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Oligocene-Lower Miocene sandstones of Western Tethys
The changing nature of detrital signatures in clastic wedges of the Circum-Mediterranean orogenic systems reflect the provenance relations from different source rocks of evolving geo-puzzle terranes, including ophiolite bearing, uplifted continental crust (both shallow to deep crust terranes), volcanic and sedimentary source rocks. We selected here sandstone suites directly occurring over the Mesomediterranean Micropaleoplate during the final stages of closure of the western-southern Tethyan realm. They are unconformably over the internal domains of the Circum-Mediterranean thrust belts, and include Oligocene-to-lower Miocene siliciclastic formations of the Betic Cordillera (As, Bosque, Río Pliego, El Niño, Ciudad Granada, Fuente-Espejos, Alozaina and Viñuela fms), Rif Chain (Fnideq and Sidi Abdeslam fms), and Calabrian terranes (Paludi, Pignolo and Stilo Capo d’Orlando fms). All these sandstone suites range from quartzolitic to quartzofeldspathic detrital modes reflecting close relations with their Paleozoic metasedimentary and plutonic source rocks and their related Mesozoic sedimentary covers.
Marked differences have been recognized from western (Betic-Rif) to eastern (Calabria) portions in terms of detritic suites. Detrital suites of the Betic-Rif portions reflect a transition between a craton, transitional and recycled orogenic provenance type. Contrarily, detrital suites of the Calabria portions reflect their transition from transitional continental to basement uplift orogenic provenance reflecting deposition in wedge-top basins during final subduction of the Magrebian-Lucanian-Ionian Basin below the Mesomediterranean and the opening of the Mediterranean basin as a backarc.
Provenance and paleogeographic implications for the Cenozoic sedimentary cover of the Ghomaride Complex (Internal Rif Belt), Morocco
The Cenozoic sedimentary cover from the Ghomaride Complex (Internal Rif Belt) has been studied in the Tetuan area (N Morocco) where a suite of sedimentary successions from shallow-marine to deep-marine environments crops out. For that purpose stratigraphic relations and petrological and geochemical signatures have been analyzed. Sandstone suites of the overall succession are heterogeneous and testify a multi-source area, in response of accretionary processes of the Ghomaride-Malaguide units and the exhumation of the lower units of the Internal Rif Zone (e.g. Sebtide-Alpujarride Complex). Pre-orogenic and Syn-orogenic (according to the eoalpine phase) deposits have been identified consisting in two depositional sequences: lower Paleocene and Cuisian-Bartonian, and upper Oligocene-upper Aquitanian and lower Burdigalian, respectively. Pre-orogenic deposits are mainly intra-arenite and hybrid arenites made of a minor amount of siliciclastic detritus but with abundance of intrabasinal carbonate grains. The syn-orogenic sandstone suites are quartzolithic, having abundance of low-grade metamorphic and sedimentary lithic fragments. Sedimentary lithic fragments are derived from the Mesozoic successions of the Ghomaride-Malaguide Complex while metamorphic detritus is related to an unknow Internal Rif Zone basement that was exhumed starting from the late Oligocene and mainly early Miocene. Modal analyses of sandstone suites for the extrabasinal grains mainly indicate lower rank metamorphic and sedimentary source terranes of a recycled orogen. Major and trace elements coupled to the mineralogical composition of the mudrock samples indicate a provenance from felsic source area(s) with a minor but not negligible contribution from mafic rocks mainly in the syn-orogenic suites.
Geochemical analyses (Al–Ti–Zr ternary plot) indicate minor reworking and recycling processes before the final deposition through prolonged processes of sedimentary transportation. The trends evident in both CIA and CIA’ diagrams indicate source areas characterized by moderate weathering in non-steady-state conditions with a weak change of weathering condition from the pre-orogenic to the syn-orogenic cycle. Deposition during the Paleocene and Eocene, took place in the southern continental margin of the Ghomaride-Malaguide domain as a carbonate ramp. Contrarily, sedimentation in the late Oligocene-late Aquitanian took place in wedge-top basins within the Ghomaride- Malaguide domain. These changes occurred during the Burdigalian, when back arc basins were developed in the Internal Betic-Rif Zone. The Cenozoic reconstructed record was contemporaneous of the structuring of the Circum-Mediterranean chains and the Ghomaride-Malaguide Complex played a key role in the geodynamic evolution of the Rif Cordillera, representing a key tectonic element of the western Mesomediterranean domains.
