Jorunn Os Vigran

Smithian-Spathian boundary event: Evidence for global climatic change in the wake of the end-Permian biotic crisis

One of the most important carbon cycle perturbations following the end-Permian mass extinction event straddles the Smithian-Spathian boundary (SSB) (Olenekian, Early Triassic). This anomaly is characterized by a prominent positive carbon isotope excursion known from Tethyan marine rocks. Its global signifi cance is established here by a new high paleolatitude record (Spitsbergen). Paleontological evidence, such as Boreal palynological data (Barents Sea, Norway) and global patterns of ammonoid distribution, indicates a synchronous major change in terrestrial and marine ecosystems near the SSB. The reestablishment of highly diverse plant ecosystems, including the rise of woody gymnosperms and decline of the formerly dominating lycopods, is interpreted as an effect of a major climate change. This hypothesis is supported by modeling of ammonoid paleobiogeography, the distribution patterns of which are interpreted as a proxy for sea surface temperatures (SST). The latest Smithian thus appears to have been a time of a warm and equable climate as expressed by an almost fl at pole to equator SST gradient. In contrast, the steep Spathian SST gradient suggests latitudinally differentiated climatic conditions. We propose that this drastic climate change and the global carbon cycle perturbation were triggered by a massive end-Smithian CO2 injection. The SSB event could therefore represent one of the causes for stepwise and delayed recovery of marine and terrestrial biotas in the wake of the end-Permian biotic crisis.

Biostratigraphy and sequence stratigraphy of the lower and middle Triassic deposits from the Svalis Dome, Central Barents Sea, Norway

Abstract Material from shallow cores drilled through the uplifted and truncated deposits near the Svalis Dome in the Barents Sea contains Lower and Middle Triassic palynomorphs and ammonoids. Eight miospore assemblage zones have been established in this paper, and six of them are calibrated by ammonoids: Svalis‐1 is dated by ammonoids of the late Griesbachian commune Zone. The assemblage is recovered from the Havert Formation overlying the Permian limestone. Svalis‐2 is dated by ammonoids to the late Smithian tardus Zone. The deposits belong to the lower and middle parts of Klappmyss Formation. The unit represents the transgressive systems tract of a Smithian‐early Spathian T‐R Sequence. Svalis‐3 is recorded from the youngest part of Klappmyss Formation which is missing age conclusive faunal evidence. The palynological assemblage is correlated as early Spathian in age. The deposits represent the regressive systems tract of the Smithian‐early Spathian T‐R Sequence. Svalis‐4 is recovered from rocks deposite...

Multiple climatic changes around the Permian-Triassic boundary event revealed by an expanded palynological record from mid-Norway

Here, we present the palynological record from two shallow core holes (6611/09-U-01 and -02) from the Trondelag Platform offshore mid-Norway consisting of 750 m of Upper Permian and Lower Triassic sediments. The relatively homogeneous assemblages recovered from the Upper Permian deposits are dominated by gymnosperm pollen, mainly pteridosperms. At the base of the Griesbachian, numerous spore species appear in the record, leading to an increased diversity. The change at this boundary is also marked by the massive reduction of one group of pteridosperm pollen ( Vittatina ). Together with other typical Permian elements (e.g., Lueckisporites virkkiae ), this group is rare but consistently present in the lower part of the Griesbachian, and it gradually disappears in its upper part. The distribution of other groups such as taeniate and non-taeniate bisaccate gymnosperm pollen (pteridosperms and conifers) shows no significant change across the boundary, whereas spores and other gymnosperm pollen increase in diversity and abundance. These changes coincide with the formational change between the Schuchert Dal Formation (Upper Permian) and the Wordie Creek Formation (Griesbachian) equivalents. Late Permian and Griesbachian palynomorph assemblages display different patterns. The former show a homogeneous composition of low diversity, whereas the latter reflect diverse and variably composed floras. The data suggest that the arid phase of the Late Permian was followed by a humid phase at the base of the Griesbachian. In the Griesbachian section, a succession of six distinct palynological assemblages (phase II–VII) can be inferred. Comparable changes have been described from East Greenland. The variations in the palynological record are interpreted to reflect changing ecological conditions (e.g., changing humidity). Comparable variations in the distribution of δ 13 C isotope values reported from various sections from Greenland and China, showing stable values during the Late Permian and highly variable values during the Griesbachian, suggest common causes for the observed fluctuations. Multiphase volcanic activity of the Siberian traps seems to be the most likely candidate to have caused the variations in the δ 13 C isotope as well as in the palynological record. In contrast to the common claim that marine and terrestrial biota both suffered a mass extinction related to the Permian-Triassic boundary event, the studied material from the Norwegian midlatitudinal sites shows no evidence for destruction of plant ecosystems. The presence of diverse microfloras of Griesbachian age supports the idea that the climate in this area allowed most plants to survive the Permian-Triassic boundary event.

