The relative roles of CO2 and palaeogeography in determining Late Miocene climate: results from a terrestrial model-data comparison

The Late Miocene (∼11.6–5.3 Ma) palaeorecord provides evidence for a warmer and wetter climate than that of today and there is uncertainty in the palaeo-CO2 record of at least 150 ppmv. We present results from fully coupled atmosphere-ocean-vegetation simulations for the Late Miocene that examine the relative roles of palaeogeography (topography and ice sheet geometry) and CO2 concentration in the determination of Late Miocene climate through comprehensive terrestrial model-data comparisons. Assuming that the data accurately reflects the Late Miocene climate, and that the Late Miocene palaeogeographic reconstruction used in the model is robust, then results indicate that the proxy-derived precipitation differences between the Late Miocene and modern can be largely accounted for by the palaeogeographic changes alone. However, the proxy-derived temperatures differences between the Late Miocene and modern can only begin to be accounted for if we assume a palaeo-CO2 concentration towards the higher end of the range of estimates

The antiquity of the Rhine River : stratigraphic coverage of the Dinotheriensande (Eppelsheim Formation) of the Mainz Basin (Germany)

Background: Mammalian fossils from the Eppelsheim Formation (Dinotheriensande) have been a benchmark for Neogene vertebrate palaeontology since 200 years. Worldwide famous sites like Eppelsheim serve as key localities for biochronologic, palaeobiologic, environmental, and mammal community studies. So far the formation is considered to be of early Late Miocene age (~9.5 Ma, Vallesian), representing the oldest sediments of the Rhine River. The stratigraphic unity of the formation and of its fossil content was disputed at times, but persists unresolved. Principal Findings: Here we investigate a new fossil sample from Sprendlingen, composed by over 300 mammalian specimens and silicified wood. The mammals comprise entirely Middle Miocene species, like cervids Dicrocerus elegans, Paradicrocerus elegantulus, and deinotheres Deinotherium bavaricum and D. levius. A stratigraphic evaluation of Miocene Central European deer and deinothere species proof the stratigraphic inhomogenity of the sample, and suggest late Middle Miocene (~12.5 Ma) reworking of early Middle Miocene (~15 Ma) sediments. This results agree with taxonomic and palaeoclimatic analysis of plant fossils from above and within the mammalian assemblage. Based on the new fossil sample and published data three biochronologic levels within the Dinotheriensand fauna can be differentiated, corresponding to early Middle Miocene (late Orleanian to early Astaracian), late Middle Miocene (late Astaracian), and early Late Miocene (Vallesian) ages. Conclusions/Significance: This study documents complex faunal mixing of classical Dinotheriensand fauna, covering at least six million years, during a time of low subsidence in the Mainz Basin and shifts back the origination of the Rhine River by some five million years. Our results have severe implications for biostratigraphy and palaeobiology of the Middle to Late Miocene. They suggest that turnover events may be obliterated and challenge the proposed ‘supersaturated’ biodiversity, caused by Middle Miocene superstites, of Vallesian ecosystems in Central Europe

A revision of the fossil genus Miocepphus and other Miocene Alcidae (Aves: Charadriiformes) of the Western North Atlantic Ocean

This study reviews and describes all known fossils of Alcidae from the Miocene of the western North Atlantic. Because the majority of alcid fossils recovered from Miocene sediments are allied with the genus Miocepphus Wetmore, 1940, the genus is revised here. Three new species of Miocepphus are described: Miocepphus bohaskai and Miocepphus blowi from the Early to Late Miocene, and Miocepphus mergulellus of uncertain Neogene age but probably Miocene. A new genus and species, Pseudocepphus teres, from the Middle and Late Miocene, has uncertain relationships within the Alcinae (a clade comprising Miocepphus, Alle, Uria, Alca and Pinguinus). The genus Alca is also reported from Late Miocene sediments. The newly recognised presence of three genera of the Alcinae in the Miocene of the North Atlantic indicates that the diversity of the subfamily was considerably greater than was evident previously. Miocepphus may be regarded as ancestral to modern Alcinae. The Alcinae as a group was well established in the Early Miocene, indicating that the divergence of the family Alcidae predates 20 Ma. The divergence of Uria and Alca predates 10 M

Neogene stratigraphic architecture and tectonic evolution of Wanganui, King Country, and eastern Taranaki Basins, New Zealand

Analysis of the stratigraphic architecture of the fills of Wanganui, King Country, and eastern Taranaki Basins reveals the occurrence of five 2nd order Late Paleocene and Neogene sequences of tectonic origin. The oldest is the late Eocene-Oligocene Te Kuiti Sequence, followed by the early-early Miocene (Otaian) Mahoenui Sequence, followed by the late-early Miocene (Altonian) Mokau Sequence, all three in King Country Basin. The fourth is the middle Miocene to early Pliocene Whangamomona Sequence, and the fifth is the middle Pliocene-Pleistocene Rangitikei Sequence, both represented in the three basins. Higher order sequences (4th, 5th, 6th) with a eustatic origin occur particularly within the Whangamomona and Rangitikei Sequences, particularly those of 6th order with 41 000 yr periodicity

