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Rift-basins are the shallow effects of lithosphere-scale extensional processes often producing polyphase faulting. Their sedimentary evolution depends on the mutual interplay between tectonics, climate, and eustasy. Estimating the role of each factor is generally a challenging issue. This paper is focused on the tectono-sedimentary evolution of the Neogene Siena-Radicofani Basin, a polyphase structural depression located in the inner Northern Apennines. Since Miocene, this basin developed after prolonged extensional tectonics, first as a bowl-shaped structural depression, later reorganized into a half-graben structure due to the activation of high-angle normal faults in the Zanclean. At that time the basin contained coeval continental and marine settings controlled by the normal faulting that caused the development of local coarse-grained depositional systems. These were investigated to: (i) discriminate between the influences of tectonics and climate on sedimentation patterns, and (ii) provide detailed time constraints on fault activity. The analysed successions were deposited in an interval between 5.08 and 4.52 Ma, when a climate-induced highstand phase occurred throughout the Mediterranean. However, evidence of local relative sea-level drops is registered in the sedimentary record, often associated with increased accommodation space and sediment supply. Such base-level fluctuations are not connected to climate changes, suggesting that the faults generally control sedimentation along the basin margins. [ABSTRACT FROM AUTHOR]

The Middle Triassic epoch is the key to understanding the environment changes after the Permian–Triassic mass extinction. The Anisian Badong Formation is a carbonate and siliciclastic succession deposited on the Yangtze Platform, Upper Yangtze Block. In this paper, we use facies analysis combined with sequence stratigraphy of the Badong Formation in the Nashuixi section, Yangtze Block, to discuss the Anisian relative sea-level changes. Microfacies analyses were used to define ten microfacies in four depositional facies zones (tidal flat, restricted platform, restricted to open platform, and open platform) indicating an epeiric platform depositional environment. The lowstand, transgressive, and highstand systems tracts and two sequences were identified. Sequence stratigraphy interpretations indicate that relative sea-level at Nashuixi experienced two rises in the Middle Anisian, which is correlated with those in the Yangtze Block, confirming that sea-level changes during the Anisian were of eustatic origin. However, a distinct regression at Nashuixi occurred in the late Bithynian to IIIyrian while the global sea-level rose, which is likely to be caused by interference from regional tectonics during IIIyrian. The carbon and oxygen isotopic shifts in the Nashuixi section exhibit two negative-values stage in the time near end of Aegean and early Pelsonian, which is well correlated with the global typical sections, indicating two middle Anisian warming events. Our study indicated that the relative sea-level at Nashuixi was controlled by global sea-level change and regional tectonics (Indosinian Orogeny), and the C and O isotopes records respond to global climate change. [ABSTRACT FROM AUTHOR]

Deserts and sandylands that are located in the semi-arid and arid regions in the middle latitudes of the Northern Hemisphere are usually regarded as environmentally sensitive change belts which respond to global climatic change. In northern China, activation or immobilization of sand dunes is mainly influenced by humid and dry variation and is related to stronger or weaker Asian monsoons. In this paper, the history of Holocene millennial-scale climatic and environmental change is reconstructed by the systematic analysis of the geochemical element contents and parameters, along with the OSL and C chronologies, from the different lithologies of the palaeosol-aeolian sand sequence in the south-eastern Mu Us Desert, northern China. Our results indicate that the region was dominated by a dry climate with intensive aeolian activity before 7.2 ka BP, and there was an optimal humid climate and fixed desert in 7.2-4.6 ka. Afterwards, the dune fields became mobile again as the effective humidity declined. Additionally, six dry events were discovered with times of ~7.2, 7.0-6.8, 6.6-5.7, 4.6-4.1, 3.7-3.5, and 3.3-2.5 ka, which were not only coincident with the intervals of millennial-scale weaker Asian summer monsoons, but also accordant with the cold events evidenced in the ice cores and deep-sea deposits of the high latitudes in the Northern Hemisphere. In general, the Holocene climatic and environmental changes had the characteristics of the 'monsoonal mode' and 'abrupt millennial-scale oscillation' in the Mu Us Desert. [ABSTRACT FROM AUTHOR]

The lower and middle Miocene sediments of the North Croatian Basin belong to the south-western margin of the Central Paratethys. The timing of the first marine transgression is of great importance for understanding the palaeogeography of the Paratethys. Based on micropalaeontological analyses (calcareous nannoplankton, planktonic and benthic foraminifera, ostracods and palynomorphs), we determined the local-to-regional palaeoecological characteristics of Miocene deposits from south-eastern Medvednica Mt., as well as identifying global-to-regional events. Marine index fossils point to calcareous nannofossil Zones NN4 and NN5 (equivalent to the Mediterranean MNN4 and MNN5) and planktonic foraminiferal Zones M5 and M6 (Mediterranean MMi4). The lowermost part of the investigated marls was generally deposited on a mid-outer shelf––which received an input of fine-grained clastic material––in a sedimentary basin that had a restricted connection with the Mediterranean during the Mi2 climatic event. In addition, an important nannofossil bioevent––the paracme of Sphenolithus heteromorphus––in the Mediterranean was recorded in the lower part of the section, close to the Karpatian/Badenian boundary (identified based on the Coccolithus pelagicus/Reticulofenestra minuta shift), which supports other evidence for a shift in global climate change. Warm-water ostracods (Paijenborchella iocosa) and benthic foraminifera (Glabratella and Pararotalia) in the middle part of the sequence indicate a warmer climate, an open connection with the Mediterranean Sea (and, indirectly, with the Indian Ocean), associated with the third-order TB 2.3 relative sea-level cycle of the early Badenian transgression. The upper part of the sequence (in the Plaz outcrop) contains coarsening–upwards cycles, consisting of silty and sandy sediments, sandstones and calcarenites, indicating a regional regressive phase close to the M5/M6 planktonic foraminifera zonal boundary (15.1 Ma). Infaunal benthic foraminifera species were replaced by shallow, warm-water benthic foraminifera (Elphidium, Biasterigerina, Ammonia, Amphistegina) and ostracods with ornamented shells, which occurred in tandem with shallow, warm-water R. minuta, more proximal dinocysts, coralline red algae, echinoids and bryozoans, all indicating the Middle Miocene Climatic Optimum (MMCO), with sedimentation taking place in a middle- to inner-shelf environment. A tuff layer is present at the top of the sequence; it contains planktonic foraminifera (Globigerina tarchanensis, G. subcretacea, Globigerinita uvula), suggesting a redeepening and influence of the TB 2.4 sea-level cycle. [ABSTRACT FROM AUTHOR]

