Field Guide
Geology and Tectonics of Western Cuba
IV Cuban Earth Sciences Convention, 2011
Manuel A. Iturralde-Vinent Museo Nacional de Historia Natural
Obispo no. 61, Plaza de Armas La Habana Vieja, 10100, Cuba
La Habana April 2011
USEFUL DATA
CLIMATE Cuba has a humid and warm tropical climate. Very much influenced by sea breezes. The mean temperature is 25oC (77oF). It has two well-differenciated seasons: a dry season, from November to April, and a rainy season, from May to October. CLOTHING Since Cuba is a tropical country, cotton, lenen or light mixed materials are recommended. For the mid Cuban winter, a sweater or light jacket is sufficient. Avoid shorts for walking in the wild grass, there may be poisoning plants. LANGUAGE The national lenguage is Spanish. SANITARY REGULATIONS Cuba has no special sanitary regulations applicable to foreign visitors, except to those coming from countries where yellow fever or cholera are endemic. In such cases, an International Vaccination Certificate will be demanded. MONEY The Cuban monetary unit is the Peso. Direct payment, however, in the following foreign currencies are accepted and recommended: Canadian and US dollars; German Marks; French, Swiss or Belgian Francs, etc. Traveler's checks as well as credit cards not issued in the U.S.A. are accepted. OTHER DATA Official Cuban time is based on that of Greenwich Meridian. Daylight saving time is used during the summer months. Traffic signals correspond to those of the International Code. Driving in Cuba is on the right-hand side. The standard electric power supply is 110 volts, 60 cycles AC. The International System of Units of Weight and Measures is used. There are not dangerous poisoning animals. ©2011 by M. Iturralde-Vinent, All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any mean, electric or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the author.
G e o l o g y a n d T e c t o n i c s o f C u b a I N T R O D U C T I O N
The geological framework and deep structure of the Cuban archipelago is by far the most complex among the Caribbean islands. The great variety of rocks and landscapes that characterize the territory determined the formation of many different types of soils under the conditions of a tropical island climate. In this conditions, zoned ecosystem evolved from marine shallow shelf, into small islands and keys, coastal areas, dissected plains and mountain ranges whose highest pick (Turquino) reach 2 000 m. Geologically speaking, the Cuban territory can be subdivided into two main geological entities (or structural levels): the foldbelt and the neoautochthon (Figure 1).
PURIAL
CAMAGUEY
HOLGUINM A Y A R I
TURQUINO
ESCAMBRAY
CIEGO
SANTA CLARA
ISLE OF YOUTH
GIBARA
BAHAMAS
SOUTHWESTERNTERRANES
C O N T I N E N T A L MARGIN U N I T S
NORTHERN OPHIOLITE
OCEANIC BASEMENT
VULCANO-PLUTONICCOMPLEX
CRETACEOUS ARC
NEOAUTOCHTHONLATE EOCENETO RECENT
100 Km
PINOS
BARACOA
MATANZASHABANA
VULCANO-PLUTONICCOMPLEX
PALEOGENE ARC
GEOLOGY OF CUBA
LAS TUNASMOA
NIPE
PINAR DEL RIO
PRINCIPAL TECTONIC UNITS
M.I.V.
BAHIA HONDA
GUANIGUANICO
OCEANIC UNITS
HICACOS
Blue -
- Jurassic
Green - Cretaceous Brow - Paleocene-Eocene Yellow -
- Oligocene
Gre -
- Miocene -Quaternary
The darker the tone of the color, the older the rocks
rocks
Red and Pink - Plutonic rocks
rocks Purple - Ophiolites
Figure 1. Geology map of Cuba with the main tectonic units
The f o l d b e l t encompass different suites of sedimentary, igneous and metamorphic rocks whose ages are as old as Neoproterozoic (1000 Ma), but usually of Early Jurassic (220-230 Ma) to early Late Eocene (42 Ma). They outcrop mostly in mountain areas, but also in some dissected hilly and flattened terrains. These rocks were originated within the old continental margins of the Bahamas and the Yucatan borderland; and within oceanic areas that represented ancient sea floors and chains of volcanic islands. These tectonic units originally were located far away of the present-day area of Cuba; so they reached their present position as a consequence of tectonic transportation and amalgamation during early Tertiary.
