A Rb/Sr record of the weathering response to environmental changes in westerly winds across the Tarim Basin in the late Miocene to the early Pleistocene

AbstractVegetation inherited from a Pliocene subtropical climate evolved through obliquity oscillations and global cooling leading to modern conditions. An integrated, highly time-resolved record of pollen and stable isotopes (δ18O and δ13C of Globigerina bulloides) was obtained to understand vegetation responses to Early Pleistocene climate changes. Continental and marine responses are compared in the Central Mediterranean region with a particular consideration of environmental changes during anoxic events.Pollen data illustrate vegetation dynamics as follows: [1] development of mesothermic elements (warm and humid conditions); [2] expansion of mid- and high-altitude elements (cooler but still humid conditions); and [3] strengthening of steppe and herb elements (cooler and dry conditions). These successions correlate with precession. δ18O variations recorded by Globigerina bulloides define two cycles (MIS 43-40) related to obliquity. At northern low- to mid-latitudes, the pollen signal records temperature and wetness changes related to precession even during global climate changes induced by obliquity. This may result in unexpected increasing wetness during glacial periods, which has to be considered specific to the Central and Eastern Mediterranean region. Lastly, an analysis of anoxic events reveals that enhanced runoff is indicated by increasing frequency of the riparian trees Liquidambar and Zelkova.

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The Late Miocene-Early Pliocene out-of-sequence thrusting event: new insights into the tectonic evolution of the southern Apennines (Italy)

10.5194/egusphere-egu21-803 ◽

2021 ◽

Author(s):

Vitale Stefano ◽

Prinzi Ernesto Paolo ◽

Francesco D'Assisi Tramparulo ◽

Sabatino Ciarcia

Keyword(s):

Late Miocene ◽

Hanging Wall ◽

Early Pleistocene ◽

Normal Faults ◽

Southern Apennines ◽

Campania Region ◽

Early Pliocene ◽

Upper Miocene ◽

Thrust System ◽

Tectonic Windows

<p>We present a structural study on late Miocene-early Pliocene out-of-sequence thrusts affecting the southern Apennine chain. The analyzed structures are exposed in the Campania region (southern Italy). Here, leading thrusts bound the N-NE side of the carbonate ridges that form the regional mountain backbone. In several outcrops, the Mesozoic carbonates are superposed onto the unconformable wedge-top basin deposits of the upper Miocene Castelvetere Group, providing constraints to the age of the activity of this thrusting event. We further analyzed the tectonic windows of Giffoni and Campagna, located on the rear of the leading thrust. We reconstructed the orogenic evolution of this part of the orogen. The first was related to the in-sequence thrusting with minor thrusts and folds, widespread both in the footwall and in the hanging wall. A subsequent extension has formed normal faults crosscutting the early thrusts and folds. All structures were subsequently affected by two shortening stages, which also deformed the upper Miocene wedge top basin deposits of the Castelvetere Group. We interpreted these late structures as related to an out-of-sequence thrust system defined by a main frontal E-verging thrust and lateral ramps characterized by N and S vergences. Associated with these thrusting events, LANFs were formed in the hanging wall of the major thrusts. Such out-of-sequence thrusts are observed in the whole southern Apennines and record a thrusting event that occurred in the late Messinian-early Pliocene. We related this tectonic episode to the positive inversion of inherited normal faults located in the Paleozoic basement. These envelopments thrust upward crosscut the allochthonous wedge, including, in the western zone of the chain, the upper Miocene wedge-top basin deposits. Finally, we suggest that the two tectonic windows are the result of the formation of an E-W trending regional antiform, associated with a late S-verging back-thrust, that has been eroded and crosscut by Early Pleistocene normal faults.</p>

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Suidae Transition at the Miocene-Pliocene Boundary: a Reassessment of the Taxonomy and Chronology of Propotamochoerus provincialis

Journal of Mammalian Evolution ◽

10.1007/s10914-020-09521-w ◽

2020 ◽

Author(s):

