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The Haiyuan-Liupan Shan delimits the northeastern margin of the Tibetan Plateau. We present the integrated results of new stratigraphic investigations, apatite fission track analyses, and related thermal history modeling tied to the structural fabric of this region. These constraints provide insight into the timing of northward propagation of the plateau with (1) local relief creation and enhanced erosion in the latest Jurassic to earliest Cretaceous, representing the local element of a complex, regional, far-field deformation response to the Lhasa-Qiangtang collision with the south Asian margin; (2) evidence for likely Late Cretaceous exhumation, but this is uncertain given the regional sedimentary gap that exists across this interval; (3) Eocene relief generation as a first likely response to far-field effects of the India-Asia collision and related to wider regional events recognized in this part of northwestern China; and (4) the latest deformation episode propagating strongly into the Haiyuan-Liupan Shan in the early Miocene, increasing in intensity in the later Miocene and possibly again in the Quaternary. The diachronous nature of the apparent responses to distant plate-boundary events demonstrates that structural preconditioning on its own is inadequate to account for this far-field deformation, suggesting that subcrustal tectonic architecture may play a role in the transfer of stress north of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Detailed mapping and new structural observations on Kythera demonstrate that there is a major detachment fault, here termed the Potamos detachment fault (PDF), exposed on the northern part of the island and bordering the domed structure of a metamorphic core complex. The detachment forms the contact of contrasting metamorphic and nonmetamorphic units, and both ductile and brittle structures are found, related to its extensional development. The earliest Potamos mylonites, as well as some other early ductile structures near the mapped detachment fault, indicate initiation of the PDF under NE-trending extension, in mid- to late Miocene time. Later ductile, ductile-brittle, and some brittle structures in the metamorphic unit near the detachment indicate (in contrast) a significant NW-SE extension along the forearc ridge. The younger brittle structures indicate return to NE-SW extension. Late Miocene-Pliocene strata cover the detachment unconformably and are affected only by the late faults. Trench rollback and slab retreat of the subducting African lithosphere in the late Miocene requires expansion and increased curvature of the Hellenic (Crete-Peloponnese) forearc ridge. Differential movement between and vertical axis rotation of segments of the forearc ridge may have localized along-arc stretching. Cross-ridge strike-slip faults may be linked to the later parts of this process. Evidence of young E-W dextral faulting is seen in northern Kythera outcrops, related to a significant submarine fault of this type located between Kythera and the Peloponnese. [ABSTRACT FROM AUTHOR]

Rhizomes with tubers of Equisetum cf. pratense Ehrhart are described for the first time from the late Miocene of Lühe, Yunnan Province, southwestern China. The rhizomes consist of distinct nodes and internodes. The nodes bear one to four bunches of tubers (two to four tubers per bunch). The tubers are elliptical, rounded, ovate, or spindle shaped, and the most distal is mucronate. The occurrence of E. cf. pratense would indicate a wet habitat, and the presence of rhizomes with tubers implies that burial occurred during the late fall or winter, assuming that the fossil and its nearest living relative have similar climatic tolerances and phenology. These finds, combined with the presence of thermophilous genera Cyclobalanopsis, Castanopsis, and Liquidambar and hygrophilous elements Alnus and Taxodioxylon, indicate a warm and humid subtropical climate at Lühe in the Miocene. [ABSTRACT FROM AUTHOR]

Well-preserved legume fruits and associated leaflets are described from the middle Miocene Shanwang Formation of Shandong Province, eastern China. They are assigned to the extant temperate genus Wisteria (Leguminosae, Papilionoideae), which is a deciduous climbing vine native to eastern Asia and eastern North America. Wisteria is one of many genera with an eastern Asian and eastern North American disjunct distribution. Based on fruit and leaflet architecture, two new organ species are established. Wisteria shanwangensis sp. nov. is proposed for the fossil fruits, which are similar to fruits of extant Wisteria sinensis and are the only confirmed occurrences of Wisteria fruit fossils from China. Wisteria taoiana sp. nov. is proposed for the co-occurring leaflets. These two new taxa may represent the same Wisteria population in the Miocene Shanwang flora. Based on fossil records, Wisteria had a more northern distribution in the Neogene of the Northern Hemisphere than today, representing an archaic boreal lineage during the Miocene. We support the recognition of an independent tribe Wisterieae. Wisteria fossils have frequently been described in Neogene floras of China, Japan, and far eastern Russia, but not North America, which implies that eastern Asia may have been its initial center of diversification earlier in the Cenozoic. [ABSTRACT FROM AUTHOR]

