliated. Since the chert itself has a relatively thin thickness (several meters to 10–20 m) in each outcrop, and basically has a north-south strike. These cherts occurrence and lithofacies of both areas are similar and indicate that cherts of both areas are geologically comparable as pointed out by Ueno et al. (2012). Ueno et al. (2012) clarified that the central part of Thailand, where the geotectonic division was unclear, can be divided into three geotectonic units from west to east: Sibumasu Block, Sukothai Zone and Indochin Block. However, the origin of the Permian chert has not been clarified. Paleozoic and Mesozoic cherts distributed in Thailand remind us bedded cherts deposited in the Paleo-Tethys from the Devonian to the Triassic. However, no cherts other than the Permian have been reported in the central part of mainland Thailand. Instead of the Paleo-Tethys chert, the Sa Kaeo-Chanthaburi suture and the Nan-Uttaradit suture are well-known as geological units containing Permian chert in southeastern Thailand. These sutures have been understood as a closed remnant of the Permian to Triassic back-arc basin stretched between the Indochina Block and the Sukhothai Arc. The fact that the Permian cherts of the central plain are distributed in the eastern part of the Sukhothai Zone and near Indochina Block suggests that these Permian cherts comparable to the Permian chert of the Sa Kaeo-Chanthaburi Suture. In addition to the geological evidence, the geochemical features of the Permian chert represented by the REE pattern are similar to those of the Permian chert in the Sa Keo area. Line of evidence mentioned above suggests that the Permian bedded chert distributed the central Thailand (TS and NS-UT areas) have originated to the Permian chert of the Sa Kae-Chanthaburi or Nan-Uttaradit sutures which is a remnant of backarc basin.

3

Does the East European branch of the Caledonides exist?

Mizerski W., Stupka O., Olczak-Dusseldorp I.

Biuletyn Państwowego Instytutu Geologicznego

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2012

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nr 449

109--117

EN

Since the beginning of the introduction of the concept of the East European branch of the Caledonides by Limanowski (1922), there has been much discussion on the trend of this branch towards the southwest of the East European craton. The extreme interpretations were given by Stille (1950), and later by Dadlez (1994). According to those authors, the East European branch of the Caledonides could trend along the entire course of the south-eastern boundary of the East European craton, from the western Baltic Sea to Ukraine. Analysis of existing geological data, in relation to the current geotectonic theories, puts in doubt the existence of this branch. The proved Caledonian structures, which could be considered as orogenic, are located exclusively in the West Pomeranian segment of the East European craton foreland. The other parts of the foreland should be considered either a lowered marginal edge of the craton or blocks of Avalonian origin.

PL

Od początku wprowadzenia pojęcia wschodnioeuropejskiej gałęzi kaledonidów przez Limanowskiego (1922) trwa dyskusja dotycząca przebiegu tej gałęzi na południowy zachód od kratonu wschodnioeuropejskiego. W skrajny sposób przedstawiał go Stille (1950), a później Dadlez (1994). Według nich wschodnioeuropejska gałąź kaledonidów przebiegałaby wzdłuż całej południowo-wschodniej granicy kratonu wschodnioeuropejskiego, od zachodniego Bałtyku po Ukrainę. Analiza istniejących danych geologicznych, w nawiązaniu do obowiązujących dzisiaj teorii geotektonicznych, stawia w wątpliwość istnienie tej gałęzi. Udokumentowane struktury kaledońskie, które można by uznać za orogeniczne, znajdują się wyłącznie w zachodniopomorskim segmencie przedpola kratonu wschodnioeuropejskiego. Pozostałe fragmenty tego przedpola trzeba uznać bądź za obniżoną, brzeżną krawędź kratonu, bądź za bloki pochodzenia awalońskiego.

4

Jurajskie i kredowe dajki neptuniczne w północnej Tetydzie i na obszarze pery-Tetydy - reperkusje geotektoniczne

Krobicki M., Golonka J., Kucharski J.

Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2008

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T. 34, z. 3/1

185-188

5

Uwagi o wpływie struktury przedpola na formowanie się frontu nasunięć płaszczowinowych

Stupka O., Mizerski W.

