All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
1994.
The derivation of an anisotropic velocity model from a combined surface and borehole seismic survey in crystalline environment at the COSC-1 borehole, central Sweden
Geophysical Journal International,
210
(3)
1332--1346
2017
ISSN: 0956-540X1993.
The effect of anorthite content and water on quartz-feldspar cotectic compositions in the rhyolitic system and implications for geobarometry
Journal of Petrology,
58
(4)
789-818
2017
ISSN: 00223530
Publisher: Oxford University Press
Keywords:▾
anorthite; crystallization; feldspar; geobarometry; magma; meltwater; petrology; phase equilibrium; quartz; rhyolite
Abstract: ▾ The position of the cotectic curve separating quartz and feldspar stability fields in the rhyolite system Qz-Ab-Or(-An-H2O) depends on pressure, making it a potential geobarometer applicable to high-silica volcanic products if melt water contents (H2Omelt) are known. Until recently, the applicability of this geobarometer has been limited because pressure effects can be largely obscured by the effects of nearly ubiquitous normative anorthite (An, CaAl2Si2O8) in rhyolitic melts. In this study, we present new phase equilibria data that allow us to constrain the position of thermal minima and quartz-sanidine-plagioclase triple points on the quartz-feldspar cotectic curves at various pressures and melt normative An contents. Data were derived by conducting crystallization experiments to determine phase relations at the following conditions: 200 MPa, 1·4wt%H2Omelt, 3·5wt% An; 200 MPa, 1·3wt % H2Omelt, 7 wt % An; 500 MPa, 3wt % H2Omelt, 3·5wt % An; 500 MPa, 1·4wt % H2Omelt, 3·5wt % An; 500 MPa, 1·3wt%H2Omelt, 7 wt % An. Using this dataset with published phase equilibria results, we present a geobarometer based on the main parameters influencing cotectic compositions in the rhyolitic system: pressure, H2Omelt and melt An content. Our new geobarometer DERP (DEtermining Rhyolite Pressures) is calibrated to calculate pressures of magma storage from cotectic glass compositions with up to 7wt % normative melt An. DERP is calibrated for any H2Omelt in the pressure range 50-500 MPa. Its application is restricted to high-silica rhyolitic systems saturated with respect to quartz and feldspar(s). DERP was tested against various independent methods for estimating rhyolite pressures available in the literature (with an overall error of less than 100 MPa). Comparing pressures estimated with DERP and rhyolite-MELTS, which are based on the same approach, suggests that rhyolite-MELTS underestimates the effect of An. © The Author 2017. Published by Oxford University Press. All rights reserved.
1992.
The effect of gradational velocities and anisotropy on fault-zone trapped waves
Geophysical Journal International,
210
(2)
964-978
2017
ISSN: 0956540X
Publisher: Oxford University Press
Keywords:▾
Anisotropy; Dispersion (waves); Faulting; Fracture; Guided electromagnetic wave propagation; Numerical models; Shear waves; Velocity; Water waves, Amplitude information; Fault-zone trapped waves; High strain deformation zones; Higher frequencies; Seismic anisotropy; Shear wave velocity; Transverse isotropy; Transversely isotropic, Shear flow, deformation mechanism; fault zone; faulting; fracture zone; numerical model; seismic anisotropy; seismic attenuation; seismic velocity; strain analysis
Abstract: ▾ Synthetic fault-zone trapped wave (FZTW) dispersion curves and amplitude responses for FL (Love) and FR (Rayleigh) type phases are analysed in transversely isotropic 1-D elastic models. We explore the effects of velocity gradients, anisotropy, source location and mechanism. These experiments suggest: (i) A smooth exponentially decaying velocity model produces a significantly different dispersion curve to that of a three-layer model, with the main difference being that Airy phases are not produced. (ii) The FZTW dispersion and amplitude information of a waveguide with transverse-isotropy depends mostly on the Shear wave velocities in the direction parallel with the fault, particularly if the fault zone to country-rock velocity contrast is small. In this low velocity contrast situation, fully isotropic approximations to a transversely isotropic velocity model can be made. (iii) Fault-aligned fractures and/or bedding in the fault zone that cause transverse-isotropy enhance the amplitude and wave-train length of the FR type FZTW. (iv) Moving the source and/or receiver away from the fault zone removes the higher frequencies first, similar to attenuation. (v) In most physically realistic cases, the radial component of the FR type FZTW is significantly smaller in amplitude than the transverse. © The Authors 2017.
1991.
