Global Sea-level Changes Research Articles

Modeling gas hydrate petroleum systems of the Pleistocene turbiditic sedimentary sequences of the Daini-Atsumi area, eastern Nankai Trough, Japan

We have performed 2D and 3D gas hydrate (GH) petroleum systems modeling for the Pleistocene turbiditic sedimentary sequences distributed in the Daini-Atsumi area in the eastern Nankai Trough to understand the accumulation mechanisms and their spatial distribution related to geologic and geochemical processes. High-resolution seismic facies analysis and interpretations were used to define facies distributions in the models. We have created a new biogenic methane generation model based on the biomarker analysis using core samples and incorporated it into our model. Our 2D models were built and simulated to confirm the parameters to be used for 3D modeling. Global sea level changes and paleogeometry estimated from 3D structural restoration results were taken into account to determine the paleowater depth of the deposited sedimentary sequences. Pressure and temperature distributions were modeled because they are the basic factors that control the GH stability zone. Our 2D modeling results suggested that the setting of biogenic methane generation depth is one of the most important controlling factors for GH accumulation in the Nankai Trough, which may be related to the timing of methane upward migration (expulsion) and methane solution process in pore water. Our 3D modeling results suggested that the distribution of sandy sediments and the formation dip direction are important controlling factors in the accumulation of GHs. We also found that the simulated amount of GH accumulation from the petroleum systems modeling compares well with independent estimations using 3D seismic and well data. This suggests that the model constructed in this study is valid for this GH system evaluation and that this type of evaluation can be useful as a supplemental approach to resource assessment.

Last Glacial Cycle and seismic stratigraphic sequences offshore western Hainan Island, NW South China Sea

Abstract In order to investigate the relationship between sea-level changes during the Last Glacial Cycle (LGC) and seismic stratigraphic sequences on the NW continental shelf of the South China Sea, a sparker single-channel high-resolution seismic profiling was correlated with a sediment core taken offshore western Hainan Island. Interpretation of the seismic stratigraphy in relation to local and global sea-level changes could be refined. According to the age model, developed from AMS (accelerator mass spectrometry)- 14 C and OSL (optically stimulated luminescence) dates, and δ 18 O (oxygen isotope) stratigraphy, the 88.3 m sediment core reflects environmental change since 110 ka. Correlation with a sediment core in the adjacent basin based on stable oxygen isotope records allows a zonation of the top 15 m of the sediment core and the identification of marine isotope stages (MIS) 1–5e. Seven seismic reflectors interpreted as unconformities were identified. These erosional surfaces have been dated by interpolation using an age–depth model compared to global eustatic curves. The results indicate that seven sea-level cycles can be distinguished in the study area during the LGC, and these are correlated with regional and global sea-level change models. Further research confirms that seismic stratigraphy in the NW South China Sea can be intimately related to LGC sea-level changes associated with regional surface uplift and sediment supply.

The ELSA tephra stack: Volcanic activity in the Eifel during the last 500,000 years

Tephra layers of individual volcanic eruptions are traced in several cores from Eifel maar lakes, drilled between 1998 and 2014 by the Eifel Laminated Sediment Archive (ELSA). All sediment cores are dated by 14C and tuned to the Greenland interstadial succession. Tephra layers were characterized by the petrographic composition of basement rock fragments, glass shards and characteristic volcanic minerals. 10 marker tephra, including the well-established Laacher See Tephra and Dümpelmaar Tephra can be identified in the cores spanning the last glacial cycle. Older cores down to the beginning of the Elsterian, show numerous tephra sourced from Strombolian and phreatomagmatic eruptions, including the 40Ar/39Ar dated differentiated tephra from Glees and Hüttenberg. In total, at least 91 individual tephra can be identified since the onset of the Eifel volcanic activity at about 500,000 b2k, which marks the end of the ELSA tephra stack with 35 Strombolian, 48 phreatomagmatic and 8 tephra layers of evolved magma composition. Many eruptions cluster near timings of the global climate transitions at 140,000, 110,000 and 60,000 b2k. In total, the eruptions show a pattern, which resembles timing of phases of global sea level and continental ice sheet changes, indicating a relation between endogenic and exogenic processes.

