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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.04.008 Byline: Julie C. Castillo-Rogez (a), Thomas B. McCord (b) Keywords: Geophysics Abstract: We model Ceres' thermo-physical-chemical evolution by considering a large range of initial conditions as well as various evolutionary scenarios. Models are constrained by available shape measurements, which point to a differentiated interior for Ceres. We address the role played by hydrothermal activity in the long-term evolution of Ceres and especially the evolution of its hydrosphere. We suggest that models with times of formation shorter than about 5My after the production of calcium-aluminum inclusions are more likely to undergo hydrothermal activity in their early history, which affects Ceres' long-term thermal evolution. We evaluate the conditions for preserving liquid water inside Ceres, a possibility enhanced by its warm surface temperature and the enrichment of its hydrosphere in a variety of chemical species. However, thermal modeling of the hydrosphere needs to be further investigated. We show that shape data can help constrain the amount of hydrated silicate in the core, and thus the extent of hydrothermal activity in Ceres. We discuss the importance of these results for the Dawn mission's arrival at Ceres in 2015. Author Affiliation: (a) Jet Propulsion Laboratory, California Institute of Technology, M/S 79-24, 4800 Oak Grove Drive, Pasadena, CA 91109, USA (b) The Bear Fight Center, P.O. Box 667, 22 Fiddler's Road, Winthrop, WA 98862, USA Article History: Received 19 November 2008; Revised 10 April 2009; Accepted 17 April 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.07.020 Byline: Jafar Arkani-Hamed Keywords: Mars; Asteroids; Dynamics; Orbit determination; Satellites; Dynamics; Rotational dynamics Abstract: We investigate the polar wander of Mars in the last [approximately equal to]4.2Ga. We identify two sets of basins from the 20 giant impact basins reported by Frey [Frey, H., 2008. Geophys. Res. Lett. 35, L13203] which trace great circles on Mars, and propose that the great circles were the prevailing equators of Mars at the impact times. Monte Carlo tests are conducted to demonstrate that the two sets of basins are most likely not created by random impacts. Also, fitting 63,771 planes to randomly selected sets of 5, 6, or 7 basins indicated that the identified two sets are unique. We propose three different positions for the rotation pole of Mars, besides the present one. Accordingly, Tharsis bulge was initially formed at [approximately equal to]50N and moved toward the equator while rotating counterclockwise due to the influence of the two newly forming volcanic constructs, Alba Patera and Elysium Rise. The formation of the giant impact basins, subsequent mass concentrations (mascons) in Argyre, Isidis, and Utopia basins, and surface masses of volcanic mountains such as Ascraeus, Pavonis, Arsia and Olympus, caused further polar wander which rotated Tharsis bulge clockwise to arrive at its present location. The extensive polar motion of Mars during 4.2-3.9Ga implies a weak lithosphere on a global scale, deduced from a total of 72,000 polar wander models driven by Tharsis bulge, Alba Patera and Elysium Rise as the major mass perturbations. Different compensation states, 0-100%, are examined for each of the surface loads, and nine different thicknesses are considered for an elastic lithosphere. The lithosphere must have been very weak, with an elastic thickness of less than 5km, if the polar wander was driven by these mass perturbations. Author Affiliation: Department of Physics, University of Toronto, Toronto, ON, Canada M5S 1A7 Department of Earth and Planetary Sciences, McGill University, Montreal, QC, Canada H3A 2A7 Article History: Received 6 November 2008; Revised 13 July 2009; Accepted 20 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.05.021 Byline: Javier Ruiz Keywords: Mars; Magnetic fields; Mars; Climate Abstract: Large areas of strongly magnetized crust are located in Terra Cimmeria and Terra Sirenum, in the southern highlands of Mars, the older terrains on the planet. The typical depth to the base of the magnetized layer, deduced from the magnetic spectrum of Mars and modeling of isolated magnetic anomalies, would [approximately equal to]40-60km. In this paper the thermal state of Terra Cimmeria is revisited by calculating heat flows and crustal geotherms consistent with a previous estimation of the effective elastic thickness of the lithosphere, and with