New insights on East Finnmark Platform palynostratigraphy

New insights on East Finnmark Platform palynostratigraphy and paleogeography — A study of three shallow cores from a Mississippian succession in the Barents Sea, Norway

Authors:

Lopes et al

Abstract:

Palynomorph assemblages from cores from three shallow stratigraphic boreholes (7029/3-U-1; 7127/10-U-2; 7127/10-U-3) drilled on the East Finnmark Platform have enabled the recognition of four miospore assemblages and two sub-assemblages from the Billefjorden Group in this area, rectifying earlier biozonations. The assemblages are correlated to the Western European biozonation and are based mainly on taxa abundance and the first and last appearances of selected species. All assemblages are Visean to possibly early Serpukhovian in age. Correlations with other biozonations from areas of similar paleolatitude are suggested. Our results suggest that strata assigned to the Billefjorden Group in the offshore may be slightly older than previously assumed. Even so, the Billefjorden Group succession in the offshore is younger than that recognized in the onshore. A mixed signature between the flora from the Arctic region and areas further south in the Euramerican Supercontinent has been observed which may be indicative that the Finnmark Platform was located in a microfloristic transitional region. Generically, the climate in this region was humid and warm during the Visean time which is reflected in the significant amount of neutral, humid and moderately humid floral elements represented by the miospore assemblages.

The Paleobotanical Changes Across the Jurassic/Cretaceous Boundary in India

Integrated palaeobotanical and palynological analysis of subsurface Gondwana sedimentary succession (Jurassic–Cretaceous) in Jangareddygudem area, Chintalapudi Sub-basin, South India: Stratigraphical and phytogeographical implications

Authors:

Jha et al

Abstract:

Here we present an integrated palaeobotanical and palynological analysis of sub-surface terrestrial deposits of Jangareddygudem area, Chintalapudi Sub-basin, Godavari Graben, India. Plant megafossil impressions and palynomorphs were recovered in the bore core MJR-11 from Jangareddygudem area. Plant megafossils impressions: Equisetites sp., Ptilophyllum acutifolium, Pachypteris indica, Elatocladus jabalpurensis, Pagiophyllum gollapallensis, and Ptilophyllum cutchense are recorded at different depths in the bore core MJR-11. Palynological investigations carried out in these megafossil bearing beds reveal the presence of Coptospora sp., Ceratosporites equalis, Appendicisporites erdtmanii, Biretisporites spectabilis, Cicatricosisporites hughesii, Cicatricosisporites sp., Concavissimisporites sp., Contignisporites cooksoniae, C. fornicatus, C. glebulentus, C. multimuratus, C. psilatus, Converrucosisporites sp., Gleicheniidites sp., Klukisporites scaberis, Plicifera delicata, Balmeiopsis limbatus, Araucariacites australis, A. cooksonii, Callialasporites dampieri, C. monoalasporus, C. segmentatus, C. turbatus, Dacrycarpites australiensis, Podocarpidites ellipticus, Podosporites variabilis, Crybelosporites stylosus, and Foraminisporis wonthaggiensis. Very rare occurrence of monocolpate, tetracolpate and tricolpate pollen is also recorded. Both plant mega- and microfloral evidences indicate Late Jurrassic–Early Cretaceous (Tithonian–Valanginian) age for these sediments. A comparative study of present mega and microfossil assemblages with known megafloral and microfloral assemblage from the Upper Gondwana sediments of Godavari and other Indian basins has also been attempted. The floral assemblage clearly indicates the presence of Gangapur sediments in Jangareddygudem area.

Similarity of the Antarctic palynofloras with those known from Godavari and other basins on the east coast of India confirms continental reconstructions that show Lambert Graben of East Antarctica to have been contiguous with eastern India prior to Gondwana break-up. The non-marine character of the palynomorphs suggests that marine conditions in this region of the Godavari Graben did not develop until at least early Early Cretaceous time.

