Titanosaur (Dinosauria: Sauropoda) Osteoderms from the Maastrichtian of Uberaba, Minas Gerais State, Brazil

Titanosaur remains are common findings at the paleontological site of Peirópolis in Uberaba. Among those remains, two osteoderms referred to titanosaur sauropods were reported. Both dermal bones share many features, such as the coarse texture, parallel ventral grooves, lack of the cingulum and presence of a ventral ridge (crest). Armored titanosaurs had wide distribution in the Upper Cretaceous, and have been reported from Argentina, Brazil, France, Madagascar, Malawi, Romania and Spain. In the present work we describe and compare the Brazilian titanosaur osteoderms found thus far.     

Biotic effects of late Maastrichtian mantle plume volcanism: implications for impacts and mass extinctions

During the late Maastrichtian, DSDP Site 216 on Ninetyeast Ridge, Indian Ocean, passed over a mantle plume leading to volcanic eruptions, islands built to sea level, and catastrophic environmental conditions for planktic and benthic foraminifera. The biotic effects were severe, including dwarfing of all benthic and planktic species, a 90% reduction in species diversity, exclusion of all ecological specialists, near-absence of ecological generalists, and dominance of the disaster opportunist Guembelitria alternating with low O₂-tolerant species. These faunal characteristics are identical to those of the K–T boundary mass extinction, except that the fauna recovered after Site 216 passed beyond the influence of mantle plume volcanism about 500 kyr before the K–T boundary. Similar biotic effects have been observed in Madagascar, Israel, and Egypt. The direct correlation between mantle plume volcanism and biotic effects on Ninetyeast Ridge and the similarity to the K–T mass extinction, which is generally attributed to a large impact, reveal that impacts and volcanism can cause similar environmental catastrophes. This raises the inevitable question: Are mass extinctions caused by impacts or mantle plume volcanism? The unequivocal correlation between intense volcanism and high-stress assemblages necessitates a review of current impact and mass extinction theories.     

Glacial meltwater impounding: Evidence from the late Quaternary glaciogenic sediments in the Sangla valley, district Kinnaur, Himachal Pradesh, India

Sangla valley is situated at an altitude of ~ 3500 m above mean sea level and lies in the Kinnaur district of Himachal Pradesh. It is fed by river Baspa, a tributary of river Sutlej, that entrenches through the Quaternary glaciogenic deposits before emerging out of the valley and joining the river Sutlej at Karcham. The unstratified to stratified glaciogenic deposits consist of large boulders to fine silt and are classified into four major depositional facies on the basis of sedimentary texture and depositional environment. The facies — basal conglomerates, debris flow, water/sheet flow and laminites — represents the change in the environment of deposition from glaciofluvial to lacustrine and also the extent of the glacier to the valley floor during late Quaternary.     

中国天山-北山地区晚古生代岩石地层系统厘定及沉积环境分析

通过编制天山一北山地区地质图对该区晚古生代岩石地层系统进行了重新厘定，并初步分析了这一地区晚古生代不同阶段的沉积环境，论述了晚古生代时天山与北山应属于同一沉积构造区的地层结构与沉积特征证据。     

Late Pleistocene and Holocene climate and geomorphic histories as interpreted from a 23,000 C yr B.P. paleosol and floodplain soils, southeastern West Virginia, USA

Field, micromorphological, pollen, whole soil (XRF), and stable isotope geochemical methods were used to evaluate the latest Pleistocene to Holocene climate record from a floodplain-terrace system in southeastern West Virginia. A late Pleistocene (22,940 ± 150 ¹⁴C yr B.P.) silt paleosol with low-chroma colors formed from fluviolacustrine sediment deposited during the last glacial maximum (Wisconsinan) and records a cooler full-glacial paleoclimate. Fluvial gravel deposited between the latest Pleistocene and earliest Holocene (prior to 6360 ± 40 ¹⁴C yr B.P.) was weathered in the middle Holocene under warmer, drier climate conditions, possibly correlated with the Hypsithermal and Altithermal Events of the eastern and southwestern United States, respectively. The glacial to interglacial climate shift is recorded by: (1) changes from a poorly drained landscape with fine-textured soil, characterized by high organic C and redoximorphic features related to Fe removal and concentration, to a well-drained, coarse-textured setting without gley and with significant argillic (Bt) horizon development; (2) changes from a high Zr and Ti silt-dominated parent material to locally derived, coarse fluvial gravels lower in Zr and Ti; (3) a shift from dominantly conifer and sedge pollen in the paleosol to a modern oak/hickory hardwood assemblage; and (4) a shift in δ¹³C values of soil organic matter from −28‰ to −24‰ PDB, suggesting an ecosystem shift from cooler, C3-dominated flora to one that was mixed C3 and C4, but still predominantly composed of C3 plants. A root-restrictive placic horizon developed between the late Pleistocene silt paleosol and the overlying fluvial gravel because of the high permeability contrast between the two textures of soil materials. This layer formed a barrier that effectively isolated the Pleistocene paleosol from later Holocene pedogenic processes.     