The interaction of tectonics and climate is considered the main determining factor in the development of different depositional systems (from aeolian to alluvial to lacustrine environments) in intermontane basins. The role of these allogenic controls forces the paleoenvironmental evolution of intermontane basins. In this work, we analyse a Miocene (15–11.5 Ma) synorogenic and volcaniclastic succession of an intermontane basin of the Northpatagonian Andean foreland region. The evolution of the infill was synchronously developed with the Andean uplift and, consequently, with the rain shadow effect generation. A detailed sedimentological and stratigraphic analysis allowed to define eight facies associations, which are lateral and vertical stacked into three different depositional systems. Alluvial depositional systems occurred between 15 and 14.6 Ma, deltaic–lacustrine systems took place between 14.6 and 12.75 Ma, and a reinstatement of alluvial depositional systems occurred between 12.75 and 11.5 Ma. These variations in the depositional systems were contrasted with synchronous tectonic and climatic changes and some considerations about the role of these allogenic controls were discussed to unravel their influence on the paleoenvironmental evolution. The onset of the deltaic–lacustrine depositional system was related to a tectonic reconfiguration whereas the reinstatement of the alluvial depositional system was associated with a regional aridization. Additionally, since the composition of the succession is mainly volcaniclastic, the explosive volcanism is considered and discussed as an extra allogenic control on the evolution of the basin. [ABSTRACT FROM AUTHOR]

The temperature fluctuations in the Eocene climate are one of the most mysterious phenomena in Cenozoic climate dynamics, and they severely affected the marine and terrestrial biospheres. However, quantitative and comprehensive temperature reconstructions for middle Eocene climatic variations remain limited due to fragmentary paleotemperature records, especially in the easternmost proto-Paratethys sea (Kuqa Depression), where traditional paleoclimatic proxies are restricted by the occurrence of extensive and thick evaporite deposits. In this study, we reconstruct middle Eocene sea surface temperatures (SST) and even air temperatures in the Kuqa Depression based on 584 homogenization temperatures (Th) for fluid inclusions in cumulate and chevron halite crystals from cores DW1 and KL4. The Th values from core DW1 have ranges of 10.5–45.7 °C, the Th values from core KL4 have ranges of 12.6–35.2 °C. The measured Th values are mainly concentrated within 20–30 °C, and an average Th value of 25.6 °Crepresents the SST and is consistent with previous coeval research results. The highest recorded Th is 45.7 °C, clearly representing local hot climate conditions. The average and maximum SST in the middle Eocene Kuqa Depression are cooled by 5.2–11.3 °C and 6.5–14.1 °C, respectively. The cooling trend in the Kuqa Depression occurred in response to global and Tethyan realm cooling in the middle Eocene, but the cooling amplitude in the study area was greater than that of the global climate. The Th data for primary halite fluid inclusions can effectively and quantitatively track past environmental and climatic variations, especially in evaporitic basins where traditional paleoclimatic proxies are often not available. [ABSTRACT FROM AUTHOR]

We report the results of a multidisciplinary study of the early Permian (Artinskian–Kungurian) Sotres Formation of northern Spain integrating sedimentology, palaeosols, mineralogy, stable isotopes, palynology, ichnology and tectonics. This continental unit was deposited in the near-equatorial Peri-Tethyan Cantabrian Basin. Having developed in the middle of the Variscan fold belt, it is preserved within the present-day Cantabrian Mountains. Three subunits are recognised in the Sotres Formation based on tectono-stratigraphic and sedimentological data: a lower alluvial subunit, a middle carbonate lacustrine subunit, and an upper palustrine subunit. Multidisciplinary results reveal an upward change in climate from humid-subhumid conditions at the base of the formation (Artinskian) to semi-arid and arid conditions at the top of the formation (Kungurian), which may reflect global deglaciation near the end of the Late Paleozoic Ice Age and a probable northward migration of the Intertropical Convergence Zone. This general upward warming/drying climate trend was interrupted by a short-lived interval of monsoon conditions in mid-Kungurian times, which may have coincided with a pulse of global cooling. Our findings are in agreement with the climate trends reported for other central Pangaean basins. Rising CO2 levels may have been a driving factor for climate transition during this time interval. However, in our study area, which lies within the active central Variscan orogenic belt, tectonic conditions must have also played a role in driving climate change. [ABSTRACT FROM AUTHOR]