The Cenozoic evolution of the Intrarif (Rif, Morocco)
The sedimentary-tectonic evolution of the Cenozoic strata of the El Habt and Ouezzane Tectonic Units (Intrarif, External Rif) in Morocco is presented by a new work by Martín-Martin et al., (2022) in Geosphere.
New data provide information about the depositional architecture and enable a correlation of the evolution of the External Rif in Morocco with that of the Betic Cordillera in Spain and the Tunisian Tell, which provides new insights for hydrocarbon exploration in the region regarding possible source, reservoir, and seal rocks. The reconstructed Cenozoic succession was bio-chronologically defined, and the major unconformities and stratigraphic gaps were identified. The presence of these unconformities allowed three main stratigraphic sequences to be defined by age: Danian p.p., early Ypresian–early Bartonian p.p., and the early Rupelian–early Serravallian p.p. Three secondary stratigraphic sequences in the former upper main sequence were also defined by age: early Rupelian–late Chattian p.p., Burdigalian p.p., and the Langhian–Serravallian p.p. The depositional setting evolved from deep basin during the Late Cretaceous–Paleocene to external platform-slope during the Eocene–Miocene.
The Cenozoic sandstones contain metamorphic and sedimentary rock fragments derived from a recycled orogen source area. The clay mineralogy in the Cenozoic strata consists of associations of Ill+(I–S) ± Sme, Ill+(I–S) ± Sme+Kln and Ill+(I–S) ± Sme+Kln+ Chl. These associations indicate an initial unroofing in the Paleogene period, then in the Cretaceous period, and finally in the Late Jurassic period during the Eocene–Oligocene. This detritus was followed by variable amounts of a sedimentary mix of Paleogene to Late Jurassic terrains due to several phases of erosion and deposition partly related to syn-sedimentary tectonics during the Miocene. Equivalent features (similar types of sediments, tectofacies, gaps, and unroofing) were also recognized along the Betic Cordillera in Spain and Maghrebian Chain (Morocco and Tunisia) and interpreted as related to a pre-nappe tectonic activity of soft basement folding, which occurred during the Paleogene after the generalized tectonic inversion (from extension to compression) occurred in the Late Cretaceous. The Upper Cretaceous is considered to be the hydrocarbon source rock, while the fractured Eocene and the porous Oligo-Miocene suites are proposed as possible hydrocarbon reservoirs. The Cenozoic stratigraphic architecture and the nappe structure of the region could provide the necessary trap structures.
Historical Earthquakes in Valencia
The “1396 Tabernes” earthquake occurred in the Valldigna valley and it has been considered one of the largest Iberian Peninsula recorded earthquakes. The information used for such claims has always been from secondary sources in the area because the originals were believed to be lost. In this work, the recently edited copy of the book about the Royal Monastery Nuestra Señora de la Valldigna history, the “Chronological history” of Father Estevan Gil, has permitted to correct the date of December 16th instead of December 18thfor the main earthquake. The earthquake damage is reinterpreted from the original source. In addition, the importance of the November 7th 1330 earthquake which represents the first destruction of the monastery, is pointed out. The original book provides information on the last destruction of the church in the 1644 earthquake, its damage and reconstruction. Together with another book, also recently published by Tomás Gómez, on the castilian visit of 1666, it allows us to discover what the monastery was like and understand the damage and reconstruction. Finally, two other earthquakes are mentioned in the years 1724 and 1748 that are also reflected in Father Gil’s book.
Cite as: Tent-Manclús, J. E. (2022): Los terremotos del sur de la provincia de Valencia según las fuentes del Real Monasterio de Nuestra Señora de la Valldigna (E de España, Provincia de Valencia). Cuaternario y Geomorfología, 36 (1-2): 77-103. https://doi.org/10.17735/cyg.v36i1-2.91108
K-nearest neighbors algorithm used for classifying geological variables.