Late Glacial and Holocene Palaeoenvironmental Changes in the Rostov-Yaroslavl’ Area, West Central Russia

Three lake sediment sequences (lakes Nero, Chashnitsy, Zaozer’e) from the Rostov-Jaroslavl’ region north of Moscow were studied to provide information on palaeoclimatic and palaeoenvironmental changes during the past 15,000 cal yr. The multi-proxy study (i.e., pollen, macrofossils, mineral magnetic measurements, total carbon, nitrogen and sulphur) is chronologically constrained by AMS ¹⁴C measurements. Lake Nero provided the longest sedimentary record back to ca. 15,000 cal yr BP, while sediment accumulation began around ca. 11,000 cal yr BP in the two other lakes, possibly due to melting of permafrost. Limnic plant macrofossil remains suggest increased lake productivity and higher mean summer temperatures after 14,500 cal yr BP. While the late glacial vegetation was dominated by Betula and Salix shrubs and various herbs, it appears that Betula sect. Albae became established as early as 14,000 cal yr BP. Major hydrological changes in the region led to distinctly lower lake levels, starting 13,000 cal yr BP in Lake Nero and ca. 9000 cal yr BP in lakes Chashnitsy and Zaozer’e, which are situated at higher elevations. These changes resulted in sedimentary hiatuses in all three lakes that lasted 3500–4500 cal yr. Mixed broad-leaved – coniferous forests were widespread in the area between 8200 and 6100 cal yr BP and developed into dense, species-rich forests between 6100 and 2500 cal yr BP, during what was likely the warmest interval of the studied sequences. Agricultural activity is documented since 500 cal yr BP, but probably began earlier, since Rostov was a major capital by 862 A.D. This apparent gap may be caused by additional sedimentary hiatuses around 2500 and 500 cal yr BP.     

黄河源区冰楔假型群的发育及其古气候意义*

在黄河源区两岸的第二级阶地砂砾层和基座中发现了两种不同形态的冰楔假型群。一种是发育在阶地砂砾石层的冰楔假型,其特点宽而浅,底部边界呈圆滑锅状,深约0.5~0.9m,宽0.8~1.4m;另一种是发育在第二级阶地基座的基岩中,以窄深倒三角状为特点,其底部尖锐,深约0.7~2.0m,宽为0.3~1.0m。前者形成于全新世中期(5.69±0.43kaB.P.,5.43±0.41kaB.P.),后者形成于末次冰期的冰消期(13.49±1.43kaB.P.)。另外,还在洪积的砂砾石层中发现了规模较大的冻融褶皱(宽3~4m),其时代晚于39.83±3.84kaB.P.,也是末次冰期的产物。根据冰楔假型的对比研究,在全新世的中期(约5.5kaB.P.前后)和冰消期,黄河源区的降温幅度达6~7℃。尤其值得注意的是全新世中期的冰楔假型形成,表明了大暖期气温的不稳定性。     

SHRIMP zircon U-Pb age and significance of Early Paleozoic volcanic rocks in East Kunlun orogenic belt, Qinghai Province, China

A great deal of practical data in recent years have proved that the East Kunlun orogenic belt and even the China central orogenic belt are complex orogenic belts that underwent polycycle orogenic evolvement[1―7]. Each orogenic cycle has left a compositional print, the multi-period ophiolites[4―6] and various types of tec-tono-magmatic production in the same orogenic belt. There is a suite of shallow metamorphic volcanic rocks in the Nuomuhong area in the east part of the East Kunlun orogen…     

Paleozoic rocks in infrastructure of the metamorphic core, the Greater Caucasus Main Range zone

Granitoid orthogneisses and migmatites are widespread in the lower, deeply metamorphosed gneiss-migmatite complex of the pre-Alpine basement (infrastructure) exposed within northern part of the Greater Caucasus Main Range zone. Like the other rocks of the complex, they have been traditionally attributed to the Proterozoic, but the U-Pb dating revealed the Late Paleozoic age of migmatites and Devonian age of orthogneiss protolith. Bodies of blastomylonitic apogranite gneisses, which are confined to boundary between gneiss-migmatite complex and overlying Makera Complex of supracrustal rocks, turned out to be of the Late Paleozoic age as well. The dating results suggest synchronism and, apparently, genetic interrelations between the high-T/low-P metamorphism and granite formation in the Main Range zone of the Greater Caucasus.     

The Alpine evolution of the Southern Alps around the Giudicarie faults: A Late Cretaceous to Early Eocene transfer zone

Data supporting relevant Late Cretaceous–Early Eocene sinistral displacement along the Giudicarie fault zone and a minor Neogene dextral displacement along the Periadriatic lineament are discussed. The pre-Adamello structural belt is present only in the internal Lombardy zone, located W of the Adamello massif. This belt is unknown in the Dolomites and surrounding areas located to the E of the Giudicarie lineament. Upper Cretaceous–Early Eocene thick syntectonic Flysch deposits of Lombardy and Giudicarie are well preserved along the southern and eastern border of the pre-Adamello belt (S-vergent Alpine orogen). Towards the E, in the Dolomites and in the Carnic Alps and external Dinarides, only incomplete remnants of Flysch deposits, Aptian–Albian and Turonian–Maastrichtian in age, are present. They can be considered as equivalent to those of Lombardy and Giudicarie formerly in connection to each other along the N-Giudicarie corridor. To the S, the syntectonic Flysch deposits are laterally replaced by the calcareous red pelagites of the Scaglia Rossa and by the carbonate shelf deposits of the Friuli (to the E) and Bagnolo (to the S) carbonate platforms. The different location in the southern structural accretion of the eastern and western opposite blocks (the Dolomites versus the pre-Adamello belt) can be related to the Cretaceous–Eocene convergence. In this frame, the N-Giudicarie fault has been considered as part of a former transfer zone, which produced the sinistral lateral displacement of the Southern Alps front for an amount of some 50 km. During the Late Eocene to Early Oligocene the transfer zone was mostly sealed by the Paleogene Adamello batholith. Oligocene to Neogene compressional evolution inverted the N-Giudicarie fault into a backthrust of the Austroalpine units over the South-Alpine chain.