Alessio Iannucci ◽

Marco Cherin ◽

Leonardo Sorbelli ◽

Raffaele Sardella

Keyword(s):

Late Miocene ◽

Central Italy ◽

Early Pleistocene ◽

Messinian Salinity Crisis ◽

Compelling Evidence ◽

Large Mammals ◽

Faunal Assemblages ◽

Paleoenvironmental Changes ◽

Species Diagnosis ◽

Eurasian Species

Abstract The Miocene-Pliocene (Turolian-Ruscinian) transition represents a fundamental interval in the evolution of Euro-Mediterranean paleocommunities. In fact, the paleoenvironmental changes connected with the end of the Messinian salinity crisis are reflected by a major renewal in mammal faunal assemblages. An important bioevent among terrestrial large mammals is the dispersal of the genus Sus, which replaced all other suid species during the Pliocene. Despite its possible paleoecological and biochronological relevance, correlations based on this bioevent are undermined by the supposed persistence of the late surviving late Miocene Propotamochoerus provincialis. However, a recent revision of the type material of this species revealed an admixture with remains of Sus strozzii, an early Pleistocene (Middle Villafranchian to Epivillafranchian) suid, questioning both the diagnosis and chronological range of P. provincialis. Here we review the late Miocene Suidae sample recovered from the Casino Basin (Tuscany, central Italy), whose taxonomic attribution has been controversial over the nearly 150 years since its discovery. Following a comparison with other Miocene, Pliocene, and Pleistocene Eurasian species, the Casino Suidae are assigned to P. provincialis and the species diagnosis is emended. Moreover, it is recognized that all the late Miocene (Turolian) European Propotamochoerus material belongs to P. provincialis and that there is no compelling evidence of the occurrence of this species beyond the Turolian-Ruscinian transition (MN13-MN14).

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Baffin Bay late Neogene palynostratigraphy at Ocean Drilling Program Site 645

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2019-0227 ◽

2021 ◽

Vol 58 (1) ◽

pp. 67-83

Author(s):

Aurélie M.R. Aubry ◽

Anne de Vernal ◽

Paul C. Knutz

Keyword(s):

Surface Waters ◽

Late Miocene ◽

Early Pleistocene ◽

Ocean Drilling Program ◽

Cold Surface ◽

Early Pliocene ◽

Baffin Bay ◽

Ocean Drilling ◽

Tundra Vegetation ◽

Late Neogene

Analyses of marine and terrestrial palynomorphs of Ocean Drilling Program (ODP) Site 645 in Baffin Bay led us to define a new biostratigraphical scheme covering the late Miocene to Pleistocene based on dinocyst and acritarch assemblages. Four biozones were defined. The first one, from 438.6 m below sea floor (mbsf) to 388 mbsf, can be assigned a late Miocene to early Pliocene age (>4.5 Ma), based on the common occurrence of Cristadinium diminutivum and Selenopemphix brevispinosa. Biozone 2, spanning from an erosional unconformity to a recovery hiatus, is marked by the highest occurrences (HOs) of Veriplicidium franklinii and Cristadinium diminutivum, which suggest an early Pliocene age >3.6 Ma (∼4.5 to ∼3.6 Ma). Biozone 3, above the recovery hiatus and up to 220.94 mbsf, corresponds to a late Pliocene or early Pleistocene age based on occurrences of Bitectatodinium readwaldii, Cymatiosphaera? icenorum, and Lavradosphaera canalis. Finally, between 266.4 and 120.56 mbsf, Biozone 4, marked by the HO of Filisphaera filifera, Filisphaera microornata, and Habibacysta tectata, has an early Pleistocene age (>1.4 Ma). Our biostratigraphy implies that horizon b1 of the Baffin Bay seismic stratigraphy corresponds to the recovery hiatus at ODP Site 645, which suggests a very thick Pliocene sequence along the Baffin Island slope. Dinocyst assemblages and terrestrial palynomorphs in our records indicate that the late Miocene and (or) early Pliocene were characterized by relatively warm coastal surface waters and boreal forest or forested tundra vegetation over adjacent lands. In contrast, the early Pleistocene dinocyst assemblages above the recovery hiatus indicate cold surface waters, while pollen data suggest reduced vegetation cover on adjacent lands.

