Late Miocene Event Research Articles

Species delimitation and phylogenetic analyses of a New Guinean frog genus (Microhylidae: Hylophorbus) reveal many undescribed species and a complex diversification history driven by late Miocene events

Abstract New Guinea is the largest tropical island in the world and hosts immense endemic biodiversity. However, our understanding of how the gradual emergence of the terrestrial ecosystems of the island over the last 40 Myr has generated this biological richness is hampered by poorly documented species diversity and distributions. Here, we address both these issues through an integrative taxonomy and biogeographical approach using Hylophorbus, a New Guinea-endemic genus of frogs with 12 recognized species. We delimited candidate species by integrating mitochondrial DNA, nuclear DNA, and bioacoustics, then investigated their evolutionary history. Our results suggest that the current taxonomy of the genus misses true species diversity by ≥3.5-fold. Nevertheless, most candidate species (27) remain unconfirmed because of missing data, whereas five were identified unambiguously as undescribed (we describe three of these formally). Time-calibrated phylogenetic analyses suggest that Hylophorbus diversification began ~9 Mya in the northern or eastern portion of New Guinea. It would appear that lineages dispersed to new terrestrial habitats in the west, notably uplifted by the central range orogeny, until eventually reaching the Bird’s Head during the Mio-Pliocene (7–5 Mya). Conversely, a past barrier appears to have prevented north–south dispersal. These data suggest that new habitat availability has primarily driven the diversification of Hylophorbus.

Abyssal Manganese Nodule Recording of Global Cooling and Tibetan Plateau Uplift Impacts on Asian Aridification

AbstractThe impact of central Asian aridification on the low latitude North Pacific Ocean since the late Miocene remains unclear. To address this question, we systematically studied an abyssal manganese nodule from the northwestern Pacific Ocean, which is expected to be sensitive to eolian dust sourced from central Asia. Geochemical variations and the fossilized remains of magnetotactic bacteria within the studied nodule manifest two prominent Asian aridification events at ∼8–7 Ma and 3.6–0 Ma. These results suggest that central Asian aridification impacted both primary productivity and abyssal microbial activity in the NW Pacific Ocean via eolian dust inputs. In contrast to the Pliocene aridification event, the late Miocene event was associated with a primary productivity bloom that is not evident in coeval global primary productivity records, which indicates that the ∼8–7 Asian aridification event was likely due to NE Tibetan Plateau uplift rather than to global cooling.

The Early Pliocene global expansion of C4 grasslands: A new organic carbon-isotopic dataset from the north China plain

C4-grasslands are known to have first expanded globally in the Late Miocene, and recent research has hinted at a second expansion phase during the Early Pliocene; however, the geographic extent of this second event and its driving force are debated. In this study, we present organic carbon-isotopic evidence from a high-resolution drillcore in North China spanning the interval from ∼8.0 Ma to the present. A prominent positive δ13Corg shift at ∼4.1 Ma marks C4-grassland expansion on the North China Plain, and rapid oscillations of >6‰ from ∼3.2 to 2.2 Ma imply large shifts between C3- and C4-dominated floras. Our δ13Corg profile mirrors carbon isotope shifts in loess-red clay deposits of the Chinese Loess Plateau, confirming the regional nature of this event. Furthermore, coeval carbon isotope records from Africa, North America, and South America provide evidence that the Early Pliocene C4-grassland expansion was global in scale and temporally distinct from the Late Miocene event. Whereas the Late Miocene event may have been related to aridification and altered fire regimes, this mechanism cannot account for the Early Pliocene expansion owing to contemporaneous increases in humidity at many Northern Hemisphere sites. We hypothesize that C4-grassland expansion in the Early Pliocene was triggered by falling atmospheric CO2 levels, as evidenced by multiple pCO2 proxy records and supported by quantum photosynthetic efficiency modeling.

