A Latest Carboniferous Warming Spike Recorded by a Fusulinid-Rich Bioherm in Timor Leste: Implications for East Gondwana Deglaciation

During the late Paleozoic and early Mesozoic Timor lay in the northern part of the north–south East Gondwana rift system along which the western margin of Australia later developed. Discovery of a latest Gzhelian bioherm in the central highlands of Timor Leste has implications for latest Carboniferous–earliest Permian climate history and deglaciation in basins further south in the rift system. Limestone outcrop of the Maubisse Formation near the village of Kulau is recognized as a bioherm with a massive lower unit, including reef framework at the base, and a bedded grainstone upper unit. The bioherm developed on a basalt substrate in warm shallow-water, as indicated by photozoan assemblages in the massive lower unit. Foraminifera belonging to 17 genera are recorded from the bioherm. These include representatives of the families Biseriamminidae, Biwaellidae, Bradyinidae, Cornuspiridae, Lasiodiscidae, Palaeotextulariidae, Pseudotaxidae, Ozawainellidae, Schubertellidae, Schwagerinidae, Staffellidae and Textrataxidae. Twenty-one species have been referred to known types and 12 species are left in open nomenclature. The assemblage probably belongs within the uppermost Gzhelian Schwagerina robusta–Ultradaixina bosbytauensis Zone although a possible lowest Asselian correlation cannot be excluded. The bioherm is the oldest carbonate unit so far recorded from the Maubisse Formation, and the oldest sedimentary unit biostratigraphically dated in Timor. The dominantly heterozoan composition of the skeletal component of the limestone (except for the basal photozoan assemblage) and the taxonomic diversity of the larger foraminifera suggest a subtropical environment consistent with a paleolatitude of about 40° S. The late Pennsylvanian was a time of glaciation that in Australia is represented by a significant stratigraphic hiatus in basins to the south of Timor in the East Gondwana rift system. The development of the Kulau bioherm during the latest Gzhelian may have coincided with a global warming spike that led to rapid melting of continental ice sheets and a substantial influx of glacigene sediment (alternating diamictite and mudstone) in the southern basins

Data from: Latest Carboniferous (late Gzhelian) fusulinids from Timor Leste and their paleobiogeographic affinities

An uppermost Gzhelian bioherm discovered in the central highlands of Timor Leste contains abundant foraminifera belonging to 17 genera. Representatives of the families Biseriamminidae, Biwaellidae, Bradyinidae, Cornuspiridae, Lasiodiscidae, Palaeotextulariidae, Pseudotaxidae, Ozawainellidae, Schubertellidae, Schwagerinidae, Staffellidae and Textrataxidae are present, including 21 species referred to known types and 12 species left in open nomenclature. Two new Schwagerina species are described: Schwagerina timorensis new species, and Schwagerina maubissensis new species. The assemblage belongs to the uppermost Gzhelian Schwagerina robusta–Ultradaixina bosbytauensis Zone although a possible lowest Asselian correlation cannot be excluded (the name Ultradaixina is controversial and sometimes synonymized as Bosbytauella. The case to resolve this issue has been submitted to the Bulletin of Zoological Nomenclature). The bioherm is the oldest carbonate unit so far recorded from the Maubisse Formation and the oldest sedimentary unit biostratigraphically dated in Timor. This discovery has implications for the latest Carboniferous–earliest Permian climate history of Timor that lay in the northern part of the north-south East Gondwana rift system along which the western margin of Australia later developed. The highest peak in fusulinid diversity within the Pennsylvanian–Cisuralian interval and a major marine transgression documented in many regions in Northern Pangaea took place during the latest Gzhelian to earliest Asselian and evidence for this is now extended to southern Pangaea. Cluster analysis, using the Jaccard similarity index at species level, of late Gzhelian fusulinids from 16 regions has been performed. This shows that the Timor fauna is most closely related to faunas from South China and the Changning-Menlian region of Yunnan (China). The assemblages here are distinct from those of three biogeographic regions (Arctic, Uralo-Asian and Irano-Taurids) recognized within the Tropical belt

Latest Carboniferous (Late Gzhelian) Fusulinids from Timor Leste and Their Paleobiogeographic Affinities