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Phylogenetic analysis of the Baikalodrilus species flock (Annelida: Clitellata: Naididae), an endemic genus to Lake Baikal (Russia)

Zoological Journal of the Linnean Society ◽

10.1093/zoolinnean/zlz066 ◽

2019 ◽

Vol 187 (4) ◽

pp. 987-1015 ◽

Cited By ~ 1

Author(s):

Patrick Martin ◽

Gontran Sonet ◽

Nathalie Smitz ◽

Thierry Backeljau

Keyword(s):

Lake Baikal ◽

Environmental Changes ◽

Morphological Characteristics ◽

Early Pleistocene ◽

Species Flock ◽

Nominal Species ◽

Additional Species ◽

Endemic Genus ◽

Candidate Species ◽

Time Of Divergence

Abstract Lake Baikal is populated by an endemic genus of oligochaetes (Baikalodrilus), which currently comprises 24 morphospecies. The genus can be considered as a ‘species flock’. However, the validity of many species is questionable: the great similarity in their description and the lack of unequivocal diagnostic characters often lead species identification to an impasse. In order to clarify the systematics of this genus, we analysed two nuclear and two mitochondrial DNA markers of 40 Baikalodrilus specimens. DNA and morphological approaches are mostly congruent in suggesting ten candidate species, although two additional species are suspected. A reassessment of the taxonomic value of the morphological characteristics of Baikalodrilus suggests that there are few that can be used as distinctive, specific criteria in the genus. The association between candidate and nominal species remains problematic, except for three species identified prior to molecular analyses. Baikalodrilus trituberculum sp. nov. is described. Phylogenetic inferences suggests that the earliest split in Baikalodrilus and the time of divergence of most lineages corresponding to species are consistent with the hypothesis of a general rearrangement of the Baikal fauna, following major environmental changes due to a general cooling in the Early Pleistocene.

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Quaternary structural partitioning within the rigid Tarim plate inferred from magnetostratigraphy and sedimentation rate in the eastern Tarim Basin in China

Quaternary Research ◽

10.1016/j.yqres.2013.10.018 ◽

2014 ◽

Vol 81 (3) ◽

pp. 424-432 ◽

Cited By ~ 4

Author(s):

Hong Chang ◽

Zhisheng An ◽

Weiguo Liu ◽

Hong Ao ◽

Xiaoke Qiang ◽

...

Keyword(s):

Tarim Basin ◽

Sedimentation Rate ◽

Structural Evolution ◽

Early Pleistocene ◽

Tectonic Activity ◽

Geological Time ◽

Geological Time Scale ◽

Abrupt Decrease ◽

Accommodation Space ◽

Pleistocene Climate

AbstractIt has been proposed that within the Tarim Basin tectonic activity has been limited since Triassic time. However, on the basis of magnetostratigraphy from the eastern Tarim Basin, which defines the chronology of sedimentation and structural evolution of the basin, we show that the basin interior has been uplifted and partitioned during Quaternary. The magnetostratigraphy was constructed from 2228 samples that yielded acceptable inclination values. Characteristic remnant magnetization (ChRM) with both normal (N1–N11) and reversed (R1–R11) polarity was isolated by thermal demagnetization. The data correlate best with polarity chrons C3r to C1n, which range from 5.39 Ma to recent on the geological time scale 2004 (GTS2004). An abrupt decrease in the sedimentation rate is observed at 1.77 Ma in the Ls1 core. This change does not overlap with known Pleistocene climate-change events. We attribute this sedimentation rate decrease to a structurally controlled local decrease in accommodation space where basin basement uplifts occur. This period of sedimentary environmental change reveals that structural partitioning in the basement of the Tarim Basin occurred since ~ 1.77 Ma, and we speculate that tilting of the Southeast Uplift (a sub-basin unit) within the Tarim Basin began in early Pleistocene time.

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