The environmental and evolutionary history of Lake Ohrid (FYROM/Albania): Interim results from the SCOPSCO deep drilling project
Biogeosciences,
14
(8)
2033 – 2054
2017
ISSN: 17264170
Publisher: Copernicus GmbH
Keywords:▾
Albania; Lake Ohrid; Macedonia [Southern Europe]; Mediterranean Region; Animalia; catchment; climate variation; data set; deep drilling; environmental change; environmental history; extinction; gastropod; glacial-interglacial cycle; Heinrich event; historical record; lake; Miocene; paleoclimate; Pleistocene; Pliocene; project assessment; proxy climate record; seismotectonics; tephra
Abstract: ▾ This study reviews and synthesises existing information generated within the SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) deep drilling project. The four main aims of the project are to infer (i) the age and origin of Lake Ohrid (Former Yugoslav Republic of Macedonia/Republic of Albania), (ii) its regional seismotectonic history, (iii) volcanic activity and climate change in the central northern Mediterranean region, and (iv) the influence of major geological events on the evolution of its endemic species. The Ohrid basin formed by transtension during the Miocene, opened during the Pliocene and Pleistocene, and the lake established de novo in the still relatively narrow valley between 1.9 and 1.3 Ma. The lake history is recorded in a 584 m long sediment sequence, which was recovered within the framework of the International Continental Scientific Drilling Program (ICDP) from the central part (DEEP site) of the lake in spring 2013. To date, 54 tephra and cryptotephra horizons have been found in the upper 460 m of this sequence. Tephrochronology and tuning biogeochemical proxy data to orbital parameters revealed that the upper 247.8 m represent the last 637 kyr. The multi-proxy data set covering these 637 kyr indicates long-term variability. Some proxies show a change from generally cooler and wetter to drier and warmer glacial and interglacial periods around 300 ka. Short-term environmental change caused, for example, by tephra deposition or the climatic impact of millennial-scale Dansgaard-Oeschger and Heinrich events are superimposed on the long-term trends. Evolutionary studies on the extant fauna indicate that Lake Ohrid was not a refugial area for regional freshwater animals. This differs from the surrounding catchment, where the mountainous setting with relatively high water availability provided a refuge for temperate and montane trees during the relatively cold and dry glacial periods. Although Lake Ohrid experienced significant environmental change over the last 637 kyr, preliminary molecular data from extant microgastropod species do not indicate significant changes in diversification rate during this period. The reasons for this constant rate remain largely unknown, but a possible lack of environmentally induced extinction events in Lake Ohrid and/or the high resilience of the ecosystems may have played a role. © Author(s) 2017.
1990.
The fallacy of interpreting SSDS with different types of breccias as seismites amid the multifarious origins of earthquakes: Implications
Journal of Palaeogeography,
6
(1)
12-44
2017
Abstract: ▾ At present, there are no criteria to distinguish soft-sediment deformation structures (SSDS) formed by earthquakes from SSDS formed by the other 20 triggering mechanisms (see a companion paper in Vol. 5, No. 4 of this journal by Shanmugam, 2016). Even if one believes that earthquakes are the true triggering mechanism of SSDS in a given case, the story is still incomplete. This is because earthquakes (seismic shocks) are induced by a variety of causes: 1) global tectonics and associated faults (i.e., mid-ocean ridges, trenches, and transform faults); 2) meteorite-impact events; 3) volcanic eruptions; 4) post-glacial uplift; 5) tsunami impact; 6) cyclonic impact; 7) landslides (mass-transport deposits); 8) tidal activity; 9) sea-level rise; 10) erosion; and 11) fluid pumping. These different causes are important for developing SSDS. Breccias are an important group of SSDS. Although there are many types of breccias classified on the basis of their origin, five types are discussed here (fault, volcanic, meteorite impact, sedimentary-depositional, sedimentary-collapse). Although different breccia types may resemble each other, distinguishing one type (e.g., meteorite breccias) from the other types (e.g., fault, volcanic, and sedimentary breccias) has important implications. 1) Meteorite breccias are characterized by shock features (e.g., planar deformation features in mineral grains, planar fractures, high-pressure polymorphs, shock melts, etc.), whereas sedimentary-depositional breccias (e.g., debrites) do not. 2) Meteorite breccias imply a confined sediment distribution in the vicinity of craters, whereas sedimentary-depositional breccias imply an unconfined sediment distribution, variable sediment transport, and variable sediment provenance. 3) Meteorite, volcanic, and fault breccias are invariably subjected to diagenesis and hydrothermal mineralization with altered reservoir quality, whereas sedimentary-depositional breccias exhibit primary (unaltered) reservoir quality. And finally, 4) sedimentary-collapse breccias are associated with economic mineralization (e.g., uranium ore), whereas sedimentary-depositional breccias are associated with petroleum reservoirs. Based on this important group of SSDS with breccias, the current practice of interpreting all SSDS as “seismites” is inappropriate. Ending this practice is necessary for enhancing conceptual clarity and for advancing this research domain. © 2016 China University of Petroleum (Beijing)
1989.