An uppermost Gzhelian bioherm discovered in the central highlands of Timor Leste contains abundant foraminifera belonging to 17 genera. Representatives of the families Biseriamminidae, Biwaellidae, Bradyinidae, Cornuspiridae, Lasiodiscidae, Palaeotextulariidae, Pseudotaxidae, Ozawainellidae, Schubertellidae, Schwagerinidae, Staffellidae and Textrataxidae are present, including 21 species referred to known types and 12 species left in open nomenclature. Two new Schwagerina species are described: Schwagerina timorensisnew species, and Schwagerina maubissensis new species. The assemblage belongs to the uppermost Gzhelian Schwagerina robusta–Ultradaixina bosbytauensis Zone although a possible lowest Asselian correlation cannot be excluded (the name Ultradaixina is controversial and sometimes synonymized as Bosbytauella. The case to resolve this issue has been submitted to the Bulletin of Zoological Nomenclature). The bioherm is the oldest carbonate unit so far recorded from the Maubisse Formation and the oldest sedimentary unit biostratigraphically dated in Timor. This discovery has implications for the latest Carboniferous–earliest Permian climate history of Timor that lay in the northern part of the north-south East Gondwana rift system along which the western margin of Australia later developed. The highest peak in fusulinid diversity within the Pennsylvanian–Cisuralian interval and a major marine transgression documented in many regions in Northern Pangaea took place during the latest Gzhelian to earliest Asselian and evidence for this is now extended to southern Pangaea. Cluster analysis, using the Jaccard similarity index at species level, of late Gzhelian fusulinids from 16 regions has been performed. This shows that the Timor fauna is most closely related to faunas from South China and the Changning-Menlian region of Yunnan (China). The assemblages here are distinct from those of three biogeographic regions (Arctic, Uralo-Asian and Irano-Taurids) recognized within the Tropical belt

Supplement_genera and species

Matrixe

Late Artinskian–Early Kungurian (Early Permian) warming and maximum marine flooding in the East Gondwana interior rift, Timor and Western Australia, and comparisons across East Gondwana

© 2016Substantial new information is presented on upper Artinskian–Kungurian deposits in Timor-Leste and in the Canning, Southern Carnarvon and northern Perth basins of Western Australia. These basins, situated between about 35°S and 55°S palaeolatitude, formed part of the East Gondwana interior rift, a precursor to the rift that 100 my later formed the Indian Ocean in this region. Timor lay near the main axis of the East Gondwana interior rift, whereas the Western Australian basins were marginal splays from the rift axis. The main depocentres developed as a result of faulting that was initiated during the Late Pennsylvanian. Detailed lithostratigraphic and biostratigraphic analyses have been made on the newly recognized Bua-bai limestone and the type Cribas Group in Timor, the Noonkanbah Formation in the Canning Basin, the Byro Group in the Merlinleigh Sub-basin of the Southern Carnarvon Basin, and the Carynginia Formation in the northern Perth Basin. In Timor the succession, which is highly disrupted by faulting, was deposited under open-marine conditions probably in a shelf–basin setting. Restricted, very shallow-water seas flooded the Canning Basin and the Merlinleigh–Byro–Irwin sub-basins of the Southern Carnarvon and northern Perth basins and had highly variable oxygen levels and salinities typical of estuarine environments. A similar pattern of warming and bathymetric change is recognized in all studied basins. During the early part of the late Artinskian cool conditions prevailed, with water temperatures 0–4 °C forming sea ice in the Merlinleigh–Byro–Irwin rift. Rapid warming during the latter part of the late Artinskian was accompanied by maximum marine flooding close to the Artinskian–Kungurian boundary. Climatic and bathymetric conditions then allowed carbonate mounds, with larger fusulines and a variety of algae, to develop in the northern part of the rift system, and Tubiphytes, conodonts, and brachiopods with Tethyan affinities to migrate into the marginal-rift basins despite the generally adverse water quality at these depositional sites. Comparison between the stratigraphic record from the East Gondwana interior rift and coeval records from Lhasa and Sibumasu indicate a similar pattern of climate change during the Carboniferous to end Cisuralian. Similar trends probably are present in Eastern Australia although there is confusion over the correlation of some units