Asselian Research Articles

FACIES, MICROFOSSILS (SMALLER FORAMINIFERS, CALCAREOUS ALGAE) AND BIOSTRATIGRAPHY OF THE HUECO GROUP, DOÑA ANA MOUNTAINS, SOUTHERN NEW MEXICO, USA

The Lower Permian Hueco Group of the Dona Ana Mountains (south-central New Mexico, USA) is studied in three sections (A, B, C) located east of Leasburg, Dona Ana County. Regionally, the Hueco Group has been subdivided into four formations termed Shalem Colony, Community Pit, Robledo Mountains and Apache Dam formations; the lower three are exposed in the Dona Ana Mountains. The succession shows a shallowing upward trend from dominantly shallow, open marine conditions (Shalem Colony Fm) to increasingly restricted marine environments (Community Pit Fm) and siliciclastic influx (Robledo Mountains Formation). Sedimentation, particularly siliciclastic influx, was mainly controlled by reactivation of basement uplifts during the last pulses of the Ancestral Rocky Mountains deformation. The microfossils and microfacies of the two first formations are studied in detail here. The Shalem Colony Formation can be divided into a lower biozone with Triticites pinguis , which is Newwellian (latest Pennsylvanian, early Wolfcampian) in age, and an upper division characterized by the first occurrence of Geinitzina , and lower-middle Asselian (late early Wolfcampian) in age. By comparison with the subdivisions of the Carnic Alps (Austria), the Community Pit Formation is characterized as Sakmarian (middle Wolfcampian) in age due to the first occurrence of the genus Pseudovermiporella , and its probable complete phylogeny from Hedraites . The late Asselian is restricted to the uppermost part of the Shalem Colony and lowermost part of the Community Pit Formation. Due to the occurrence of Pseudoreichelina the Robledo Mountains Formation is dated as Artinskian (late Wolfcampian). Some bioconstructions of Archaeolithophyllum are emphasized, as well as some species of foraminifers-globivalvulinids, Miliolata and Nodosariata.

FUSULINOIDEAN FAUNAS FROM THE UPPER CARBONIFEROUS AND LOWERPERMIAN PLATFORM LIMESTONE IN THE HADIM AREA, CENTRAL TAURIDES, TURKEY

Sixty-one species assignable to 31 genera of Late Carboniferous and Early Permian fusulinoideans were distinguished from the Hadim area, central Taurides, Turkey. They are biostratigraphically divided into eleven zones in ascending order: Protriticites variabilis , Montiparus umbonoplicatus and Schwageriniformis schwageriniformis zones in the Kasimovian; the Jigulites aff. formosus , Daixina asiatica and Rugosofusulina sp. A zones in the Gzhelian; Paraschwagerina sp. and Dutkevichia complicata zones in the Asselian; Paraschwagerina pseudomira and Robustoschwagerina nucleo lata zones in the Sakmarian; and the Dunbarula ? sp. zone of possible Artinskian age. Basal Kasimovian strata, Kasimovian-Gzhelian boundary strata and lower Asselian strata are missing due to erosion and/or non-deposition on the basis of faunal analysis of these fusulinoideans. Among the described species, newly proposed herein are Eoparafusulina brevis , Robustoschwagerina hadimensis , Pseudoschwagerina globosa , and Pseudoschwagerina ozguli . E. brevis is thought to be phylogenetically related to the Monodiexodina lineage along with E. ferganica . R. hadimensis represents a small form of the genus. P. globosa showing Sphaeroschwagerina -like appearance has a distinct Triticites -type juvenarium suggesting a specialized descendant derived from an Asselian Pseudoschwagerina . P. ozguli is distinguished from most of known species of Pseudoschwagerina by its smaller test and its occurrence from the Sakmarian.

CARBONIFEROUS-PERMIAN STRATIGRAPHY AND FUSULINIDS OF THE EAST IRAN. GZEHELIAN AND ASSELIAN DEPOSITS OF THE OZBAK-KUH REGION

Deposits of the Gzhelian-Asselian Stages were recognized by fusulinid occurrences in the upper part of the Sardar Formation (Zaladu Member) of the Ozbak Kuh region, East Iran. These deposits cannot be referred to the Bage-Vang Formation, which contains Bolorian fusulinids of the early Permian and lies at the base of a trangressive carbonate sequence. The results obtained in the Carboniferous-Permian section of East Iran are similar to those of western and southern Tethys. Everywhere the Asselian and, locally, the Sakmarian deposits are closely related to the Upper Carboniferous ones. After the late Sakmarian.Yakhtashian regression, carbonate platforms were formed from the Bolorian time through the Late Permian. The Zaladu Member contains 10 genera – Rauserites , Kushanella (?), Schellwieina , Anderssonites (?), Praepseudofusulina , Quasitriticites , Ruzhenzevites , Paraschwagerina , Pseudoschwagerina , Sphaeroschawagerina (?), and 37 species and subspecies of fusulinids. New species and subspecies are described: Rauserites infrequentis, R. tabasensis , R. fusoides , R. inobservabilis , R. (?) persicus , Quasitriticites iranicus, Ruzhenzevites zaladuensis zaladuensis , R. zalanduensis brevis , and R. ferganensis curtus .