The n e o a u t o c h t h o n represent sedimentary rocks of latest Eocene (42 Ma) to Recent ages, which have not been significantly displaced from its original site of deposition. Study of the neoautochthon provides clues to the understanding of the evolution and consolidation of the present-day Cuban archipelago and shelf areas.
G E N E R A L S C H E D U L E
During the field trip the following subjects of the Cuban sedimentary geology will be visited. In general are planned more stops that actualy possible in the time given, so there will be different options for every day: 1. A geotransect of the Guaniguanico Mesozoic continental margin and its foreland basin 2. The Tertiary synorogenic sediments of the allochthonous piggyback basins 3. The K/T boundary impact-related deposits First Day Arrival Transfer to Viñales, Pinar del Río Scenery view of Valle de Viñales and introduction to the geology and paleontology of the Guaniguanico terrane (Geology of Sierra de los Organos belt) Stop 1. Mogote La Mina (Jurassic Callovian-Tithonian San Cayetano, Jagua, Guasasa Fms) Stop 2. Velle San Vicente (Oxfordian Jagua Fm, Kimmeridgian-Berriasian Guasasa Fm ) Stop 3. Moncada K/T and Albian-Eocene Pons, Moncada, Ancón and Manacas Fms) Stop 4. Optional. Cueva de Santo Tomas, the largest cave system of Cuba Stop 5. Optional. Rio Piedra (Albian-Eocene Pons, Peña and Ancón Fms (Geology of Sierra del Rosario and Cajalbana belts) Traveling to Soroa via Carretera de Montaña Stop 6. Exotic serpentinite blocks in Paleocene-Eocene Manacas Fm Stop 7. Allochthonous thrust sheet of Cajalbana ophiolites Stop 8. KTB Cacarajicara Fm and view of the Guajaibón Aptian-Cenomanian platform
Stop 9. Veloz-Carmita Fms (Pelagic Cretaceous) Stop 10. Artemisa Fm (Pelagic Late Jurassic section) Stop 11. San Cayetano Fm (Altos de Francisco section) Stop 12. Oxfordian Basalts (Continental margin magmatism) Stop 13 to 16. Transect of the Rosario belt, Cajalbana belt and Bahia Honda Belt. TRAVEL SCHEDULE DAY 09- Transfer Havana to Viñales. Hotel in Viñales. DAY 10- Visits to Viñales, Moncada, Pons, road to Esperanza and San Cayetano, Hotel in Viñales. DAY 11- Visit to stops in Valle de San Vicente, Mogote La Mina, Laguna de Piedra and road to La Palma. Hotel in Viñales DAY 12- Trip from Viñales to Soroa, along the so called carretera de montaña, toward Niceto Pérez, Cajalbana, etc. Hotel in Soroa. DAY 13- Road Soroa to Bahía Honda and back to Soroa from Road from San Diego de Nuñez to the south. Hotel in Soroa. DAY 14- Road Soroa to Cabañas, Mariel and return to Havana
Geology and Tectonics of Western Cuba Within the area of interest, the following tectonic elements can be distinguished from north to south: the Bahía Honda tectonic unit which include ophiolites, Cretaceous arc volcanics, and sedimentary rocks of latest Cretaceous and Tertiary age; the Guaniguanico terrane which includes Jurassic-Paleocene continental margin sequences and Paleogene foreland deposits; the Los Palacios tectonic unit which contains Upper Cretaceous and Tertiary sedimentary rocks; the Guanal high which includes Miocene sedimentary rocks and a poorly known unexposed older section consisting of serpentinites and mafic igneous rocks; the La Coloma-Sabana Grande tectonic unit which contains Upper Cretaceous and Tertiary sedimentary rocks underlain by Cretaceous volcanic arc rocks; and the Pinos tectonic unit which includes Mesozoic barrovian metasiliciclastics and marbles of continental origin. Each one of these tectonic units exhibits a distinct stratigraphy and tectonic history (Iturralde-Vinent 1994a, Figure 2).
