Early Permian Fauna Research Articles

Micromorphic brachiopods from the early Permian (Kungurian) of Hidalgo, Mexico. Stratigraphic, paleoenvironmental and paleobiogeographic significance

This work describes for the first time a fauna of micromorphic brachiopods from Mexico. The biota comprises Permian species of the order Productida: Dyoros (Dyoros) extensiformis, Quadrochonetes girtyi, Rugaria hessensis, Fimbrinia ovata, as well as a productid indeterminate. The samples were located in the Calnali 2 section, belonging to the Tuzancoa Formation. The Kungurian (upper Cisuralian) relative age of the section was established by employing brachiopods, which were associated with bivalves, crinoids, trilobites, and bryozoans. The rocks with invertebrates are interbedded with strata bear plant remains. Sedimentological traits and preservation of brachiopods and associated fauna suggest that the marine community was deposited in a subtidal shallow and restricted environment with very low energy and continuous terrigenous input. On the other hand, the productid indeterminate is the largest brachiopod and displays the worst preservation, with evident traits suggesting that it was transported from a faraway region of the coast. Given that all taxa were previously identified in different units of Texas, considered a region where the Grandian Province was extended, it can be proposed that brachiopods of the Tuzancoa Formation also belonged to the same province. Thus, apart from New Mexico and Texas (USA), Huehuetenango (Guatemala), Palmarito (Venezuela), and Coahuila and Chiapas (Mexico), also Hidalgo's early Permian fauna could be included in the same biotic province.

New Pennsylvanian Bivalvia (Mollusca), the Early Permian glaciation and the Carboniferous–Permian boundary in western Argentina

This paper deals with new finds from the Upper Paleozoic Santa Elena Formation that crops out to the east of Uspallata, western Argentina. Current studies reveal the existence in these rocks of a faunal assemblage characterized by the bivalve Myonia aparicioi sp. nov, fossil guide of a new biozone. This fauna is regarded as the youngest of the Pennsylvanian, age confirmed by its relationships with other Late Carboniferous faunas and flora. During the past several years, the relationships between the Late Carboniferous and early Permian faunas contained in this formation had been obscured by strong faulting. However, this uncertainty was answered by the discovery of a structurally uncomplicated section in which the Myonia aparicioi and the early Permian Costatumulus amosi faunas are separated by some tens of meters. These finds reveal the actual relationships between these important key fossils and allow a more precise definition of the Carboniferous–Permian boundary. This locality is recommended for establishing the stratotype and section of this systemic boundary in western Argentina. The existence of an earliest Permian glacial phase is confirmed by the association of these rocks with the brachiopod Costatumulus amosi. The new faunal assemblage occurs in various localities to the east of Uspallata city; the material is very poorly preserved, and the identification of the specimens is based mainly on shape. However, because of its biostratigraphic interest, three new bivalve species are described: Promytilus rochacamposi sp. nov., Permophorus? yrigoyeni sp. nov, and Myonia aparicioi sp. nov. Six further species are also included with nomina aperta because of insufficient material or doubtful generic assignment; these are: Aphanaia? sp., Leptodesma (Leiopteria) sp., Schizodus sp., Vacunella? sp., Myonia? sp., and Streblopteria sp. Specimens previously thought to be “eurydesmatids” probably belong to a new genus.