Late Cretaceous marine fossils and seawater incursion events in the Songliao Basin, NE China

The Songliao Basin is the largest non-marine oil-bearing basin in China. Because of the absence of substantial evidence, the hypothesis of seawater incursion events into the Songliao Basin remains controversial. The presence of marine fossils could provide direct proof to support this supposition. Here, we report new discoveries of foraminifera, calcareous nannofossils, brackish dinoflagellates, and other marine and brackish-water fossils to support the suggestion of seawater incursion events in the Songliao Basin. Relatively abundant benthic and planktonic foraminifera, calcareous nannofossils, marine and brackish-water dinoflagellates, fish, and bivalves have been discovered in Members 1 and 2 of the Nenjiang Formation, a few foraminifera and brackish-water dinoflagellates have been found in the lower Qingshankou Formation, and just a few brackish-water bivalves have been found in the uppermost Qingshankou Fm. Based on the presence of marine molecular fossils and other evidence, we suggest that relatively large seawater incursion events occurred during the sedimentation of the lower Nenjiang Fm., relatively smaller seawater incursions occurred during the deposition of the lower Qingshankou Fm., and possibly a very small seawater incursion occurred during the sedimentation of the uppermost Qingshankou Fm. These seawater incursion events in the Songliao Basin were controlled by regional tectonic activity, evolution of the palaeo Songliao Lake, and global sea level change. These periodic seawater incursions brought marine biota into the palaeo Songliao Lake.

Earth rotation and geodynamics

Abstract This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth’ magnetic field.

Different frequencies and triggers of canyon filling and flushing events in Nazaré Canyon, offshore Portugal

Submarine canyons are one of the most important pathways for sediment transport into ocean basins. For this reason, understanding canyon architecture and sedimentary processes has importance for sediment budgets, carbon cycling, and geohazard assessment. Despite increasing knowledge of turbidity current triggers, the down-canyon variability in turbidity current frequency within most canyon systems is not well constrained. New AMS radiocarbon chronologies from canyon sediment cores illustrate significant variability in turbidity current frequency within Nazaré Canyon through time. Generalised linear models and Cox proportional hazards models indicate a strong influence of global sea level on the frequency of turbidity currents that fill the canyon. Radiocarbon ages from basin sediment cores indicate that larger, canyon-flushing turbidity currents reaching the Iberian Abyssal Plain have a significantly longer average recurrence interval than turbidity currents that fill the canyon. The recurrence intervals of these canyon-flushing turbidity currents also appear to be unaffected by long-term changes in global sea level. Furthermore, canyon-flushing and canyon-filling have very different statistical distributions of recurrence intervals. This indicates that the factors triggering, and thus controlling the frequency of canyon-flushing and canyon-filling events are very different. Canyon-filling appears to be predominantly triggered by sediment instability during sea level lowstand, and by storm and nepheloid transport during the present day highstand. Canyon-flushing exhibits time-independent behaviour. This indicates that a temporally random process, signal shredding, or summation of non-random processes that cannot be discerned from a random signal, are triggering canyon flushing events.

Foraminiferal biostratigraphy and glacioeustatic control on cyclic carbonate microfacies in the Viséan–Serpukhovian boundary beds (Aladağ Unit, Eastern Taurides, Turkey)