Late Quaternary paleoclimate records from arid regions help us understand the response of ecological systems to natural climate change to place recent changes in a longer-term perspective. In this research, a biogeochemical analysis of a sediment core from Lake Ebinur, Xinjiang, allowed us to infer the climate and environmental changes in the late Quaternary in arid northwestern China. The combined lipid biomarkers and bulk biogeochemical properties (TOC, δ13Corg) revealed moderately wet conditions from 34 to 28 ka, favoring the growth of terrestrial vegetation. The subsequent period from 28 to 13 ka was dominated by aquatic plants, algae and microbes, indicating cold and dry conditions. Ameliorated regional moisture conditions were deduced from the higher carbon preference index (CPI) and from δ13Corg values from 13 to 3.6 ka. The optimum climate conditions occurred from 9 to 5 ka. Several climatic events also exist in the Lake Ebinur records with a wide distribution into other regions. Our biogeochemical-based paleoclimate and paleoenvironmental reconstruction is generally synchronous with sedimentary records from mid-latitude Eurasia and the NGRIP ice core record, which probably has a certain linkage with the 45°N summer insolation. We propose that summer insolation conditions in the northern hemisphere might have an impact on the climate and environmental changes in arid northwestern China in the late Quaternary. [ABSTRACT FROM AUTHOR]

Understanding the change in the climate at the regional scale during the industrial period is essential for future climate projections. Among various proxy methods, temperatures from thermally conductive boreholes offer a direct method of determination of surface temperatures changes in time. In this study, we use temperature-depth data from six boreholes in western and central Anatolia regions of Turkey, and present reconstructions of the surface temperatures during the last century. The boreholes are located in rural areas where urban heat island effects are minimal. Regionally averaged GST models give cooling of 0.33 °C and 0.42 °C between 1900 and 1990, and warming of 1.47 °C and 1.66 °C between 1990 and 2010, for the western and central Anatolian sites, respectively. The overall changes in the surface temperatures since the beginning of the twentieth-century are calculated to be + 1.14 °C and + 1.13 °C, in each region. The instrumental SAT records in these regions which are available from 1950 show a general agreement with the GST models. The rate of recent warming since the early 1990's is calculated to be 5.7 °C per 100-year for both regions. This value is within the range proposed by regional climate projections for the Eastern Mediterranean region. [ABSTRACT FROM AUTHOR]

Using a previously published temperature log of the 2363-m-deep borehole Hunt well (Alberta, Canada) and the results of its previous interpretation, the new reconstructions of ground surface temperature and surface heat flux histories for the last 30 ka have been obtained. Two ways to adjust the timescale of geothermal reconstructions are discussed, namely the traditional method based on the a priori data on thermal diffusivity value, and the alternative one including the orbital tuning of the surface heat flux and the Earth's insolation changes. It is shown that the second approach provides better agreement between geothermal reconstructions and proxy evidences of deglaciation chronology in the studied region. [ABSTRACT FROM AUTHOR]

The analysis of the warming/cooling patterns from inversion of 94 well temperature logs for the study area of Central Canada shows very high variability (−1 to 3 °C). Analysis of the warming/cooling patterns in last 2-3 centuries indicates that warming has not affected the whole study area and some surface areas have significantly cooled. Regions of large cooling as well as regions of large warming are apparent. Largest cooling is observed in the NE part of the study area while large warming is observed in the area south-east of it in a ridge running NW-SE slightly north of Great Lakes. These patterns go against patterns of land development which is an unlikely factor forcing these regional scale changes derived mainly from the well sites chosen to be in remote and forested areas. [ABSTRACT FROM AUTHOR]

This work examines the causal relationship between the value of the ground-air temperature offset and the precipitation changes for monitored 5-min data series together with their hourly and daily averages obtained at the Sporilov Geophysical Observatory (Prague). Shallow subsurface soil temperatures were monitored under four different land cover types (bare soil, sand, short-cut grass and asphalt). The ground surface temperature (GST) and surface air temperature (SAT) offset, Δ T(GST-SAT), is defined as the difference between the temperature measured at the depth of 2 cm below the surface and the air temperature measured at 5 cm above the surface. The results of the Granger causality test did not reveal any evidence of Granger causality for precipitation to ground-air temperature offsets on the daily scale of aggregation except for the asphalt pavement. On the contrary, a strong evidence of Granger causality for precipitation to the ground-air temperature offsets was found on the hourly scale of aggregation for all land cover types except for the sand surface cover. All results are sensitive to the lag choice of the autoregressive model. On the whole, obtained results contain valuable information on the delay time of Δ T(GST-SAT) caused by the rainfall events and confirmed the importance of using autoregressive models to understand the ground-air temperature relationship. [ABSTRACT FROM AUTHOR]

In the Transdanubian Range (Hungary), dolostone and dolomitic limestone appear in a number of sedimentary successions formed from the Late Permian to the Late Triassic in various depositional settings and under various diagenetic conditions, whereas only a negligible amount of dolomite was detected in the post-Triassic formations. Seven dolomite-bearing units representing ramp, small and large carbonate platforms, and intraplatform basin settings are presented in this synopsis. In most cases, multi-stage and polygenetic dolomitization was inferred. The main mass of the dolostones was formed via near-surface diagenetic processes, which were commonly preceded by the formation of synsedimentary dolomite. Accordingly, surficial conditions that prevailed during sediment deposition controlled the dolomite-forming processes and thus the lateral extension and the time span of dolomitization. The area of episodic subaerial exposure was a critical controlling factor of the lateral extension of the near-surface dolomite genesis, whereas its temporal extension was mostly governed by climate. Burial diagenesis usually resulted in only moderate dolomitization, either in connection with compactional fluid flow or via thermal convection. The Triassic fault zones provided conduits for fluid flow that led to both replacive dolomitization and dolomite cement precipitation. In the Late Triassic extensional basins, synsedimentary fault-controlled dolomitization of basinal deposits was reconstructed. [ABSTRACT FROM AUTHOR]