Revision of the Chen and Yao Devonian to Permian crinoids from Western Yunnan

In 1993, Chen and Yao described the first major Paleozoic echinoderm faunas reported from China. Restudy of these Middle and Late Devonian, Early Carboniferous, and Early Permian faunas collected from the Basoshan tectonic block of western Yunnan resulted in some systematic and paleogeographic revisions. The Baoshan block originated on the northern part of Gondwana at about 30°S latitude in the Devonian and Carboniferous, drifted away in the Early Permian, and docked with Cathaysia by the Late Triassic, becoming part of South China. Devonian and Early Carboniferous crinoids lived in a carbonate shelf environment, but Early Permian faunas lived in a colder water glaciogene environment. The Devonian and Mississippian faunas are more closely related to coeval European faunas than they are to North American faunas. The Yunnan Devonian and Mississippian faunas are camerate dominated, with few cladids, and lack flexible crinoids. As currently recognized, Middle Devonian endemic crinoids of western Yunnan are Shidianocrinus, Parascyphocrinites, Ovalocrinus, and Quasicydonocrinus. Early Carboniferous endemics of western Yunnan are Yunnanocrinus and Parabarycrinus. The crinoids in the Yudong Formation support a Tournaisian age for these crinoidal rich beds. The stratigraphic range of Stomiocrinus is extended downward into the Tournaisian. Shidianocrinus is reassigned to the Dimerocrinitidae and Parascyphocrinites is reassigned to the Melocrinitidae. Parabarycrinus is reassigned to the Gasterocomidae. New combinations are Ectocrinus anthodeus, Cantharocrinus sphaeroides, Rhodocrinites intermedius, Rhodocrinites excavatus, Rhodocrinites baoshanensis, Holcocrinus irregularis, and Separocrinus discoides. New taxa introduced are Amphoracrinus cheni n. sp., Synbathocrinus yaoi n. sp., and Platycrinites s.s. langbaensis n. sp.

U–Pb geochronology of the Acatlán Complex and implications for the Paleozoic paleogeography and tectonic evolution of southern Mexico

Even though the Acatlán Complex in southern Mexico contains the largest exposure of Paleozoic rocks in Mexico, it is commonly ignored in reconstructions of Pangea because of poor geochronologic data. Presently, this complex is understood to be composed of metasedimentary units (Cosoltepec, Magdalena, Chazumba and Tecomate Formations), a major magmatic suite (Esperanza Granitoids), and a suite with eclogites and blueschists (Xayacatlán Fm). Sedimentary cover includes unmetamorphosed upper Paleozoic units. Here we provide single-crystal laser ablation U–Pb geochronology of the metasedimentary and magmatic suites of the Acatlán Complex and its upper Paleozoic sedimentary cover. The data reveal a complex geological evolution recording tectonic events from the assembly of Rodinia to the break-up of Pangea. Data for the Esperanza Granitoids record three major tectonothermal events: (1) a Grenvillian (1165 ± 30 to 1043 ± 50 Ma), (2) a Taconian (478 ± 5 to 471 ± 5 Ma), and (3) a Salinian (Acatecan; 461 ± 9 to 440 ± 14 Ma). Eclogitic rocks from the Xayacatlán Formation of Neoproterozoic–Early Ordovician age contain detrital zircons derived most probably from the southwestern North America Grenville province. Data for the blueschists are consistent with a Middle Ordovician depositional age and derivation from Laurentian sources. The Tecomate Formation is composed of two unrelated units of contrasting age and lithology: a Neoproterozoic–Early Ordovician, arc- and rift-related volcanosedimentary unit containing detrital zircons derived from the southwestern North America Grenville province; and an essentially sedimentary unit containing Early Permian fauna. The Cosoltepec Formation has a maximum Devonian depositional age and contains detrital zircons consistent with derivation from South American sources. The age of the Magdalena and Chazumba Formations is established to be Late Pennsylvanian–Early Permian. These units contain detrital zircons indicating ultimate derivation from both North and South America crustal sources. The Late Paleozoic sedimentary cover contains detrital zircons shed mainly from Grenvillian sources with a significant contribution of Pennsylvanian magmatic rocks. The new U–Pb geochronologic data indicate that the traditional stratigraphic scheme used for the Acatlán Complex needs complete revision. Data further indicate that the earliest stages of the tectonic evolution of the Acatlán Complex are tied to the evolution of Rodinia and that the actual configuration of the Acatlán Complex was ultimately achieved by amalgamation of the Magdalena–Chazumba suite during the final stages of Pangea assembly. The Early Jurassic tectonothermal event affecting only the Chazumba and Cosoltepec units to produce the Magdalena Migmatite is related to the break-up of Pangea and the opening of the Gulf of Mexico. The Acatlán Complex contains a section of the suture between Laurentia and Gondwana with some sediments arriving from Laurentia and others from Gondwana and mirrors the structure and evolution of the Appalachian–Caledonian chains of North America.