Supradetachment basin evolution unravelled by detrital apatite fission track analysis: the Gediz Graben (Menderes Massif, Western Turkey)

AbstractThe Menderes Massif is a Tertiary metamorphic core complex tectonically exhumed in the late Oligocene–Miocene during coeval development of a series of E–W‐trending basins. This study analyses the source‐to‐sink evolution of the Gediz Graben and the exhumation pattern of the Central Menderes Massif at the footwall and hanging wall of the Gediz Detachment Fault. We use a comprehensive approach to detrital apatite fission track dating combining analysis of modern river sediments, analysis of fossil sedimentary successions and mineral fertility determinations. This approach allowed us to: (i) define the modern short‐term erosion pattern of the study area, (ii) unravel the long‐term exhumation history, (iii) identify major exhumation events recorded in the sedimentary basin fill and (iv) constrain the maximum depositional age of the sedimentary succession. Three main exhumation events are recorded in the analysed detrital samples: (i) a late Oligocene/early Miocene exhumation event involving the whole Menderes Massif; (ii) a late Miocene event involving the northern edge of the Central Menderes Massif; (iii) a Plio‐Quaternary more localized event involving only the western part of the southern margin of the basin (Salihli area) and bringing to the surface the Gediz Detachment and its intrusive footwall (Salihli granodiorite). The modern short‐term erosion pattern closely reflects this latter Plio‐Quaternary event. Single grain‐age distributions in the sedimentary basin fill highlight drainage pattern reorganizations in correspondence of the transition between different stratigraphic units, and allowed to better constrain the depositional age of the sedimentary units of the basin pointing to a possible onset of sedimentation in the basin during the middle Miocene.

Late Neogene Radiolarian Biostratigraphy of the Eastern North Pacific ODP Sites 1020/1021

Abstract. During Ocean Drilling Program Leg 167, Sites 1020/1021 were drilled to assess the paleoceanographic conditions within the northern region of the California Current. Radiolarian records from the upper middle Miocene to Pleistocene were obtained at Sites 1020/1021 cores in order to develop a correlation between Neogene biostratigraphic data and paleomagnetic chronostratigraphy. Of 66 radiolarian events identified during this study, 26 Pleistocene to late Miocene events were directly tied to the paleomagnetic stratigraphy, and 40 middle to late Miocene events were correlated with that result by second-order methods based on the diatom biostratigraphy. The updated ages of radiolarian bioevents were estimated based on the geologic time scale of Ogg (2012). Of these events, 12 bioevents that define low-latitude tropical radiolarian zones were either missing at Sites 1020/1021, or proved to have different ranges from those in the tropics. Using selected bioevents of the temperate and subarctic species,...

Biogeographic history of Pistacia (Anacardiaceae), emphasizing the evolution of the Madrean-Tethyan and the eastern Asian-Tethyan disjunctions

Pistacia L. exhibits a disjunct distribution in Mediterranean Eurasia and adjacent North Africa, eastern Asia, and North to Central America. The spatio-temporal diversification history of Pistacia was assessed to test hypotheses on the Madrean-Tethyan and the Eurasian Tethyan disjunctions through phylogenetic and biogeographic analyses. Maximum parsimony and Bayesian methods were employed to analyze sequences of multiple nuclear and plastid loci of Pistacia species. Bayesian dating analysis was conducted to estimate the divergence times of clades. The likelihood method LAGRANGE was used to infer ancestral areas. The New World species of Pistacia formed a clade sister to the Old World clade in all phylogenetic analyses. The eastern Asian Pistacia weinmannifolia–P. cucphuongensis clade was sister to a clade of the remaining Old World species, which were further resolved into three subclades. Pistacia was estimated to have originated at 37.60mya (with 95% highest posterior density interval (HPD): 25.42–48.51mya). A vicariance event in the early Miocene (19.79mya with 95% HPD: 10.88–30.36mya) was inferred to account for the intercontinental disjunction between the New World and the Old World species, which is consistent with the Madrean-Tethyan hypothesis. The two Old World eastern Asian-Tethyan disjunctions are best explained by one vicariance event in the early Miocene (15.87mya with 95% HPD: 8.36–24.36mya) and one dispersal event in late Miocene (5.89mya with 95% HPD: 2.68–9.16mya). The diversification of the Old World Pistacia species was significantly affected by extensive geological and climatic changes in the Qinghai-Tibetan plateau (QTP) and in the Mediterranean region.