The Aladag Unit, one of the tectonostratigraphic units in the Tauride Belt (Turkey), comprises a nearly uninterrupted Upper Paleozoic succession including the Visean–Serpukhovian boundary beds. These boundary beds in the Eastern Taurides are made up of mainly carbonates with some intercalations of sandstone and shale. A detailed micropaleontological study has revealed three biozones based on foraminifera. These biozones are, in ascending order, Eostaffella ikensis-Vissarionovella tujmasensis Zone (Mikhailovsky; Late Visean), Endothyranopsis (Reitlingeropsis) cf. sphaerica-Biseriella parva Zone (Venevsky; Late Visean) and Eostaffella pseudostruvei Zone (Tarussky; Early Serpukhovian). Traditional Visean–Serpukhovian boundary lies between the Endothyranopsis (Reitlingeropsis) cf. sphaerica-Biseriella parva Zone and the Eostaffella pseudostruvei Zone. The presence of ‘Millerella’ sp. aff. ‘M.’ tortula specimens in the last levels of the Venevsky horizon also suggests that the measured section, has the potential for the redefinition of the Visean–Serpukhovian boundary, which would coincide with the datum marked by the evolutionary appearance of the conodont Lochriea ziegleri. Boundary beds were deposited in open-marine, shoal, or bank and tidal flat environments, which were interpreted based on the analysis of 12 microfacies and 11 sub-microfacies types. The main microfacies types are (1) bioclastic packstone; (2) bioclastic packstone to grainstone; (3) bioclastic grainstone; (4) bioclastic-intraclastic grainstone; (5) intraclastic grainstone; (6) sandy bioclastic grainstone; (7) peloidal packstone to wackestone (8) wackestone-mudstone; (9) shale; (10) peloidal grainstone or peloidal packstone to grainstone with dark micritic intraclasts; (11) peloidal packstone to grainstone with fenestral fabric; (12) quartz arenitic sandstone. Based on the stacking patterns and vertical evolution of microfacies, several meter-scale shallowing-upward cycles, three sequences, and two intervening sequence boundaries were recognized in the studied section. Sequence boundaries, lying within the Mikhailovsky and Venevsky horizons, are the records of global sea-level changes during the first episodes of the Late Paleozoic Ice Age. The Visean–Serpukhovian boundary falls within the transgressive systems tract of the third sequence and is correlatable with the boundary delineated in Russia. The duration of cycles is calculated as 117 ky and interpreted as orbitally induced (Milankovitch eccentricity) glacioeustatic cycles.

Sedimentology, rhythmicity and basin-fill architecture of a carbonate ramp depositional system with intermittent terrigenous influx: The Albian Kharfot Formation of the Jeza-Qamar Basin, Dhofar, Southern Oman

The Albian Kharfot Formation is preserved in the eastern margin of the Jeza-Qamar Basin which straddles across the Oman–Yemen border. This study addresses the sedimentological attributes of the formation and deduces its depositional setting, cyclicity and relative sea level changes in local (within the basin) and regional (Arabian) contexts. The interaction among siliciclastic influxes, in-situ carbonate production and tectono-climatic controls on the stacking nature of the various lithofacies that build-up the formation is discussed. In the study area, the formation lies unconformably over Barremian–Aptian Qishn Formation and conformably under late Albian–?Turonian Dhalqut Formation. The Kharfot Formation thickens from ~140m in the eastern side of the study area to ~300m at the Oman–Yemen border. It consists of eight lithofacies: Orbitolina-rich marls, peloidal bioclastic packstone, bioclastic mudstone to wackestone, argillaceous, bioclastic floatstone to rudstone, bioclastic rudstone, sandy, peloidal, bioclastic mudstone to packstone, peloidal, bioclastic grainstone and dolostone. The vertical arrangement of these lithofacies defines recurring meter- to decameter-scale, shallowing-upward units deposited on a westward-deepening inner- to outer-ramp setting. Tectonic rejuvenation of the siliciclastic source area was accompanied by warm, humid climatic conditions as suggested by high kaolinitic marls of the Kharfot Fm. and coeval quartz-rich sandstone units (Harshiyat Fm.). The shallowing-upward rhythmic sedimentation of the formation has close resemblance with cycles of the Nahr Umr Formation in northern Oman and partially comparable with the global sea level changes. The Kharfot basin was an intrashelf depression that was part of the much larger Arabian epeiric platform. The latter is defined by a rimmed margin in northern Oman where Al-Hassanat Formation represents platform margin deposits and Nahr Umr Formation representing back-rim intrashelf depression which received fine-grained siliciclastic influx from the land (westward). In southern Oman where Kharfot Formation accumulated, the platform was unrimmed ramp type basin with high fine clastic influx along with elevated carbonate production.

