No abstract

No abstract

The Barents Sea sedimentary basin represents one of the key prospective regions for hydrocarbon resources in the Arctic realm (Figures 1a and 1b). However, while the Norwegian part of the Barents Sea is covered by a dense network of seismic lines and penetrated by numerous wells, the Russian portion is comparatively poorly studied. To date, the sedimentary succession of the Russian part has only been penetrated by a few wells drilled in the southern part of the basin and four wells drilled onshore across the Franz Josef Land (FJL) archipelago. FJL represents an important region, where the Mesozoic succession is exposed onshore for geological study (Figure 2b). Due to the lack of offshore wells, this archipelago represents the only area in the north-eastern Barents Sea where the Mesozoic succession can be directly described and sampled, offering vital insights into the geological evolution of this insufficient studied region.The deeper pre-Mesozoic succession of the north-eastern Barents Sea has been mainly constrained by seismic data (

No abstract

No abstract

This study presents new whole rock major and trace element, Sr-Nd isotopic, petrographic, and geochronologic data for seven latest Permian (Changhsingian)–Late Triassic (Carnian) granitoid intrusions of the northwestern and northeastern Taimyr Peninsula in the Russian High Arctic. U-Pb zircon ages, obtained using secondary ion mass spectrometry (SIMS), sensitive high-resolution ion microprobe (SHRIMP), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), define the crystallization age of the Taimyr intrusions studied as ranging from ca. 253 Ma to 228 Ma, which suggests two magmatic pulses of latest Permian–Early Triassic and Middle–Late Triassic age. Ar-Ar dating of biotite and amphibole indicate rapid cooling of the intrusions studied, but Ar-Ar ages of several samples were reset by secondary heating and hydrothermal activity induced by the Middle–Late Triassic magmatic pulse. Petrographic data distinguish two groups of granites: syenite–monzonites and granites–granodiorites. Sr-Nd isotopic data, obtained from the same intrusions, show a variation of initial (87Sr/86Sr)i ratios between 0.70377 and 0.70607, and εNd(t) values range between –6.9 and 1.2. We propose that the geochemical and isotopic compositions of the Late Permian–Triassic Taimyr granites record the existence of a magma mush zone that was generated by the two pulses of Siberian Traps large igneous province (LIP) magmatism.

<p>The studied intrusions are located within the Northern Taimyr domain (southern part of the Kara terrane) on the northwestern coast of the Taimyr Peninsula and on several islands in Kara Sea. Intrusions cut the Lower Paleozoic metasedimentary rocks.</p><p>Late Permian – Early Triassic intrusions are represented by coarse- to medium-grained quartz-syenites and alkali-feldspar-granites. U-Pb dating of these granites yelled age of 253 Ma. Ar-Ar micas ages varies from 236 to 251 Ma. The granites are high- to medium acidic, high alkaline (alkali-calcic to alkalic), ferroan and magnesian, mainly peraluminous. Granites are characterized by relatively low initial <sup>87</sup>Sr/<sup>86</sup>Sr ratio (0.7041) and slightly positive εNd(t) value (1.03).</p><p>Middle – Late Triassic intrusions are represented by coarse-grained granodiorites and granites. U-Pb zircon ages of these granites range from 228 to 238 Ma. Ar-Ar micas and amphibole ages varies from 206 to 235 Ma. They are acidic to low acidic, moderately alkaline (alkali-calcic, calc-alkalic), magnesian, peraluminous and metaluminous. Middle – Late Triassic granites are characterized by higher initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios (0.7045-0.7060) and negative εNd(t) values (-5.47 to -0.80).</p><p>Late Permian – Early Triassic high alkalic predominantly ferroan granites are most likely related to A-type granites. Middle – Late Triassic moderate alkalic magnesian granites have transitional I/S-type character. Thus, Late Permian – Early Triassic granites likely form an outer rim of the Permo-Triassic Siberian plume. Middle – Late Triassic granites of Northern Taimyr were formed from different source with more significant crustal component contribution. Obtained data suggests two magmatic events throughout Early Mesozoic that affected Northern Taimyr.</p><p>This research was supported by RFBR project No. 19-35-90006</p>

<div>Table S1: Results for the SIMS SHRIMP and LA–ICPMS U-Pb zircon analysis. Table S2: Ar–Ar analytical data for studied samples. Table S3: Rb–Sr, Sm-Nd isotopic data of studied samples. Table S4: Major and trace element analyses of studied samples with the coordinates of studied samples (WGS84 projection). Figure S1: BSE–CL images of zircon grains from the studied granites. Figure S2: Concordia and weighted average diagrams for studied granites. Figure S3: Ar–Ar spectra on biotite and amphibole for studied latest Permian–Triassic granites.<br></div>