TheLeporidDatum: a lateMiocene biotic marker

AbstractAlthoughLagomorpha (rabbits, hares and pikas) have a long evolutionary history inEurasia andAfrica, including primitive genera ofEurasia historically considered assignable at the family level toLeporidae, the predecessors of modern rabbits were absent throughout this vast region for most of theMiocene until late in that epoch. During the early and middleMiocene, crown groupLeporidae differentiated inNorthAmerica, then dispersed to northernAsia in the lateMiocene around 8 Ma(million years before present) and afterward. They then spread widely and apparently rapidly throughoutEurasia, reachingSouthAsia by 7.4 Maand penetratingAfrica about 7 Ma.The apparently abrupt introduction ofLeporidae is a striking lateMiocene event that we call theLeporidDatum. Perceived in terms of biochrons, theLeporidDatum includes localities inEurope and westernAsia of lateMN11 (MammifèresNéogènes system) age and younger, and precedes by less than one million years theBahean‐Baodean land mammal age boundary inChina.The lateMiocene spread ofLeporidae throughoutEurasia was a successful invasion in terms of the numerous occurrences and abundant fossils preserved. Where dating is sufficiently robust, theLeporidDatum is lateMiocene, nowhere certainly more than ∼8 Ma.In contrast to this sudden and widespread invasion, rare older finds suggest two possible refinements to this scenario: stem lagomorphs close to modernLeporidae may have lingered into the middleMiocene ofEurasia, or an independent, unsuccessful leporid invasion fromNorthAmerica may have preceded the 8 Madatum.TheLeporidDatum marks an important palaeoecological event for theOldWorld and complements the significance of molecular dates for origins of modern genera.

北海道豊羽- 無意根地域における 新第三紀- 第四紀重複熱水系 脈石英の酸素同位体の研究

An oxygen isotopic study of vein quartz in the Toyoha-Muine area was conducted using a CO2 laser microprobe technique, in order to determine origin of hydrothermal fluids. The oxygen isotopic values of the hydrothermal fluids resulting in the vein formations were calculated to be between -10.6 and 1.0 ‰, using the obtained oxygen isotopic values of quartz and previous data on the formation temperature of quartz from fluid inclusion studies. Combined with existing chronological data on the hydrothermal activities related to the vein formations, the isotopic values are classified into two different chronological ranges: -6.3 to 1.0 ‰ in Middle to Late Miocene and -10.6 to -6.7 ‰ in Pliocene-Pleistocene. Based on the previous geological reconstruction at the area, the values for the Middle to Late Miocene event indicate mixtures of fluids with variable ratios of meteoric water, seawater and magmatic water, whereas the values for Pliocene-Pleistocene result from fluids with high ratios of meteoric water to magmatic water.

Tectonics changes in NW South American Plate and their effect on the movement pattern of the Boconó Fault System during the Mérida Andes evolution

Abstract The NE–SW trending Merida–Andes fold-and-thrust belt, in the southern boundary of the Maracaibo Block, formed by a collisional event in Late Miocene at the boundary of the Maracaibo Block and Guyana Shield in the northwestern South American plate. The 500 km long, NE–SW striking right-lateral strike-slip Bocono Fault System lies in the Merida–Andes area. Mylonitic fault rocks along the Bocono Fault System developed during pre-Late Miocene-Early Pliocene. Microscopic and mesoscopic structures such as mica fish, asymmetrical porphyroclasts, S–C shear bands, and asymmetrical ductile folds in Bocono Fault mylonite indicate a sinistral movement along the fault. The movement is probably related to pre-collision extensional tectonics that began in the Late Triassic–Jurassic interval, and continued until the Late Cretaceous or Middle Eocene. Following the collision of the Panama Arc and the South American plate in the Late Miocene, and the change from extensional to contractional tectonic regime, the Bocono was reactivated as a dextral fault system.