MICROFACIES AND MICROFOSSIL ASSEMBLAGES (SMALLER FORAMINIFERS, ALGAE, PSEUDOALGAE) OF THE HUECO GROUP AND LABORCITA FORMATION (UPPER PENNSYLVANIAN-LOWER PERMIAN) SOUTH-CENTRAL NEW MEXICO, USA

During the latest Carboniferous and earliest Permian (Virgilian-Wolfcampian), the eastern margin of the Orogrande Basin in south-central New Mexico was rimmed by a narrow, tectonically unstable shelf, on which sediments of the Laborcita and Abo formations were deposited. Sediments of the Hueco Group accumulated on the more stable western margin of the Orogrande Basin. On the eastern shelf, the Laborcita Formation of the northern Sacramento Mountains represents a transition from marine to terrestrial facies and is composed of clastic-carbonate cycles. Limestones accumulated during relative sea-level highstands in a shallow marine shelf environment. Clastic sediments were deposited during relative lowstands when there was strong clastic influx in a nearshore to terrestrial environment. The overlying Abo Formation is composed of terrestrial red beds. On the western shelf, the Shalem Colony Formation of the Hueco Group, equivalent to the Laborcita Formation, is composed of mostly normal marine shallow shelf limestones with only minor interbedded clastics. The Robledo Mountains Formation and Hueco Group reflects a trend from a restricted shallow shelf and tidal flat clastics facies in the lower part to more open conditions in the upper part, which also prevailed during deposition of the overlying Apache Dam Formation. Limestones of the Laborcita Formation and Hueco Group contain smaller foraminifers, algae and problematic carbonate microfossils. All taxa except two pseudoalgae in open nomenclature ( Litostroma (?) sp. and “problematicum gen. 1”) are taxa already described. Compared with the Carnic Alps (Austria/Italy), the assemblages of smaller foraminifers of the Laborcita Formation and Shalem Colony Formation are very similar to those of the Auernig and Carnizza Formations (Auernig Group), and Lower Pseudoschwagerina Limestone (Rattendorf Group), indicating an Orenbugian (“Bursumian”) to Asselian age. Smaller foraminifers of the Robledo Mountains Formation allow correlation with the Grenzland Formation and Upper Pseudoschwagerina Limestone (Rattendorf Group) of the Carnic Alps, dated as Asselian to Sakmarian. Smaller foraminifers of the Apache Dam Formation suggest an Artinskian age, correlating with the Wolfcampian, or the Trogkofel Group of the Carnic Alps.

SMALLER FORAMINIFERS, CHARACTERISTIC ALGAE AND PSEUDO-ALGAE OF THE LATEST CARBONIFEROUS-EARLY PERMIAN RATTENDORF GROUP,CARNIC ALPS (AUSTRIA/ITALY)

Limestones of the latest Carboniferous-early Permian Rattendorf Group (Lower Pseudoschwagerina Limestone, Grenzland Formation and Upper Pseudoschwagerina Limestone) of the Carnic Alps (Austria/Italy) contain a rich and interesting assemblage of smaller foraminifers, algae and pseudo-algae. The foraminiferal assemblage of the Lower Pseudoschwagerina Limestone is identical to that of the Auernig Formation. The Grenzland Formation is characterized by the appearance of the genus Geinitzina and Pseudovermiporella, and the disappearance of Bradyinidae. The Upper Pseudoschwagerina Limestone contains the same species as the Grenzland Formation, but is characterized by the local appearance of Neoendothyra (?) and diverse species of Hemigordiidae and Nodosarioidea. The biostratigraphical value of diverse species of Hemigordius, iA renovidalinai sensu Baryshnikov = iNeohemigordiusi sensu Pinard & Mamet, Nodosinelloides , Protonodosaria and Geinitzina for the Asselian and early Sakmarian stages is briefly discussed. The systematical part contains some generic remarks on the Hemigordiidae and Nodosarioidea. Due to the porcelaneous wall, the microfossils Ellesmerellapermica (Pia) (= iGirvanellai subparallela Flugel & Flugel-Kahler) and Pseudovermiporella spp., which are generally interpreted as algae, are considered as attached miliolinid foraminifera. A new genus of problematical Chlorophyta, Homannisiphon, is established.