The Sea Level Response to External Forcings in Historical Simulations of CMIP5 Climate Models*

Abstract Changes in Earth’s climate are influenced by internal climate variability and external forcings, such as changes in solar radiation, volcanic eruptions, anthropogenic greenhouse gases (GHG), and aerosols. Although the response of surface temperature to external forcings has been studied extensively, this has not been done for sea level. Here, a range of climate model experiments for the twentieth century is used to study the response of global and regional sea level change to external climate forcings. Both the global mean thermosteric sea level and the regional dynamic sea level patterns show clear responses to anthropogenic forcings that are significantly different from internal climate variability and larger than the difference between models driven by the same external forcing. The regional sea level patterns are directly related to changes in surface winds in response to the external forcings. The spread between different realizations of the same model experiment is consistent with internal climate variability derived from preindustrial control simulations. The spread between the different models is larger than the internal variability, mainly in regions with large sea level responses. Although the sea level responses to GHG and anthropogenic aerosol forcing oppose each other in the global mean, there are differences on a regional scale, offering opportunities for distinguishing between these two forcings in observed sea level change.

Increased Water Storage in the Qaidam Basin, the North Tibet Plateau from GRACE Gravity Data.

Groundwater plays a key role in maintaining the ecology and environment in the hyperarid Qaidam Basin (QB). Indirect evidence and data from sparse observation wells suggest that groundwater in the QB is increasing but there has been no regional assessment of the groundwater conditions in the entire basin because of its remoteness and the severity of the arid environment. Here we report changes in the spatial and temporal distribution of terrestrial water storage (TWS) in the northern Tibetan Plateau (NTP) using Gravity Recovery and Climate Experiment (GRACE) data. Our study confirms long-term (2003–2012) TWS increases in the NTP. Between 2003 and 2012 the TWS increased by 88.4 and 20.6 km3 in the NTP and the QB, respectively, which is 225% and 52% of the capacity of the Three Gorges Reservoir, respectively. Soil and water changes from the Global Land Data Assimilation System (GLDAS) were also used to identify groundwater storage in the TWS and to demonstrate a long-term increase in groundwater storage in the QB. We demonstrate that increases in groundwater, not lake water, are dominant in the QB, as observed by groundwater levels. Our study suggests that the TWS increase was likely caused by a regional increase in precipitation and a decrease in evaporation. Degradation of the permafrost increases the thickness of the active layers providing increased storage for infiltrated precipitation and snow and ice melt water, which may also contribute to the increased TWS. The huge increase of water storage in the NTP will have profound effects, not only on local ecology and environment, but also on global water storage and sea level changes.

Projection of the Zhujiang (Pearl) River Delta’s potential submerged area due to sea level rise during the 21st century based on CMIP5 simulations

Projections of potential submerged area due to sea level rise are helpful for improving understanding of the influence of ongoing global warming on coastal areas. The Ensemble Empirical Mode Decomposition method is used to adaptively decompose the sea level time series in order to extract the secular trend component. Then the linear relationship between the global mean sea level (GMSL) change and the Zhujiang (Pearl) River Delta (PRD) sea level change is calculated: an increase of 1.0 m in the GMSL corresponds to a 1.3 m (uncertainty interval from 1.25 to 1.46 m) increase in the PRD. Based on this relationship and the GMSL rise projected by the Coupled Model Intercomparison Project Phase 5 under three greenhouse gas emission scenarios (representative concentration pathways, or RCPs, from low to high emission scenarios RCP2.6, RCP4.5, and RCP8.5), the PRD sea level is calculated and projected for the period 2006–2100. By around the year 2050, the PRD sea level will rise 0.29 (0.21 to 0.40) m under RCP2.6, 0.31 (0.22 to 0.42) m under RCP4.5, and 0.34 (0.25 to 0.46) m under RCP8.5, respectively. By 2100, it will rise 0.59 (0.36 to 0.88) m, 0.71 (0.47 to 1.02) m, and 1.0 (0.68 to 1.41) m, respectively. In addition, considering the extreme value of relative sea level due to land subsidence (i.e., 0.20 m) and that obtained from intermonthly variability (i.e., 0.33 m), the PRD sea level will rise 1.94 m by the year 2100 under the RCP8.5 scenario with the upper uncertainty level (i.e., 1.41 m). Accordingly, the potential submerged area is 8.57×103 km2 for the PRD, about 1.3 times its present area.

