Gondwanan Faunas Research Articles

Gondwanan faunal signatures from Early Palaeozoic terranes of Kazakhstan and Central Asia: evidence and tectonic implications

Abstract Two separate tectonic blocks in the southwestern segment of the Kazakhstanian orogen, the Chu–Ili terrane and the Karatau–Naryn terrane (with particular attention to Malyi Karatau), are selected to illustrate their geological history and major biogeographical signatures from the Cambrian to the early Silurian. Mid- to Late Ordovician brachiopod and trilobite faunas of Chu–Ili show increased endemicity of shallow shelf assemblages, whereas distinct links to equatorial (‘east’) peri-Gondwanan are more evident in trilobite assemblages of the outer shelf. In the Late Ordovician, strong biogeographical affinities to equatorial Gondwanan faunas became firmly established and they are also traceable into the Silurian. Early Cambrian faunas of Malyi Karatau show remarkable similarity to those of South China. From the Middle Cambrian this region evolved as an isolated carbonate seamount, but until the Early Ordovician links to South China faunas were still evident. Benthic faunas from both regions show weak links to contemporaneous faunas of Baltica and little in common with Cambrian and Ordovician faunas of the Siberian craton. This suggests their location in low southern latitudes, in relative proximity to East Gondwana, which places some constraints on plate-tectonic reconstructions in relation to the southern cluster of Kazakhstanian terranes, including Karatau–Naryn, North Tien Shan and Chu–Ili.

Considerations on the age of the Tiouaren Formation (Iullemmeden Basin, Niger, Africa): Implications for Gondwanan Mesozoic terrestrial vertebrate faunas

Pre-Aptian mid-Mesozoic terrestrial vertebrates from the African continent are still very poorly known. In Niger, the Tiouaren Formation in the Iullemmeden Basin has yielded dinosaur and other vertebrate remains, and this unit has been dated as Early Cretaceous, most probably pre-Aptian, on the basis of its fish fauna and geological relations to other units in the basin. A review of the fish fauna and invertebrates from this formation does not provide any evidence for such an age, and the geological relations only help to constrain the upper limit for the age of the formation (Aptian). In contrast, the described dinosaur taxa are phylogenetically nested with late Middle Jurassic to Early Late Jurassic taxa from other localities, and thus indicate a pre-Kimmeridgian, probably late Middle Jurassic age for the Tiouaren Formation. Under the assumption of such an age, the dinosaur fauna of this formation provides new insights into dinosaur faunal provincialism during the latest Middle Jurassic. Northern Gondwanan faunas of that time seem to have been different from southern Gondwanan faunas, and show closer affinities to Eurasian faunas than to the latter. A possible explanation for this might be a climatically controlled geographic barrier due to pronounced arid conditions and thus desert environments in central Gondwana during this time.

Synthesis and tectonic interpretation of the westernmost Paleozoic Variscan orogen in southern Mexico: From rifted Rheic margin to active Pacific margin