Permian brachiopods from the Tupe Formation, San Juan Province, Precordillera, Argentina

The brachiopod fauna from the Tupe Formation at La Herradura Creek, located on the west flank of Perico Hill, San Juan Province, Argentina, palaeogeographically belongs to the western sector of the Paganzo basin (‘Guandacol embayment’). The stratigraphical section of the Tupe Formation at La Herradura Creek is the stratotype of the Tivertonia jachalensis-Streptorhynchus inaequiornatus biozone, was previously regarded as being of Late Carboniferous age but here is assigned to the earliest Permian (Asselian). We describe and review the biozone assemblage, which consists of Streptorhynchus inaequiornatus, Tivertonia jachalensis, Kochiproductus sp., Costatumulus sp., Coronalosia argentinensis, Tupelosia paganzoensis, Trigonotreta pericoensis, Septosyringothyris sp. aff. Septosyringothyris jaguelensis and Crurithyris? sp. This brachiopod assemblage is related to Indian and Australian Early Permian faunas and its presence in the La Herradura Creek section provides new evidence in support of an Asselian (Early Permian) age for the Tivertonia jachalensis-Streptorhynchus inaequiornatus biozone. This assemblage is also important for intra- and inter-basinal correlation because several of its characteristic species have been identified from other sections of the Paganzo basin and the Río Blanco basin. The proposed age for this biozone is consistent with the age of palynological data from slightly above the marine faunas from the stratotype locality.

Upper Paleozoic Ostracodes of the Harper Ranch Beds (South-Central British Columbia, Canada)

Upper Paleozoic Ostracodes of the Harper Ranch Beds (South-Central British Columbia, Canada)

An Early Permian fauna from the Mantle Volcanics Formation, Skippers Range, northwest Otago

An Early Permian fauna from the Mantle Volcanics Formation in the Skippers Range is described and correlated with others in New Zealand. The fauna confirms the Permian age of the formation and includes the first New Zealand record of the Gondwana bivalve family Eurydesmidae. This and other bivalves, gastropods, brachiopods, bryozoans, rugosans, and echinoderms are described. The Mantle Volcanics Formation is composed entirely of proximal vent facies pyroclastic and epiclastic sediments extensively intruded by tholeiitic dikes and sills which probably fed the vent(s).

Paleoclimate of some Permo-Triassic carbonates of Malaysia

Four hundred thin-sections of Permian (Chuping and Summalayang Limestones) and Triassic (Kodiang Limestone) carbonates of Malaysia were studied, mainly to interpret probable climatic zones during their formation. Chuping Limestone is rich in skeletal grains and intraclasts formed in shallow, high-energy environments. Original mineralogy of skeletal grains and early diagenetic cements were chiefly calcites with some aragonite. The faunal assemblage is similar to that of subpolar carbonates. The brachiopods are characterized by heavy δ 13C and light δ 18O and these values lie in the same field as an Early Permian fauna from eastern Australia. The δ 18O values of fauna show unrealistic temperatures because the fauna has equilibrated with melt waters. However, calculated original δ 18O values of the fauna from δ 13C indicate temperatures ranging from 2 to 13°C with δ w of +1.2. These features reflect cool-temperate (to ?subpolar) conditions. Summalayang Limestone is rich in fusulinids and was deposited in bar to shelf environments. Fusulinids are often filled with fine, equigranular sparry calcite. Early diagenetic origin of these cements is indicated by erosion of cements during transportation and also by the cross-cutting relationship of veins with cements. These cements were originally Mg calcites. The foramol faunal assemblage, and predominantly Mg calcite mineralogy of both fauna and cements, reflect temperate climate. Kodiang Limestone was deposited in peritidal environments. This limestone formation has all the characteristic features of modern, warm, tropical carbonates such as chlorozoan assemblage, diverse non-skeletal grains, abundant early diagenetic dolomites and predominance of aragonitic fauna, non-skeletal grains and cements. The formation of temperate carbonates during the Permian suggests that Malaysia was probably part of Gondwanaland.

