Jesús Galindo-Zaldívar

Bio: Jesús Galindo-Zaldívar is an academic researcher from University of Granada. The author has contributed to research in topics: Fault (geology) & Tectonics. The author has an hindex of 40, co-authored 252 publications receiving 5493 citations. Previous affiliations of Jesús Galindo-Zaldívar include Spanish National Research Council & British Antarctic Survey.

40Ar/39Ar geochronology of Alpine tectonism in the Betic Cordilleras (southern Spain)

Abstract: The 40 Ar/ 39 Ar dating method has been applied to metamorphic rocks of the Alpujarride and Nevado-Filabride nappes (Alboran domain, SE Spain) in a first attempt to discriminate individual phases of deformation and metamorphism. The upper Nevado-Filabride nappes experienced an early eclogitic and blueschist metamorphism for which a barroisitic amphibole indicates a minimum age of 48 Ma. An Early Miocene age is attributed to the subsequent amphibolite facies metamorphism. Deformation associated with this metamorphic evolution is of unknown direction. The Alpujarride nappes record a plurifacial metamorphic evolution with the superimposition of low-pressure assemblages upon high-pressure ones with variable P – T ratios. Phengite from a carpholite-bearing high pressure-low temperature ( HP / LT ) assemblage gives an age of 25 Ma interpreted to reflect the end of the high-pressure evolution. Biotite and muscovite from high-grade metamorphic rocks overprinted under low-pressure conditions yield similar closure ages of 19 Ma dating cooling after the main episode of E – NE directed ductile deformation. This deformation was followed by W–SW directed extensional events producing brittle structures in the Alpujarride nappes and ductile-brittle shearing in the Nevado-Filabride nappes. Biotite and muscovite from ductile sheared rocks in the detachment zone between the two complexes have concordant ages of 16–17 Ma related to the end of the extensional ductile deformation. Therefore, a correlation of metamorphic and tectonic events between the two nappe complexes seems possible only since the Early Miocene and later.

Active continental subduction beneath the Betic Cordillera and the Alborán Sea

Abstract: P- and S-wave seismic tomography detect a low-velocity anomaly in the upper mantle beneath the Betic Cordillera and the Alboran Sea region. The anomaly is associated with the intermediate-depth seismicity (h

First evidence of high-pressure, low-temperature metamorphism in the Alpujarride nappes, Betic Cordilleras (S. E. Spain)

Abstract: HP-LT assemblages and minerals are described for the first time in the Alpujarride nappes of the Central and Eastern Betic Cordilleras. These assemblages occur in Permo-Triassic metapelites and include ferroand magnesio-carpholite, aragonite, kyanite and Mg-rich chloritoid. The estimated P-T conditions range from 4-5 kbar at 280-300 °C to 7-9 kbar at 450-500 °C. Hence, these nappes underwent HP-LT metamorphism (thermal gradient of 12-16 °C/km), just as did the underlying Nevado-Filabride units, prior to their lowto intermediate pressure evolution. Key-words : Betic Cordilleras, high-pressure metamorphism, carpholite, aragonite, Mg-rich chloritoid. High-pressure, low-temperature (HP-LT) terrains are widespread in the Alpine Belt. More particularly, the Western Alps and Cor­ sica are characterized by the superposition of low-grade HP-LT units (blueschists and car­ pholite-bearing schists) upon high-grade eciogi­ tic units (Saliot et al., 1980 ; Goffe and Chopin, 1986 ; Caron and Pequignot, 1986 ; Gibbons et al., 1986). In the Betic Cordilleras, HP-LT metamorphism has until now only been reco­ gnized in the deepest zones (Nevado-Filabride Complex) through the occurrence of high-grade assemblages in the eciogite facies (Nijhuis, 1964 ; Kampschuur, 1975 ; Puga, 1977 ; Marti­ nez-Martinez, 1986 ; Gomez-Pugnaire and Fer­ nandez-Soler, 1987). Low-grade HP-LT rocks, on the other hand, were unknown in the belt. DOI:10.1127/ejm/01/1/0139 The higher Betic units (Alpujarride nappes) were thought to have only suffered lowto intermediate-pressure metamorphism of various grades from lower greenschist to granulite facies (Westra, 1969; Torres-Roldan, 1979; Aldaya et al., 1979; Akkerman et al., 1980; Platt, 1986), while the still higher nappes (Malaguides, Sub-Betic) are virtually unmeta­ morphosed. We report he re new petrographical observations from the Alpujarride nappes which decisively change this previous concep­ tion. Geological setting of HP-LT facies rocks HP-LT assemblages and associated relicts can be identified in the Alpujarride nappes of 0935-1221/89/0001-139 $ 1.00 o 1989 E. Schweizerbart'sche Verlagsbuchhandlung, D-7000 Stuttgart 1

