scholarly journals PALEOMAGNETISM OF THE MIDDLE JURASSIC SEDIMENTARY ROCKS OF THE ELGON FORMATION OF THE ULBAN TERRANE

2021 ◽  
Vol 40 (3) ◽  
pp. 3-15
Author(s):  
A.Yu. Peskov ◽  
◽  
A.V. Kudymov ◽  
S.V. Zyabrev ◽  
A.S. Karetnikov ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Magnetization Vector ◽  
Sikhote Alin ◽  
Paleomagnetic Pole ◽  
Inclination Shallowing ◽  
New Findings ◽  
Show Evidence ◽  
Formed Part ◽  
Characteristic Component

The paper presents new findings of paleomagnetic studies on Middle Jurassic sedimentary rocks of the Elgon Formation of the Ulban Terrane from coastal outcrops along the Ulban Bay (53.5°N, 137.7°E). Demagnetization yielded a pre-folding characteristic component of magnetization. No inclination shallowing effect for the characteristic magnetization vector was revealed in sandstone specimens of the Elgon Formation. The coordinates of the paleomagnetic pole and the paleolatitude at which the studied rocks deposited were calculated: Plat = -34.3 (34.3)°; Plong = 161.2 (341.2)°; dm = 2.7 dp = 5.3, paleolatitude = 0.1° (+2.7°/-2.6°) S. The acquired paleomagnetic data show evidence for the deposition of rocks of the Ulban Terrane in the Middle Jurassic at the boundary between the Asian paleocontinent and the Paleo-Pacific which later formed part of the Sikhote-Alin Orogenic Belt.

scholarly journals Paleomagnetism of the Sette-Daban Meso-Neoproterozoic magmatic complex of the southeastern margin of the Siberian platform

2021 ◽  
Vol 66 (4) ◽  
Author(s):  
Aleksandr D. Savelev ◽  
◽  
Anna A. Pazukhina ◽  
Aleksandr M. Pasenko ◽  
◽  
...  
Keyword(s):  
Siberian Platform ◽  
Sedimentary Rocks ◽  
Yenisei Ridge ◽  
Geochemical Data ◽  
Magmatic Complex ◽  
Paleomagnetic Pole ◽  
Southeastern Margin ◽  
History Of ◽  
Age Limits ◽  
Characteristic Component

The interval of ~ 1000 - ~ 900 Ma is one of the key ones in the history of the evolution of the Siberian Platform. At this time, the formation of the neoproterozoic supercontinent Rodinia took place, which undoubtedly found its reflection in the geological annals of Siberia. A reflection of the kinematics of the Siberian platform is its apparent pole wander path (APWP), the development of which will help to clarify the geodynamic in which the platform was at the beginning of the Neoproterozoic. However, not many objects of this age are known within the Siberian Platform, suitable for performing paleomagnetic determinations. The consequence of this is a very limited number of existing reliable poles, obtained either from sedimentary rocks with very imprecise age limits, or from rocks of the Yenisei Ridge and Taimyr with an ambiguous structural position. This paper presents the results of paleomagnetic studies of the Proterozoic igneous rocks of the Sette-Daban complex of the southern Verkhoyansk region, the formation of which took place ~ 1000-970 Ma ago. Detailed thermal magnetic cleaning made it possible to reveal the high-temperature (HT) characteristic component in a significant part of the samples. It has maximum unblocking temperatures of about 580 ° C, lying in the region of the Curie point of magnetite. The average direction of the characteristic component for the sills sampled in the valley of the Yudoma, coincides with the direction obtained earlier on the same bodies. The calculated paleomagnetic pole for the intrusive bodies of the Sette-Daban magmatic complex (Plat = 5.8 °, Plong = 182.9 °, dp / dm = 9.0 ° / 14.4 °) confirms and refines the previously obtained pole for the rocks of this complex, and also indicates that Siberia in the range of ~ 970-1000 Ma was located in the northern hemisphere in tropical latitudes (~ 26 ° N). The analysis of the available geochronological and geochemical data, coupled with new paleomagnetic data, made it possible to clarify the age of the Sette-Daban magmatic event and limit it within ~ 970-1000 Ma.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

Two new fossil species of Itaphlebia (Mecoptera: Nannochoristidae) from Jiulongshan Formation, Inner Mongolia, China

Zootaxa ◽  
2010 ◽  
Vol 2420 (1) ◽  
pp. 37 ◽  
Author(s):  
NAN LIU ◽  
Yunyun Zhao ◽  
DONG REN
Keyword(s):  
New Species ◽  
Middle Jurassic ◽  
Inner Mongolia ◽  
Northeastern China ◽  
Fossil Species ◽  
New Findings ◽  
Two New Species ◽  
Jiulongshan Formation ◽  
Southern Russia

Two new species, Itaphlebia exquisita sp. nov and Itaphlebia laeta sp. nov., were collected from the Jiulongshan Formation (Middle Jurassic) of Daohugou, Inner Mongolia, China. A key to the species of the genus Itaphlebia is provided and diagnosis of the genus is revised. Itaphlebia exquisita sp. nov differs from other species in having an extra medial vein branch. Itaphlebia laeta sp. nov shows a transitional character to the extant genera by having a simple Sc. These new findings expand the distribution of Itaphlebia from middle-southern Russia to northeastern China.