Paleozoic rocks in southern Mexico occur in two terranes, Oaxaquia (Oaxacan Complex) and Mixteca (Acatlán Complex) that appear to record: (1) Ordovician rifting on the southern margin of the Rheic Ocean, (2) passive drifting with Amazonia during the Silurian, (3) Devonian-Permian subduction beneath southern Mexico producing an arc complex that was partially removed by subduction erosion, subjected to HP metamorphism and Mississippian extrusion into the upper plate, followed by reestablishment of a Permian arc. In the Oaxaquia terrane, the 920–1300 Ma basement is unconformably overlain by a ∼ 200 m uppermost Cambrian–lowest Ordovician shelf sequence containing Gondwanan fauna (Tiñu Formation), unconformably overlain by 650 m of shallow marine-continental Carboniferous sedimentary rocks containing a Midcontinent (USA) fauna. In the Mixteca terrane, the low-grade Paleozoic sequence is composed of: (a) a ?Cambrian–Ordovician clastic sequence intruded by ca. 480–440 Ma bimodal, rift-related igneous rocks; and (b) a latest Devonian-Permian shallow marine sequence (> 906 m) consisting of metapsammites, metapelites and tholeiitic mafic volcanic rocks. High pressure (HP) metamorphic rocks in the Mixteca terrane consists of: (i) a Cambro-Ordovician rift-shelf intruded by bimodal rift-related intrusions that are similar to the low-grade rocks; (ii) periarc ultramafic rocks, and (iii) arc and MORB rocks. The Ordovician granitoids contain concordant inherited zircons that range in age from ca. 900 to 1300 Ma, indicating a source in the Oaxacan Complex. Concordant ages of detrital zircons in both the low- and high-grade Cambro-Ordovician metasedimentary rocks indicate a provenance in local Ordovician plutons and/or ca. 1 Ga Oaxacan basement, and distal northwestern Gondwana sources with a unique source in the 900–750 Ma Goiás magmatic arc within the Brasiliano orogen. These data combined with the rift-related nature of the Cambro-Ordovician rocks are most consistent with an origin along the southern margin of the Rheic Ocean. Latest Devonian-Permian deposition was synchronous with Mississippian extrusion of the HP rocks into the upper plate during extensional deformation. The HP Cambro-Orodivician rift-shelf rocks are inferred to have originated in the forearc region of the upper plate that was removed by subduction erosion, carried down the subduction channel, and then extruded into the upper plate in the middle of the Mixteca terrane. The presence of arc-related rocks in the HP assemblage suggests that the arc complex was also removed, whereas the MORB rocks may have been derived from the subducting slab. Detrital zircons in the Carboniferous rocks of both the Mixteca and Oaxaquia terranes contain Devonian detrital zircons and volcanic clasts that are inferred to have come from the removed Devonian arc on the western margin of the Mixteca terrane and/or from exhumed HP rocks. During the Permian, arc-related intrusions in both the Mixteca and Oaxaquia terranes were accompanied by dextral transtensional deformation and deposition of clastic rocks containing Permian detrital zircons and carbonates in periarc, pull-apart basins. Empirical relationships between the dip of the Benioff zone and the widths of arc and forearc indicate that the Permian trench lay beneath the eastern edge of the Mesozoic Guerrero terrane.

Neoproterozoic-early Palaeozoic tectonostratigraphy and palaeogeography of the peri-Gondwanan terranes: Amazonian v. West African connections