The uplift of the Troodos ophiolite is reflected in the development of the Akaki River catchment in the northeast Troodos Massif. Four main stages (F1-F4) of geomorphological terrace development and related deposits are recognised using satellite imagery and field observations. The geomorphological terraces have been tectonically uplifted during the Pleistocene so that they dip northwards from the Troodos Mountains until they merge with the Mesaoria Plain. Lithology (e.g. hard diabase versus soft extrusive rock) has exerted an important control on the geomorphology of the Akaki River channel. The F1 terraces and related deposits are well preserved in the lower reaches of the catchment. The F2 terraces are more widely preserved but with few preserved deposits. The F3 erosional surfaces (e.g. strath terraces) and related deposits are widespread up into the higher reaches of the catchment. The F4 to recent geomorphological surfaces and deposits are confined to near the modern river channel. The F1- to F3-aged deposits each include very high-energy mass-flow deposits and somewhat lower-energy traction-flow deposits, with minimal sand preservation. Stages of fluvial aggradation were followed by soil development (e.g. terra rossa). The F1- to F4-aged terraces and related deposits mainly formed in response to a combination of very long-term tectonic uplift and climatic-related change (long term and short term). Tectonic uplift was the dominant driver related to the updoming of the Troodos ophiolite, especially during the earlier time period (F1 and F2), whereas climate-related effects appear to have dominated more recently (F3 and F4). Sedimentary aggradation is likely to have predominated during interglacial periods, while interglacial-glacial transitions (when climate fluctuated) are seen as times of increased incision. Previous correlations of the F1-F4 fluvial deposits with similar deposits elsewhere in Cyprus, including coastal marine carbonate deposits, suggest that the F1 and F2 deposits are likely to be of Middle Pleistocene age and the F3-F4 deposits of Late Pleistocene to Holocene age. [ABSTRACT FROM AUTHOR]

Lake Ohrid (Macedonia/Albania) is the oldest extant lake in Europe and exhibits an outstanding degree of endemic biodiversity. Here, we provide new high-resolution stable isotope and geochemical data from a 10 m core (Co1262) through the Late Glacial to Holocene and discuss past climate and lake hydrology (TIC, δC, δO) as well as the terrestrial and aquatic vegetation response to climate (TOC, TOC/N, δC, Rock Eval pyrolysis). The data identifies 3 main zones: (1) the Late Glacial-Holocene transition represented by low TIC and TOC contents, (2) the early to mid-Holocene characterised by high TOC and increasing TOC/N and (3) the Late Holocene-Present which shows a marked decrease in TIC and TOC. In general, an overall trend of increasing δO from 9 ka to present suggests progressive aridification through the Holocene, consistent with previous records from Lake Ohrid and the wider Mediterranean region. Several proxies show commensurate excursions that imply the impact of short-term climate oscillations, such as the 8.2 ka event and the Little Ice Age. This is the best-dated and highest resolution archive of past Late Glacial and Holocene climate from Lake Ohrid and confirms the overriding influence of the North Atlantic in the north-eastern Mediterranean. The data presented set the context for the International Continental scientific Drilling Program Scientific Collaboration On Past Speciation Conditions in Lake Ohrid project cores recovered in spring-summer 2013, potentially dating back into the Lower Pleistocene, and will act as a recent calibration to reconstruct climate and hydrology over the entire lake history. [ABSTRACT FROM AUTHOR]

Holocene slackwater deposits along the river channels were used to study the magnitude and frequency of the palaeofloods that occurred prior to gauged and historical data sets all over the world. Palaeohydrological investigations along the Shanxi-Shaanxi Gorge of the middle Yellow River, China, identified palaeoflood slackwater deposits (SWDs) at several sites along the cliffs bordering the river channel. The SWDs are intercalated within Holocene eolian loess-soil profiles and clastic slope deposits. The palaeoflood SWDs were differentiated from eolian loess and soil by the sedimentary criteria and analytical results including magnetic susceptibility and particle-size distribution, similar to the flood SWDs in 2012, which indicated that these well-sorted palaeoflood SWD beds were deposited from the suspended sediment load in floodwaters. They have recorded the extraordinary palaeoflood events which occurred between 3200 and 3000 a BP as dated by the optically stimulated luminescence method in combination with pedostratigraphic correlations with the previously studied Holocene pedo-stratigraphy in the Yellow River drainage basin. Manning slope-area calculations estimate the peak discharged for these palaeoflood events to range from 43,290 to 49,830 m/s. The drainage area of the study site is 489,900 km. It is 2.0-2.5 times the largest gauged flood (21,000 m/s) that has ever occurred since 1934. These events also occurred on Yellow River tributaries, including the Weihe, Jinghe and Qishuihe Rivers. These flood events are therefore considered to be a regional expression of known climatic events in the northern hemisphere and demonstrate Holocene climatic instability. This study provides important data in understanding the interactions between regional hydro-climatic systems and global change in semiarid and subhumid regions. [ABSTRACT FROM AUTHOR]

The history of climate change and related driving mechanisms of the Gonghe Basin, northeastern Qinghai-Tibetan Plateau, China, was reconstructed in the Holocene epoch, based on the comprehensive analysis of multi-proxies consisting of magnetic susceptibility, grain size, and geochemical elements from eolian and peat deposits at different altitudes. The results indicate that Holocene climate change at different altitudes is both consistent and different: a synchronous record of an increased warm-humid phase (10.0-8.5 ka) and a cold phase around 8.2 ka in the Early Holocene; an optimal warm-humid condition in marginal mountains of the Gonghe Basin in the Mid-Holocene; and a gradual decline in temperature and humidity in the Late Holocene. The Gonghe Basin interior in the Mid-Holocene was relatively arid, with increased moisture in the Late Holocene. On this basis, we compared our results to the paleoclimatic record in the low-latitude Asian monsoonal region, which indicates that, in addition to the Asian summer monsoonal strength having influenced regional climate change, the upward and subsidence motion of airflow over the Qinghai-Tibetan Plateau induced by topographic conditions, evaporation, and the feedback effect by the substrate was also influential. The latter was especially important for spatial-temporal differences in Middle and Late Holocene climatic changes at different altitudes. [ABSTRACT FROM AUTHOR]