Sea-level reconstruction for Turonian sediments from Tanzania based on integration of sedimentology, microfacies, geochemistry and micropaleontology

Despite many advances in sea-level research, the nature of cyclic eustatic sea-level fluctuations during warm periods without, or with much reduced, polar ice remains enigmatic. Recently published δ18O records from extremely well-preserved Turonian microfossils from Tanzania do not support the contentious idea of glacio-eustatic control of global sea-level changes during the warmest period of the Cretaceous. For the same locality (site TDP 31) we reconstruct relative sea-level changes based on sequence stratigraphy and integration of sedimentology, microfacies, geochemistry, and micropaleontology. Four local sequence boundaries (SBs TuTz1–4) are recognized: at the base, middle, and top of the Helvetoglobotruncana helvetica Zone and in the Late Turonian. The lowstands are characterized by increased grain size, enhanced organic carbon flux, faunal assemblage changes, and bulk δ13Corg and foraminiferal δ13Cf and δ18Of minima. Strong benthic and planktic foraminiferal turnovers above the top Middle Turonian SB TuTz3 probably reflect shallowing (from upper slope to outer shelf) and/or eutrophication.The TDP 31 age model is refined through inter-regional comparison of planktic foraminiferal ranges and δ13C records from three other South-Tethyan localities (ODP Holes 762C and 763B, Exmouth Plateau, and the Guru section, Tibet). This age model enables correlation of the regressive events at a global scale and suggests that, within stratigraphic uncertainty, the TDP 31 depositional sequences are synchronous with the global Turonian third-order sequences and are likely driven by eustasy. These correlations, together with recent astrochronological and radiometric dating, indicate a considerably younger age (91.17±0.52Ma) for the top H. helvetica Zone than currently assumed, resulting in zonal duration of 2.35±0.52 myr. Foraminiferal stable-isotope data from TDP 31 indicate slight surface- and bottom-water warming during the regressions and possibly a minor surface-water salinity decrease, which is inconsistent with glacio-eustatic forcing of Turonian third-order sea-level cycles and is more in line with the model of aquifer-eustasy.

Relative sea-level change in Connecticut (USA) during the last 2200 yrs

We produced a relative sea-level (RSL) reconstruction from Connecticut (USA) spanning the last ∼2200 yrs that is free from the influence of sediment compaction. The reconstruction used a suite of vertically- and laterally-ordered sediment samples ≤2 cm above bedrock that were collected by excavating a trench along an evenly-sloped bedrock surface. Paleomarsh elevation was reconstructed using a regional-scale transfer function trained on the modern distribution of foraminifera on Long Island Sound salt marshes and supported by bulk-sediment δ13C measurements. The history of sediment accumulation was estimated using an age-elevation model constrained by radiocarbon dates and recognition of pollution horizons of known age. The RSL reconstruction was combined with regional tide-gauge measurements spanning the last ∼150 yrs before being quantitatively analyzed using an error-in-variables integrated Gaussian process model to identify sea-level trends with formal and appropriate treatment of uncertainty and the temporal distribution of data. RSL rise was stable (∼1 mm/yr) from ∼200 BCE to ∼1000 CE, slowed to a minimum rate of rise (0.41 mm/yr) at ∼1400 CE, and then accelerated continuously to reach a current rate of 3.2 mm/yr, which is the fastest, century-scale rate of the last 2200 yrs. Change point analysis identified that modern rates of rise in Connecticut began at 1850–1886 CE. This timing is synchronous with changes recorded at other sites on the U.S. Atlantic coast and is likely the local expression of a global sea-level change. Earlier sea-level trends show coherence north of Cape Hatteras that are contrasted with southern sites. This pattern may represent centennial-scale variability in the position and/or strength of the Gulf Stream. Comparison of the new record to three existing and reanalyzed RSL reconstructions from the same site developed using sediment cores indicates that compaction is unlikely to significantly distort RSL reconstructions produced from shallow (∼2–3 m thick) sequences of salt-marsh peat.