crustal abundances of heat-producing elements based on surface measurements performed by the Mars Odyssey Gamma Ray Spectrometer. The results suggest that, at the time of formation of the magnetized terrains surface (which have a minimum age of 4.1Ga), Curie depths for magnetite and hematite were shallower and similar, respectively, than the typical depth to the base of the magnetized layer. This implies that hematite is an important (if not dominant) contributor to the magnetization of the martian crust. However, an early warm climate would enhance the chance of magnetite to be a significant, even dominant, magnetization carrier in the lower portion of the magnetic layer. Author Affiliation: Centro de Biologi'a Molecular, CSIC-Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid, Spain Article History: Received 28 September 2008; Revised 16 April 2009; Accepted 25 May 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2009.06.005 Byline: Giacomo Corti Keywords: continental rifting; rift evolution; continental break-up; magmatism; deformation; East African Rift; Main Ethiopian Rift; Nubia-Somalia kinematics Abstract: The Main Ethiopian Rift is a key sector of the East African Rift System that connects the Afar depression, at Red Sea-Gulf of Aden junction, with the Turkana depression and Kenya Rift to the South. It is a magmatic rift that records all the different stages of rift evolution from rift initiation to break-up and incipient oceanic spreading: it is thus an ideal place to analyse the evolution of continental extension, the rupture of lithospheric plates and the dynamics by which distributed continental deformation is progressively focused at oceanic spreading centres. The first tectono-magmatic event related to the Tertiary rifting was the eruption of voluminous flood basalts that apparently occurred in a rather short time interval at around 30Ma; strong plateau uplift, which resulted in the development of the Ethiopian and Somalian plateaus now surrounding the rift valley, has been suggested to have initiated contemporaneously or shortly after the extensive flood-basalt volcanism, although its exact timing remains controversial. Voluminous volcanism and uplift started prior to the main rifting phases, suggesting a mantle plume influence on the Tertiary deformation in East Africa. Different plume hypothesis have been suggested, with recent models indicating the existence of deep superplume originating at the core-mantle boundary beneath southern Africa, rising in a north-northeastward direction toward eastern Africa, and feeding multiple plume stems in the upper mantle. However, the existence of this whole-mantle feature and its possible connection with Tertiary rifting are highly debated. The main rifting phases started diachronously along the MER in the Mio-Pliocene; rift propagation was not a smooth process but rather a process with punctuated episodes of extension and relative quiescence. Rift location was most probably controlled by the reactivation of a lithospheric-scale pre-Cambrian weakness; the orientation of this weakness (roughly NE-SW) and the Late Pliocene (post 3.2Ma)-recent extensional stress field generated by relative motion between Nubia and Somalia plates (roughly ESE-WNW) suggest that oblique rifting conditions have controlled rift evolution. However, it is still unclear if these kinematical boundary conditions have remained steady since the initial stages of rifting or the kinematics has changed during the Late Pliocene or at the Pliocene-Pleistocene boundary. Analysis of geological-geophysical data suggests that continental rifting in the MER evolved in two different phases. An early (Mio-Pliocene) continental rifting stage was characterised by displacement along large boundary faults, subsidence of rift depression with local development of deep (up to 5km) asymmetric basins and diffuse magmatic activity. In this initial phase, magmatism encompassed the whole rift, with volcanic activity affecting the rift depression, the major boundary faults and limited portions of the rift shoulders (off-axis volcanism). Progressive extension led to the second (Pleistocene) rifting stage, characterised by a riftward narrowing of the volcano-tectonic activity. In this phase, the main boundary faults were deactivated and extensional deformation was accommodated by dense swarms of faults (Wonji segments) in the thinned rift depression. The progressive thinning of the continental lithosphere under constant, prolonged oblique rifting conditions controlled this migration of