The k-nearest neighbors (KNN) algorithm is a non-parametric supervised machine learning classifier; which uses proximity and similarity to make classifications or predictions about the grouping of an individual data point. This ability makes the KNN algorithm ideal for classifying datasets of geological variables and parameters prior to 3D visualization. This paper introduces a machine learning KNN algorithm and Python libraries for visualizing the 3D stratigraphic architecture of sedimentary porous media in the Quaternary onshore Llobregat River Delta (LRD) in northeastern Spain. A first HTML model showed a consecutive 5 m-equispaced set of horizontal sections of the granulometry classes created with the KNN algorithm from 0 to 120 m below sea level in the onshore LRD. A second HTML model showed the 3D mapping of the main Quaternary gravel and coarse sand sedimentary bodies (lithosomes) and the basement (Pliocene and older rocks) top surface created with Python libraries. These results reproduce well the complex sedimentary structure of the LRD reported in recent scientific publications and proves the suitability of the KNN algorithm and Python libraries for visualizing the 3D stratigraphic structure of sedimentary porous media, which is a crucial stage in making decisions in different environmental and economic geology disciplines.
Interactive figures here
A Python Application for Visualizing the 3D Stratigraphic Architecture
A Python application for visualizing the 3D stratigraphic architecture of porous sedimentary media has been developed. The application uses the parameter granulometry deduced from borehole lithological records to create interactive 3D HTML models of essential stratigraphic elements.
On the basis of the high density of boreholes and the subsequent geological knowledge gained during the last six decades, the Quaternary onshore Llobregat River Delta in northeastern Spain was selected to show the application. The public granulometry dataset produced by the Water Authority of Catalonia from 433 boreholes in this strategic coastal groundwater body was clustered into the clay–silt, coarse sand, and gravel classes. Three interactive 3D HTML models were created. The first shows the location of the boreholes granulometry. The second includes the main gravel and coarse sand sedimentary bodies (lithosomes) associated with the identified three stratigraphic intervals, called lower (>50 m b.s.l.) in the distal Llobregat Delta sector, middle (20–50 m b.s.l.) in the central Llobregat, and upper (<20mb.s.l.) spread over the entire Llobregat. The third deals with the basement (Pliocene and older rocks) top surface, which shows an overall steeped shape deepening toward the marine platform and local horsts, probably due to faulting. The modeled stratigraphic elements match well with the sedimentary structures reported in recent scientific publications.
This proves the good performance of this incipient Python application for visualizing the 3D stratigraphic architecture, which is a crucial stage for groundwater management and governance.
Field work in the Eocene Prebetic II
The rain in Spain…
Well the second field work campaign in the Eocene Prebetic was conditional by the bad weather, rain, wind, snow and cold.
The picture shows the members of the team imply in this field try to the Eocene rocks within the provinces of Alicante and Murcia.
This is the second field season of the project of the Spanish research agency (Agencia Estatal de Investigación) of the Spanish Science and innovation minister (Ministerio de Ciencia e Innovación) entitle as “EVOLUCION TECTONO-DEPOSICIONAL DE CUENCAS SEDIMENTARIAS CENOZOICAS: CARACTERIZACION 2D-3D Y MEJORA DE PATRONES ESTANDAR” (PID2020-114381GB-I00). See previous post.
Field work in the Eocene Prebetic
The good weather in Alicante during the winter season has permitted to do the first field season of our project of the Spanish research agency (Agencia Estatal de Investigación) of the Spanish Science and innovation minister (Ministerio de Ciencia e Innovación) entitle as “EVOLUCION TECTONO-DEPOSICIONAL DE CUENCAS SEDIMENTARIAS CENOZOICAS: CARACTERIZACION 2D-3D Y MEJORA DE PATRONES ESTANDAR” (PID2020-114381GB-I00). See previous post.
The picture shows the members of the team imply in this field try to the Eocene rocks within the provinces of Alicante and Murcia.
Crina Miclaus (Alexandru Ioan Cuza University)
Josep Tosquella (Huelva University)
Manuel Martin-Martin (Alicante University)
Jose Enrique Tent-Manclus (Alicante University)
Next picture shows a nummulite-rich limestone in a quarry near Onil, one of the visited sections in our field work.
Software for Geological modelling (part I)
Geological modelling is the ability to create computerized representations of subsurface geology. Many times, every once in a while, I have searched internet to find nice-looking geological models, just to find ideas or whatever the workers were doing. I like the ones with many colours (using all-the-rainbow) with a 3d immersive-perspective, nice vertical and horizontal axis lines and a 3d north-arrow. The idea of being true or just being a well-documented cartoon of something real was not important at the first point. For most geologists a nice looking 3d geological model is supposed to be truer than a simple map.