An infructescence from the Middle Miocene of Clarkia, Idaho, conforms to the extant Asian trochodendraceous genus Tetracentron. The infructescence of Tetracentron remberi sp. n. bears numerous sessile fruits in a helical arrangement. The fruits are thin-walled capsules with two pairs of greatly recurved hornlike styles that protrude basally from the lateral margins of the fruit. The adaxial surface of the style is papillose and is covered with tricolpate pollen that also corresponds morphologically to that of extant Tetracentron. The new fossil shows that Tetracentron, like the related Trochodendron, was formerly established in western North America, whereas both of these genera are now endemic to eastern Asia. Although these two genera were sympatric in the Miocene of Clarkia, Idaho, they have nonoverlapping geographic ranges today. [ABSTRACT FROM AUTHOR]

New paleomagnetic data from southern Mexico provide a magnetostratigraphic framework to correlate mammal-bearing continental sections of the Suchilquitongo Formation to the Early Miocene part of the geomagnetic polarity time scale. A total of 127 paleomagnetic samples were collected from 40 horizons belonging to two sections. The sequence is characterized by a succession of cream to light pink to gray, thin- to medium-bedded tuffaceous sandstones and siltstones, partly silicified limestones, and a dominantly light green ignimbrite deposited in a fluviolacustrine environment. Remanent magnetization generally has been characterized by two components, a present-day field component with low-unblocking temperatures up to 350°C and a characteristic component with unblocking temperatures up to 580°–610°C. The characteristic component is interpreted as primarily based on antipodal populations of remanence data. Six sites at the top of the section (inclination = 40.5°, declination = 11.3°, α[sub 95] = 1.4, and Κ = 471) have a mean paleomagnetic direction rotated clockwise about 17° with respect to the expected Miocene direction derived from the North American polar wander curve (inclination = 354°, declination = 30°). According to bio-chronologic age, the magnetostratigraphic results from the mammal-bearing sedimentary-type section in the Suchil-quitongo area can be correlated with chron C5Dn-C5Cn3n at approximately 17.61­16.55 Ma. An age of about 17 Ma is proposed for the fossiliferous level, corresponding to an Early Miocene age. [ABSTRACT FROM AUTHOR]

Paired apatite fission track and U-Th/He dates provide the first Late Cenozoic cooling ages for the northern Tien Shan. These data clearly argue for pulsed deformation since the Late Miocene, with early (10-11 Ma) and late (0-3 Ma) intervals of rapid exhumation separated by an extended interval of much slower rates. By integrating these bedrock cooling rates with shortening estimates derived from a balanced section, detrital cooling ages, and geomorphological estimates of conditions before deformation, we reconstruct a four-stage history of range growth and exhumation. Following ∼100 m.yr. of tectonic quiescence, abruptly accelerated rock uplift, exhumation, and cooling in the Kyrgyz Range commenced at ∼11 Ma with rates exceeding ∼1 km/m.yr. During the subsequent 7 m.yr., deformation and cooling rates decreased three- to sixfold before accelerating by comparable amounts during the past 3 m.yr. Since mid-Miocene times, the surface elevation of the Kyrgyz Range has increased ∼2 km, consistent with the reconstructed magnitude of crustal shortening (∼11 km) and thickening (∼12 km) across the range. The highly pulsed deformation rates indicate that the locus of deformation probably shifted repeatedly within the Tien Shan from the Miocene to present. Even at their most rapid, Cenozoic shortening rates in the Kyrgyz Range were equivalent to only 10%-20% of the modern geodetic convergence rate across the entire Tien Shan. This requires several ranges within the Tien Shan to have deformed simultaneously since the Middle Miocene, a situation analogous to the distributed shortening seen today. [ABSTRACT FROM AUTHOR]

Presents the results of a study which synthesized the volcaniclastic deposits from the Rusinga and Kisingiri groups with the volcanic history deciphered from the exposed core and flanks of the Miocene Kisingiri volcano in southwest Kenya. Interpretation of volcanic eruptive styles; Cycles of doming and eruption; Alluvial response to pyroclastic volcanism.

Presents geochemical data for commingled rocks of the Miocene Mount Perkins pluton in northwestern Arizona. Isotopic disequilibrium; Regional geology; Geology of the Mount Perkins pluton; Geochemistry.

Examines apatite fission track ages and mean etchable track lengths for sandstones from the Breathitt Formation in Kentucky and Tennessee. Evidences of an unroofing of the southern Appalachian Basin during the Miocene Period; Shift from chemical to mechanical weathering due to drier conditions resulting to increased erosion rates.