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2017 | Buch

Oil and Gas Exploration in Cuba

Geological-Structural Cartography using Potential Fields and Airborne Gamma Spectrometry

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A summary of the results achieved in the geological-structural mapping, by potential fields and airborne gamma spectrometry data, of the units of igneous and metamorphic rocks in the western regions (Havana-Matanzas), central (Cienfuegos, Villa Clara-Sancti Spiritus) and central-eastern (Camagüey-Las Tunas-Holguín) of Cuba is presented. In addition, the structural- tectonic regionalization with hydrocarbon exploration purposes, focusing mapping of possible new oil-gas targets in the regions of Land Blocks 9, 23 and 17-18 are detailed in this volume. In certain case study locations (Majaguillar, North Motembo, Guamutas and Maniabón) reconnaissance work by a profile of Redox Complex (complex of unconventional geophysical-geochemical exploration techniques) was performed with positive results.

In an attempt to contribute to the geological-structural mapping of the metamorphic massif Isla de la Juventud, with emphasis on acid magmatism, the gravi-magnetometric data is used. According to the results, the presumed post metamorphic granitic bodies of low density are located, mainly, in the central and southwestern part of the massif. The granitic bodies apparently were introduced through the system of longitudinal faults (syn metamorphic) and transverse (post metamorphic) at the end of the process multyfolding and metamorphism of the massif sequences, taking a leading role the deep longitudinal fracture zones of sublatitudinal direction in the central and southern part of the massif. On the map of the magnetic field vertical derivative the anomalies, basically, reflected the direction and limits of the folded tectonic structure, the development area of ​​ volcanogenic rocks, the presumed development zones of migmatitic rocks and tectonised rocks in North and center of the massif, respectively, and the prevailing direction of the main tectonic dislocations.