The Late Miocene Southern and Central Taranaki Inversion Phase (SCTIP) and related sequence stratigraphy and paleogeography

We present a new sequence stratigraphic scheme for Taranaki Basin that identifies four 3rd order duration (3 - 4 m.y.) sequences of Middle Miocene to Pleistocene age. These include: (i) the late-Middle Miocene (upper Lillburnian to uppermost Waiauan) Otunui Sequence; (ii) the Late Miocene (lower and lowermost-upper Tongaporutuan) Mt Messenger Sequence; (iii) the latest Miocene (uppermost-upper Tongaporutuan) to Early Pliocene (lower Opoitian) Matemateaonga Sequence, and (iv), the Late Pliocene (upper Opoitian) to Late Pleistocene (Castlecliffian) Rangitikei Sequence, which includes the Giant Foresets Formation offshore in northern Taranaki Basin. Full sequence development can be observed in the parts of these four sequences exposed on land in eastern Taranaki Basin and in Wanganui Basin, including the sequence boundaries and component systems tracts; the character of the various depositional systems and their linkage to correlatives in subsurface parts of Taranaki Basin can be reasonably inferred, although we do not develop the detail here. Our sequence framework, with its independent age control, is integrated with established evidence for the timing of Late Miocene structure development in southern Taranaki (the Southern Inversion Zone of King & Thrasher (1996)) and new evidence presented here for the extent of Late Miocene unconformity development in central Taranaki. This shows that the Mt Messenger Sequence, particularly its regressive systems tract, results from a major phase of tectonism in the plate boundary zone, the crustal shortening then extending into the basin at c. 8.5 Ma and differentially exhuming parts of the sequence and underlying units in southern and central Taranaki Basin. This Southern and Central Taranaki Inversion Phase (SCTIP) peaked at around 7.5 Ma (mid-upper Tongaporutuan). At that time it extended across the whole of the area presently covered by Wanganui Basin, all of southern Taranaki Basin (Southern Inversion Zone), west to the Whitiki and Kahurangi Faults, and across southern parts of Taranaki Peninsula. We have also identified in outcrop sections, wireline logs for Peninsula exploration holes, and selected seismic reflection profiles, the occurrence of forced regressive deposits of the Mt Messenger Sequence. These deposits are mainly preserved beneath distal parts of the unconformity and basinward of it in central Taranaki Peninsula and west to the Tui Field, and need to be distinguished from the much younger Giant Forests Formation within the 3rd-order Rangitikei Sequence, which also shows clinoform development. The new sequence framework with its inferred stratal patterns also helps clarify understanding of the lithostratigraphic nomenclature for Late Miocene – Pliocene units beneath Taranaki Peninsula

Seismic and Sequence Analysis of Middle to Late Miocene Deposits of Northeast Java Basin

DOI:10.17014/ijog.2.2.101-110This study is focused on Middle to Late Miocene sediments. As depicted in the regional geology of Indonesia, the area of study is part of Northeast Java Basin. There are three phases of tectonism in the basin: extensional tectonics at Eocene-Oligocene time, compressional tectonics at Middle Miocene, and compressional tectonics at Miocene-Pliocene time. The result of the study shows three sequences were developing during Middle to Late Miocene, those are: (1) Middle Miocene sequence-1 (MM-1 sequence) consisting of a Lowstand Tract System deposition in Middle Miocene-1 (LST MM-1), Transgressive System Tract deposition in Middle Miocene-1 (TST MM-1), and Highstand System Tract deposition in Middle Miocene-1 (HST MT-2); (2) Middle Miocene sequence-2 (MT-2 sequence), comprising Transgressive System Tract Middle Miocene-1 (TST MM-2), and Highstand System Tract deposition in Middle Miocene-1 (HST MM-2); (3) Late Miocene sequence-1 (LM-1 sequence), composed of a Lowstand Tract System deposition in Late Miocene -1 (LST LM-1) and a Transgressive System Tract deposition in Late Miocene-1 (TST LM-1)

Two Crusafontina (Mammalia, Insectivora) fossils from the Miocene of the Transdanubian Central Range (Hungary)

Two isolated teeth of Anourosoricini shrews, Crusafontina (Mammalia, Insectivora, Soricidae) are present in this paper. A complete left maxillary molar was found in the Sarmatian (Middle Miocene) locality of Várpalota Lignite Mine, Pit III. The species is different from all known Crusafontina species in its smaller size and less reduced talone of this tooth, so we described it as Crusafontina sp. On the basis of its less evolved morphology, the here described form seems the most ancient known species of the genus. A fragmented upper molar of Crusafontina kormosi (Bachmayer & Wilson 1970) came from the Late Miocene locality of Tihany, Fehér-part. The most probable age of the remain is Early Turolian. It might have been transported by flowing water to the Late Miocene lacustrine basin and indicates well watered, wooded environment in the surroundings