A new species of the Permian trilobiteDoublatiafrom the Manning District, New South Wales

A new species of trilobite, Doublatia matheri is described from the Early Permian Colraine Mudstone (Manning Group) of the Kimbriki district, near Wingham in central eastern New South Wales. Further Early Permian faunas are recorded from the diamictites of the ‘Kullatine Series’ underlying the Manning Group.

Two new bivalves from the permian "Eurydesma fauna" of eastern Argentina

Vacunella camachoi sp. nov. and Deltopecten harringtoni sp. nov. are described from the Eurydesma fauna, Bonete Formation (Pillahuinco Group), in the Sierras Australes of the Buenos Aires Province, Argentina. A reassesment of the taxonomy, provincial affinities and age of the fauna reinforces its Gondwana character and indicates its probable correlation with early Permian faunas of Australia.

Stratigraphy of Pennsylvanian, Permian, and Lower Triassic Rocks of Confusion Range, West-Central Utah

Work by the United States Geological Survey in the Confusion Range of west-central Utah during the past few years has resulted in the accumulation of considerable data regarding the stratigraphy of rocks ranging in age from Late Mississippian through Early Triassic. These rocks are here discussed as six formations, whose physical limits more or less coincide with the boundaries selected by earlier workers in the area, although considerable changes in stratigraphic nomenclature have been made. The Ely limestone of Late Mississippian, Early and Middle Pennsylvanian, and Permian age consists of 1,850-2,000 feet of alternating resistant thick-bedded limestone and slabby slope-forming limestone. The upper 100-350 feet of the formation contains an early Permian fauna and is generally more massive and less cherty than the remainder of the formation, which contains a fauna characteristic of the lower half of the Pennsylvanian and locally Late Mississippian. A hiatus representing Late Pennsylvanian time separates Middle Pennsylvanian and Permian faunas. The Arcturus formation, which conformably overlies the Ely limestone, consists of poorly indurated yellowish gray calcareous sandstone with thin, ledge-forming interbeds of dark gray to tan limestone and dolomite. The few fossils found in the Arcturus formation, and its stratigraphic position, suggest that the formation is early to middle Permian in age. The total thickness of the formation is uncertain, but a minimum thickness of 2,700 feet has been measured. The succeeding three formational units, the Kaibab limestone, the Plympton formation (new name), and the Gerster limestone, all of Permian age, have been included in the Park City group. The Kaibab limestone overlies the Arcturus formation and consists of 480 feet of somewhat cherty bioclastic limestone. The lithologic character of the Kaibab is in sharp contrast to the succeeding unit which is here named the Plympton formation and is predominantly dolomite and chert. The Plympton formation is 690 feet thick and contains phosphatic beds believed to be lithologic correlatives with parts of the Park City formation of northwestern Utah. The overlying Gerster limestone consists of 1,100 feet of very fossiliferous cherty bioclastic limestone and argillaceous limestone. The Gerster limestone is the youngest Permian unit in the Confusion Range. Like the Kaibab, it is differentiated from the Plympton formation by its high limestone content and lack of dolomite. The contact be ween the Plympton and the Gerster limestone is conformable throughout the area. The Kaibab limestone, the Plympton formation, and the Gerster limestone are believed to be correlative with units within the Park City and related formations of nearby areas in northern and northwestern Utah and northeastern Nevada. In areas south of the Confusion Range, the younger Permian units, the Plympton formation, and the Gerster limestone, are absent and only the Kaibab limestone is present in the Grand Canyon area. The Thaynes formation of late Early Triassic age consists of thick beds of predominantly greenish gray calcareous clay shale interbedded with thin beds of gray to chocolate brown limestone, and is more than 1,900 feet thick in the Confusion Range. It is unconformably overlain by Tertiary and Quaternary strata, and no younger Mesozoic rocks crop out in the area. The contact of the Thaynes formation with the underlying Gerster limestone appears conformable; however, faunal evidence indicates a considerable hiatus between the two formations.