Ronald J. Litwin

Preliminary palynological zonation of the Chinle Formation, southwestern U.S.A., and its correlation to the Newark Supergroup (eastern U.S.A.)

Abstract Three informal palynological assemblage zones can be distinguished in samples from Chinle Formation outcrops in Utah, Arizona and New Mexico. The oldest zone (zone I) is in the Temple Mountain Member in southeastern Utah; the middle zone (zone II) is in the Shinarump, Moss Back, Monitor Butte and (lower part of the) Petrified Forest Members (Utah, Arizona and New Mexico); the youngest zone (zone III) is in the upper Petrified Forest Member and silstone member in Arizona and Utah and the silstone member in northcentral New Mexico. Present palynological evidence suggests that Chinle deposition on the Colorado Plateau began locally in late Carnian time and continued at least into the early part of Norian time of the Late Triassic period. Because the upper boundary of the Chinle Formation is an unconformity and the overlying formations are palynologically barren, the length of time represented by this stratigraphic hiatus is not known with certainty. Current palynological evidence suggests, however, that the unconformity at the top of the Chinle cannot be older than early Norian nor younger than Hettangian. Zones I, II and III can now be recognized in the palynomorph assemblage sequences from the Eastern Mesozoic basins, which modifies earlier palynological zonations for the lower portions of the Newark Supergroup. This is based on our identification of palynomorphs not previously known from portions of the Newark Supergroup and the discovery that specific biomarker taxa combinations are the same for both the western and eastern palynomorph sequences. At present palynomorph assemblages from the Chinle Formation and Newark Supergroup compare more closely for zones II and III than they do for zone I, but research is still in progress.

Terrestrial and marine records of climatic and environmental changes during the Pliocene in subtropical Florida

Pollen, ostracode, and benthic foraminifer assemblages deposited during sea-level high-stands in subtropical Florida record a climate change during the period 4.5-1.0 Ma. Before 3.5 Ma, open-shelf marine faunas and pollen assemblages with abundant Pinus , Quercus , Fagus , Carya , and nonarboreal pollen were present, indicating cooler conditions than today. From ∼3.5 to 1.0 Ma, marine and terrestrial records indicate warmer conditions, similar to those existing in south Florida today. Combined with evidence for much warmer than modern conditions at high latitudes, these data suggest that increased poleward oceanic heat transport, possibly related to the emergence of the Central American isthmus between ∼3.5 and 2.5 Ma, was a major influence on mid-Pliocene warmth.

Revision of the biostratigraphy of the Chatham Group (Upper Triassic), Deep River basin, North Carolina, USA

Abstract Paleontological evidence from the Upper Triassic Chatham Group in the three subbasins of the Deep River basin (North Carolina, USA) supports a significant revision of the ages assigned to most of this non-marine continental sedimentary sequence. This study confirms an early(?) or mid-Carnian age in the Sanford subbasin for the base of the Pekin Formation, the lowest unit of the Chatham Group. However, diagnostic late Carnian palynomorphs have been recovered from coals in the lower part of the Cumnock Formation in the Sanford subbasin, and from a sample of the Cumnock Formation equivalent in the Wadesboro subbasin. Plant megafossils and fossil verebrates from rocks in the Sanford subbasin also support a late Carnian age for the Cumnock Formation and its equivalents. The overlying Sanford Formation, which has not yet been dated paleontologically, probably includes beds of Norian age, as over 1000 m of strata may be present between the Cumnock Formation coals (dated here as late Carnian) and the top of the Sanford Formation. This chronostratigraphic interval appears similar to, but slightly longer than, that preserved in the Dan River-Danville and Davie County basins 100 km to the northwest. Our evidence, therefore, indicates that the Chatham Group was deposited over a much longer time interval [early(?) to mid-Carnian through early Norian] than previously was believed.

First early Mesozoic amber in the Western Hemisphere

Detrital amber pebbles and granules have been discovered in Upper Triassic strata on the Colorado Plateau. Although amber pre-viously has been reported from Pennsylvanian, Jurassic, Cretaceous, and Tertiary strata, we know of no other reported Triassic occurrence in North America or the Western Hemisphere. The newly discovered occurrences of amber are at two localities in the lower part of the Petrified }Forest Member of the Upper Triassic Chinle Formation in Petrified Forest National Park, Arizona. The paper coals and carbonaceous paper shales containing the amber also contain fossil palynomorph assemblages that indicate a late Carnian age for these occurrences.

Palynological analysis of a newly recognized upper cretaceous marine unit at Cheesequake, New Jersey

Abstract Palynological analysis of a newly recognized stratigraphic unit, situated between the top of the Magothy Formation and the bottom of the Merchantville Formation in northern New Jersey, has revealed that this newly recognized marine interval is biostratigraphically within the overlap of two previously established pollen zonations, which together focused on the Upper Cretaceous interval from the Raritan Formation (Cenomanian) to the Red Bank Sand (Maestrichtian). The outcrop section at Morristown Road, Cheesequake, New Jersey, contains a more complete upper Santonian to lower Campanian interval than previously has been known from eastern North America. Reex‐amination of selected samples from the original two studies also has resulted in the recognition of additional taxa in each of the two older datasets. Our expanded dataset indicates that the Morristown Road section may form a suitable palynological “bridge”; between these two previous zonations. Present evidence now indicates that the Santonian‐...

Morphology and palynostratigraphy of the genus Camerosporites Leschik 1956

Abstract The genus Camerosporites Leschik 1956 is here emended and the seven species attributed to it are reduced to four. Assemblages of Camerosporites isolated from Upper Triassic strata from sites in the eastern U.S. (the Newark, Culpeper, Richmond, Taylorsville, and Danville basins) and the western U.S. (Chinle Formation) consistently segregate into three recognizable species: C. secatus, C. verrucosus, and C. pseudoverrucatus. Of these, C. secatus and C. verrucosus are more common and more easily recognized. Examination of the morphologic characteristics and regional stratigraphic occurrence of these taxa demonstrates that they can be differentiated by light and electron microscopy, that the enigmatic host plant probably was either a primitive pteridophyte or a primitive gymnosperm, and that C. secatus and C. verrucosus are biostratigraphically useful for differentiating Carnian and Norian (Upper Triassic) continental deposits, especially within the eastern Mesozoic basins. The status of the only rep...

Reexamination of the fossil fern genus Dryopterites Berry based on reproductive characteristics

Abstract The specimens assigned to the genus Dryopterites Berry were reexamined and details of the reproductive characters including the spores are described for the first time. Based upon this new information about the ferns, two species have remained in the genus Dryopterites with one designated as the type species ( D. virginica ) and a lectotype for this species is chosen: one species ( D. dentata ) has previously been reassigned to the family Schizaeaceae, and the remaining species ( D. macrocarpa, D. elliptica, D. cystopteroides ) have been assigned to the genus Delosorus in the family Matoniaceae. This new information and comparisons with Sporae Dispersae suggest a later Cretaceous occurrence of ferns related to the modern dryopterids.