Abstract Within the Appalachian–Variscan orogen of North America and southern Europe lie a collection of terranes that were distributed along the northern margin of West Gondwana in the late Neoproterozoic and early Palaeozoic. These peri-Gondwanan terranes are characterized by voluminous late Neoproterozoic ( c . 640–570 Ma) arc magmatism and cogenetic basins, and their tectonothermal histories provide fundamental constraints on the palaeogeography of this margin and on palaeocontinental reconstructions for this important period in Earth history. Field and geochemical studies indicate that arc magmatism generally terminated diachronously with the formation of a transform margin, leading by the Early–Middle Cambrian to the development of a shallow-marine platform–passive margin characterized by Gondwanan fauna. However, important differences exist between these terranes that constrain their relative palaeogeography in the late Neoproterozoic and permit changes in the geometry of the margin from the late Neoproterozoic to the Early Cambrian to be reconstructed. On the basis of basement isotopic composition, the terranes can be subdivided into: (1) Avalonian-type (e.g. West Avalonia, East Avalonia, Meguma, Carolinia, Moravia–Silesia), which developed on juvenile, c . 1.3–1.0 Ga crust originating within the Panthalassa-like Mirovoi Ocean surrounding Rodinia, and which were accreted to the northern Gondwanan margin by c . 650 Ma; (2) Cadomian-type (e.g. North Armorican Massif, Ossa–Morena, Saxo-Thuringia, Moldanubia), which formed along the West African margin by recycling ancient ( c . 2.0–2.2 Ga) West African crust; (3) Ganderian-type (e.g. Ganderia, Florida, the Maya terrane and possible the NW Iberian domain and South Armorican Massif), which formed along the Amazonian margin of Gondwana by recycling Avalonian and older Amazonian basement; and (4) cratonic terranes (e.g. Oaxaquia and the Chortis block), which represent displaced Amazonian portions of cratonic Gondwana. These contrasts imply the existence of fundamental sutures between these terranes prior to c . 650 Ma. Derivation of the Cadomian-type terranes from the West African craton is further supported by detrital zircon data from their Neoproterozoic–Ediacaran clastic rocks, which contrast with such data from the Avalonian- and Ganderian-type terranes that suggest derivation from the Amazonian craton. Differences in Neoproterozoic and Ediacaran palaeogeography are also matched in some terranes by contrasts in Cambrian faunal and sedimentary provenance data. Platformal assemblages in certain Avalonian-type terranes (e.g. West Avalonia and East Avalonia) have cool-water, high-latitude fauna and detrital zircon signatures consistent with proximity to the Amazonian craton. Conversely, platformal assemblages in certain Cadomian-type terranes (e.g. North Armorican Massif, Ossa–Morena) show a transition from tropical to temperate waters and detrital zircon signatures that suggest continuing proximity to the West African craton. Other terranes (e.g. NW Iberian domain, Meguma) show Avalonian-type basement and/or detrital zircon signatures in the Neoproterozoic, but develop Cadomian-type signatures in the Cambrian. This change suggests tectonic slivering and lateral transport of terranes along the northern margin of West Gondwana consistent with the transform termination of arc magmatism. In the early Palaeozoic, several peri-Gondwanan terranes (e.g. Avalonia, Carolinia, Ganderia, Meguma) separated from West Gondwana, either separately or together, and had accreted to Laurentia by the Silurian–Devonian. Others (e.g. Cadomian-type terranes, Florida, Maya terrane, Oaxaquia, Chortis block) remained attached to Gondwana and were transferred to Laurussia only with the closure of the Rheic Ocean in the late Palaeozoic.

Dinosaur teeth from the Cenomanian of Charentes, Western France: evidence for a mixed Laurasian-Gondwanan assemblage

ABSTRACT The teeth of six dinosaur taxa (Carcharodontosauridae indet., Dromaeosauridae indet., Troodontidae indet., Brachiosauridae indet., Iguanodontoidea indet., and Nodosauridae indet.) are identified and described from the early Cenomanian of the Charentes region, western France. The composition and paleoecology of this coastal, insular fauna is discussed. The Charentes dinosaur assemblage shares affinities with Asiamerican and Gondwanan faunas. This clarifies and highlights the role of the European islands in the paleobiogeography of Cretaceous dinosaurs.

The Late Cretaceous fauna and flora of the Uberaba area (Minas Gerais State, Brazil)

The Uberaba area, in Minas Gerais State, Brazil, yields a rich continental fauna and flora from the Late Cretaceous Uberaba and Marília formations. This paper reviews the diversity of the biota recorded from these formations. The most significant taxa from Peirópolis are the frog Baurubatrachus pricei, the turtle Cambaremys langertoni, the lizard Pristiguana brasiliensis, the crocodyliforms Itasuchus jesuinoi, Peirosaurus tormini and Uberabasuchus terrificus, the titanosaurian Baurutitan britoi, Trigonosaurus pricei, Aeolosaurus sp., indeterminate titanosaurians, and abelisaurid, carcharodontosaurid and maniraptoran theropods. Together with faunas of a similar age in Argentina and Madagascar, the assemblages contribute to a better understanding of Late Cretaceous Gondwanan faunas as a whole.