Fig. 2. General tectonic map of Western Cuba
The stratigraphy and tectonic relationships of the Bahía Honda tectonic unit have been discussed previously (Hatten, 1957; Furrazola et al., 1964; Pszczolkowski and Albear, 1982; Pushcharovski et al., 1989). With a few exceptions (e.g., Piotrowska, 1993), it is agreed that the Bahía Honda unit has been thrust from the south-southeast on top of the Guaniguanico unit (Hatten, 1957; Pszczolkowski, 1994). The exotic character of the Bahía Honda unit is observed in the Martín Mesa window, northeast of Guaniguanico, where deformed Guaniguanico rocks underlie in tectonic contact Bahía Honda units (Albear et al., 1985). The Bahía Honda allochthon is represented by a lower, deformed ophiolite sheet (Cajálbana ophiolites of Iturralde-Vinent (1994a)), overlain by thrust sheets of Cretaceous calc-alkaline volcanics, pyroclastic and epiclastic deposits of ?Albian to Campanian age. These units were deformed late in the Campanian at the time of the extinction of the volcanic arc (Furrazola et al., 1964; Pardo, 1975; Pszczolkowski and Albear, 1982; Pushcharovski et al., 1989). The volcanic arc section in the Bahía Honda unit is unconformably overlain by upper Campanian and younger sedimentary rocks. Upper Campanian-lower Maastrichtian sedimentary rocks consist of deep-water sandstone, claystone, and conglomerate of the Vía Blanca Fm. The clastic debris in these rocks is mostly derived from the erosion of an extinct volcanic arc (Brönnimann and Rigassi, 1963; Pszczolkowski and Albear, 1982; Albear and Iturralde-Vinent, 1985). Upper Maastrichtian deposits include calcareous megaturbidites (Peñalver Fm), which are similar to coeval deposits of the Rosario belts (Brönnimann and Rigassi, 1963; Pszczolkowski, 1986; Iturralde-Vinent, 1992).
The Paleogene section has been divided into the Vibora Group (well-stratified conglomerate, sandstone, siltstone and claystone, usually with slumping and olistostromic intercalations), the Capdevila Fm (well-bedded sandstone, claystone and siltstone, with minor intercalations of conglomerate), the Universidad Fm (hemipelagic marl, radiolarian marl and marly limestone, with rare intercalations of fine clastics rocks toward the base); and the Punta Brava Fm (hemipelagic marl and marly limestone) (Pushcharovski et al., 1989). Some authors have used Capdevila Fm to include all of the Paleogene clastic rocks underlying the Universidad Fm in the Bahía Honda (Pszczolkowski, 1978; 1987) and Los Palacios units (Piotrowski, 1987), but we prefer to follow Brönnimann and Rigassi (1963) and Albear and Iturralde-Vinent (1985) in restricting use of the Capdevila Fm to describe uppermost Paleocene-lower Eocene clastic sedimentary rocks, because in the Bahía Honda and Los Palacios units, conglomerate dominates the Vibora Group. The Vibora Group overlies the oldest rocks unconformably or in tectonic contact; but the Vibora Group, and the Capdevila and Universidad Fms are conformable, and the Punta Brava Fm unconformably overlies all of the previous units (Brönnimann and Rigassi, 1963; Pszczolkowski and Albear, 1982; Albear and Iturralde-Vinent, 1985). Clastic rocks of the Vibora and Capdevila yield abundant debris derived from the erosion of the extinct volcanic arc, including quartz, rock fragments and biogenic clasts (Pszczolkowski and Albear, 1982; Cobiella and Hernández, 1990). The upper Campanian-Eocene sedimentary basins that overlie the extinct arc in Cuba have been classified in general as "post-arc" or "superimposed on the arc" because they evolved in the new structural framework which existed after the extiction of the Cretaceous arc (Pushcharovski et al., 1989). Some of these basins, for example the Bahía Honda unit, evolved in a "piggy-back" style during Paleocene-middle Eocene time (Iturralde-Vinent, 1994a). The ophiolites and Cretaceous volcanic rocks are intensely deformed, but show no signs of metamorphism. The Upper Cretaceous-Eocene sedimentary section is less deformed with the exception of the area along the Pinar Fault (Pushcharovsky et al., 1989).