deformation, possibly in tandem with the weakening related to magmatic processes and/or a change in rift kinematics. Owing to the oblique rifting conditions, the fault swarms obliquely cut the rift floor and were characterised by a typical right-stepping arrangement. Ascending magmas were focused by the Wonji segments, with eruption of magmas at surface preferentially occurring along the oblique faults. As soon as the volcano-tectonic activity was localised within Wonji segments, a strong feedback between deformation and magmatism developed: the thinned lithosphere was strongly modified by the extensive magma intrusion and extension was facilitated and accommodated by a combination of magmatic intrusion, dyking and faulting. In these conditions, focused melt intrusion allows the rupture of the thick continental lithosphere and the magmatic segments act as incipient slow-spreading mid-ocean spreading centres sandwiched by continental lithosphere. Overall the above-described evolution of the MER (at least in its northernmost sector) documents a transition from fault-dominated rift morphology in the early stages of extension toward magma-assisted rifting during the final stages of continental break-up. A strong increase in coupling between deformation and magmatism with extension is documented, with magma intrusion and dyking playing a larger role than faulting in strain accommodation as rifting progresses to seafloor spreading. Author Affiliation: Consiglio Nazionale delle Ricerche, Istituto di Geoscienze e Georisorse, via G. La Pira, 4, 50121, Firenze, Italy Article History: Received 15 January 2009; Accepted 23 June 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.02.006 Byline: Michelle R. Kirchoff, William B. McKinnon Keywords: Io; Tectonics; Volcanism; Satellites; surfaces; Geophysics Abstract: Thermal stresses are potentially important drivers of Io's tectonics and mountain building. It has been hypothesized that sustained local or regional shut down of heat-pipe volcanism on Io could lead to deep crustal heating and large compressive stresses [McKinnon, W.B., Schenk, P.M., Dombard, A.J., 2001. Geology 29, 103-106]. Such large stresses would then be relieved by thrust faulting and uplifting of crustal blocks, producing mountains like those observed on Io. Here we analyze the tectonic consequences of the heat-pipe model in detail, considering both the initial thermal stress state of a basalt or peridotite crust created by heat-pipe volcanism, and relative roles of subsidence stresses (due to burial of preexisting layers) and thermal stresses arising from variable volcanism and changes in crustal ([approximately equal to]lithosphere) thickness. We limit the magnitude of the potential subsidence stresses in our study, because the magnitude of subsidence stresses can be quite large, if not dominant. Results indicate that for a fixed crustal thickness, the region of failure and faulting moves closer to the surface as eruption rate decreases and time increases. When the crust melts at its base as volcanism decreases (as might occur under steady state tidal heating), resulting in crustal thinning, the region of failure is brought even closer to the surface. Naturally, when compressive, subsidence stresses are included, the vertical extent of crust in brittle failure thickens to include most of the lithosphere. In contrast, increases in eruption rate cause the extent of the region in compressional failure to decrease and be driven very deep in the crust (in the absence of sufficient subsidence stress). Therefore, regions of declining volcanism are more likely to produce mountains, whereas regions of extensive or increasing volcanism are less likely to do so. This is consistent with the observation of a global anticorrelation between mountains and volcanic centers on Io. Finally, we find that the choice of crustal composition/rheology (dry basalt vs. dry peridotite) has little effect on our results implying that basalt, peridotite and komatiite are all similarly 'stiff' in the Io environment. Author Affiliation: Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, One Brookings Dr., St. Louis, MO 63130, USA Article History: Received 14 January 2008; Revised 29 January 2009; Accepted 2 February 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.01.025 Byline: J. Andreas Ritzer, Steven A. Hauck Keywords: Mars; Tectonics; Geophysics Abstract: We characterize the lithospheric structure of Isidis Planitia on Mars by analyzing Mars Global Surveyor and Mars Odyssey gravity and topography data using a flexural model of a thin elastic shell including bending and membrane stresses. Isidis Planitia is a circular, relatively flat plain formed near the end of the Early Noachian, at the edge of the highlands-lowlands boundary and the site of a large free-air gravity anomaly, features consistent with modification and filling of an impact basin. Our results suggest that the bulk density of the fill material inside Isidis must be more than 2600 kgam.sup.