Biogeographical origins and diversification of the exoneurine allodapine bees of Australia (Hymenoptera, Apidae)

Aim Early diversification of allodapine bees occurred in Africa c. 50 Ma. They are most abundant in sub-Saharan Africa and Australia, and one of the oldest phylogenetic divergences in the tribe involves a split between an African + Malagasy clade and an Australian clade. The historical biogeographical scenario for this has been highly problematic, entailing an Eocene dispersal from Africa to Australia, followed by an unresolved, and apparently rapid, set of bifurcations leading to the Australian ‘exoneurine’ genera. Here we use an expanded taxon set of Australian species to explore the timing and historical biogeography of the exoneurine radiation. Location Australia, Africa, Madagascar. Methods One nuclear gene (F2 copy of elongation factor 1α) and two mitochondrial genes (cytochrome c oxidase subunit I and cytochrome b) were sequenced for 33 Australian exoneurine species from all five genera found on the continent, as well as for an additional 37 species from all non-parasitic genera in the remainder of the tribe. We used Bayesian inference analyses to study phylogenetic topology and penalized likelihood analyses to infer key dates of divergence within the tribe. We also used lineage-through-time (LTT) analyses and Bayesian analyses to explore the tempo of radiations and biogeographical history of the exoneurines. Results Results from the phylogenetic analyses were congruent with previous studies, indicating a single colonization event c. 34 Ma, too late for Gondwanan vicariance models, and too early for a Laurasian dispersal route. In contrast to earlier studies, we show that this colonization event did not result in an ancient rapid radiation. However, LTT patterns indicated a rapid radiation of the temperate-adapted genera Exoneura and Brevineura, but not of the xeric-adapted genus Exoneurella, from 10 to 6 Ma. Main conclusions Our results indicate a trans-oceanic dispersal event from Africa to Australia, most likely via Antarctica, with an accelerated diversification of temperate-adapted lineages during the major Late Miocene event referred to as the ‘Hill Gap’. This is the first study to link radiations in Australian bee faunal elements to changing climate, and differs from many other plant and insect phylogenetic studies by showing increased radiation of temperate clades, rather than xeric clades, with increasing aridification of Australia.

Phylogeographic patterning in a freshwater crab species (Decapoda: Potamonautidae:Potamonautes) reveals the signature of historical climatic oscillations

AbstractAim The phylogeographic relationships among populations of the common Cape River crab,Potamonautes perlatus, are examined to investigate whether the contemporary population genetic structure is congruent with the hypothesized hydrographic evolution of drainage systems established during the Pliocene, or whether it reflects an older Miocene climatic amelioration.Location 139 samples ofP. perlatuswere collected from 31 populations distributed among the five major perennial drainage systems and a number of smaller catchments in the Western and Eastern Cape, South Africa.Methods Phylogeographic analysis using parsimony, maximum likelihood, minimum evolution and Bayesian inferences was employed for the 16S rRNA mtDNA gene region, while bootstrapping and posterior probabilities were used to assess the robustness of clades. In addition, nested clade analysis was performed in an attempt to disentangle the contemporary and historical factors that have sculpted genealogical relationships among conspecific populations ofP. perlatus.Results Phylogenetic topologies were congruent irrespective of the evolutionary method employed. Two highly distinct reciprocally monophyletic clades characterized by marked levels of corrected sequence divergence were present, with no shared haplotypes between the two major phylogroups. Phylogroup one comprises the populations of the westward‐flowing drainages (mainly the Berg and Olifants drainages), and phylogroup two comprises all of the southward‐flowing drainages and can further be divided into two subclades – one containing the Breede River populations, and the other containing the Gamtoos and Gourits drainage systems. The nested clade analysis demonstrated restricted gene flow and long‐distance dispersal for a number of higher clade levels. The higher‐level groups and results for the total cladogram suggest either fragmentation or isolation by distance.Main conclusions Freshwater crabs are generally highly philopatric, and dispersal, although not common, has occurred historically. The westward‐flowing drainages (Berg, Olifants, Eerste, Liesbeeck and Tokai) are isolated from the southward‐flowing drainages by the Cape Fold Mountains, while the southward‐flowing drainages have a number of tributaries that extend into the low‐lying regions, allowing for gene flow between these three major drainages systems (Breede, Gamtoos and Gourits). Among the westward‐flowing drainages, a more intensive sampling regime is required to understand evolutionary relationships. Our molecular results suggest that the observed patterns pre‐date the formation of contemporary hydrographic patterns in the Cape. This suggests that an older Late Miocene event has severely impacted the contemporary population structure in this species, as recent Pliocene hydrographic boundaries do not correspond to the phylogeographic pattern observed. Conservation efforts for aquatic taxa should clearly be directed at the catchments, in an attempt to conserve biological diversity.