Australian treehoppers (Hemiptera:Membracidae:Centrotinae:Terentiini): phylogeny and biogeography

This work presents the first hypothesis of phylogenetic relationships among all 40 genera of the treehopper tribe Terentiini (Hemiptera : Membracidae : Centrotinae). This phylogeny, based on a parsimony analysis of 77 morphological characters, made possible an analytical approach to determining the likely ancestral host-plant family and geographic distribution of the tribe, based on present-day hosts and distributions. Of Australia’s 37 treehopper genera, 36 belong to the tribe Terentiini, with their centre of diversity in Queensland (30 genera). Optimisations of present-day distributions mapped on our phylogeny suggest that the ancestor of the tribe occurred in the Australian region, around north-eastern Australia (Queensland) and New Guinea (which has 8–10 terentiine genera). Subsequent dispersals from the Australian region (with 37 genera) took the tribe to the Indomalayan (11 genera) and Palaearctic (1 genus) regions. At least 13 terentiine genera include representatives that occur beyond the borders of Australia and New Guinea. Notable among the migrant lineages is the clade ‘Polonius + (Bulbauchenia + (Funkhouserella + Pyrgonota))’, which includes genera with such extraordinary pronotal modifications that some members were previously placed in separate tribes (Bulbaucheniini or Funkhouserellini). Members of this remarkable breakaway clade are known from Australia (Polonius only), Indonesia, the Malay Peninsula, Thailand, the Philippines, southern China (Taiwan and Hainan Island) and Japan. With regard to terentiine host plants, optimisations of present-day host associations point to the Leguminosae as the ancestral host family, even though plant families of Gondwanan origin, especially Myrtaceae and Proteaceae, are also prominent terentiine hosts. The overall evidence to date indicates that Terentiini are not a remnant of the early Gondwanan fauna, but rather a more recent tribe derived from Indomalayan ancestors.

Geochemistry of the Tremadocian Tiñu Formation (Southern Mexico): Provenance in the Underlying ∼1 Ga Oaxacan Complex on the Southern Margin of the Rheic Ocean

In southern Mexico, the Tremadocian Tiñu Formation with a Gondwanan fauna rests unconformably upon the ∼1 Ga Oaxacan Complex, and is unconformably overlain by Carboniferous sedimentary rocks containing a Laurentian fauna. The Tiñu Formation is inferred to represent deposition along the southern margin of the Rheic Ocean in its early stages of development. The geochemistry of sandstones and shales of the formation show: (1) high iron, magnesium, and titanium, indicating chemical immaturity in some samples; (2) a positive correlation between Zr and SiO2; (3) derivation from crust with mafic and felsic components; (4) LREE enrichment with a moderate Eu anomaly; (5) low εNd(t) values (-7.0 to 7.8, calculated for t = 485 Ma); and (vi) Mesoproterozoic TDM ages (1.5-1.83 Ga). Taken together, these data indicate a proximal source with two main components, an ancient, felsic-intermediate, moderately differentiated continental component, and a minor mafic component. These data are consistent with derivation from the underlying Oaxacan Complex, with little or no input from distal or juvenile sources. This is in accord with: (1) published Nd data from the Oaxacan Complex that yielded TDM ages of 1.5-1.8 Ga; (2) detrital zircon data from the Tiñu Formation, which gave 990-1200 Ma ages; and (3) the Gondwanan affinity of Silurian fauna from northeastern Mexico. The lack of a juvenile, Cambrian signature in these geochemical data is inconsistent with an origin in the Iapetus Ocean, and is compatible with a rift-to-drift model involving opening of the Rheic Ocean.

Theropod pedal unguals from the Late Cretaceous (Cenomanian) of Morocco, Africa

Two different theropod pedal unguals from the Upper Cretaceous (Cenomanian) of Tafilalt, Morocco are described. One of them belongs to a slender kind of abelisauroid theropod. Comparison with other members of this group reveals that abelisauroid unguals show high morphological diversity in congruence with what is known on other parts of the skeleton. Another large-sized ungual resembles that described as “Spinosaurus B” by Stromer (1934), and is here referred with caution to Theropoda, although ignoring to which theropod lineage it belongs. Comparisons between northern (e.g., Sahara, Africa and Brazil) and southern (e.g., Patagonia) Gondwanan Cretaceous dinosaur faunas reveal some differences leading to the conclusion that Gondwanan faunas were not uniform across this supercontinent.