The origin and degassing history of the Earth's atmosphere revealed by Archean xenon
Nature Communications,
8
2017
ISSN: 20411723
Publisher: Nature Publishing Group
Keywords:▾
Barberton; Mpumalanga; South Africa; argon; chlorine; inert gas; xenon; atmospheric chemistry; degassing; isotopic composition; isotopic fractionation; noble gas; paleoatmosphere; quartz; solar system; tracer; xenon; Archean; Article; astronomy; atmosphere; comparative study; fractionation; irradiation; thermodynamics; thermogenesis; volumetry
Abstract: ▾ Xenon (Xe) is an exceptional tracer for investigating the origin and fate of volatile elements on Earth. The initial isotopic composition of atmospheric Xe remains unknown, as do the mechanisms involved in its depletion and isotopic fractionation compared with other reservoirs in the solar system. Here we present high precision analyses of noble gases trapped in fluid inclusions of Archean quartz (Barberton, South Africa) that reveal the isotopic composition of the paleo-atmosphere at ≈3.3 Ga. The Archean atmospheric Xe is mass-dependently fractionated by 12.9±2.4 ‰ u-1 (± 2σ, s.d.) relative to the modern atmosphere. The lower than today 129 Xe excess requires a degassing rate of radiogenic Xe from the mantle higher than at present. The primordial Xe component delivered to the Earth's atmosphere is distinct from Solar or Chondritic Xe but similar to a theoretical component called U-Xe. Comets may have brought this component to the Earth's atmosphere during the last stages of terrestrial accretion. © 2017 The Author(s).
1988.
Utilizing the International Geo Sample Number Concept in Continental Scientific Drilling During ICDP Expedition COSC-1
Data Science Journal,
16
(1)
2017
ISSN: 1683-1470Abstract: ▾ Article: Utilizing the International Geo Sample Number Concept in Continental Scientific Drilling During ICDP Expedition COSC-1
1987.
The structural elements and tectonics of the Lake Van basin (Eastern Anatolia) from multi-channel seismic reflection profiles
Journal of African Earth Sciences,
129165-178
2017
ISSN: 1464343X
Publisher: Elsevier Ltd
Keywords:▾
deformation; graben; normal fault; reverse fault; sedimentation; seismic data; seismic reflection; strike-slip fault; tectonic structure; uplift; vertical seismic profile, Lake Van; Turkey
Abstract: ▾ This study analyzed multi-channel seismic reflection data from Lake Van, Eastern Anatolia, to provide key information on the structural elements, deformational patterns and overall tectonic structure of the Lake Van basin. The seismic data reveal three subbasins (the Tatvan, northern and Ahlat subbasins) separated by structural ridges (the northern and Ahlat ridges). The Tatvan basin is a tilted wedge-block in the west, it is a relatively undeformed and flat-lying deep basin, forming a typical example of strike-slip sedimentation. Seismic sections reveal that the deeper sedimentary sections of the Tatvan basin are locally folded, gently in the south and more intensely further north, suggesting a probable gravitational “wedge-block” instability, oblique to the northern margin. The northern subbasin, bounded by normal oblique faults, forms a basin-margin graben structure that is elongated in a northeast-southwest direction. The east-west trending Ahlat ridge forms a fault-wedged sedimentary ridge and appears to offset by reverse oblique faults forming as a push-up rhomb horst structure. The Ahlat subbasin is a fault-wedged trough fill that is elongated in the west-east direction and appears as a horst-foot graben formed by the normal oblique faults. The northeast-southwest directed northern ridge is a faulted crestal terrace of a sublacustrine basement block. Its step-like morphology, in response to the downfaulting of the Tatvan basin, as well as its backthrusted appearance, indicates the normal oblique nature of the bounding faults. The lacustrine shelf and slope show distinctive stratigraphic features; progradational deltas, submerged fluvial channels, distorted and collapsed beddings and soft sediment deformation structures, characterizing a highly unstable nature of shelf caused by strong oblique faulting and related earthquakes. The faulting caused uplift of the Çarpanak spur zone, together with the northeastern Erek delta, deformation of deltaic structures and subsequently exposing the shelf and slope areas. The exposed areas are evident in the angular unconformity surface of the Çarpanak basement block with the northeastern Erek delta and thinned sediments. The uplift resulted in the asymmetric depositional emplacement of the southeastern delta that is controlled by a series of ramp anticlines/low angle reverse faults. The Deveboynu subbasin and Varis spur zone form wide fault-controlled depressions with thick sediments that are elongated in the north-south direction. These subbasins appear as a small pull-apart boundary formed by normal oblique faults at the western end of the southeastern delta. © 2017 Elsevier Ltd
1986.