Inhaltsverzeichnis

Frontmatter
Chapter 1. The State of Art
Abstract
In the application of potential fields in regional investigations, the gravimetric method solves the problems of the study of regional geological constitution, with better results for the folded belts. Regional studies that make use of gravimetric surveys also permit detailing the main tectonic features such as faults and other alignments, with which various mineral and energy resources are linked. Meanwhile, the aeromagnetic survey is helpful for geological mapping of vast regions with a thick sedimentary cover, where geological-structural features can be revealed if some magnetic horizons are present within the sedimentary sequence. In the absence of magnetic sediments, aeromagnetic survey data can provide information on the nature and form of basic–ultrabasic and/or crystalline basement. Both cases are applicable to oil and gas exploration. Regarding airborne gamma spectrometry, this provides a direct measurement of the naturally distribution of radioelements (K, U, and Th) occurring in the ground surface. Potassium is a major constituent of most rocks, while uranium and thorium are present in trace amounts, such as mobile and immobile elements, respectively. As the concentration of these radioelements varies among different types of rocks (and derived residual soils), distribution can be used to distinguish the different lithologies. Regarding hydrocarbon exploration, changes in mineral stability on columns of mineralized rocks above hydrocarbon deposits derived different types of morphometric, geophysics, and geochemistry significant responses.
Manuel Enrique Pardo Echarte, Jorge Luis Cobiella Reguera
Chapter 2. Overview of the Geology of Cuba
Abstract
The Cuban Orogen can be divided into two major structural and stratigraphic units: basement and cover. The basement is the mega complex of igneous, metamorphic, and sedimentary rocks that lies below the little deformed section of the cover. It is divided into several tectonic large units, according to its structural style and age of the rocks. We can distinguish three large complexes: (a) Proterozoic basement, (b) Mesozoic basement, and (c) Paleogene folded belt. The Proterozoic basement outcrops in very limited areas and its structure is unclear. The Mesozoic basement consists of four complexes of very different nature: the Mesozoic paleomargin of the SE North American plate, containing Jurassic-Cretaceous sequences with varying degrees of deformation; the remaining three units, the ophiolite association, successions of volcanic arcs, and southern metamorphic terrains, have traits of tectono stratigraphic terrains. The links between the four major structures of the Paleogene deformed belt are much clearer. However the outstanding deformations and horizontal transport suffered by some units, the primary spatial relationships (paleogeographic) between them are essentially preserved. At the Paleogene folded and faulted belt are distinguished: • Foreland basin successions. • Piggyback basins successions. • Sierra Maestra-Cresta Caimán volcanic arc. • Synorogenic basin of Middle and Upper Eocene S Eastern Cuba. The cover composed of deposits from Lower or Middle Eocene to Quaternary, comprises the younger deposits of the section, little deformed in relation to the underlying layers, usually separated from these by remarkable structural discordance. Throughout Cuba, the cover is completely devoid of evidences of magmatic, metamorphic, and hydrothermal activity.
Manuel Enrique Pardo Echarte, Jorge Luis Cobiella Reguera
Chapter 3. Tectonic-Structural Regionalization with Purposes of Hydrocarbon Exploration and Mapping of New Potential Oil–Gas Goals
Abstract
A summary of the main results achieved in the tectonic-structural regionalization with hydrocarbon exploration purposes, focusing mapping of new possible oil–gas targets in the regions of Onshore Blocks 9, 23, and 17–18 is given. In some of the new places of interest (Majaguillar, Southeast Motembo, Guamutas, El Pinto, and Maniabón), there were performed reconnaissance work by a profile of Redox Complex (complex of unconventional geophysical–geochemical exploration techniques) with positive results. In Block 9, from the presence of a complex of indicator anomalies, three locations of greater oil–gas interest were established: Majaguillar (Placetas Tectonic-Stratigraphic Unit), Southeast Motembo (Ophiolites), and Guamutas (northern boundary of Mercedes Basin). Block 23, in the locality of El Pinto (near the Zaza Dam), is distinguished as an anomalous complex (AC) given by a local gravimetric maximum, coincident with a geomorphic maximum with the same position and dimensions. Block 17–18 is distinguished, in the locality of Maniabón (south of Puerto Padre and Nuevitas bays), as an AC given by a local gravimetric–geomorphic maximum within a regional gravimetric minimum, a minimum of K/Th ratio, and U(Ra) local anomalies at the end of the AC. Definitively, for its geological significance (associated to foreland basin), it was established as main interest of all locations, the Maniabón area.
Manuel Enrique Pardo Echarte, Jorge Luis Cobiella Reguera
Chapter 4. Geological-Structural Mapping of Weathered Igneous and Metamorphic Rock Units
Abstract
A summary of the main results achieved in the geological-structural mapping, from the data of potential fields and airborne gamma spectrometry, from units of igneous and metamorphic rocks in the western (Havana-Matanzas), central (Cienfuegos-Villa Clara-Sancti Spiritus), and central-eastern (Camagüey-Tunas-Holguín) regions of Cuba offers. The gravimetric data allow to identify different geological-structural traits: by lows, those associated with the Northern Cuban Thrusts Belt, the southern metamorphic massifs, the granitic igneous bodies and the synorogenic structural basins and depressions; by highs, those linked with powerful thickness of volcanic rocks and ophiolitic bodies; as well as geophysical alignments, major tectonic boundaries within the Cuban Orogen. Aeromagnetic data allow mapping the main tectonic boundaries; the southern metamorphic massifs; the synorogenic structural basins and depressions; granitoid belts; ophiolitic bodies and the development area of volcanic rocks. The faculty of lithological mapping that gives the differential distribution of magnetite in various rock units gives this possibility. The airborne gamma spectrometry identifies, by increased values of U(Ra), units with high contents of graphite (organic matter) and those associated with acid igneous rocks. Potassium increases are linked, mainly, to the alkaline and acidic medium-igneous rocks. Incremented values of thorium generally characterize the metamorphites and, U(Ra) and Th increments express some highly developed weathering crusts on ultrabasites.
Manuel Enrique Pardo Echarte, Jorge Luis Cobiella Reguera
Metadaten
Titel
Oil and Gas Exploration in Cuba
verfasst von
Manuel Enrique Pardo Echarte
Jorge Luis Cobiella Reguera
Copyright-Jahr
2017
Electronic ISBN
978-3-319-56744-0
Print ISBN
978-3-319-56743-3
DOI
https://doi.org/10.1007/978-3-319-56744-0