-3 and higher densities are probable. A comparison of the faulting observed at Nili Fossae to the predicted zone of extensional strain northwest of Isidis constrains the thickness of the elastic lithosphere to be 100-180 km thick beneath the basin at the time of loading. We also find that loads outside of the basin play a significant role in the interpretation of the tectonics; simplified models tend to overestimate the lithospheric thickness. We place relatively narrow bounds on the thermal gradient (3.4-6.5 Kakm.sup.-1) and heat flux (13.6-26 mWam.sup.-2) at Isidis at the time of loading. Author Affiliation: Department of Geological Sciences, Case Western Reserve University, 112 A.W. Smith Bldg., 10900 Euclid Ave, Cleveland, OH 44106-7216, United States Article History: Received 2 May 2008; Revised 3 December 2008; Accepted 21 January 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.11.002 Byline: John Wahr (a), Zane A. Selvans (b), McCall E. Mullen (a), Amy C. Barr (c), Geoffrey C. Collins (d), Michelle M. Selvans (e), Robert T. Pappalardo (f) Keywords: Europa; Satellites; general; Tides; solid body; Tectonics; Geophysics Abstract: The tidal stress at the surface of a satellite is derived from the gravitational potential of the satellite's parent planet, assuming that the satellite is fully differentiated into a silicate core, a global subsurface ocean, and a decoupled, viscoelastic lithospheric shell. We consider two types of time variability for the tidal force acting on the shell: one caused by the satellite's eccentric orbit within the planet's gravitational field (diurnal tides), and one due to nonsynchronous rotation (NSR) of the shell relative to the satellite's core, which is presumed to be tidally locked. In calculating surface stresses, this method allows the Love numbers h and l, describing the satellite's tidal response, to be specified independently; it allows the use of frequency-dependent viscoelastic rheologies (e.g. a Maxwell solid); and its mathematical form is amenable to the inclusion of stresses due to individual tides. The lithosphere can respond to NSR forcing either viscously or elastically depending on the value of the parameter [DELTA]a [mu]/I*I, where [mu] and I* are the shear modulus and viscosity of the shell respectively, and I is the NSR forcing frequency. [DELTA] is proportional to the ratio of the forcing period to the viscous relaxation time. When [DELTA]a'1 the response is nearly fluid; when [DELTA]a*1 it is nearly elastic. In the elastic case, tensile stresses due to NSR on Europa can be as large as [approximately equal to]3.3 MPa, which dominate the [approximately equal to]50kPa stresses predicted to result from Europa's diurnal tides. The faster the viscous relaxation the smaller the NSR stresses, such that diurnal stresses dominate when [DELTA]a[sup.3]100. Given the uncertainty in current estimates of the NSR period and of the viscosity of Europa's ice shell, it is unclear which tide should be dominant. For Europa, tidal stresses are relatively insensitive both to the rheological structure beneath the ice layer and to the thickness of the icy shell. The phase shift between the tidal potential and the resulting stresses increases with [DELTA]. This shift can displace the NSR stresses longitudinally by as much as 45[degrees] in the direction opposite of the satellite's rotation. Author Affiliation: (a) Department of Physics, University of Colorado, UCB 390, Boulder, CO 80309-0390, USA (b) Laboratory for Atmospheric and Space Physics and the NASA Astrobiology Institute, University of Colorado, UCB 392, Boulder, CO 80309-0392, USA (c) Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, USA (d) Department of Physics and Astronomy, Wheaton College, 26 East Main Street, Norton, MA 02766-2322, USA (e) Division of Geological and Planetary Sciences, California Institute of Technology, MC 252-21, Pasadena, CA 91125, USA (f) Jet Propulsion Laboratory, California Institute of Technology, M/S 183-301, 4800 Oak Grove Dr., Pasadena, CA 91109, USA Article History: Received 4 March 2008; Revised 2 October 2008; Accepted 