The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)
Quaternary Geochronology,
42117 – 129
2017
ISSN: 18711014
Publisher: Elsevier B.V.
Keywords:▾
Kenya; Turkana; core analysis; hominid; human evolution; iron sulfide; magnetic reversal; magnetostratigraphy; Olduvai event; paleolimnology; Pleistocene; remagnetization
Abstract: ▾ One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a ∼216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the ‘Vrica Subchron’ previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies. © 2017
1985.
The variation of paleo-lake environment in the Lower Member 2 of Qingshankou Formation in the Songliao Basin
Earth Science Frontiers,
24
(1)
205 – 215
2017
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Aquatic organisms; Bacteria; Biogeochemistry; Biological materials; Biology; Biomarkers; Carbon dioxide; Lakes; Lipids; Organic compounds; Oxygen; Water; Anoxic conditions; Geochemical data; Green sulfur bacteria; Salinity; Semi-arid climate; Songliao basin; Stratified waters; Variable content; Salt water intrusion
Abstract: ▾ The data of rock-eval and biomarkers in the samples of the Lijiatuozi Section were analyzed for better understanding the paleo-lake environment of the Lower Member 2 of the Qingshankou Formation(K2qn2)in the Songliao Basin. The organic matters (OMs) were mainly originated from aquatic organisms according to plot of hydrogen index (210-773 mg HC/g TOC) and oxygen index (2-188 mg CO2/g TOC) in low maturity source rock. The evolution of paleo-lake environment could be divided into three stages based on geochemical data. In the stage I, low values of gammacerane index and aryl isoprenoid/phenanthrene ratio, corresponding with low ratios of diasterane/sterane and the plot of pristane/phytane and dehydroxyl vitamin-E index, parameters mentioned above all indicated that the lake was considered as being anoxic and brackish water conditions. In the stage II, the occurrence of short time marine incursion was defined by variable contents of 24-n-propyl-cholestanes and 24-i-propyl-cholestanes, leading to semi-deep or deep water environment; seawater intrusion with sea creatures, oxygen, nutrition, organic matter and sulfurous substances, which were helpful with formation of increasing salinity for brackish water and salt water; abundant composition of aryl isoprenoid displayed that stratified lake water was rich in free state of H2S with euphotic zone of anoxia and upward chemocline during this period. However, the lake was dominantly given priority to fresh water to the brackish water deposition with increasing oxygen content at the same time, which suggested that fresh water input increased in the latter stages of stage II. The lake was in high salinity water, anoxia, and the shallow chemocline due to being influenced by semi-arid climate conditions during the sedimentary period of stage III, and turbulent water body was against growth of green sulfur bacteria and preservation of free H2S. © 2017, Editorial Office of Earth Science Frontiers. All right reserved.
1984.
Timescales of magmatic processes prior to the ∼4.7 ka Agnano-Monte Spina eruption (Campi Flegrei caldera, Southern Italy) based on diffusion chronometry from sanidine phenocrysts
Bulletin of Volcanology,
79
(2)
2017
ISSN: 02588900
Publisher: Springer Verlag
Keywords:▾
Campania [Italy]; Campi Flegrei; Italy; Napoli [Campania]; backscatter; caldera; electron probe analysis; geochronology; magmatism; phenocryst; sanidine; timescale; trigger mechanism; volcanic eruption
Abstract: ▾ Barium diffusion chronometry applied to sanidine phenocrysts from the trachytic Agnano-Monte Spina eruption (∼4.7 ka) constrains the time between reactivation and eruption of magma batches in the Campi Flegrei caldera. Backscattered electron imaging and quantitative electron microprobe measurements on 50 sanidine phenocrysts from representative pumice samples document core-to-rim compositional zoning. We focus on compositional breaks near the crystal rims that record magma mixing processes just prior to eruption. Diffusion times were modeled at a magmatic temperature of 930 °C using profiles based on quantitative BaO point analyses, X-ray scans, and grayscale swath profiles, yielding times ≤60 years between mixing and eruption. Such short timescales are consistent with volcanological and geochronological data that indicate that at least six eruptions occurred in the Agnano-San Vito area during few centuries before the Agnano-Monte Spina eruption. Thus, the short diffusion timescales are similar to time intervals between eruptions. Therefore, the rejuvenation time of magma residing in a shallow reservoir after influx of a new magma batch that triggered the eruption, and thus pre-eruption warning times, may be as short as years to a few decades at Campi Flegrei caldera. © 2017, Springer-Verlag Berlin Heidelberg.