The Implications of the Pollen of the Norian/Rhaetian Triassic New Mexico

Palynology of the upper Chinle Formation in northern New Mexico, U.S.A.: Implications for biostratigraphy and terrestrial ecosystem change during the Late Triassic (Norian–Rhaetian)

Authors:

Lindström et al

Abstract:

A new densely sampled palynological record from the vertebrate-bearing upper Chinle Formation at Ghost Ranch in the Chama Basin of northwestern New Mexico provides insights into the biostratigraphy and terrestrial ecosystem changes during the Late Triassic of northwestern Pangaea. Spore-pollen assemblages from the Poleo Sandstone, Petrified Forest, and 'siltstone' members are dominated by pollen of corystospermous seed ferns (Alisporites) and voltziacean conifers (Enzonalasporites, Patinasporites). Other abundant taxa include Klausipollenites gouldii and the enigmatic fused tetrad Froelichsporites traversei, whereas spores of ferns and fern allies are generally rare. The assemblages are correlated with Zone III Chinle palynofloras of previous authors. The lower assemblages contain rare occurrences of typical Zone II taxa, namely Cycadopites stonei, Equisetosporites chinleanus and Lagenella martini, that may either be reworked or represent relictual floral elements. Marked step-wise losses of species richness, along with only minor appearances of new taxa, led to a total 50% drop in range-through diversity during the late Norian of the Chama Basin. Correlations with other Chinle records in the western U.S. reveal differences in the stratigraphic ranges of some spore-pollen taxa, likely attributable to local/regional differences in environmental conditions, such as groundwater availability, precipitation, nutrients, and temperature, rather than stratigraphic miscorrelation. This is interpreted as a consequence of environmental stress resulting from increased aridity coincident with the northward movement of Pangaea. Similarly, major differences between the western and eastern U.S. and northwest Europe can be attributed to floral provincialism governed by climatic zones during the Late Triassic.

Palm Pollen (!) From Barremian/Albian Cretaceous Patagonia

Early Cretaceous palm pollen tetrads from Patagonia, Argentina

Authors:

Martinez et al

Abstract:

Pollen tetrads and monads of spiny pollen grains with close affinities to palms have been found in several localities from the Lower Cretaceous (Barremian-Albian) of the Austral Basin (Magallanes), Patagonia (Argentina). When found dispersed, spiny and zonasulcate pollen grains, are commonly referred to the fossil genus Spinizonocolpites Muller, with close affinities to the extant palm Nypa. The Patagonian specimens were compared with fossil and extant members of the Arecaceae, showing close similarities in shape and sculpture with the primitive members of the subfamily Calamoideae. Nypa produces tetragonal tetrads different from the tetrahedral tetrads of the Spinizonocolpites-type recovered from Patagonia. The specimens were studied with LM and SEM. The polarity, aperture orientation and tetrad type allow segregating the Patagonian grains from the Nypoideae and relating it to the Calamoideae subfamily. These records suggest an antique origin of monocots and a probably initial diversification of calamoid palms during the Early Cretaceous in high latitudes of Gondwana. The presence of palmae during the Early Cretaceous in southern South America suggests a warm and humid climate, similar to that found in present days at tropics.

Climate Variability during the Carnian Pluvial Phase (Carnian Triassic Wet Phase)

Climate variability during the Carnian Pluvial Phase — A quantitative palynological study of the Carnian sedimentary succession at Lunz am See, Northern Calcareous Alps, Austria

Authors:

Mueller et al

Abstract:

The Middle and Upper Triassic prevailing dry climate was interrupted by a global phase of increased humidity during the Early Carnian, the Carnian Pluvial Phase (CPP). It started at the Julian 1–2 boundary and lasted approximately until the latest Julian or early Tuvalian. In the Tethys this is reflected by a change from limestone deposits to, first, organic rich mudstones and then to siliciclastics. The CPP occurred along the northern rim of the Tethys and is reported from many locations within and surrounding Europe. In this study samples from Lunz am See in Austria were analyzed for palynology and for bulk carbon isotope values covering a 450 m thick succession. A known − 3‰ bulk organic carbon isotope excursion, possibly as a result of the eruption of large amounts of volcanogenic material, in the Göstling Member and the basal Reingraben Formation has been confirmed. A total of five distinctive palynology assemblages were recognized and correlated regionally. While the under- and overlying formations yield terrestrial and subordinate also marine palynomorphs, the palynoflora of the Lunz Formation is near wholly terrestrial in origin. Climate trends were inferred from multivariate statistical analysis (PCA) of the palynofloral record. Palynomorphs show a general trend from a dry climate during the Julian 1 to wetter conditions during the Julian 2. The wetter conditions were periodically interrupted by shorter periods of dryer climate. In terms of temperature trends the climate was warmer during the early Julian 2 which corresponds with the deposition of the Reingraben Formation, temperature decreased again and remained fairly stable during most of later part of the Julian 2, which corresponds to the deposition of the Lunz Formation. This study correlates with similar observations from other locations from the western Tethys region that support the theory of a wide-ranging to global Carnian Pluvial Phase.