19 November 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.06.016 Byline: Caleb I. Fassett, James W. Head Keywords: Mars; surface; Geological processes Abstract: A new catalog of 210 open-basin lakes (lakes with outlet valleys) fed by valley networks shows that they are widely distributed in the Noachian uplands of Mars. In order for an outlet valley to form, water must have ponded in the basin to at least the level of the outlet. We use this relationship and the present topography to directly estimate the minimum amount of water necessary to flood these basins in the past. The volumes derived for the largest lakes ([approximately equal to]3x10.sup.4 to [approximately equal to]2x10.sup.5km.sup.3) are comparable to the largest lakes and small seas on modern Earth, such as the Caspian Sea, Black Sea, and Lake Baikal. We determine a variety of other morphometric properties of these lakes and their catchments (lake area, mean depth, volume, shoreline development, outlet elevation, and watershed area). Most candidate lakes have volumes proportional to and commensurate with their watershed area, consistent with precipitation as their primary source. However, other lakes have volumes that are anomalously large relative to their watershed areas, implying that groundwater may have been important in their filling. Candidate groundwater-sourced lakes are generally concentrated in the Arabia Terra region but also include the Eridania basin [Irwin, R.P., Howard, A.D., Maxwell, T.A., 2004a. J. Geophys. Res. 109, doi: 10.1029/2004JE002287. E12009; Irwin, R.P., Watters, T.R., Howard, A.D. Zimbelman, J.R., 2004b. J. Geophys. Res. 109, doi: 10.1029/2004JE002248. E09011] and several lakes near the dichotomy boundary. This areal distribution is broadly consistent with where groundwater should have reached the surface as predicted by current models. Both surface runoff and groundwater flow appear to have been important sources for lakes and lake chains, suggesting a vertically integrated hydrological system, the absence of a global cryosphere, and direct communication between the surface and subsurface hydrosphere of early Mars. Author Affiliation: Department of Geological Sciences, Brown University, Providence, RI 02912, USA Article History: Received 27 March 2008; Revised 24 June 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.04.009 Byline: Susana E. Jorge Villar (a), Howell G.M. Edwards (b), Liane G. Benning (c) Keywords: Spectroscopy; Astrobiology; Mars; Search for extraterrestrial life Abstract: A novel type of colonisation of a basaltic rock, collected on the Arctic island of Svalbard, Norway, during the AMASE expedition in 2004, was characterised using Raman spectroscopy and Scanning Electron Microscopy (SEM). The sample contains two different types of extremophile communities, one occurring behind a radial white crystallisation and the other occurring inside a dark vacuole. Several types of minerals and microbial colonies have been identified by both Raman spectroscopy and SEM analyses. It is the first time that photosynthetic communities have been documented to colonise the inside of dark basaltic rocks. Our discovery has important implications for planetary exploration because it extends the analytical capability and our understanding of microbial rock colonisations to subaerial volcanic outcrops and has wide implications towards the search for life in extraterrestrial planets. In this work we also demonstrate that the use of different laser wavelengths for Raman spectroscopic studies and complementary microscopic analysis are critical for a comprehensive organic and inorganic compound identification. Author Affiliation: (a) Area de Geodinamica Interna, Facultad de Humanidades y Educacion, C/Villadiego s/n, 09001 Burgos, Spain (b) Chemical and Forensic Sciences, University of Bradford, West Yorkshire, BD7 1DP, UK (c) Earth and Biosphere Institute, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK Article History: Received 25 October 2005; Revised 1 April 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2006.01.002 Byline: W.P. Schellart (a)(b), G.S. Lister (a), V.G. Toy (a)(c) Keywords: subduction; slab; rollback; hinge-retreat; backarc; extension; spreading; Southwest Pacific; tectonics; geodynamics; reconstruction; Cretaceous; Cenozoic Abstract: A Cenozoic tectonic reconstruction is presented for the Southwest Pacific region located east of Australia. The reconstruction is constrained by large geological and geophysical datasets and recalculated rotation parameters for Pacific-Australia