1983.
Understanding volcanic hazard at the most populated caldera in the world: Campi Flegrei, Southern Italy
Geochemistry, Geophysics, Geosystems,
18
(5)
2004 – 2008
2017
ISSN: 15252027
Publisher: Blackwell Publishing Ltd
Keywords:▾
Volcanoes; Caldera formation; Geothermal activity; Innovative models; Magma intrusion; Scientific drilling; Volcanic activities; Volcanic centers; Volcanic hazards; Hazards
Abstract: ▾ Naples and its hinterland in Southern Italy are one of the most urbanized areas in the world under threat from volcanic activity. The region lies within range of three active volcanic centers: Vesuvius, Campi Flegrei, and Ischia. The Campi Flegrei caldera, in particular, has been in unrest for six decades. The unrest followed four centuries of quiescence and has heightened concern about an increased potential for eruption. Innovative modeling and scientific drilling are being used to investigate Campi Flegrei, and the results highlight key directions for better understanding the mechanisms of caldera formation and the roles of magma intrusion and geothermal activity in determining the volcano's behavior. They also provide a framework for evaluating and mitigating the risk from this caldera and other large ones worldwide. © 2017. American Geophysical Union. All Rights Reserved.
1982.
Utilizing supercritical geothermal systems: a review of past ventures and ongoing research activities
Geothermal Energy,
5
(1)
2017
ISSN: 21959706
Publisher: SpringerOpen
Keywords:▾
Energy resources; Enthalpy; Geothermal energy; Geothermal wells; International cooperation; Volcanoes; Well completion, Extreme temperatures; Geothermal resources; Geothermal systems; International collaborations; Supercritical condition; Supercritical systems; Taupo Volcanic Zone; Temperature and pressures, Geothermal fields, chemical composition; enthalpy; geothermal system; high temperature; hydrothermal system; permeability; reservoir; transition zone; well completion, California; Geysers; Hawaii [United States]; Honshu; Iceland; Italy; Iwate; Japan; Kakkonda Geothermal Field; Kenya; Krafla; Larderello; Los Humeros; Menengai Volcano; Mexico [North America]; Nakuru; New Zealand; Newberry Volcano; North Island; Oregon; Pisa [Tuscany]; Puebla [Mexico]; Reykjanes Peninsula; Salton Sea; Taupo Volcanic Zone; Tohoku; Tuscany; United States
Abstract: ▾ Supercritical geothermal systems are very high-temperature geothermal systems that are located at depths near or below the brittle–ductile transition zone in the crust where the reservoir fluid is assumed to be in the supercritical state, that is for pure water, temperature and pressure are, respectively, in excess of 374 °C and 221 bar. These systems have garnered attention in recent years as a possible type of unconventional geothermal resource due to their very high enthalpy fluids. Supercritical conditions are often found at the roots of volcanic-hosted hydrothermal systems. More than 25 deep wells drilled in geothermal fields such as The Geysers, Salton Sea, and on Hawaii (USA), Kakkonda (Japan), Larderello (Italy), Krafla (Iceland), Los Humeros (Mexico), and Menengai (Kenya) have encountered temperatures in excess of 374 °C, and in some cases have encountered magma. Although fluid entries were documented for some of these wells, it remains an open question if permeability can be maintained at high enthalpy conditions. The IDDP-1 well at Krafla encountered magma, and ended up producing very high enthalpy fluids; however, these fluids were very corrosive and abrasive. Innovative drilling and well completion techniques are therefore needed to deal with the extreme temperatures and aggressive fluid chemistry compositions of these systems. New efforts are underway in Japan (northern Honshu), Italy (Larderello), Iceland (Reykjanes peninsula and Krafla), Mexico (Los Humeros), USA (Newberry), and New Zealand (Taupo Volcanic Zone) to investigate supercritical systems. Here, we review past studies, describe current research efforts, and outline the challenges and potential opportunities that these systems provide for international collaboration to ultimately utilize supercritical geothermal systems as a geothermal energy resource. © 2017, The Author(s).
1981.
Location of the pilot borehole for investigations of reservoir triggered seismicity at Koyna, India
Gondwana Research,
42133-139
2017
ISSN: 1342937X
Publisher: Elsevier Inc.