Investigations into the most plausible causes which triggered the Late Miocene global expansion of C grasslands have reached no consensus and are still being debated. The global decline in CO levels in the Late Miocene has been thought to be the most common driver. Although C grassland expansion was largely confined to the Late Miocene, their first appearance varied significantly in different parts of the Old and New world and therefore emphasizes role of local and/or regional factors may or may not be in combination with one or more global factors. The dynamic Himalayan orogen constitutes a significant global tectonic event that is believed to have affected global climate. Hence, a study of the Himalayan foreland basin sediments could help in gleaning out possible causes behind this major paleoecologic event, which could perhaps be directly or indirectly related. Stable carbon isotope analyses of a total of 141 pedogenic carbonates in the Mio-Pleistocene Siwalik paleosols of the Ramnagar sub-basin are coherent, providing a better insight into paleovegetational changes across the sub-basin on temporal and spatial scales. Furthermore, paleovegetational history during Oligocene is reconstructed from Dagshai paleosols exposed in the Subathu sub-basin. The isotopic results show dominance of C vegetation pre-7 Ma and dominance of C vegetation post-5 Ma. Percentage abundance of C vegetation was less than 20 % pre-7 Ma but increased to more than 40 % post-5 Ma, reaching up to 100 % in the youngest analyzed sediments. There is exclusive dominance of C vegetation during Oligocene. These results conform to the pattern of change in vegetation documented in other parts of the Himalayan belt. The global expansion of C grasslands largely during Late Miocene have long been linked with then climate changes, particularly brought by declining atmospheric CO level, large-scale fires, intensification of monsoon, seasonality, and aridity as demonstrated by various researchers. These major hypotheses explaining expansion of C grasslands during Late Miocene are not very convincing due to significant shortcomings associated with them, for example, expansion of C grasslands in non-monsoonal regions put serious constraints on the monsoonal intensification hypothesis. Likewise, aridity as being the primary driver of C grassland expansion seems hard to support since there is no substantial evidence that could suggest global onset of arid conditions at about same geologic time, and some most arid periods, like the Triassic, show no evidence of C plants. We suggest that the initial lowering of CO below 450 ppmV created an environment for the beginning of C vegetation, but the persistence of this threshold value for a considerable time during Late Miocene appears to be the probable cause of the Late Miocene global expansion of C grasslands irrespective of their time of first appearance. It has been deduced through the correlation of Himalayan tectonic events with atmospheric CO levels and paleovegetational changes since Upper Miocene times that it was indeed the Late Miocene continuous, intense tectonic instability of the Himalayas that significantly decreased atmospheric CO levels and which perhaps played a key role in changing the nature of photosynthetic pathways. [ABSTRACT FROM AUTHOR]

Environmental proxies of a stable carbon isotope, total organic carbon, free iron oxide, and particle size distribution in sediments as well as the stable carbon and oxygen isotopes in fossil human and animal teeth were used to reconstruct the history of climate change and natural disasters near the Jinsha Relic Site and to track their effect on the ancient Shu Civilization, which was established in the Chengdu Plain of southwest China during the late Holocene. In general, the late Holocene climate in the Chengdu Plain demonstrated a drying and cooling trend, with evident cooler events ~4100 and ~2700 a BP, which coincided with global climate changes. The ancient Shu Civilization was interrupted twice, and it included three stages-the Baodun (4700-3700 a BP), the Sanxingdui (3700-3150 a BP), and the Shi'erqiao (3150-2600 a BP)-that were slightly related to the abrupt climate changes that resulted from the collapse of the classic Sanxingdui Civilization, which was founded in a regional warm period. The abrupt increase in sand content in the sediment from the Jinsha Site coincided with the palaeoearthquake and palaeodam burst in the Longmen Mountains when the Baodun and Shi'erqiao desisted, indicating that a flood had occurred due to a dam burst and may likely have caused the ancient civilization's destruction. Although the warm and humid climate, flat terrain and rich water resources prompted the prosperity of the ancient towns of Sanxingdui and Jinsha, frequent natural disasters, such as powerful earthquakes, landslide dams, and outburst floods, consistently affected the ancient Shu inhabitants. [ABSTRACT FROM AUTHOR]

We used a 55-cm sediment core from shallow Chaiwopu Lake in the central Tianshan Mountains of Xinjiang, northwest China, to investigate climate and environmental changes in this arid region over the past ~150 years. The core was dated using Cs. We compared temporal changes in several sediment variables with recent meteorological and tree-ring records. Organic matter had a positive correlation with the Palmer Drought Severity Index in the central Tianshan Mountains, and the δC of organic matter had a positive correlation with regional temperature. We applied constrained incremental sum-of-squares cluster analysis to element concentrations in the core and identified three distinct zones: (1) 55-46 cm, ~1860-1910, (2) 46-26 cm, ~1910-1952, and (3) 26-0 cm, 1952-present. Between 1880 and 1910 AD, following the Little Ice Age (LIA), the sediment environment was relatively stable, climate was cold and dry, and the lake water displayed high salinity, in contrast to conditions during the LIA. During the LIA, westerlies carried more water vapor into Central Asia when the North Atlantic Oscillation was in a negative phase, and encountered the enhanced Siberia High, which probably led to increased precipitation. In the period 1910-1950 AD, the lake was shallow and the regional climate was unstable, with high temperatures and humidity. In the last ~15-20 years, human activities caused an increase in sediment magnetic susceptibility, and heavy metal and total phosphorus concentrations in the sediment were substantially enriched. Mean annual temperature displays a warming trend over the past 50 years, and the lowest temperature was observed in the 1950s. There has been an increase in annual total precipitation since the 1990s. The combined influences of climate and human activity on the lake environment during this period were faithfully recorded in sediments of Chaiwopu Lake. This study provides a scientific basis for environmental management and protection. [ABSTRACT FROM AUTHOR]