Vertical ground motion and historical sea-level records in Dakar (Senegal)

With growing concerns regarding future impacts of sea-level in major coastal cities, the most accurate information is required regarding local sea-level changes with respect to the coast. Besides global and regional sea-level changes, local coastal vertical ground motions can substantially contribute to local changes in sea-level. In some cases, such ground motions can also limit the usefulness of tide-gauge records, which are a unique source of information to evaluate global sea-level changes before the altimetry era. Using satellite synthetic aperture radar interferometry, this study aims at characterizing vertical coastal ground motion in Dakar (Senegal), where a unique century-long record in Africa has been rediscovered. Given the limited number of available images, we use a stacking procedure to compute ground motion velocities in the line of sight over 1992–2010. Despite a complex geology and a rapid population growth and development, we show that the city as a whole is unaffected by differential ground motions larger than 1 mm year−1. Only the northern part of the harbor displays subsidence patterns after 2000, probably as a consequence of land reclamation works. However, these ground motions do not affect the historical tide gauge. Our results highlight the value of the historical sea-level records of Dakar, which cover a 100 year time-span in a tropical oceanic region of Africa, where little data are available for past sea-level reconstructions.

Facies Analysis and Sequence Stratigraphy of Silurian Carbonate Ramps in the Turan (Kopeh‐Dagh) and Central Iran Plates with Emphasis on Gondwana Tectonic Event

AbstractTwo sections from the Silurian deposits in the Central Iran Micro and Turan Plates were measured and sampled. These deposits are mostly composed of submarine volcanic rocks, skeletal and non‐skeletal limestone, shale and sandstone that were deposited in low to high energy conditions (from tidal flat to deep open marine). According to gradual deepening trend, wide lateral distribution of facies as well as absence of resedimentation deposits, a depositional model of a homoclinal ramp was proposed for these deposits. Field observations and facies distribution indicate that, two depositional sequences were recognized in both sections. These sections show similarities in facies and depositional sequence during the Early Silurian in the area. Although there are some opinions and evidences that demonstrated Paleo‐Tethys rifting phase started at the Late Ordovician‐Early Silurian, similarities suggest that the Turan and Iran Plates were not completely detached tectonic block during this time, and that their depositional conditions were affected by global sea level changes and tectonic events.

Late Hirnantian (latest Ordovician) carbonate rocks and shelly fossils in Shiqian, northeastern Guizhou, Southwest China

The Kuanyinchiao Formation has generally been regarded as representing the only carbonate sediments deposited during the Hirnantian (Late Ordovician) interval in South China, where the Hirnantian GSSP is situated. Reinvestigation of several key Ordovician-Silurian boundary sections in Shiqian, northeastern Guizhou Province, Southwest China, reveals a lithologically distinct carbonate unit with abundant shelly fossils, including tabulate and rugose corals, conodonts, brachiopods, trilobites and stromatoporoids, many showing close Silurian affinities and suggesting a level stratigraphically much higher than the Kuanyinchiao Formation. This observation, together with further evidence that graptolites indicative of the Akidograptus ascensus biozone are present in immediately overlying rocks at a nearby section, implies that these shelly fossiliferous strata are of latest Hirnantian age (possibly straddling the Ordovician-Silurian boundary). Hence they were most likely deposited after the Hirnantian glaciation, rather than representing glacial cool water sediments (the Kuanyinchiao Formation) as was previously thought. Ordovician-Silurian boundary sequences in South China typically reflect global glacio-eustatic sea-level changes. Owing to their unique lithology and palaeontology, these newly recognized carbonate rocks, here formally named the Shiqian Formation, add substantially to our knowledge of Ordovician-Silurian stratigraphy in this region.

Anthropogenic Black Carbon Emission Increase during the Last 150 Years at Coastal Jiangsu, China.

Black carbon (BC) is one of the major drivers of climate change and a useful indicator of environmental pollution from industrialization, and thus it is essential to reconstruct the historical trend in BC flux to better understand its impact. The Yancheng coastal wetland reserve in Jiangsu province is an area sensitive to global sea level change and is also located in the most developed as well as most polluted region of China. We investigated the concentration and historical flux of BC over the past 150 years through geochemical analysis of two 210Pb-dated sediment cores from Yancheng coastal wetland. Measured BC contents ranged from 0.24 mg g-1 to 1.41 mg g-1 with average values of 0.51mg g-1-0.69 mg g-1, and BC fluxes ranged from 0.69 g m-2 yr-1 to 11.80 g m-2 yr-1 with averages of 2.94g m-2 yr-1-3.79 g m-2 yr-1. These values are consistent with other records worldwide. Both BC content and flux show a gradual and continuous increase over time and clearly reflect increased emissions from anthropogenic activities. The BC records have a significant peak in recent years (from 2000 to 2007), which is accompanied by the sharp increase of energy consumption and total carbon emission in the region. It is reasonable to conclude that changes in BC from increasing human activities have controlled BC fluxes during the last 150 years. Industrial contamination, especially BC emission, in the coastal region of eastern China should be taken into account when developing management strategies for protecting the natural environment.