Then the next search is about the new accepted manuscripts of recently published papers in some scholarly journals, academic journals, to see what was new about illustrating works. My filling and also of my staff companions are that nice-looking figures illustrating a geological manuscript permit a better, faster, less time-consuming publish research results. All of us remember some not top-quality (debatable quality) works published because they have awesome figures.
Well, now we known the interest of geological modelling but most of the time what we need just a geoscience art-work.
A geological model can be obtained after doing three phases, that can produce each one a geological 3d illustration, and can be considered a computerized subsurface geological representation.
- The first level is the geological 3D sketch in this level show a simplistic way of showing a complex geology. The software to do so is the kind of a “mudball” modelling software as for instance (sketchup) https://www.sketchup.com/, Blender (https://www.blender.org), or Tinkercad (https://www.tinkercad.com). But taking in an account that we normally like to start with a geological map or an aerial photomosaic (like google Earth). The software must have 2D mapping and mosaic tiles import filters capabilities. As my experience of working with 2D for mapping the best choice is Autocad 3d Map (Autodesk). I can map then, then create surface an made simplistic geological model, what a sketch is.
- The second level is the realistic 3d model representation. In this step we like to integrate the relief, using a Digital Elevation Model (DEM), with the aerial photomosaic, and the information below the land surface. For geological model we like a 3d net used as scale to appreciate the rock volumes. Also, we like a software with capabilities of change the vertical factor and to create immersive perspectives. All this can be done also with Autodesk programs, but it takes a lot of time to produce the model because they are designed for computer-lovers than like to spend days in front of the screen. The final result can be the better one, but geologist usually like to check the results in the field, not spending all the time with the computer. This last reason is that I prefer a simpler graphical interface so do a nice-looking illustration from a point of view of an Earth scientist, not a blockbuster movie. Therefore, my choose is the golden software surfer program.
- The third level is using the realistic model to go back and forth in time to see the deformation history and trying to understand the forces and the deformation phases to produce the 3d geometry. This is the goal of the structural geology. To achieve this level most of the time it has to be a simplified the previous model to work with because some information is useless in this level as for instance the aerial photomosaics. For this phase are designed the principal geomodelling software as for instance Petrel, Gocad or MOVE. All mentioned software is oriented to the petroleum industry so it means that are not cheap. In my case the easier to get access has been the MOVE and that’s my choice.
Finally, the example that I most like is the British Geological Survey model of the Assynt culmination Geologica 3D model that you can download here in a 3D pdf file.
http://nora.nerc.ac.uk/id/eprint/504722/1/Assynt_Culmination.pdf
New project to study sedimentary basins.
The Spanish research agency (Agencia Estatal de Investigación) of the Spanish Science and innovation minister (Ministerio de Ciencia e Innovación) has conceded a new project to study the Cenozoic sedimentary basins entitle as “EVOLUCION TECTONO-DEPOSICIONAL DE CUENCAS SEDIMENTARIAS CENOZOICAS: CARACTERIZACION 2D-3D Y MEJORA DE PATRONES ESTANDAR” (PID2020-114381GB-I00).
This research project will develop techniques for the analysis of various types of Cenozoic sedimentary basins in a general compressive or convergent framework (associated with strike-slip faults, transported -piggy-back or wedge-top-, and complex foreland systems). The stratigraphic architecture, biostratigraphic control of the different sedimentary bodies, stratigraphic discontinuities will be studied, as well as sediments sources (both terrigeneous and biogenic) through mineralogical, petrographic and geochemical studies.
TEAM
Principal investigator: Manuel Martín-Martín (Alicante University)
Jesús M. Soria (Alicante University)
Manuel Bullejos Lorenzo (Granada University)
Antonio Sánchez Navas (Granada University)
Agustín Martín-Algarra (Granada University)
José Enrique Tent-Manclús (Alicante University)
Josep Tosquella (Huelva University)
Carlos Ureña Almagro (Granada University)
Fernando Pérez-Valera (Alicante University)
Francisco Javier Alcalá-García (Instituto Geológico y Minero de España, IGME)
Estelle Mortimer (University of Leeds)
Douglas Patton (University of Leeds)
Francesco Perri (Calabria University)
Salvatore Critelli (Calabria University)
Crina Miclaus (Alexandru Ioan Cuza University)
Francisco Serrano (Malaga University)
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