Of Theory and Practice

Abstract: Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

An updated digital model of plate boundaries

Abstract: [1] A global set of present plate boundaries on the Earth is presented in digital form. Most come from sources in the literature. A few boundaries are newly interpreted from topography, volcanism, and/or seismicity, taking into account relative plate velocities from magnetic anomalies, moment tensor solutions, and/or geodesy. In addition to the 14 large plates whose motion was described by the NUVEL-1A poles (Africa, Antarctica, Arabia, Australia, Caribbean, Cocos, Eurasia, India, Juan de Fuca, Nazca, North America, Pacific, Philippine Sea, South America), model PB2002 includes 38 small plates (Okhotsk, Amur, Yangtze, Okinawa, Sunda, Burma, Molucca Sea, Banda Sea, Timor, Birds Head, Maoke, Caroline, Mariana, North Bismarck, Manus, South Bismarck, Solomon Sea, Woodlark, New Hebrides, Conway Reef, Balmoral Reef, Futuna, Niuafo'ou, Tonga, Kermadec, Rivera, Galapagos, Easter, Juan Fernandez, Panama, North Andes, Altiplano, Shetland, Scotia, Sandwich, Aegean Sea, Anatolia, Somalia), for a total of 52 plates. No attempt is made to divide the Alps-Persia-Tibet mountain belt, the Philippine Islands, the Peruvian Andes, the Sierras Pampeanas, or the California-Nevada zone of dextral transtension into plates; instead, they are designated as “orogens” in which this plate model is not expected to be accurate. The cumulative-number/area distribution for this model follows a power law for plates with areas between 0.002 and 1 steradian. Departure from this scaling at the small-plate end suggests that future work is very likely to define more very small plates within the orogens. The model is presented in four digital files: a set of plate boundary segments; a set of plate outlines; a set of outlines of the orogens; and a table of characteristics of each digitization step along plate boundaries, including estimated relative velocity vector and classification into one of 7 types (continental convergence zone, continental transform fault, continental rift, oceanic spreading ridge, oceanic transform fault, oceanic convergent boundary, subduction zone). Total length, mean velocity, and total rate of area production/destruction are computed for each class; the global rate of area production and destruction is 0.108 m2/s, which is higher than in previous models because of the incorporation of back-arc spreading.

Mediterranean extension and the Africa‐Eurasia collision

Abstract: A number of tectonic events occurred contemporaneously in the Mediterranean region and the Middle East 30–25 Myr ago. These events are contemporaneous to or immediately followed a strong reduction of the northward absolute motion of Africa. Geological observations in the Neogene extensional basins of the Mediterranean region reveal that extension started synchronously from west to east 30–25 Myr ago. In the western Mediterranean it started in the Gulf of Lion, Valencia trough, and Alboran Sea as well as between the Maures massif and Corsica between 33 and 27 Ma ago. It then propagated eastward and southward to form to Liguro-Provencal basin and the Tyrrhenian Sea. In the eastern Mediterranean, extension started in the Aegean Sea before the deposition of marine sediments onto the collapsed Hellenides in the Aquitanian and before the cooling of high-temperature metamorphic core complexes between 20 and 25 Ma. Foundering of the inner zones of the Carpathians and extension in the Panonnian basin also started in the late Oligocene-early Miocene. The body of the Afro-Arabian plate first collided with Eurasia in the eastern Mediterranean region progressively from the Eocene to the Oligocene. Extensional tectonics was first recorded in the Gulf of Aden, Afar triple junction, and Red Sea region also in the Oligocene. A general magmatic surge occurred above all African hot spots, especially the Afar one. We explore the possibility that these drastic changes in the stress regime of the Mediterranean region and Middle East and the contemporaneous volcanic event were triggerred by the Africa/Arabia-Eurasia collision, which slowed down the motion of Africa. The present-day Mediterranean Sea was then locked between two collision zones, and the velocity of retreat of the African slab increased and became larger than the velocity of convergence leading to backarc extension. East of the Caucasus and northern Zagros collision zone the Afro-Arabian plate was still pulled by the slab pull force in the Zagros subduction zone, which created extensional stresses in the northeast corner of the Afro-Arabian plate. The Arabian plate was formed by propagation of a crack from the Carlsberg ridge westward toward the weak part of the African lithosphere above the Afar plume.

Lateral slab deformation and the origin of the western Mediterranean arcs

Abstract: [1] The western Mediterranean subduction zone (WMSZ) extends from the northern Apennine to southern Spain and turns around forming the narrow and tight Calabrian and Gibraltar Arcs. The evolution of the WMSZ is characterized by a first phase of orogenic wedging followed, from 30 Ma on, by trench retreat and back-arc extension. Combining new and previous geological data, new tomographic images of the western Mediterranean mantle, and plate kinematics, we describe the evolution of the WMSZ during the last 35 Myr. Our reconstruction shows that the two arcs form by fragmentation of the 1500 km long WMSZ in small, narrow slabs. Once formed, these two narrow slabs retreat outward, producing back-arc extension and large scale rotation of the flanks, shaping the arcs. The Gibraltar Arc first formed during the middle Miocene, while the Calabrian Arc formed later, during the late Miocene-Pliocene. Despite the different paleogeographic settings, the mechanism of rupture and backward migration of the narrow slabs presents similarities on both sides of the western Mediterranean, suggesting that the slab deformation is also driven by lateral mantle flow that is particularly efficient in a restricted (upper mantle) style of mantle convection.

Origin of the Betic-Rif mountain belt

Abstract: In recent years, the origin of the Betic-Rif orocline has been the subject of considerable debate. Much of this debate has focused on mechanisms required to generate rapid late-orogenic extension with coeval shortening. Here we summarize the principal geological and geophysical observations and propose a model for the Miocene evolution of the Betic-Rif mountain belts, which is compatible with the evolution of the rest of the western Mediterranean. We regard palaeomagnetic data, which indicate that there have been large rotations about vertical axes, and earthquake data, which show that deep seismicity occurs beneath the Alboran Sea, to be the most significant data sets. Neither data set is satisfactorily accounted for by models which invoke convective removal or delamination of lithospheric mantle. Existing geological and geophysical observations are, however, entirely consistent with the existence of a subduction zone which rolled or peeled back until it collided with North Africa. We suggest that this ancient subducting slab consequently split into two fragments, one of which has continued to roll back, generating the Tyrrhenian Sea and forming the present-day Calabrian Arc. The other slab fragment rolled back to the west, generating the Alboran Sea and the Betic-Rif orocline during the early to middle Miocene.