U–Pb geochronology of Cretaceous magmatism on Svalbard and Franz Josef Land, Barents Sea Large Igneous Province

2013 ◽  
Vol 150 (6) ◽  
pp. 1127-1135 ◽  
Author(s):  
FERNANDO CORFU ◽  
STÉPHANE POLTEAU ◽  
SVERRE PLANKE ◽  
JAN INGE FALEIDE ◽  
HENRIK SVENSEN ◽  
...  

AbstractThe opening of the Arctic oceanic basins in the Mesozoic and Cenozoic proceeded in steps, with episodes of magmatism and sedimentation marking specific stages in this development. In addition to the stratigraphic record provided by sediments and fossils, the intrusive and extrusive rocks yield important information on this evolution. This study has determined the ages of mafic sills and a felsic tuff in Svalbard and Franz Josef Land using the isotope dilution thermal ionization mass spectrometry (ID-TIMS) U–Pb method on zircon, baddeleyite, titanite and rutile. The results indicate crystallization of the Diabasodden sill at 124.5 ± 0.2 Ma and the Linnévatn sill at 124.7 ± 0.3 Ma, the latter also containing slightly younger secondary titanite with an age of 123.9 ± 0.3 Ma. A bentonite in the Helvetiafjellet Formation, also on Svalbard, has an age of 123.3 ± 0.2 Ma. Zircon in mafic sills intersected by drill cores in Franz Josef Land indicate an age of 122.7 Ma for a thick sill on Severnaya Island and a single grain age of ≥122.2 ± 1.1 Ma for a thinner sill on Nagurskaya Island. These data emphasize the importance and relatively short-lived nature of the Cretaceous magmatic event in the region.

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 457-461 ◽  
Author(s):  
J. Gregory Shellnutt ◽  
Thuy Thanh Pham ◽  
Steven W. Denyszyn ◽  
Meng-Wan Yeh ◽  
Tuan-Anh Tran

Abstract The eruption of Emeishan lava in southwestern China and northern Vietnam is considered to be a contributing factor to the Capitanian mass extinction and subsequent global cooling event, but the duration of volcanism is uncertain. The difficulty in assessing the termination age is, in part, due to the lack of high-precision age data for late-stage volcanic rocks. The Tu Le rhyolite of northern Vietnam is the most voluminous silicic unit of the Emeishan large igneous province (ELIP) and is spatially associated with the Muong Hum and Phan Si Pan hypabyssal plutons. Chemical abrasion–isotope dilution–thermal ionization mass spectrometry U-Pb dating of zircons from the Tu Le rhyolite (257.1 ± 0.6 Ma to 257.9 ± 0.3 Ma) and Muong Hum (257.3 ± 0.2 Ma) and Phan Si Pan (256.3 ± 0.4 Ma) plutons yielded the youngest high-precision ages of the ELIP yet determined. The results demonstrate that Emeishan lavas erupted over a period of ∼6 m.y,. with plutonism ending shortly thereafter. Thus, it is possible that Emeishan volcanism contributed to global cooling into the middle Wuchiapingian. It appears that these rocks represent a distinct period of ELIP magmatism, as they are young and were emplaced oblique to the main north-south–trending Panxi rift.


Geology ◽  
2021 ◽  
Author(s):  
Cedric Djeutchou ◽  
Michiel O. de Kock ◽  
Hervé Wabo ◽  
Camilo E. Gaitán ◽  
Ulf Söderlund ◽  
...  

The 1.87–1.84 Ga Black Hills dike swarm of the Kalahari craton (South Africa) is coeval with several regional magmatic provinces used here to resolve the craton’s position during Columbia assembly. We report a new 1850 ± 4 Ma (U-Pb isotope dilution–thermal ionization mass spectrometry [ID-TIMS] on baddeleyite) crystallization age for one dike and new paleomagnetic data for 34 dikes of which 8 have precise U-Pb ages. Results are constrained by positive baked-contact and reversal tests, which combined with existing data produce a 1.87–1.84 Ga mean pole from 63 individual dikes. By integrating paleomagnetic and geochronological data sets, we calculate poles for three magmatic episodes and produce a magnetostratigraphic record. At 1.88 Ga, the Kalahari craton is reconstructed next to the Superior craton so that their ca. 2.0 Ga poles align. As such, magmatism forms part of a radiating pattern with the coeval ca. 1.88 Ga Circum-Superior large igneous province.


Author(s):  
Yu-Ting Zhong ◽  
Zhen-Yu Luo ◽  
Roland Mundil ◽  
Xun Wei ◽  
Hai-Quan Liu ◽  
...  