Identifying Late Miocene episodes of connection and isolation in the Mediterranean–Paratethyan realm using Sr isotopes

After decades of research, the timing and nature of Late Miocene connections between the Mediterranean, Paratethys and the global ocean are still speculative. The hydrologic flux implications of exchange or isolation are central to all hypotheses for generating the major lithological changes that represent the Messinian Salinity Crisis. Moreover, differences in the hydrologic fluxes envisaged are the primary distinction between models. Despite this, these fluxes remain largely unconstrained. This paper describes the basis for using Sr isotope data innovatively combined with salinity data through hydrologic budget modelling to determine the timing and nature of Mediterranean hydrologic connectivity. We examine the hypotheses for three Late Miocene events to illustrate how this approach allows us to test implied hydrologic scenarios and exclude incompatible models. 1) Pre-evaporite restriction of the Mediterranean; 2) the initiation of salt precipitation; 3) connection between the Sea of Marmara and both Paratethys and the Mediterranean during the Messinian. This process suggests that the Atlantic–Mediterranean exchange was significantly reduced up to three million years before evaporite precipitation. It also indicates that end-member hypotheses for initiating salt precipitation in the Mediterranean (desiccation and connected basin models) are inconsistent with Sr isotope data. A contrasting model where evaporite formation was triggered by Atlantic transgression into a strongly evaporation-dominated Mediterranean is shown to be more compatible with available datasets. The application to Sea of Marmara samples indicates that salinity changes in the basin were not caused by changes to the amount of inflow from either Paratethys or the Mediterranean. Other possible as yet untested applications important for constraining different aspects of the Messinian Salinity Crisis are highlighted.

Episodic unroofing of the Kohistan Batholith, Pakistan: Implications from K‐feldspar thermochronology

New 40Ar/39Ar and U‐Pb mineral ages from plutonic rocks help constrain the thermal and tectonic evolution of the Kohistan island arc terrane following its collision with India in early Tertiary time. Kohistan has experienced a prolonged tectonomagmatic history extending from the Early Cretaceous through the Tertiary. Thermal histories derived from multi diffusion domain analyses of K‐feldspar within the Kohistan batholith reveal rapid cooling events (70–140°C/m.y.) distributed through space and time. The cooling histories show a systematic variation along the length of the batholith suggesting that Kohistan experienced differential unroofing. An episode of rapid cooling in the middle Eocene is recognized in western Kohistan, whereas rapid cooling occurs substantially later, during the middle and late Miocene, in eastern Kohistan. Rapid cooling in western Kohistan might have been caused by postemplacement cooling of hot magma against cold country rocks at relatively shallow crustal levels. Within the NW region of eastern Kohistan, rapid cooling at 13–12 Ma is recorded in K‐feldspars ∼60 km from the contact with the Nanga Parbat‐Haramosh Massif (NPHM), whereas cooling does not occur until 11 Ma only 2.5 km from the contact. This temporal and spatial variation in cooling histories may record differential unroofing in response to the development and propagation of the NPHM structure beneath Kohistan. The NPHM has experienced rapid cooling and unroofing over the last 10 m.y., and our results are consistent with this mid–late Miocene event.

Formula omitted] analysis of supergene jarosite and alunite: Implications to the paleoweathering history of the western USA and West Africa

Supergene alunite (KAl 3(SO 4) 2(OH) 6) and jarosite (KFe 3(SO 4) 2(OH) 6) are often precipitated during the oxidation of sulfide-bearing rocks by meteoric solutions. Dating of these phases by the 40Ar 39Ar method allows us to time the progression of the oxidation front during chemical weathering. Finescale laser-heating 40Ar 39Ar dating of hypogene alunite and supergene jarosites allows us to precisely and accurately time hydrothermal alteration and subsequent supergene oxidation in Goldfield, Nevada. The results indicate that pervasive weathering occurred in the western USA during the Late Miocene (~ 10 Ma ago). Similar application of this technique to the study of weathering and laterite formation in West Africa indicates that the last pervasive oxidation event recorded in the weathering profile in this area also occurred in the Miocene (~ 13 Ma ago). The occurrence of a pervasive Mid to Late Miocene oxidation event recorded in these weathering profiles in the western USA and Africa, and also previously measured in Brazil and Chile, indicates that climatic conditions at that time were conducive to worldwide development of deep weathering sequences. Subsequent weathering processes have not been as pervasive as the Late Miocene event, indicating a general climatic transition to cooler, drier climates in most of the areas studied. Our results indicate that deep weathering profiles reflect past climatic conditions and may not be directly linked to the present climates.