Water storage changes in North America retrieved from GRACE gravity and GPS data

As global warming continues, the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management. In North America as elsewhere in the world, changes in water resources strongly impact agriculture and animal husbandry. From a combination of Gravity Recovery and Climate Experiment (GRACE) gravity and Global Positioning System (GPS) data, it is recently found that water storage from August, 2002 to March, 2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005. In this paper, we use GRACE monthly gravity data of Release 5 to track the water storage change from August, 2002 to June, 2014. In Canadian Prairies and the Great Lakes areas, the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a, which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error. We also find a long term decrease of water storage at a rate of −12.0 ± 4.2 Gt/a in Ungava Peninsula, possibly due to permafrost degradation and less snow accumulation during the winter in the region. In addition, the effect of total mass gain in the surveyed area, on present-day sea level, amounts to −0.18 mm/a, and thus should be taken into account in studies of global sea level change.

Tectono-climatic implications of Eocene Paratethys regression in the Tajik basin of central Asia

Plate tectonics and eustatic sea-level changes have fundamental effects on paleoenvironmental conditions and bio-ecological changes. The Paratethys Sea was a large marine seaway that connected the Mediterranean Neotethys Ocean with Central Asia during early Cenozoic time. Withdrawal of the Paratethys from central Asia impacted the distribution and composition of terrestrial faunas in the region and has been largely associated with changes in global sea level and climate such as cooling associated with the Eocene/Oligocene transition (EOT).Whereas the regression has been dated in the Tarim basin (China), the pattern and timing of regression in the Tajik basin, 400 km to the west, remain unresolved, precluding a test of current paleogeographic models. Here we date the Paratethys regression in Tajikistan at ca. 39 million years ago (Ma), which is several million years older than the EOT (at ca. 34 Ma) marking the greenhouse to icehouse climate transition of the Cenozoic. Our data also show a restricted, evaporitic marine environment since the middle–late Eocene and establishment of desert like environments after ca. 39 Ma. The overall stratigraphic record from the Tajik basin and southern Tien Shan points to deposition in a foreland basin setting by ca. 40 Ma in response to active tectonic growth of the Pamir–Tibet Mountains at the same time. Combined with the northwestward younging trend of the regression in the region, the Tajik basin record is consistent with northward growth of the Pamir and suggests significant tectonic control on Paratethys regression and paleoenvironmental changes in Central Asia.

New insights on the Oligo-Miocene succession bearing phosphatic layers of the Maltese Archipelago

The Maltese Archipelago sedimentary succession is nowadays very well studied and known, mostly due to the excellent exposures of the outcrops, the well-preserved calcareous microfossil content, and the cyclic lithological pattern of most of the stratigraphic intervals. Therefore, the Maltese sediments have been studied to establish updated calcareous plankton biostratigraphic schemes, and the Ras il Pellegrin section, along the western coast of Malta Island, has been chosen to host the Global Stratigraphic Section and Point of the Serravallian Stage. This paper focuses on the Maltese Oligo-Miocene succession bearing well-developed phosphatic beds, with particular attention to the evaluation of the associated sedimentary hiatuses. To achieve this goal, the calcareous nannofossils content of the marine sediments inter-bedded to the phosphatic horizons has been analysed in two key sections: Il Blata (W of the Malta Island) and Qammieh (N of the Malta Island). Furthermore, the good correspondence of the examined succession with the third-order sequences of the New Jersey passive margin, allowed a more refined definition of the intervals characterized by absence of normal marine sedimentation. Dissimilarities in the number of the phosphatic horizons characterizing the two sections have been explained supposing different locations of the two depositional areas within the sedimentary basin, probably affected by local syn-sedimentary tectonic activity. Finally, the correlation of the two investigated successions with the stable Oxygen isotope curve provided relationships between the origin of the phosphatic layers and global sea-level changes.