Keywords:▾
borehole geophysics; borehole logging; broadband data; detection method; drilling; earthquake hypocenter; earthquake magnitude; error analysis; estimation method; reservoir-induced seismicity; site investigation; trigger mechanism, India; Koyna; Maharashtra
Abstract: ▾ Artificial water reservoir triggered earthquakes are now known to have occurred at over 120 sites globally. The part played by the reservoirs in triggering is not exactly known due to lack of near field observations of triggered earthquakes. Koyna, located near the west coast of India, where triggered earthquakes have been occurring since 1962 provides an excellent site for near field observations of the target M ≥ 2 earthquakes. A 6 borehole seismic network has been deployed recently in the Koyna region at depths of 981–1522 m to improve the hypocenter locations. During May–December 2015, a total of 1039 earthquakes of ML ≥ 0.5 were located using the borehole seismic network. The region is also monitored through a dense network of 23 surface broad-band stations. Our analysis indicates a significant improvement in the estimation of absolute locations of earthquakes with errors of the order of ± 300 m, combining both the networks. Based on seismicity, and logistics, a block of 2 × 2 km2 area has been chosen for drilling the first pilot borehole of ~ 3 km depth, where M ≥ 2 earthquakes have been occurring frequently since 2005. © 2016 International Association for Gondwana Research
1980.
A new high-resolution pollen sequence at Lake Van, Turkey: Insights into penultimate interglacial-glacial climate change on vegetation history
Climate of the Past,
13
(6)
689-710
2017
ISSN: 18149324
Publisher: Copernicus GmbH
Keywords:▾
climate variation; core analysis; forest-steppe; glacial-interglacial cycle; marine isotope stage; oxygen isotope; paleoecology; paleoenvironment; palynology; proxy climate record; soil moisture; vegetation history, Black Sea; Caspian Sea; Lake Van; Mediterranean Sea; Turkey, Amaranthaceae; Artemisia; Quercus
Abstract: ▾ A new detailed pollen and oxygen isotope record of the penultimate interglacial-glacial cycle, corresponding to the marine isotope stage (MIS) 7-6, has been generated from the Ahlat Ridge (AR) sediment core at Lake Van, Turkey. The presented Lake Van pollen record (ca. 250.2-128.8 ka) displays the highest temporal resolution in this region with a mean sampling interval of ĝ1/4 540 years. The integration of all available proxies shows three temperate intervals of high effective soil moisture availability. This is evidenced by the predominance of steppe-forested landscapes (oak steppe-forest) similar to the present interglacial vegetation in this sensitive semiarid region between the Black Sea, the Caspian Sea, and the Mediterranean Sea. The wettest and warmest stage, as indicated by highest temperate tree percentages, can be broadly correlated with MIS 7c, while the amplitude of the tree population maximum during the oldest penultimate interglacial (MIS 7e) appears to be reduced due to warm but drier climatic conditions. The detailed comparison of the penultimate interglacial complex (MIS 7) to the last interglacial (Eemian, MIS 5e) and the current interglacial (Holocene, MIS 1) provides a vivid illustration of possible differences in the successive climatic cycles. Intervening periods of treeless vegetation can be correlated with MIS 7d and 7a, in which open landscapes favor local erosion and detrital sedimentation. The predominance of steppe elements (e.g., Artemisia, Chenopodiaceae) during MIS 7d indicates very dry and cold climatic conditions. In contrast, the occurrence of higher temperate tree percentages (mainly deciduous Quercus) throughout MIS 7b points to relatively humid and mild conditions, which is in agreement with other pollen sequences in southern Europe. Despite the general dominance of dry and cold desert-steppe vegetation during the penultimate glacial (broadly equivalent to MIS 6), this period can be divided into two parts: an early stage (ca. 193-157 ka) with higher oscillations in tree percentages and a later stage (ca. 157-131 ka) with lower tree percentages and subdued oscillations. This subdivision of the penultimate glacial is also seen in other pollen records from southern Europe (e.g., MD01-2444 and I-284; Margari et al., 2010; Roucoux et al., 2011). The occurring vegetation pattern is analogous to the division of MIS 3 and MIS 2 during the last glacial in the same sediment sequence. Furthermore, we are able to identify the MIS 6e event (ca. 179-159 ka) as described in marine pollen records, which reveals clear climate variability due to rapid alternation in the vegetation cover. In comparison with long European pollen archives, speleothem isotope records from the Near East, and global climate parameters (e.g., insolation, atmospheric CO2 content), the new high-resolution Lake Van record presents an improved insight into regional vegetation dynamics and climate variability in the eastern Mediterranean region. © Author(s) 2017.