Late Tertiary subsidence history of the southern Levant Margin, eastern Mediterranean Sea, and its implications to the understanding of the Messinian Event

The late Tertiary subsidence history of the southern Levant continental margin, situated in the southeastern Mediterranean Sea, was quantitatively analyzed. Paleodepth reconstruction across the margin off Ashdod suggests the existence of a deep basin in pre‐Messinian time which resembles the present one. This implies that, the deposition of the evaporites in the study area during the Messinian desiccation of the Mediterranean Sea occurred in a deep basin. The path of the tectonic subsidence of the basement since early Tertiary is generally smooth as expected from the nature of the thermal subsidence. The unconformity beneath the Messinian indicates erosion of 50–200 m at the coastal plain. In the Pliocene, the tectonic subsidence in the coastal plain and shelf area diverts from the expected thermal path and increases from 250 m to 450 m, respectively. In the Quaternary the rate of tectonic subsidence nearly resumed the predicted thermal subsidence. Sedimentation and subsidence rates decrease but are still higher than those of the pre‐Messinian. We suggest that the evolution of the southern Levant margin is most probably influenced by three main causes: (1) the Messinian event in late Miocene, (2) the deposition of large volumes of Nile derived sediments since the Pliocene, and (3) the flexural response of the lithosphere to the load from the Nile delta and/or from the uplift of the Judea Mountains (the western shoulder of the Dead Sea Transform). We interpret the latter to be the cause of the anomalous subsidence of the southern Levant margin during the Pliocene.

Late Miocene events in the Mediterranean as recorded by carbonate-evaporice relations

The Messinian Stage in the Mediterranean region is known mainly because of a major evaporitic event whose causes and global implications are still under discussion. Correlations between basinal evaporite-bearing series and marginal carbonate platforms allow for improvement of the classical depostional models, especially concerning the eustatic control of the environmental changes in the Mediterranean. These changes were controlled by the interplay of aperiodic and periodic factors: (1) tectonics, related to the relative motions of the African and Eurasian plates and resultant linear increase in the basin restriction; (2) sea-level fluctuations that alternately aggravated the restriction or allowed marine replenishment, and (3) climatic fluctuations that controlled the level of the Mediterranean during stages of isolation. The Messinian sedimentary succession reflects a typical sequence of progressive isolation: marine marls {yields} laminites {yields} transitional deposits {yields} evaporites {yields} lacustrine deposits. The first stage of the so-called 'salinity crisis' was characterized by a Mediterranean lowstand that resulted in erosion of former platforms and deposition of the lower evaporites. During the next stage, sea level rose (TB3.3 cycle) high enough to temporarily replenish the basin (cyclic upper evaporites, with development of stromatolite-rich deposits). Finally, the uppermost Messinian freshwater to brackish lacustrine deposits reflect both themore » cessation of sea-water input (maximum tectonic isolation, low sea level) and freshwater input related to increasing runoff.« less

Palaeorotation of the Troodos microplate, Cyprus

The Troodos ophiolite represents one of the best preserved fragments of ocean-floor crust that is exposed on land. As the extrusive series of the ophiolite retains a stable magnetization that is directed westward, the ocean crust is considered to have rotated anticlockwise through 90° since its formation in the Late Cretaceous1. To determine the timing of the rotation event, over 3,000 orientated samples have been collected from the ophiolite and from its in situ Turonian to Recent sedimentary cover. Here we report that pelagic chalks immediately overlying the highest extrusive lava units of the ophiolite complex give reliable magnetic vector directions indicating that at least 60° of rotation occurred before the Lower Eocene and that rotation was completed by the end of the Lower Eocene. Rotation cannot have occurred within a single late Miocene event, as reported previously2. Regional geological considerations support the rotation of only a small fragment of oceanic crust that was stranded adjacent to an active continental margin. In this tectonic setting the oblique consumption of oceanic crust beneath Troodos crust could provide the necessary driving force for tectonic rotation.