Dating of late Paleozoic rifting events in the North Atlantic: New biostratigraphic data from the uppermost Devonian and Carboniferous of East Greenland

The uppermost Devonian and Carboniferous sedimentary rocks in East Greenland include eight spore-pollen assemblages of early Tournaisian (Tn1) to mid-Visean (V3) and Westphalian age. The recognition of these assemblages provides the first firmly established biostratigraphic scheme of these sedimentary rocks and dates the earliest phase of late Paleozoic extensional tectonics in East Greenland as pre-Tournaisian. The latest rift pulse of the Paleozoic started in the Westphalian, and new half-graben systems continued to develop along the basin margins until Autunian(?) time. This new age information suggests that late Paleozoic rifting events were synchronous in the entire North Atlantic-Arctic region.

Biomagnetostratigraphy of the Vikinghøgda Formation, Svalbard (Arctic Norway), and the geomagnetic polarity timescale for the Lower Triassic

A bio-magnetostratigraphy for the Lower Triassic is constructed, using the ammonoid biostratigraphy from arctic Boreal successions. Combined thermal and alternating field demagnetisation determines the Triassic magnetic field polarity in 86% of specimens, with 36% showing linear trajectory line-fits and the remainder great circle trends towards the characteristic magnetisation. Mean pole directions for the Deltadalen (=50°, φ=159°, dp/dm=3.9°/5.1°), Lusitaniadalen (=56°, φ=163°, dp/dm=4.4°/5.4°) and Vendomdalen (=57°, φ=143°, dp/dm=4.4°/5.4°) members fall close to the European Lower Triassic apparent polar wander path. Mean directions for two of these member-means pass the reversal test. The remanence is predominantly carried by magnetite. The polarity stratigraphy, when integrated with the ammonoid and meager conodont data is similar to that determined from successions in the Sverdrup Basin (Canada). The Permian-Triassic boundary post-dates a pronounced palynofloral turnover, and pre-dates a short duration reverse magnetozone (LT1n.1r). In the correlated Shangsi section (in S. China) LT1n.1r occurs after the FAD of H. parvus, but in the arctic is within the Otoceras boreale Zone. The late Griesbachian to early Smithian is mostly reverse polarity, with three normal polarity intervals, overlain by mid and late Smithian normal polarity. The Spathian contains four reverse polarity intervals, the oldest one within the early Spathian with the remainder in the late Spathian. Transition into the Anisian is within the uppermost reverse magnetozone, a feature documented in other sections of this age. The polarity pattern is correlated to other marine sections, indicating the robustness of the bio-magnetostratigraphic composite and its utility in calibrating Lower Triassic time.

Magneto-biostratigraphy of the Middle to Upper Triassic transition, central Spitsbergen, arctic Norway

Palaeomagnetic and biostratigraphic data were obtained for the latest Ladinian and most of the Carnian (Botneheia Formation to basal Kapp Toscana Group), from two sections in central Spitsbergen (Svalbard archipelago). Thermal and alternating field (AF) demagnetization reveals a magnetization of both normal and reversed polarities. The mean directions pass reversal and fold tests and are similar to other European Late Triassic palaeopoles. One of the sections displays 15° of vertical-axis, clockwise, tectonic rotation on a décollement in the underlying Botneheia Formation. The magnetostratigraphy is dominated by normal polarity in the uppermost Botneheia Formation and into the Tschermakfjellet and basal De Geerdalen formations. A substantial hiatus characterizes the Ladinian–Carnian boundary in central Spitsbergen, so reverse magnetozones, identified in Tethyan sections near this boundary, are absent. Magnetostratigraphic correlation, along with palynostratigraphic constraints, indicates that most of the De Geerdalen Formation is Lower Carnian. The magnetostratigraphy and palynology indicates that the Isfjorden Member (upper unit of the De Geerdalen Formation) is probably mid-Carnian in age. Change in the lithological architecture in the Isfjorden Member, compared with the underlying parts of the De Geerdalen Fm, suggests a hiatus near the base of the member, which may represent a mid-Carnian unconformity, not previously recognized on Spitsbergen.