and Lord Howe Rise-Pacific relative plate motion. The reconstruction is based on a conceptual tectonic model in which the large-scale structures of the region are manifestations of slab rollback and backarc extension processes. The current paradigm proclaims that the southwestern Pacific plate boundary was a west-dipping subduction boundary only since the Middle Eocene. The new reconstruction provides kinematic evidence that this configuration was already established in the Late Cretaceous and Early Paleogene. From [approximately equal to]82 to [approximately equal to]52Ma, subduction was primarily accomplished by east and northeast-directed rollback of the Pacific slab, accommodating opening of the New Caledonia, South Loyalty, Coral Sea and Pocklington backarc basins and partly accommodating spreading in the Tasman Sea. The total amount of east-directed rollback of the Pacific slab that took place from [approximately equal to]82Ma to [approximately equal to]52Ma is estimated to be at least 1200km. A large percentage of this rollback accommodated opening of the South Loyalty Basin, a north-south trending backarc basin. It is estimated from kinematic and geological constraints that the east-west width of the basin was at least [approximately equal to]750km. The South Loyalty and Pocklington backarc basins were subducted in the Eocene to earliest Miocene along the newly formed New Caledonia and Pocklington subduction zones. This culminated in southwestward and southward obduction of ophiolites in New Caledonia, Northland and New Guinea in the latest Eocene to earliest Miocene. It is suggested that the formation of these new subduction zones was triggered by a change in Pacific-Australia relative motion at [approximately equal to]50Ma. Two additional phases of eastward rollback of the Pacific slab followed, one during opening of the South Fiji Basin and Norfolk Basin in the Oligocene to Early Miocene (up to [approximately equal to]650km of rollback), and one during opening of the Lau Basin in the latest Miocene to Present (up to [approximately equal to]400km of rollback). Two new subduction zones formed in the Miocene, the south-dipping Trobriand subduction zone along which the Solomon Sea backarc Basin subducted and the north-dipping New Britain-San Cristobal-New Hebrides subduction zone, along which the Solomon Sea backarc Basin subducted in the west and the North Loyalty-South Fiji backarc Basin and remnants of the South Loyalty-Santa Cruz backarc Basin subducted in the east. Clockwise rollback of the New Hebrides section resulted in formation of the North Fiji Basin. The reconstruction provides explanations for the formation of new subduction zones and for the initiation and termination of opening of the marginal basins by either initiation of subduction of buoyant lithosphere, a change in plate kinematics or slab-mantle interaction. Author Affiliation: (a) Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia (b) School of Geosciences, Monash University, Melbourne, VIC 3800, Australia (c) Department of Geology, University of Otago, Dunedin, New Zealand Article History: Received 21 July 2005; Accepted 18 January 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2005.06.001 Byline: S. Cloetingh (a), T. Cornu (a), P.A. Ziegler (b), F. Beekman (a) Keywords: neotectonics; intraplate deformation; seismicity; topography; European continental rift system; geomorphology Abstract: Research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity. Current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues. The accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years, which, on geological time scales, is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity. More reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling on-going intraplate deformation. The Alpine Orogen and the intraplate sedimentary basins and rifts in its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed. Seismicity and stress indicator data, combined with geodetic and geomorphologic observations, demonstrate that deformation of the Northern Alpine foreland is still on-going and will continue in the future. This has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area. We examine relationships between deeper lithospheric processes, neotectonics and surface processes in the northern Alpine Foreland, and their implications for tectonically induced topography. For the Environmental Tectonics Project (ENTEC), the Upper and Lower Rhine Graben (URG and LRG) and the Vienna Basin (VB) were selected as natural