Spore Diversity Trends From Eifelian/Givetian Devonian Argentina

Spore diversity trends in the Middle Devonian of the Chaco-Salteño Plain, northwestern Argentina

Author:

Noetinger et al

Abstract:

Devonian deposits in northwestern Argentina were historically studied with stratigraphical purposes, since these layers conform the source rocks of the producing basins of the region. A fairly well preserved palynomorph assemblage, from the Tonono Formation, provides an opportunity to perform the first quantitative analysis to study the evolution of diversity in the succession. Two associations are here defined by both, stratigraphic distribution of species and cluster analysis, ranging from the lower Eifelian to the lower Givetian. Rarefaction analysis reveals the existence of a relatively rich miospore population. Species richness increases while there is a drop in diversity and evenness towards the top of the column. The increment of the marine components towards the latter section indicates shifts in the shoreline. The influx of warmer water into higher latitudes, as highlighted by the arrival of the brachiopod Tropidoleptus, could have favored the inception of new spore species in the settled community. These results add to evidence that some groups build up the number of species in disturbed settings, and evenness is reduced with each new species introduced.

Pollen Hints at the Aptian/Albian Cretaceous Botanical Diversity & Turnover of Spain

Palynology of Aptian and upper Albian (Lower Cretaceous) amber-bearing outcrops of the southern margin of the Basque-Cantabrian basin (northern Spain)

Authors:

Barrón et al

Abstract:

The Lower Cretaceous deposits of the southern margin of the Basque-Cantabrian basin (northern Spain) are characterised by continental deposits interbedded with amber-bearing marine-influenced facies. These facies crop out in various localities and have yielded well-preserved palynological assemblages. The palynoflora is dominated by gymnosperm pollen grains, and shows relatively diversified spore content but scarce dinoflagellate cysts. The palynofloral evidence and regional geological setting indicate that the studied successions are dated as Aptian (Montoria-La Mina outcrop) and late Albian (Peñacerrada 1 and 2 and Salinillas de Buradón outcrops, and the Pancorbo site). Angiosperm pollen does not constitute a significant part of the Aptian assemblages but becomes diversified and numerically abundant in those dated as late Albian. Although broadly similar to contemporaneous palynofloras from eastern Spain, the Aptian assemblages of Montoria-La Mina do not yield tricolpate angiosperm pollen. Conversely, the inferred late Albian assemblages show a high content in polyaperturate angiosperm pollen grains, as occurs in other localities in Portugal, Western Europe and North America. The studied palynoflora shows significant differences from published assemblages located further north, in western France and Canada.

Evidence of a Significant Biological/Enviromental Event During the Upper Sinemurian Jurassic

Isotopic and palynological evidence for a new Early Jurassic environmental perturbation

Authors:

Riding et al

Abstract:

The Early Jurassic Epoch was a predominantly greenhouse phase of Earth history, but a comprehensive understanding of its climate dynamics is hampered by a lack of high resolution multi-proxy environmental records. Here we report a geologically brief (approximately several hundred thousand years) negative carbon isotope excursion (CIE) of 2–3‰ in both marine and terrestrial materials, recognised for the first time for the Late Sinemurian Substage (Early Jurassic, ~ 194 Ma) of eastern England. The Late Sinemurian carbon isotope excursion, which is termed the S-CIE herein, is accompanied by peaks in the abundance of the pollen grain Classopollis classoides and the dinoflagellate cyst Liasidium variabile. Classopollis classoides was thermophilic and is a reliable proxy for hot/warm climatic conditions. Liasidium variabile is interpreted as thermophilic and eutrophic using multivariate statistics, its fluorescence properties being similar to living heterotrophic dinoflagellate cysts, and its association with C. classoides. Moreover, the morphological and ecological similarities of L. variabile to the Cenozoic genus Apectodinium are noteworthy. The co-occurrence of the acmes of C. classoides and L. variabile with a negative CIE is interpreted here as having wide geographical significance due to the marine and terrestrial carbon isotope signals being precisely in phase within an open marine setting. This is consistent with an oceanic–atmospheric injection of isotopically-light carbon, coupled with global warming and increased marginal marine nutrient supply, possibly the result of increased precipitation due to an enhanced hydrological cycle or a seasonally-stratified water column. A probable sea level rise of at least regional extent has been identified at the L. variabile event in other records, which supports this putative phase of global warming. All these features are common to the Paleocene/Eocene thermal maximum (PETM, ~ 56 Ma), and there are also similarities with the Early Toarcian oceanic anoxic event (T-OAE, ~ 182 Ma).