Antonio Guerra-Merchán

Bio: Antonio Guerra-Merchán is an academic researcher from University of Málaga. The author has contributed to research in topics: Pleistocene & Neogene. The author has an hindex of 13, co-authored 32 publications receiving 434 citations.

High variability of soil erosion and hydrological processes in Mediterranean hillslope vineyards (Montes de Málaga, Spain)

Abstract: Conventional Mediterranean vineyards from the Montes de Malaga (Axarquia region, Spain) are characterized by high average temperatures, extreme rainfall events during autumn and winter, elevated stoniness and steep slopes (20–50°). Traditionally, several problems of high soil loss, rill and ephemeral gully generation, and elevated runoff are observed by farmers, which are increasing land degradation processes and a decrease of the productivity. According to this, the main aims of this paper were: i) to quantify the initial soil loss, surface flow and infiltration processes; ii) to characterize and describe the hydrological and geomorphological dynamics; iii) to detect the key factors, which control the soil erosion processes. For this purpose, a combined methodology was applied, using soil analysis, a small portable rainfall simulator and a Guelph permeameter on one experimental plot cultivated with vineyards with steep slopes. Results showed a high variability of soil erosion and permeability processes. Soil analysis showed an elevated concentration of silt particles and stoniness, with higher contents of sand particles between 0 and 5 cm, and clays from 5 cm. With a Guelph permeameter, high average of permeability and saturated hydraulic conductivity with elevated standard deviation were observed. Furthermore, an increase of these parameters from the upper to the foot slope was registered. By using rainfall simulations, on the upper and the foot slope positions the highest runoff coefficient and soil loss were registered. The most elevated peak of sediment concentration was obtained on the middle slope. In general, high infiltration coefficients between 66.5 and 100% were observed. In conclusion it was observed that the activation of the soil erosion processes was due to the distribution of the surface soil components (high roughness, several cracks and high stoniness and silt content), the steep slopes and the impact of the soil traditional tillage practices. These Mediterranean hillslope vineyards registered a mixed Hortonian-Hewlettian model, which combines surface and sub-surface flow conditioned by the micro-topographical changes and its saturation degree.

The earliest cut marks of Europe: a discussion on hominin subsistence patterns in the Orce sites (Baza basin, SE Spain).

Abstract: Ancient evidence of human presence in Europe is recorded in several Early Pleistocene archaeopalaeontological sites from Spain, France and Italy. This is the case of Barranco Leon (BL) and Fuente Nueva-3 (FN-3), two localities placed near the town of Orce (depression of Baza and Guadix, SE Spain) and dated to ~1.4 Ma. At these sites, huge assemblages of Oldowan tools and evidence of defleshing, butchering and marrow processing of large mammal bones have been recovered together with a deciduous tooth of Homo sp. in the case of level BL-D. In this study, we: (i) describe in detail the anthropic marks found in the bone assemblages from these sites; (ii) analyse patterns of defleshment, butchery and marrow processing, based on the modifications identified in the cortical surface of the fossils; and (iii) discuss on the subsistence strategies of the first hominins that inhabited the European subcontinent during Early Pleistocene times.

Oligocene-early Miocene transgressive cover of the Betic-Rif Internal Zone. Revision of its geologic significance

Abstract: The Oligocene–early Miocene sedimentation in the Betic-Rif Internal Zone (BRIZ) occurred during the same time interval as the main tectonic events that are classically considered responsible for the structuring of this zone. Therefore, its paleogeographic and tectonic significance has been the subject of much controversy. The sedimentation developed in two successive groups of formations: the Ciudad Granada group of late Oligocene–Aquitanian in age and the Vinuela group of Burdigalian p.p. in age. The former consists of reddish marls containing clastic intercalations of Malaguide origin, while the Vinuela group is made up of siliceous-intercalated marlstones and lime-poor pelites, with a basal coarse-grained clastic material inherited from both the Malaguide and Alpujarride complexes. An overview of all the outcrops of the BRIZ leads to the conclusion that the two groups are closely related both geographically and tectonically. The paleogeographic, tectonic, stratigraphic and sedimentary relationships suggest that there was no nappe stacking stage between the two groups in the BRIZ. The transition from Ciudad Granada to Vinuela seems to have been the result of a transtensive tectonic event probably related to the westward migration of the BRIZ and to the opening of the Algero-Provencal and Alboran basins. This tectonic disturbance would have caused a severe subsidence in the downfaulted blocks, thus deepening the deposition zones; at the same time, the rapid uplifting of upfaulted blocks would have uncovered Alpujarride units, thus comprising the basement and the source of detritics for the Vinuela group.

Taphonomic and Ecologic Information Form Bone Weathering

Abstract: Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

The Neogene Period

Abstract: An Astronomically Tuned Neogene Time Scale (ATNTS2012) is presented, as an update of ATNTS2004 in GTS2004. The new scale is not fundamentally different from its predecessor and the numerical ages are identical or almost so. Astronomical tuning has in principle the potential of generating a stable Neogene time scale as a function of the accuracy of the La2004 astronomical solution used for both scales. Minor problems remain in the tuning of the Lower Miocene. In GTS2012 we will summarize what has been modified or added since the publication of ATNTS2004 for incorporation in its successor, ATNTS2012. Mammal biostratigraphy and its chronology are elaborated, and the regional Neogene stages of the Paratethys and New Zealand are briefy discussed. To keep changes to ATNTS2004 transparent we maintain its subdivision into headings as much as possible.

The Betic-Rif Arc and Its Orogenic Hinterland: A Review

Abstract: The Betic-Rif arc is one of the smallest and tightest orogenic arcs on Earth, and together with its extensional hinterland, the Albor´ an Domain, it formed between two colliding continents. The region provides examples of a range of tectonic processes that are not predictable from the rules of rigid-plate tectonics. The AlborDomain reveals two stages of subduction and accre- tion, with different thermal histories and mechanisms of exhumation. The external Betic-Rif thrust belt illustrates four processes that create an arcuate orogen and a strongly divergent pattern of slip vectors: (a) the interaction between the westward moving Albor´ an Domain and the converging African and Iberian margins, (b) divergence in relative motion due to extension within the Albor´ an Domain, (c) slip partitioning onto strike-slip faults within the arc, and (d ) vertical-axis rotations resulting from oblique convergence on the limbs of the arc.