laboratories. The Vienna Basin developed during the middle Miocene as a sinistral pull-apart structure on top of the East Alpine nappe stack, whereas the Upper and Lower Rhine grabens are typical intracontinental rifts. The Upper Rhine Graben opened during its Late Eocene and Oligocene initial rifting phase by nearly orthogonal crustal extension, whereas its Neogene evolution was controlled by oblique extension. Seismic tomography suggests that during extension the mantle-lithosphere was partially decoupled from the upper crust at the level of the lower crust. However, whole lithospheric folding controlled the mid-Miocene to Pliocene uplift of the Vosges-Black Forest Arch, whereas thermal thinning of the mantle-lithosphere above a mantle plume contributed substantially to the past and present uplift of the Rhenish Massif. By contrast, oblique crustal extension, controlling the late Oligocene initial subsidence stage of the Lower Rhine Graben, gave way to orthogonal extension at the transition to the Neogene. The ENTEC Project integrated geological, geophysical, geomorphologic, geodetic and seismological data and developed dynamic models to quantify the societal impact of neotectonics in areas hosting major urban and industrial activity concentrations. The response of Europe's intraplate lithosphere to Late Neogene compressional stresses depends largely on its thermo-mechanical structure, which, in turn, controls vertical motions, topography evolution and related surface processes. Author Affiliation: (a) Netherlands Research Centre for Integrated Solid Earth Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands (b) Department of Earth Sciences, University of Basel, Bernoullistrasse 32, 4056 Basel, Switzerland (c) Department of Geological Sciences, Geo-Center, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria (d) Ecole et Observatoire des Sciences de la Terre, Institut de Physique du Globe de Strasbourg, 5 rue Rene Descartes, 67084 Strasbourg, France (e) Geologisches Institut, Albert Ludwigs Universitat, Freiburg i.Br., Albertstrasse 23-B, 79104 Freiburg i.Br., Germany (f) Netherlands Institute of Applied Geosciences, Princetonlaan 63584 CB Utrecht, The Netherlands (g) Geodatisches Institut, Universitat Fredericiana Karlsruhe, Englerstrasse 7, 76128 Karlsruhe, Germany (h) Geodesy and Geodynamics Laboratory, ETH-Honggerberg HPV G53, 8093 Zurich, Switzerland (i) Bureau de Recherches Geologiques et Minieres, Land Use Planning and Natural Risk Division, 3 Avenue Claude Guillemin, 45060 Orleans, France (j) Royal Netherlands Meteorological Institute (KNMI), P.O. Box 201, 3730AE De Bilt, The Netherlands Article History: Received 1 July 2004; Accepted 2 June 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2005.03.004 Byline: Michele Lustrino Keywords: delamination; detachment; lithosphere; mantle plume; petrology; lower crust; eclogite; pyroxenite Abstract: The Earth's lithosphere can focus basaltic magmatism along pre-existing weakness zones or discontinuities. However, apart from the influence on the geochemistry of magmas emplaced in subduction tectonic settings (mantle wedge metasomatism related to dehydration of the subducting plates) the role of lithosphere as a magma source for intra-plate (both oceanic and continental), continental margin, and mid-ocean ridge magmatism is not yet fully understood. In many cases intra-plate magmatism has been explained with the existence of deep thermal anomalies (mantle plumes) whose origin has been placed near the upper-lower mantle transition zone (660 km discontinuity) or even deeper, near the mantle-core boundary ([approximately equal to]2900 km). Also in many continental flood basalt provinces (mostly initiated at craton margins) an active role for mantle plumes has been invoked to explain the high melt productivity. In these cases, no active role for melt production has been attributed to the lithospheric mantle. Potential contaminations of asthenospheric or even deeper mantle melts are often considered the only influence of the lithosphere (both crust and mantle) in basalt petrogenesis. In other cases, an active role of the lithospheric mantle has been proposed: the thermal anomalies related to the presence of mantle plumes would trigger partial melting in the lithospheric mantle. At present there is no unequivocal geochemical tracer that reflects the relative role of lithosphere and upper/lower mantle as magma sources. In this paper another role of the lithosphere is proposed. The new model presented here is based on the role of lower crustal