Note on paramoudra-like carbonate concretions in the Urenui Formation, North Taranaki: possible plumbing system for a Late Miocene methane seep field

A reconnaissance study of calcitic and dolomitic tubular concretions in upper slope mudstone of the Late Miocene Urenui Formation exposed along the north Taranaki coastline indicates that they have a complex diagenetic history involving different phases of carbonate cementation and likely hydrofracturing associated with build up of fluid/gas pressures. The concretions resemble classical paramoudra in the European chalk, but are not siliceous and do not have a trace fossil origin. Stable oxygen and carbon isotope data suggest that the micritic carbonate cements in the Urenui paramoudra were probably sourced primarily from ascending methane fluid/gases, and that they precipitated entirely within the host mudstone below the seafloor. We suggest the paramoudra may mark the subsurface plumbing networks of a Late Miocene cold seep system, in which case they have relevance to the evolution and migration of hydrocarbons in Taranaki Basin, at this site perhaps focussed along the Taranaki Fault. The presence of dislodged and mass-emplaced paramoudra in the axial conglomerate of channels within the Urenui mudstone suggests there could be a connection between the loci of seep field development and slope failure and canyon cutting on the Late Miocene Taranaki margin

Constraints on the evolution of Taranaki Fault from thermochronology and basin analysis: Implications for the Taranaki Fault play

Taranaki Fault is the major structure defining the eastern margin of Taranaki Basin and marks the juxtaposition of basement with the Late Cretaceous-Paleogene succession in the basin. Although the timing of the basement over-thrusting on Taranaki Fault and subsequent marine onlap on to the basement block are well constrained as having occurred during the Early Miocene, the age of formation of this major structure, its character, displacement history and associated regional vertical movement during the Late Cretaceous- Recent are otherwise poorly known. Here we have applied (i) apatite fission track thermochronology to Mesozoic basement encountered in exploration holes and in outcrop to constrain the amount and timing of Late Cretaceous-Eocene exhumation of the eastern side of the fault, (ii) basin analysis of the Oligocene and Miocene succession east of the fault to establish the late-Early Miocene - Early Pliocene subsidence history, and (iii), regional porosity-bulk density trends in Neogene mudstone to establish the late uplift and tilting of eastern Taranaki Basin margin, which may have been associated with the main period of charge of the underlying Taranaki Fault play. We make the following conclusions that may be useful in assessing the viability of the Taranaki Fault play. (1) Mid-Cretaceous Taniwha Formation, intersected in Te Ranga-1 was formerly extensive across the western half of the Kawhia Syncline between Port Waikato and Awakino. (2) Taranaki Fault first formed as a normalfault during the Late Cretaceous around 85±10 Ma, and formed the eastern boundary of the Taranaki Rift-Transform basin. (3) Manganui Fault, located onshore north of Awakino, formed as a steeply east dipping reverse fault and accommodated about four km of displacement during the mid-Cretaceous. (4) Uplift and erosion, involving inversion of Early Oligocene deposits, occurred along the Herangi High during the Late Oligocene. This may have been associated with initial reverse movement on Taranaki Fault. (5) During the Early Miocene (Otaian Stage) the Taranaki and Manganui Faults accommodated the westward transport of Murihiku basement into the eastern margin of Taranaki Basin, but the amount of topography generated over the Herangi High can only have been a few hundred metres in elevation. (6) The Altonian (19-16 Ma) marked the start of the collapse of the eastern margin of Taranaki Basin that lead during the Middle Miocene to the eastward retrogradation of the continental margin wedge into the King Country region. During the Late Miocene, from about 11 Ma, a thick shelf-slope continental margin wedge prograded northward into the King Country region and infilled it (Mt Messenger, Urenui, Kiore and Matemateaonga Formations). (7) During the Pliocene and Pleistocene the whole of central New Zealand, including the eastern margin of Taranaki Basin, became involved in long wavelength up-doming with 1-2 km erosion of much of the Neogene succession in the King Country region. This regionally elevated the Taranaki Fault play into which hydrocarbons may have migrated from the Northern Graben region

Systematic lithostratigraphy of the Neogene succession exposed in central parts of Hawke’s Bay Basin, eastern North Island, New Zealand

This report presents a systematic lithostratigraphy for the Neogene (Miocene–Recent) sedimentary succession in central parts of Hawke’s Bay Basin in eastern North Island, New Zealand. It has been built up chiefly from strata exposed in outcrop, but petroleum exploration drill hole data have also been incorporated to produce this stratigraphic synthesis. Most of the strata exposed in this part of the basin are of Late Miocene (Tongaporutuan, local New Zealand Stage) to Recent age, and the majority of this report focuses on these starta, with brief description of Middle and Early Miocene formations. A companion PR report (Kamp et al. 2007) contains stratigraphic columns for sections through the Neogene succession described in this report