Stratigraphy and depositional evolution of the uppermost Devonian-Carboniferous (Tournaisian-Westphalian) non-marine deposits in North-east Greenland

Abstract The new Traill O Group comprises the uppermost Devonian to Carboniferous sedimentary rocks in East Greenland. Palynologically productive intervals contain material described as five palynological zones and four assemblages, and suggest that the rocks are of Tournaisian to mid‐Visean and early Westphalian age. The Retispora lepidophyta Abundance Zone (1) correlates to the Tournaisian (Tnla‐b) lepidophyta‐explanatus Miospore Zone, and the Spelaeotriletes spp.‐Lophozontriletes malevkensis Concurrent Range Assemblage (2) correlates to the Tournaisian (Tnlb) lepidophytanitidus Miospore Zone, both of Devonian age. The Bascaudaspora spp. Assemblage (3) has features shared with the hibernicus‐distinctus to pretiosus‐clavata Miospore zones, and the Grandispora uncata Assemblage (4) correlates to the pretiosusclavata Miospore Zone, both are of Tournaisian (Tn2–3) age. The Verrucosisporites spp.‐Lycospora spp. Assemblage (5) and the Lycospora Abundance Zone (6) both correlate to the Visean Lycospora pusilla...

Intercalibration of Boreal and Tethyan time scales: the magnetobiostratigraphy of the Middle Triassic and the latest Early Triassic from Spitsbergen, Arctic Norway

An integrated biomagnetostratigraphic study of the latest Early Triassic to the upper parts of the Middle Triassic, at Milne Edwardsfjellet in central Spitsbergen, Svalbard, allows a detailed correlation of Boreal and Tethyan biostratigraphies. The biostratigraphy consists of ammonoid and palynomorph zonations, supported by conodonts, through some 234 m of succession in two adjacent sections. The magnetostratigraphy consists of 10 substantive normal— reverse polarity chrons, defined by sampling at 150 stratigraphic levels. The magnetization is carried by magnetite and an unidentified magnetic sulphide, and is difficult to fully separate from a strong present-day-like magnetization. The biomagnetostratigraphy from the late Olenekian (Vendomdalen Member) is supplemented by data from nearby Vikinghøgda. The early and middle Anisian has a high sedimentation rate, comprising over half the ca. 140-m thickness of the Botneheia Formation, whereas the late Anisian and lower Ladinian is condensed into about 20 m. The two latest Boreal Ladinian ammonoid zones are absent as a result of erosional truncation below the Tschermakfjellet Formation. Correlation with Tethyan biomagnetostratigraphies shows the traditional base of the Boreal Anisian (base of the Grambergia taimyrensis Zone) precedes the base of the Anisian (using definitions based on the De˛ sli Caira section in Romania). The Boreal upper Anisian Gymnotoceras rotelliforme and Frechites nevadanus ammonoid zones correlate with most of the Tethyan Pelsonian and Illyrian substages. The base Ladinian defined in the Tethyan global boundary stratotype and point (GSSP) is closely equivalent to the traditional base of the Boreal Ladinian at the Intornites oleshkoi Zone. The latest Olenekian—early Anisian magnetic polarity time scale is refined using the Spitsbergen data.

MEDAL OF SCIENTIFIC EXCELLENCE

The American Association of Stratigraphic Palynologists bestows upon SVEIN B. MANUM its Medal of Scientific Excellence for four decades of outstanding contribution to the study of land plant palynology, paleobotany, dinoflagellate cyst morphology and stratigraphy. His power of meticulous observation and scholarly investigation of new fields has been combined with the unique art of blending palynological and paleobotanical observations in evolution, morphology, paleoecology and biostratigraphy. SVEIN B. MANUM Professor Svein B. Manum was born in 1926 in Askim, Norway. He received the degree of Cand. real. (M.Sc.) in 1953 and Dr. philos. (Ph.D.) in 1962 from the University of Oslo. His interest had been drawn to the modern and fossil floras of Spitsbergen by a popular book that he had read as a teenager. As a botany student he approached the late Professor Ove Arbo Hoeg, renowned for studies of the Devonian floras of Spitsbergen, to apply for a thesis project related to Spitsbergen. He was offered a palynological study of Spitsbergen’s Paleogene coals, which started a lifelong research interest in Arctic fossil floras and paleoclimates. Svein is outstanding among the palynologists and paleobotanists of his generation. He remains one of the few who has set an example of combining in his research three distinct fields: land plant palynology, dinoflagellate cyst studies, and paleobotany. With this scientific approach Svein has generated new ideas on Spitsbergen’s Cretaceous and Tertiary floras, the evolution of the North Atlantic, biogeography and climate change. In well over 50 publications Svein has consistently set the highest standards of observation and insightful analysis of pollen, dinoflagellate cyst morphology and stratigraphy, and fossil floras of the Arctic. His investigations on clitellate cocoons demonstrate his power of meticulous observation. At the University of Oslo he has taught students and associates the importance of careful observation and thoughtful interpretation. He …

A biography and obituary of Svein B. Manum (1926–2015)

Svein Manum working at the microscope at the University of Oslo in 1952 when he was undertaking his Candidatus realium research. Photographer unknown. Svein Manum at the microscope in December 2014...