The Early Permian Tarim large igneous province (LIP) in northwestern China comprises voluminous basaltic lava flows, as well as ultramafic and silicic intrusions. The age and duration of the Tarim LIP remains unclear, and thus the rate of magma production and models of potential environmental effects are uncertain. Here we present high-precision chemical abrasion−isotope dilution−thermal ionization mass spectrometry zircon U-Pb ages for three newly discovered tuff layers interlayered with lava flows in the Kupukuziman and Kaipaizileike formations in the Keping area (Xinjiang, northwest China). The volcanism of the Kupukuziman Formation is constrained to a short duration from 289.77 ± 0.95 to 289.41 ± 0.52 Ma. An age for the overlying Kaipaizileike Formation is 284.27 ± 0.39 Ma, bracketing the duration of the entire eruptive phase of the Tarim flood basalts at ∼5.5 m.y. The low eruption rate and relatively long duration of magmatism is consistent with a plume incubation model for the Tarim LIP.


Geology ◽  
2020 ◽  
Author(s):  
Eben B. Hodgin ◽  
Lyle L. Nelson ◽  
Corey J. Wall ◽  
Arturo J. Barrón-Díaz ◽  
Lucy C. Webb ◽  
...  

We present chemostratigraphy, biostratigraphy, and geochronology from a succession that spans the Ediacaran-Cambrian boundary in Sonora, Mexico. A sandy hematite-rich dolostone bed, which occurs 20 m above carbonates that record the nadir of the basal Cambrian carbon isotope excursion within the La Ciénega Formation, yielded a maximum depositional age of 539.40 ± 0.23 Ma using U-Pb chemical abrasion–isotope dilution–thermal ionization mass spectrometry on a population of sharply faceted volcanic zircon crystals. This bed, interpreted to contain reworked tuffaceous material, is above the last occurrences of late Ediacaran body fossils and below the first occurrence of the Cambrian trace fossil Treptichnus pedum, and so the age calibrates key markers of the Ediacaran-Cambrian boundary. The temporal coincidence of rift-related flood basalt volcanism in southern Laurentia (>250,000 km3 of basalt), a negative carbon isotope excursion, and biological turnover is consistent with a mechanistic link between the eruption of a large igneous province and end-Ediacaran extinction.


2017 ◽  
Vol 460 (1) ◽  
pp. 371-395 ◽  
Author(s):  
Alexander Minakov ◽  
Viktoriya Yarushina ◽  
Jan Inge Faleide ◽  
Nataliya Krupnova ◽  
Tamara Sakoulina ◽  
...  

2021 ◽  
pp. SP518-2020-253
Author(s):  
Thuy Thanh Pham ◽  
J. Gregory Shellnutt ◽  
Tuan-Anh Tran ◽  
Steven W. Denyszyn ◽  
Yoshiyuki Iizuka

AbstractThe Permian silicic rocks in the Phan Si Pan (PSP) uplift area and Tu Le (TL) basin of NW Vietnam (collectively the PSP-TL region) are associated with the Emeishan Large Igneous Province (ELIP). The Permian Muong Hum, Phu Sa Phin, and Nam Xe - Tam Duong granites, and Tu Le rhyolites are alkali ferroan A1-type granitic rocks, which likely formed by fractional crystallization of high-Ti basaltic magma that was contaminated by melts derived from the Neoproterozoic host rocks. Zircon U-Pb LA-ICP-MS geochronology yielded weighted-mean 206Pb/238U ages of 246 ± 3 Ma to 259 ± 3 Ma for granites, and 249 ± 3 Ma and 254 ± 2 Ma for rhyolites. This is contrasted with previously-published high precision U-Pb ages, obtained using CA-ID-TIMS method applied on the same zircon grains, which suggest that the calculated LA-ICP-MS U-Pb ages are variably inaccurate by up to 10 Ma, though at the single-grain level dates generally agree within uncertainty. The similarity of rock texture, whole-rock geochemistry, emplacement ages, and fractionation phases between the PSP-TL region and silicic rocks in the Inner Zone ELIP (i.e., Panzhihua, Binchuan) suggests they were spatially proximal before being sinistrally displaced along the Ailao Shan-Red River shear zone.