A biogeographically mixed late Guadalupian (late Middle Permian) brachiopod fauna from an exotic limestone block at Xiukang in Lhaze county, Tibet

A total of 17 brachiopod species belonging to 15 genera are recorded from a limestone block of about 3×4 km 2 in the Indus–Tsangbo suture zone at Xiukang in Lhaze County of Tibet. The brachiopod fauna generally indicates a Late Guadalupian age (late Wordian–Capitanian, late Middle Permian) based on its association with the Timorites-bearing ammonoid fauna and the presence of the brachiopod Urushtenoidea crenulata. Palaeobiogeographically, the fauna exhibits transitional/mixed characters between the warm-water Cathaysian and cold to temperate Gondwanan faunas and may have developed on a carbonate build-up or seamount on the oceanic crust.

A biogeographically mixed late Guadalupian (late Middle Permian) brachiopod fauna from an exotic limestone block at Xiukang in Lhaze county, Tibet

A total of 17 brachiopod species belonging to 15 genera are recorded from a limestone block of about 3×4 km2 in the Indus–Tsangbo suture zone at Xiukang in Lhaze County of Tibet. The brachiopod fauna generally indicates a Late Guadalupian age (late Wordian–Capitanian, late Middle Permian) based on its association with the Timorites-bearing ammonoid fauna and the presence of the brachiopod Urushtenoidea crenulata. Palaeobiogeographically, the fauna exhibits transitional/mixed characters between the warm-water Cathaysian and cold to temperate Gondwanan faunas and may have developed on a carbonate build-up or seamount on the oceanic crust.

Permian of West Yunnan, Southwest China: a biostratigraphic synthesis

Recent progress in the study of Permian stratigraphy of western Yunnan, southwest China, is reviewed with particular references to the Tengchong and Baoshan blocks and the Changning–Menglian Belt. Where confusion or controversy exists in stratigraphical nomenclature and/or dating, we attempt to clarify the situation based on our recent field observations and newly obtained research results. The Permian within the Changning–Menglian Belt embraces different stratigraphic successions, suggesting different tectonic settings, ranging from passive margin and active margin, to oceanic basin and seamounts. Permo-Carboniferous faunas in the carbonate sequences of the Changning–Menglian Belt are of typical Cathaysian affinity, as demonstrated by abundant fusulinaceans and compound rugose corals. The Permian stratigraphy and faunas of the Tenchong and Baoshan blocks are markedly different from those of the Changning–Menglian Belt. The Baoshan Block lacks Upper Carboniferous deposits, and its subsequent Lower Permian sequence consists predominantly of siliciclastic strata yielding cool-water faunas and possibly glaciogene diamictites, overlain by thick basaltic lava and volcaniclastics of probably rift origin. The upper part of the Permian in the Baoshan Block is characterized by carbonates containing mixed Cathaysian and Gondwanan faunas. The Tengchong Block has a similar evolutionary history to the Baoshan Block, but completely lacks volcanic rocks.

SHRIMP zircon age control of Gondwanan sequences in Late Carboniferous and Early Permian Australia

Abstract Australia during the Late Carboniferous formed part of the Gondwana supercontinent and was close to the South Pole. Resulting continental glacigene deposits and cold water marine sequences in the Southern New England Orogen cannot be correlated biostratigraphically with Late Carboniferous successions in the northern hemisphere because they contain a low diversity biota endemic to Gondwana. Magnetostratigraphic correlation via the Permian-Carboniferous reversed magnetic superchron is presently uncertain. Sensitive high-resolution ion microprobe (SHRIMP) zircon dating of volcanics horizons in the sedimentary sequence of the Southern New England Orogen is now establishing relationships between the Gondwanan faunas and warm-climate European equivalents. In Continental sediments, correlation of the major Gondwanan glaciation of Late Carboniferous Australia is revised from Stephanian to early Namurian-Westphalian in age, a timing that matches that of the Hoyada Verde glaciation in Argentina. A major hiatus of > 15 Ma between Carboniferous rocks of the Southern New England Orogen and Permian rocks of the Sydney Basin of eastern Australia probably reflects the first deformational movements within the accretionary prism of the orogen. Nothorhacopteris , traditionally a Late Carboniferous indicator in Australia, now ranges from late Viséan to Westphalian, and an ‘enriched’ assemblage, previously correlated with the top of the Nothorhacopteris flora, is confined to the late Viséan to early Namurian. Palynofloras assigned to the Spelaeotriletes ybertii/Diatomozonotriletes birkheadensis Zones (Namurian-early Westphalian), are now confined to the Namurian, and a mid to late Westphalian age is indicated for a more diverse palynoflora identified as uppermost D. birkheadensis Zone (? = Asperispora reticulatispinosus Zone). In the cold climate marine sequence, the Levipustula levis brachiopod Zone appears to be confined to the early Namurian, and so partly corresponds in age to the continental glaciation.