The present study analyses the stratal architecture of the Late Jurassic (Kimmeridgian) to Early Cretaceous (Berriasian) sedimentary succession of Mount Salève (E France), and four Berriasian stratigraphic intervals containing four sequence-boundary zones reflecting lowering trends of the relative sea-level evolution. Massive Kimmeridgian limestones characterized by the presence of colonial corals appear to be stacked in an aggrading pattern. These non-bedded thick deposits, which are interpreted to have formed in balance between relative sea-level rise and carbonate accumulation, suggest a keep-up transgressive system. Above, well-bedded Tithonian-to-Berriasian peritidal carbonates reflect a general loss of accommodation. These strata are interpreted as a highstand normal-regressive unit. During the early phase of this major normal regression, the vertical repetition of upper intertidal/lower supratidal lithofacies indicates an aggrading depositional system. This is in agreement with an early stage of a highstand phase of relative sea level. The Berriasian sequence-boundary zones investigated (up to 4 m thick) developed under different climatic conditions and correspond to higher-frequency, forced- and normal-regressive stages of relative sea-level changes. According to the classical sequence-stratigraphic principles, these sequence-boundary zones comprise more than one candidate surface for a sequence boundary. Three sequence-boundary zones studied in Early Berriasian rocks lack coarse siliciclastic grains, contain a calcrete crust, as well as marly levels with higher abundances of illite with respect to kaolinite, and exhibit fossilized algal-microbial laminites with desiccation polygons. These sedimentary features are consistent with more arid conditions. A sequence-boundary zone interpreted for the Late Berriasian corresponds to a coal horizon. The strata above and below this coal contain abundant quartz and marly intervals with a higher kaolinite content when compared to the illite content. Accordingly, this Late Berriasian sequence-boundary zone was formed under a more humid climate. The major transgressive-regressive cycle of relative sea level identified and the climate change from more arid to more humid conditions recognized during the Late Berriasian have been reported also from other European basins. Therefore, the Kimmeridgian to Berriasian carbonate succession of Mount Salève reflects major oceanographic and climatic changes affecting the northern margin of the Alpine Tethys ocean and thus constitutes a reliable comparative example for the analysis of other coeval sedimentary records. In addition, the stratigraphic intervals including sequence-boundary zones characterized in this study constitute potential outcrop analogues for sequence-boundary reflectors mapped on seismic profiles of subsurface peritidal carbonate successions. The detailed sedimentological analyses provided here highlight that on occasions the classical principles of sequence stratigraphy developed on seismic data are difficult to apply in outcrop. A sequence-boundary reflector when seen in outcrop may present successive subaerial exposure surfaces, which formed due to high-frequency sea-level changes that were superimposed on the longer-term trend of relative sea-level fall. [ABSTRACT FROM AUTHOR]

We present a synoptic overview of the Miocene-present development of the northern Alpine foreland basin (Molasse Basin), with special attention to the pattern of surface erosion and sediment discharge in the Alps. Erosion of the Molasse Basin started at the same time that the rivers originating in the Central Alps were deflected toward the Bresse Graben, which formed part of the European Cenozoic rift system. This change in the drainage direction decreased the distance to the marine base level by approximately 1,000 km, which in turn decreased the average topographic elevation in the Molasse Basin by at least 200 m. Isostatic adjustment to erosional unloading required ca. 1,000 m of erosion to account for this inferred topographic lowering. A further inference is that the resulting increase in the sediment discharge at the Miocene-Pliocene boundary reflects the recycling of Molasse units. We consider that erosion of the Molasse Basin occurred in response to a shift in the drainage direction rather than because of a change in paleoclimate. Climate left an imprint on the Alpine landscape, but presumably not before the beginning of glaciation at the Pliocene-Pleistocene boundary. Similar to the northern Alpine foreland, we do not see a strong climatic fingerprint on the pattern or rates of exhumation of the External Massifs. In particular, the initiation and acceleration of imbrication and antiformal stacking of the foreland crust can be considered solely as a response to the convergence of Adria and Europe, irrespective of erosion rates. However, the recycling of the Molasse deposits since 5 Ma and the associated reduction of the loads in the foreland could have activated basement thrusts beneath the Molasse Basin in order to restore a critical wedge. In conclusion, we see the need for a more careful consideration of both tectonic and climatic forcing on the development of the Alps and the adjacent Molasse Basin. [ABSTRACT FROM AUTHOR]