Przegląd Geologiczny

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2007

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Vol. 55, nr 5

430-434

EN

. In this paper we describe relations between geological structure, shape and relief of the crystalline basement of the Precambrian cratons, and between rigid elements in Variscan orogens and the width of the younger fold belts in their foreland. The relations can be seen between the Baltic shield and Alpine belts. In places, where the fold belt is thrust over uplifted part of the craton's fundament, the fold belt and its marginal foredeep are tight and the fold belt is very high. In places, where the fold belt is thrust over deep part of the fundament, the fold belt and its marginal foredeep are broad. Similar relations can be seen between the East European craton and Variscan fold belts.

6

Geotectonic, seismicity and seismotectonic of the Dinarides of Bosnia and Herzegovina

Hrvatović H.

Reports on Geodesy

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2006

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z. 5/80

73--91

7

Zachodni i południowy zasięg kratonu wschodnioeuropejskiego

Mizerski W., Stupka O.

Przegląd Geologiczny

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2005

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Vol. 53, nr 11

1030-1039

EN

The problem of the western and southern borders of the East European Platform is still subject to debate; different authors variously put this border on the geological maps of Europe. The deepness of the crystalline basement between the T–T zone and the Variscan orogen and within the so-called Scythian Platform makes recognizing the geotectonic structure of the area difficult. There are relatively few and small regions with rocks older than Mesozoic. There is no direct access to Precambrian strata over most of the area. Most structural information is provided by geophysical methods, but they do not allow to date the age of consolidated basement. The paleomagnetic studies of the area give equivocal results. Our analysis of available materials from between the T–T zone and the Variscan orogen and the Scythian Platform suggests that the Precambrian Platform has a larger extent than it was generally assumed. The platform extends westwards even as far as the front of the Variscan orogen, and to the SWand S it may reach the Alpine folded structures.

8

Tektoniczne a eustatyczne uwarunkowania rozwoju sedymentacji dewonu świętokrzyskiego

Racki G., Narkiewicz M.

Przegląd Geologiczny

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2000

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Vol. 48, nr 1

65-76

PL

Ranga zdarzeń tektonicznych w dewonie świętokrzyskim jest wciąż trudna do sprecyzowania, ale wydaje się drugoplanowa. Nie ma świadectw " bretońskich " deformacji tektonicznych w końcu dewonu i uprzednio eksponowana rola tej "fazy " może ograniczać się do pulsu póżnofrańskiej subsydencji tektonicznej i ruchów blokowych, modyfikujących lokalnie zapis fluktuacji eustatycznych w szeroko rozumianym interwale przejściowym franu i famenu. Związki tego ożywienia tektonicznego na obszarze świętokrzyskim z póżnodewońskąprzebudowąplatformy wschodnioeuropejskiej (inicjacją ryftuprypecko-donieckiego i rozwojem rowu lubelskiego) są prawdopodobne, ale ich korelacja wymaga dalszego postępu w badaniach stratygraficznych na obu tych obszarach.

EN

Documented evidence of synsedimentary tectonics in the Devonian of the Holy Cross Mts. in most cases indicates limited magnitude of deformations leading to modification of the sedimentary record merely in a local scale. In contrast, the events interpreted as eustatic (including i.a. backstepping of the carbonate platform) have a widespread regional record. The tectonic subsidence analysis confirms differences in a development of the Łysogóry and Kielce regions, although both regions reveal very similar scenario of the "post-Caledonian " subsidence, differing mainly in the rates and total amount of the Devonian subsidence. The latter differences may be ascribed to contrasts in a deep structure ofcrustal blocks underlying both regions, separated by the Holy Cross Fault, and responding differently to a regional stress pattern, probably in an extensional regime. Although the importance of tectonic events in the Devonian of the Holy Cross Mts. is still difficult to ascertain, it appears rather subordinate in view of available observations. So far, there is no evidence of the "Bretonnian " tectonic deformations in the latest Devonian. The role of this ,, phase", previously stressed in several publications, may be limited to the probable small pulse of the late Frasnian subsidence and small-scale block movements locally modifying the record of eustatic fluctuations in the wide interval of the Frasnian-Famennian transition. The relationship between these tectonic phenomena and the Late Devonian structural rearrangement of the East European Craton, including initiation of the Pripyat-Donets Rift and development of the Lublin Trough is probable but requires further refinement of a stratigraphic correlation between the discussed areas.

9

Synklinorium warszawskie jako przykład struktur zawodnionych możliwych do wykorzystania na PMG

Piesik W., Zamojcin J.

Wiadomości Naftowe i Gazownicze

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1999

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R. 2, Nr 9 (17)

9-10