Gondwana, Tethys, and terrestrial vertebrates during the Mesozoic and Cainozoic

Abstract During the Triassic, free dispersal of terrestrial vertebrates was possible in Pangaea; however provinciality appeared in Gondwana. Distribution of Triassic vertebrates may be explained even if the Earth diameter did not expand and if Pacifica did not exist. During the Jurassic, a free land communication persisted between Gondwana and Laurasia, and provinciality is not demonstrated. A Gondwanan pattern emerged during the Cretaceous, but since that time it is not possible to identify a global difference between Gondwanan faunas and Laurasian ones. An African/South American terrestrial community developed until the Aptian. Subsequently, the opening of South Atlantic hindered interchanges between these two areas, but did not end them; exchanges might have taken place then via trans-Atlantic filter, or sweepstakes, routes. For the Cretaceous/Eocene time interval, crossings of the Tethys occurred intermittently, the major event being the interchange that took place between North and South America by latest Cretaceous. By the Cretaceous/Palaeocene transition, a terrestrial route probably linked the still southern Indian Plate to Laurasia. It is uncertain whether this route reached Madagascar. After the Eocene/Oligocene transition, exchanges between Gondwanan continents vanished, whereas exchanges between Gondwanan areas and Laurasia sometimes occurred.

Depositional and tectonic history of the southern New England Orogen

The southern part of the New England Orogen in the Hunter‐Myall region of NSW consists of the southeasterly extremity of the Tamworth Belt, a region of Devonian‐Carboniferous shelfal deposition between a volcanic arc in the west and a deep water accretionary wedge in the east. These depositional elements, which may have been separated from the Australian continent during the Devonian‐Middle Carboniferous, were deformed during the Permian and Triassic by up to four folding events separated by episodes of granitoid emplacement. Depositional patterns were influenced by five major cycles of sea level changes between the Late Devonian and Permian, an influx of volcanic detritus from an arc which changed in composition from andesitic in the Devonian, through dacitic in the Early Carboniferous to mainly rhyolitic in the Late Carboniferous, and in the Early Carboniferous by penecontemporaneous faulting within the shelf. The overall Carboniferous pattern of deposition was regressive. Rapid southerly movement of the Yarrol‐New England Orogen and possible accretion with the Australian continent in the mid‐Carboniferous coincided with the culmination of volcanic activity, a widespread disconformity, and a rapid change of climate that led to the extinction of the cosmopolitan marine invertebrate fauna, its replacement by the cold water Gondwanan fauna, and establishment of a widespread ice cap. The first orogenic event late in the Carboniferous was followed by rifting and subsidence of the Sydney Basin on the south and west flanks of New England. Folding of the southern Tamworth Belt and injection of serpentinite into the Peel and Manning Fault Systems took place in the Early Permian and was followed by emplacement of the Barrington Tops Granodiorite, and further folding in the Late Permian was similarly followed by intrusion of the New England Batholith. The initial folding generated active basins of deposition (Stroud‐Gloucester Syncline) in which Permian marine and coal measure sediments were deposited. Uplift associated with Late Permian or Triassic granitoid intrusion caused the detachment of Carboniferous blocks which slid south and southwest, generating a low angle thrust along southern parts of the Hunter Fault System. Final folding in the Late Triassic may have been related to dextral movement along the Demon Fault in the northern New England Orogen.