Stratigraphy, structure, and geochronology of the Anyox Pendant, northwest British Columbia, and implications for mineral exploration

2002 ◽  
Vol 39 (9) ◽  
pp. 1313-1332 ◽  
Author(s):  
Carol A Evenchick ◽  
Vicki J McNicoll
Keyword(s):  
Middle Jurassic ◽  
Mineral Exploration ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Volcanogenic Massive Sulphide ◽  
Zircon Crystallization ◽  
Volcaniclastic Rocks ◽  
Mafic Magmas ◽  
Age Limit ◽  
Volcanic Succession

Anyox Pendant contains complexly deformed greenschist-facies volcanic strata overlain by a thick succession of turbidite sedimentary rocks. At the contact between the two are well-studied copper-rich volcanogenic massive sulphide deposits; however the age and correlation of the volcanic strata, including the ore horizon, are poorly known. New stratigraphic, structural, and geochronology studies elucidate the regional stratigraphic, tectonic, and metallogenic settings and significance of these strata. The thick turbidite succession is correlated with Bowser Lake Group and conformably overlies the volcanic succession. Volcanogenic units include pillowed basalt, volcaniclastic rocks, chlorite phyllite, tuffaceous siltstone, and abundant gabbroic sills and dykes. Strained leucocratic intrusions yielded U–Pb zircon crystallization ages of 176.9 ± 0.2 Ma and 185.6 ± 0.3 Ma. Volcaniclastic rocks yielded detrital zircons that constrain the maximum ages of the volcanic succession. The youngest zircon grains from four samples in different structural segments limit strata to younger than ca. 186 Ma, ca. 178 Ma, ca. 183 Ma, and ca. 186 Ma. The results, combined with the regional oldest age limit of Bowser Lake Group, constrain the volcanic succession to late Early Jurassic(?) and early Middle Jurassic age, and support correlation with Hazelton Group of Stikinia. Furthermore, they enable comparisons with the coeval Au-Ag-rich stratiform Eskay Creek deposit, expanding southward the zone of extension in western Stikinia, which tapped primitive mafic magmas and accompanied the last vestiges of Stikinian volcanism in the early Middle Jurassic.

scholarly journals Inclination shallowing in Eocene Linzizong sedimentary rocks from Southern Tibet: correction, possible causes and implications for reconstructing the India–Asia collision

2013 ◽  
Vol 194 (3) ◽  
pp. 1390-1411 ◽  
Author(s):  
Wentao Huang ◽  
Guillaume Dupont-Nivet ◽  
Peter C. Lippert ◽  
Douwe J. J. van Hinsbergen ◽  
Erwan Hallot
Keyword(s):  
Sedimentary Rocks ◽  
Southern Tibet ◽  
Inclination Shallowing

New winter crane flies (Insecta: Diptera: Trichoceridae) from the Jurassic Daohugou Formation (Inner Mongolia, China) and their associated biota

2006 ◽  
Vol 43 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Junfeng Zhang
Keyword(s):  
New Species ◽  
Middle Jurassic ◽  
Inner Mongolia ◽  
Late Jurassic ◽  
Sedimentary Rocks ◽  
New Genera ◽  
Crane Flies ◽  
Geological Age ◽  
Wide Range ◽  
Biostratigraphic Correlation

Four extinct new species referable, respectively, to three extinct new genera within Trichoceridae have been recovered from the Jurassic Daohugou Formation in Ningcheng, Chifeng, Inner Mongolia, China: Archaeotrichocera ephemera gen. et sp. nov., Tanyochoreta integera gen. et sp. nov., Tanyochoreta chifengica sp. nov., and Sinotrichocera parva gen. et sp. nov. The specimen described earlier as trichocerids from China, Mesotrichocera laiyangensis Hong and Wang 1990, does not belong to this family. The Daohugou biota comprises a wide range of vertebrate and invertebrate organisms that inhabited, a small lake, luxurious everglade, streams, and forest with volcanoes nearby. The Daohugou Formation can be compared to the Karabastau and Haifanggou formations based on biostratigraphic correlation. The geological age for trichocerid-bearing nonmarine volcano-sedimentary rocks may be latest Middle Jurassic (Callovian) or earliest Late Jurassic (Oxfordian) rather than early–middle Middle Jurassic or Early Cretaceous.

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