This study investigates the connection between sediment aggradation, erosion and climate in a desert environment of the Majes valley, southern Peru. Luminescence dating of terraces and fans shows that sediment aggradation correlates with wet time intervals on the Altiplano, suggesting a climatic influence on the aggradation-degradation cycles. Major periods of aggradation occurred between ~110-100, ~60-50 and 12-8 ka. More precipitation in the Majes catchment resulted in increased erosion and transportation of sediment from the hillslopes into the trunk river. As a result, the sediment loads exceeded the transport capacity of the Majes River and aggradation started in the lower reaches where the river gradient is less. Depletion of the hillslope sediment reservoirs caused a relative increase in the capacity of the trunk river to entrain and transport sediment, resulting in erosion of the previously deposited sediment. Consequently, although climate change may initiate a phase of sediment accumulation, degradation can be triggered by an autocyclic negative feedback and does not have to be driven by climatic change. [ABSTRACT FROM AUTHOR]

The Rwenzori Mountains (Mtns) in west Uganda are the highest rift mountains on Earth and rise to more than 5,000 m. We apply low-temperature thermochronology (apatite fission-track (AFT) and apatite (U-Th-Sm)/He (AHe) analysis) for tracking the cooling history of the Rwenzori Mtns. Samples from the central and northern Rwenzoris reveal AFT ages between 195.0 (±8.4) Ma and 85.3 (±5.3) Ma, and AHe ages between 210.0 (±6.0) Ma to 24.9 (±0.5) Ma. Modelled time-temperature paths reflect a protracted cooling history with accelerated cooling in Permo-Triassic and Jurassic times, followed by a long period of constant and slow cooling, than succeeded by a renewed accelerated cooling in the Neogene. During the last 10 Ma, differentiated erosion and surface uplift affected the Rwenzori Mtns, with more pronounced uplift along the western flank. The final rock uplift of the Rwenzori Mtns that partly led to the formation of the recent topography must have been fast and in the near past (Pliocene to Pleistocene). Erosion could not compensate for the latest rock uplift, resulting in Oligocene to Miocene AHe ages. [ABSTRACT FROM AUTHOR]

global atmosphere-ocean model has been forced with topographic and orbital scenarios in order to evaluate the relative role of both factors for the past climate of East Africa. Forcing the model with a significantly reduced topography in Eastern and Southern Africa leads to a distinct increase in moisture transport from the Indian Ocean into the eastern part of the continent and increased precipitation in Eastern Africa. Simulations with step-wise reduced height show that this climate change occurs continuously with the change in topography, i.e., an abrupt change of local climatic features with a critical height is not found. Simulations of the last interglacial (at 125,000 years before present, i.e., the Eemian interglacial) and the last glacial inception (at 115,000 years before present) are used as examples for the role of orbital-induced changes in insolation. Here, changes in meridional temperature gradients lead to modifications in moisture transport of similar order of magnitude, but with different spatial and seasonal structure. For the Eemian interglacial, a distinct increase in summer moisture transport from the Atlantic deep into the continent at around 20°N is simulated. [ABSTRACT FROM AUTHOR]

We focus on the sedimentological record of the Middle Miocene to modern deposits in the Andes of northern Chile between 19 and 21°S. These sediments, deposited at the Western Escarpment of the Central Depression, indicate successively more moisture on the western margin of the Altiplano and the Western Cordillera where the sources are. At the Pacific Coast, 20-Ma-old exposure ages and salic gypsisols reflect an existing and ongoing hyperarid climate. We interpret the increased divergence of climates between the Coast and the Altiplano as consequence of the Andean rise to elevations higher than approximately 2,500 m a.s.l., when the topography of the Altiplano was sufficiently high and areally extensive to attract Atlantic moisture. Accordingly, the inferred general increase in run-off was closely coupled with the uplift of the Andes if the steady rise model applies. In case that the rapid rise model for Andean uplift is correct, the inferred changes in sediment transport would have occurred independently of uplift, requiring an alternative, yet unknown driver. [ABSTRACT FROM AUTHOR]

Water temperature has received considerable attention as steering factor for the genesis of different types of marine carbonate sediments. However, parameters other than temperature also strongly influence ecosystems and, consequently, the carbonate grain associations in the resulting carbonate rock. Among those factors are biological evolution, water energy, substrate, water chemistry, light penetration, trophic conditions, CO concentrations, and Mg/Ca ratios in the seawater. Increased nutrient levels in warm-water settings, for example, lead to heterotrophic-dominated associations that are characteristic of temperate to cool-water carbonates. Failure to recognize the influence of such environmental factors that shift the grain associations towards heterotrophic communities in low latitudes can lead to misinterpretation of climatic conditions in the past. Modern analogues of low-latitude heterozoan carbonates help to recognize and understand past occurrences of heterozoan warm-water carbonates. Careful analysis of such sediments therefore is required in order to achieve robust reconstructions of past climate. [ABSTRACT FROM AUTHOR]

series of en echelon cracks run nearly parallel to the outer shelf edge of the mid-Norwegian margin. The features can be followed in a ~60-km-long and ~5-km-wide zone in which up to 10-m-deep cracks developed in the seabed at 400–550 m water depth. The time of the seabed cracking has been dated to 7350 C years BP (8180 cal years BP), which corresponds with the main Storegga Slide event (8100 ± 250 cal. years BP). Reflection seismic data suggest that the cracks do not appear to result from deep-seated faults, but it cannot be ruled out completely that tension crevices were created in relation to past movements on the headwall of the Storegga slide. The cracking zone corresponds well to the zone where the base of the hydrate stability zone (BHSZ) outcrops. Evidence of fluid release in the BHSZ outcrop zone comes from an extensive pockmark field. We suggest that post-glacial ocean warming triggered the dissociation of gas hydrates while the interplay between dissociation, overpressure, and sediment fracturing on the outer shelf remains to be understood. [ABSTRACT FROM AUTHOR]