1979.
Linear and non-linear responses of vegetation and soils to glacial-interglacial climate change in a Mediterranean refuge
Scientific Reports,
7
(1)
2017
ISSN: 20452322
Publisher: Nature Publishing Group
Abstract: ▾ The impact of past global climate change on local terrestrial ecosystems and their vegetation and soil organic matter (OM) pools is often non-linear and poorly constrained. To address this, we investigated the response of a temperate habitat influenced by global climate change in a key glacial refuge, Lake Ohrid (Albania, Macedonia). We applied independent geochemical and palynological proxies to a sedimentary archive from the lake over the penultimate glacial-interglacial transition (MIS 6-5) and the following interglacial (MIS 5e-c), targeting lake surface temperature as an indicator of regional climatic development and the supply of pollen and biomarkers from the vegetation and soil OM pools to determine local habitat response. Climate fluctuations strongly influenced the ecosystem, however, lake level controls the extent of terrace surfaces between the shoreline and mountain slopes and hence local vegetation, soil development and OM export to the lake sediments. There were two phases of transgressional soil erosion from terrace surfaces during lake-level rise in the MIS 6-5 transition that led to habitat loss for the locally dominant pine vegetation as the terraces drowned. Our observations confirm that catchment morphology plays a key role in providing refuges with low groundwater depth and stable soils during variable climate. © 2017 The Author(s).
1978.
Contamination Control for Scientific Drilling Operations
Advances in Applied Microbiology,
9861 – 91
2017
ISSN: 00652164
Publisher: Academic Press Inc.
Keywords:▾
Bacteria; Ecosystem; Extraction and Processing Industry; Geologic Sediments; Humans; fluorescent dye; fluorocarbon; microsphere; tracer; Article; drill; ecological procedures; extended core barrel; gravity; hydraulic piston coring; microbial contamination; nonhuman; rotary drilling; tube; wireline coring; bacterium; chemistry; devices; ecosystem; genetics; growth, development and aging; human; isolation and purification; microbiology; mining; procedures; sediment
Abstract: ▾ Drilling is an integral part of subsurface exploration. Because almost all drilling operations require the use of a drill fluid, contamination by infiltration of drill fluid into the recovered core material cannot be avoided. Because it is impossible to maintain sterile conditions during drilling the drill fluid will contain surface microbes and other contaminants. As contamination cannot be avoided, it has to be tracked to identify those parts of the drill core that were not infiltrated by the drill fluid. This is done by the addition of tracer compounds. A great variety of tracers is available, and the choice depends on many factors. This review will first explain the basic principles of drilling before presenting the most common tracers and discussing their strengths and weaknesses. The final part of this review presents a number of key questions that have to be addressed in order to find the right tracer for a particular drilling operation. © 2017 Elsevier Inc.
1977.
Carbonate and silicate cementation of siliciclastic sediments of the New Jersey shelf (IODP Expedition 313): relation with organic matter diagenesis and submarine groundwater discharge
Geo-Marine Letters,
37
(6)
537-547
2017
ISSN: 02760460
Publisher: Springer Verlag
Keywords:▾
Aquifers; Biogeochemistry; Biological materials; Carbon; Carbon dioxide; Carbonation; Cementing (shafts); Discharge (fluid mechanics); Dissolution; Groundwater; Groundwater resources; Hydrogeology; Minerals; Organic compounds; Organic minerals; Scanning electron microscopy; Sedimentology; Silicate minerals; Silicates; Submarines; Water; Weathering, Anaerobic oxidation of methanes; Bacterial sulphate reductions; Carbonate precipitation; Dissolved inorganic carbon; Fine-grained sediment; Pore water salinities; Siliciclastic sediments; Submarine groundwater discharge, Cements, carbonate sediment; cementation; chemical weathering; continental shelf; discharge; groundwater; Ocean Drilling Program; organic matter; silicate mineral; siliciclastic deposit; underwater environment, Atlantic Ocean; New Jersey Shelf, Bacteria (microorganisms)
Abstract: ▾ The New Jersey continental shelf extends 150 km off the shoreline. During IODP Expedition 313, siliciclastic deposits of late Eocene to late Pleistocene age were drilled down to 631, 669 and 755 m below seafloor at sites 27A, 28A and 29A respectively in very shallow waters (33.5 to 36 m depth). Pore water salinities display multilayered brackish-salty-brine units 10 to 170 m thick, where low-salinity water is preferentially stored in fine-grained sediments. The sharp boundaries of these buried aquifers are often marked by cemented layers a few centimetres thick. The mineralogy and scanning electron microscope observations of these layers show two phases of cementation by authigenic minerals: (1) the early carbonate cement is frequently associated with pyrite, and (2) the late silicate cement infills the residual porosity. The isotopic compositions of the carbonate cements vary widely: −2.4 < δ18O ‰ VPDB < +2.8; −15.1 < δ13C ‰ VPDB < +15.6. The δ18O values indicate that the carbonate cements precipitated with pore waters comprising variable mixtures of seawater and 18O-depleted fresh water originating from submarine groundwater discharge. The δ13C values of the carbonate cements are related to organic matter diagenesis, providing 13C-depleted dissolved inorganic carbon during bacterial sulphate reduction and anaerobic oxidation of methane, and 13C-rich dissolved inorganic carbon during methanogenesis. The diagenetic cementation processes included chemical weathering of reactive silicate minerals by the CO2-rich pore waters issued from organic matter diagenesis that released bicarbonate, cations and dissolved silica, which were further precipitated as carbonate and silicate cements. The estimated range of temperature (18±4 °C) during carbonate precipitation is consistent with carbonate cementation at moderate burial depths; however, silicate cementation occurred later during diagenesis at deeper burial depths. © 2017, Springer-Verlag Berlin Heidelberg.