and lithospheric mantle recycling by delamination and detachment. This process can explain at least some geochemical peculiarities of basaltic rocks found in large and small volume igneous provinces, as well as in mid-ocean ridge basalts. Metamorphic reactions occurring in the lower continental crust as a consequence of continent-continent can lead to a density increase (up to 3.8 g/cm.sup.3) with the appearance of garnet in the metamorphic assemblage (basalt[right arrow]amphibolite[right arrow]garnet clinopyroxenite/eclogite) leading to gravitative instability of the overthickened lithospheric keel (lower crust+lithospheric mantle). This may detach from the uppermost lithosphere and sink into the upper mantle. Accordingly, metasomatic reactions between SiO.sub.2-rich lower crust partial melts and the uprising asthenospheric mantle (replacing the volume formerly occupied by the sunken lithospheric mantle and the lower crust) lead to formation of orthopyroxene-rich layers with strong crustal signatures. Such metasomatized mantle volumes may remain untapped also for several Ma before being reactivated by geological processes. Partial melts of such sources would bear strong lower crustal signatures giving rise to Enriched Mantle type 1 (EMI)-like basaltic magmatism. Basaltic magmatism with such a geochemical signature is relatively scarce but in some cases (e.g., Indian Ocean) it can be a geographically widespread and long-lasting phenomenon. Author Affiliation: Dipartimento di Scienze della Terra, Universita degli Studi di Roma La Sapienza, P.le A. Moro, 5, 00185 Rome, Italy Istituto di Geologia Ambientale e Geoingegneria (IGAG)-CNR, P.le A. Moro, 5, 00185 Rome, Italy Article History: Received 26 July 2004; Accepted 31 March 2005

Sustainability requires living within the regenerative capacity of the biosphere. In an attempt to measure the extent to which humanity satisfies this requirement, we use existing data to translate human demand on the environment into the area required for the production of food and other goods, together with the absorption of wastes. Our accounts indicate that human demand may well have exceeded the biosphere's regenerative capacity since the 1980s. According to this preliminary and exploratory assessment, humanity's load corresponded to 70% of the capacity of the global biosphere in 1961, and grew to 120% in 1999.

The authors examine the sedimentary effects and compositional parameters of remnant organic matter in sea water. Topics include the oxic effect, carbon/surface area ratios, and oxygen penetration.

The development of a sustainable civilization is vital for the prevention of resource depletion and environmental degradation. Analysis of the complex nonlinear biosphere by ecological economists depends on knowledge tools such as theory and technological expertise that provide data on resource allocation and distribution. Furthermore, engineers and ecological economists should also develop knowledge tools that can be utilized during the decision making process involving environmental management regulations.

METAPHOR HELPS SHAPE the way we view the world and it empowers human responses to the variety of issues confronting human existence. Whether helping us conceive of ourselves as part [...]

The discovery of another domain of life in the ocean vents which does not derive energy from sunlight, but from the chemical processes originating from the Earth's interior, has spawned speculations regarding the origin of life. The ubiquity of microorganisms in almost every habitat on earth, as well as the possibility of life-sustainment in the subsurface are indications of a need to modify the concept of life and evolution. It is possible that the surface life on Earth may be only one strange branch of life, particularly adapted to the prevailing conditions. These observations makes the concept of life on other planets a feasible one.

A near-real-time optical imaging method is introduced that has worked via the detection of the intrinsic fluorescence of life forms upon excitation by deep-UV (DUV) illumination. The studies have shown the first noninvasive detection of bacteria on in situ-incubated environmental samples from the deep ocean, indicating the use of DUV native fluorescence for in situ detection in the deep biosphere and other nutrient-limited environment.

Zoologists of a certain age will remember with affection Animals Without Backbones, a classic 1938 elementary textbook by Ralph Buchsbaum that quotes a (sadly uncredited) researcher on the ubiquity of [...]