Author(s):  
T.V. Naber ◽  
S.E. Grasby ◽  
J.P. Cuthbertson ◽  
N. Rayner ◽  
C. Tegner

The High Arctic Large Igneous Province (HALIP) represents extensive Cretaceous magmatism throughout the circum-Arctic borderlands and within the Arctic Ocean (e.g., the Alpha-Mendeleev Ridge). Recent aeromagnetic data shows anomalies that extend from the Alpha Ridge onto the northern coast of Ellesmere Island, Nunavut, Canada. To test this linkage we present new bulk rock major and trace element geochemistry, and mineral compositions for clinopyroxene, plagioclase, and olivine of basaltic dykes and sheets and rhyolitic lavas for the stratotype section at Hansen Point, which coincides geographically with the magnetic anomaly at northern Ellesmere Island. New U-Pb chronology is also presented. The basaltic and basaltic-andesite dykes and sheets at Hansen Point are all evolved with 5.5−2.5 wt% MgO, 48.3−57.0 wt% SiO2, and have light rare-earth element enriched patterns. They classify as tholeiites and in Th/Yb vs. Nb/Yb space they define a trend extending from the mantle array toward upper continental crust. This trend, also including a rhyolite lava, can be modeled successfully by assimilation and fractional crystallization. The U-Pb data for a dacite sample, that is cut by basaltic dykes at Hansen Point, yields a crystallization age of 95.5 ± 1.0 Ma, and also shows crustal inheritance. The chronology and the geochemistry of the Hansen Point samples are correlative with the basaltic lavas, sills, and dykes of the Strand Fiord Formation on Axel Heiberg Island, Nunavut, Canada. In contrast, a new U-Pb age for an alkaline syenite at Audhild Bay is significantly younger at 79.5 ± 0.5 Ma, and correlative to alkaline basalts and rhyolites from other locations of northern Ellesmere Island (Audhild Bay, Philips Inlet, and Yelverton Bay West; 83−73 Ma). We propose these volcanic occurrences be referred to collectively as the Audhild Bay alkaline suite (ABAS). In this revised nomenclature, the rocks of Hansen Point stratotype and other tholeiitic rocks are ascribed to the Hansen Point tholeiitic suite (HPTS) that was emplaced at 97−93 Ma. We suggest this subdivision into suites replace the collective term Hansen Point volcanic complex. The few dredge samples of alkali basalt available from the top of the Alpha Ridge are akin to ABAS in terms of geochemistry. Our revised dates also suggest that the HPTS and Strand Fiord Formation volcanic rocks may be the hypothesized subaerial large igneous province eruption that drove the Cretaceous Ocean Anoxic Event 2.


2006 ◽  
Vol 12 ◽  
pp. 25-45 ◽  
Author(s):  
Samuel A. Bowring ◽  
Blair Schoene ◽  
James L. Crowley ◽  
Jahandar Ramezani ◽  
Daniel J. Condon

High-precision geochronological techniques have improved in the past decade to the point where volcanic ash beds interstratified with fossil-bearing rocks can be dated to a precision of 0.1% or better. The integration of high-precision U-Pb zircon geochronology with bio/chemo-stratigraphic data brings about new opportunities and challenges toward constructing a fully calibrated time scale for the geologic record, which is necessary for a thorough understanding of the distribution of time and life in Earth history. Successful implementation of geochronology as an integral tool for the paleontologist relies on a basic knowledge of its technical aspects, as well as an ability to properly evaluate and compare geochronologic results from different methods. This paper summarizes the methodology and new improvements in U-Pb zircon geochronology by isotope dilution thermal ionization mass spectrometry, specifically focused on its application to the stratigraphic record.


2021 ◽  
Author(s):  
Melanie Kling ◽  
Hallgeir Sirevaag ◽  
Emmanuelle Pucéat ◽  
Christian Haug Eide

<p><span><span>The emplacement of the Siberian Traps Large Igneous Province around the Permian–Triassic boundary significantly affected both climate and depositional environments across the world. Known long term consequences of this event are (I) global warming, (II) increased continental weathering, (III) oceanic stagnation and acidification and (IV) mass extinction. These effects have the potential to strongly alter signals from source-to-sink systems in terms of petrography, sediment volumes and geochemistry. The Barents Sea Basin is an excellent area to investigate the response of source-to-sink systems to such climatic changes because it contains a continuous record of sediments deposited before, during and after the Permian-Triassic event, and because this interval is sampled in several exploration wells.</span></span></p><p><span><span>The goal of this project is to investigate how the Triassic climatic changes were expressed in source-to-sink systems, mainly using techniques such as facies analysis, petrograpy, mudstone geochemistry and sediment volumes. Herein we present preliminary results mainly from sandstone petrology. On the Finnmark Plattform, the upper Permian strata of the Røye Formation contains spiculitic mudstones and limestones with sparse sandstones. These are overlain by mudstones, interbedded turbidites and prograding deltas of the Lower Triassic. In order to determine how the signal from the catchment changed to the great climatic changes, it is of high importance to examine changes within provenance and sediment volumes across the P-T boundary.</span></span></p><p><span><span>I wish to give this presentation as a poster</span></span></p>


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