1976.
Cellularly preserved microbial fossils from ∼3.4 Ga deposits of South Africa: A testimony of early appearance of oxygenic life?
Precambrian Research,
295117 – 129
2017
1975.
Chicxulub and the exploration of large peak-ring impact craters through scientific drilling
GSA Today,
27
(10)
4-8
2017
Abstract: ▾ The Chicxulub crater is the only wellpreserved peak-ring crater on Earth and linked, famously, to the K-T or K-Pg mass extinction event. For the first time, geologists have drilled into the peak ring of that crater in the International Ocean Discovery Program and International Continental Scientific Drilling Program (IODP-ICDP) Expedition 364. The Chicxulub impact event, the environmental calamity it produced, and the paleobiological consequences are among the most captivating topics being discussed in the geologic community. Here we focus attention on the geological processes that shaped the ~200-km-wide impact crater responsible for that discussion and the expedition's first year results. Copyright 2017, The Geological Society of America.
1974.
Chromium isotope evidence in ejecta deposits for the nature of Paleoproterozoic impactors
Earth and Planetary Science Letters,
460105--111
2017
1973.
Climatic influence of the latest Antarctic isotope maximum of the last glacial period (AIM4) on Southern Patagonia
Palaeogeography, Palaeoclimatology, Palaeoecology,
47233 – 50
2017
1972.
Contamination Control for Scientific Drilling Operations
Advances in Applied Microbiology,
9861-91
2017
ISSN: 00652164
Publisher: Academic Press Inc.
Keywords:▾
fluorescent dye; fluorocarbon; microsphere; tracer, Article; drill; ecological procedures; extended core barrel; gravity; hydraulic piston coring; microbial contamination; nonhuman; rotary drilling; tube; wireline coring; bacterium; chemistry; devices; ecosystem; genetics; growth, development and aging; human; isolation and purification; microbiology; mining; procedures; sediment, Bacteria; Ecosystem; Extraction and Processing Industry; Geologic Sediments; Humans
Abstract: ▾ Drilling is an integral part of subsurface exploration. Because almost all drilling operations require the use of a drill fluid, contamination by infiltration of drill fluid into the recovered core material cannot be avoided. Because it is impossible to maintain sterile conditions during drilling the drill fluid will contain surface microbes and other contaminants. As contamination cannot be avoided, it has to be tracked to identify those parts of the drill core that were not infiltrated by the drill fluid. This is done by the addition of tracer compounds. A great variety of tracers is available, and the choice depends on many factors. This review will first explain the basic principles of drilling before presenting the most common tracers and discussing their strengths and weaknesses. The final part of this review presents a number of key questions that have to be addressed in order to find the right tracer for a particular drilling operation. © 2017 Elsevier Inc.
1971.
Core Spatial Position Restoring of the CCSDSK-2 East Borehole in the Songliao Basin of Northeast China (in Chinese with English abstract); [松辽盆地科学钻探工程松科2井东孔岩心空间归位]
Geological Science and Technology Information,
36
(4)
271-276
2017
1970.
Call for models-A test case for the source inversion validation: The 2014 ML 5.5 Orkney, South Africa, Earthquake
Seismological Research Letters,
88
(5)
1333 – 1338
2017