The Tiscapa maar in the center of Managua city formed by a phreatomagmatic eruption <3 ka ago. The eruption excavated a crater deep into the basement exposing a coherent Pleistocene to Holocene volcaniclastic succession that we have divided into four formations. The lowermost, >60 ka old basaltic–andesitic formation F1 comprises mafic ignimbrites and phreatomagmatic tephras derived from the Las Sierras volcanic complex south of Managua. Formation F2 contains the ~60 ka basaltic–andesitic Fontana tephra erupted from the Las Nubes Caldera of the Las Sierras complex 15 km to the S, the 25 ka Upper Apoyo tephra from the Apoyo Caldera 35 km to the SE, and the Lower (~17 ka) and Upper (12.4 ka) Apoyeque tephras from the Chiltepe volcanic complex 15 km to the NW. These tephras are separated by weathering horizons and paleosols indicating dry climatic conditions. Fluvial deposits of a SSW-NNE running paleo-river system build formation F3. The fluvial sediments contain, from bottom to top, scoriae from the ~6 ka basaltic San Antonio tephra, pumice lapilli from the Apoyo and Apoyeque tephras and the 6.1 ka Xiloà tephra, and scoriae derived from the Fontana tephra. The fluvial sediment succession thus reflects progressively deeper carving erosion in the southern highlands (where a large-amplitude regional erosional unconformity exists at the appropriate stratigraphic level) that began after ~6 ka. This suggests that the mid-Holocene tropical high-precipitation climatic phase affected western Nicaragua about a thousand years later than other circum-Caribbean regions. The end of the wet climate phase ~3 ka ago is recorded by a deep weathering zone and paleosol atop formation F3 prior to the Tiscapa eruption. Formation F4 is the Tiscapa tuffring composed of pyroclastic surge and fallout deposits that cover a minimum area of 1.2 km. The 4 × 10 kg of erupted basaltic magma is compositionally and genetically related to the low-Ti basalts of the N–S striking Nejapa-Miraflores volcanic–tectonic alignment 5 km to the West of Tiscapa. Ascent and eruption mode of the Tiscapa magma were controlled by the Tiscapa fault that has a very active seismic history as it achieved 12 m displacement in about 3000 years. Managua city is thus exposed to continued seismic and volcanic risks. [ABSTRACT FROM AUTHOR]

Carbon and oxygen stable isotopic composition of Cenozoic lacustrine carbonates from the intramontane Qaidam Basin yields cycles of variable length and shows several distinct events driven by tectonics and climate changes. From Eocene to Oligocene, the over-all trend in the δ13C composition of lacustrine carbonates shows a shift toward higher values, possibly related to higher proportions of dissolved inorganic carbon transported to the lake or lower input of soil derived CO2. At the same time, the δ18O composition of lacustrine carbonates is decreasing in accordance with the global cooling trend and northwards drifting of the whole region. During the Miocene, distinct isotopic events can be recognized, although their interpretation and linkage to a certain tectonic event remains difficult. These events may be related to uplift in the Himalayas, to the strongest phase of uplift in the Altyn Mountains, to pronounced subsidence of the Qaidam Basin or to the expansion of C4 plants on land. Generally cold, highly evaporative conditions can be deduced from enrichment of δ18O isotopic compositions during Pliocene and Quaternary times. [ABSTRACT FROM AUTHOR]

Phytoplankton plays a dominant role in shelf biogeochemistry by producing the major part of organic matter. Part of the organic matter will reach the sediment where diagenetic processes like denitrification, apatite formation or burial will remove nutrients from the biogeochemical cycle. In this article current knowledge on the decadal plankton variability in the North Sea is summarized and possible implications of these changes for the biogeochemistry of the North Sea are discussed. Most of the observed interdecadal dynamics seem to be linked to large-scale oceanographic and atmospheric processes. Prominent changes in the North Sea ecosystem have taken place around 1979 and 1988. In general, the phytoplankton color (CPRS indicator of phytoplankton biomass) reached minimum values during the end of the 1970s and has increased especially since the mid 1980s. Changes with a similar timing have been identified in many time series from the North Sea through the entire ecosystem and are sometimes referred to as regime shifts. It is suggested that the impact of global change on the local biogeochemistry is largely driven by the phyto- and zooplankton dynamics during spring and early summer. At that time the extent of zooplankton–phytoplankton interaction either allows that a large part of the new production is settling to the sediment, or that a significant part of the new production including the fixed nutrients is kept within the pelagic system. The origin of the extent of the phytoplankton–zooplankton interaction in spring is probably set in the previous autumn and winter. In coastal areas, both large-scale atmospheric and oceanographic changes as well as anthropogenic factors influence the long-term dynamics. Due to eutrophication, local primary production nowadays still is up to five times higher than during pre-industrial conditions, despite a decreasing trend. Recently, introduced species have strengthened the filter feeder component of coastal ecosystems. Especially in shallow coastal seas like the Wadden Sea, this will enhance particle retention, shift organic matter degradation to the benthic compartment and enhance nutrient removal from the biogeochemical cycle by denitrification or apatite formation. [ABSTRACT FROM AUTHOR]

Mud volcanism is an abundant, global phenomenon whereby fluid-rich, low-density sediments extrude both on land and offshore. Methane, which generally exceeds 90 vol% of the gas phase, is emitted at high rates during and after emplacement of the mud domes and is known for its high global warming potential (GWP). This comprehensive estimate of the annual contribution of mud volcano degassing assesses the significance of mud volcanism for the accumulation of greenhouse gases in the atmosphere. A first-order estimate for the earlier, pre-anthropogenic volume of methane released through mud volcanoes further supports their profound effect on the Earth's climate since at least the Paleozoic (570 Ma). [ABSTRACT FROM AUTHOR]