Figure 3. Stratigraphic column of Guaniguanico terrane , sensu Iturralde-Vinent and Pszczolkowski 2011. The Guaniguanico tectonic unit has also been called the Guaniguanico Terrane (Iturralde-Vinent 1994a). The stratigraphy of this unit has been described in detail by Hatten (1957), Herrera (1961), Pardo (1975) and Pszczolkowski (1978, 1987, 1994). In general, Mesozoic rocks have been subdivided into several stratigraphic sequences, which show the evolution of the passive continental margin from Early(?)-Middle Jurassic to early Paleocene.
The Paleogene deposits have been subdivided into three belts: Northern Rosario, Southern Rosario and Los Organos, following Pszczolkowski (1994, Figure 3).In Los Organos belt, the Coniacian-Santonian interval is represented by a hiatus and Campanian?-Maastrichtian sedimentary rocks include hemipelagic limestone and chert of the Peñas Fm (Hatten, 1957; Iturralde-Vinent, 1994a, Figure 3). In parts of the Southern Rosario and in the entire Northern Rosario belt, the Campanian-Maastrichtian interval is represented by fine clastic sedimentary rocks and interbedded hemipelagic limestone of the Moreno Fm. Clastic rocks yield debris of shallow water bioclasts, volcanic lithoclasts, quartz and plagioclase derived from the volcanic arc (Pszczolkowski, 1994). In both Rosario belts, the KTB section is represented by megaturbidites (Cacarajícara Fm), which is similar to the Peñalver Fm in Bahía Honda (Pszczolkowski, 1986; Iturralde-Vinent, 1992). The Moncada Fm is the KTB section in Los Organos belt. The Lower Tertiary sedimentary rocks in Guaniguanico are related to the evolution of a foreland basin. These deposits can be separated into three main lithological units: Ancón limestone and sharpstones, Manacas (Pica Pica siliciclastics) and Manacas (Vieja olistostrome). According to Pszczolkowski (1978, 1994)
Characteristically the Guaniguanico unit shows a fold-thrust style of deformation, in which several thin-skinned thrust sheets were implaced north- and northwestward, partially over autochthonous Mesozoic-Cenozoic Gulf of Mexico deposits. The pile of thrust sheets was later folded into an anticline whose hinge plunges northeastward and is cut by the Pinar fault along its southern limb. Interpretation of the internal structure of the Guaniguanico unit shows that the thrust sheets of the Rosario area overlie those of Los Organos area (Rigassi-Stüder, 1963; Piotrowska, 1978, Figure 4). Iturralde-Vinent (1994a, Fig. 9) postulated that the original position of the nappes was inverted by thrusting on the basis of the stratigraphy and facies relationships of the Paleogene sediments in the Guaniguanico unit. Consequently the continental margin represented by the Guaniguanico unit was facing the Caribbean sea to the southeast before deformation took place.
The Los Palacios tectonic unit (Pushcharovski et al., 1989) has also been called the San Diego de los Baños tectonic unit (Piotrowska, 1993). This unit has been described by Furrazola et al. (1964), García-Sánchez (1978), Piotrowski (1987) and García et al. (1989). The composition of the unit as a whole is poorly known because few wells have penetrated the pre-Campanian section. In generalizations of the geology of Cuba, the unit is supposed to be underlain by Cretaceous volcanic arc rocks (e.g., Furrazola et al., 1964), but unequivocal volcanic arc rocks have not been recovered (García et al., 1989; Iturralde-Vinent, 1994a, b). Only the Güanal and Rojas wells, drilled in the Güanal structural high, recovered some fragments of serpentinite and mafic rocks below ~1000 m of Miocene carbonates (Furrazola et al., 1964; see also discussion in Iturralde-Vinent 1994b). No definitive conclusions can be drawn from the limited information obtained from these wells, but the possibility that the volcanic arc represents the basement of the Güanal structural high cannot be ruled out, as it is associated with large magnetic and gravity anomalies (Pardo et. al., 1990). Two deep exploratory wells drilled in Los Palacios (San Diego and Manga Larga) cut Cenomanian-Turonian sandstone and siltstone with interbedded hemipelagic limestone, a section that resemble those developed in the Northern Rosario belts of the Guaniguanico unit, as suggested by Iturralde-Vinent (1994a, b).
The Upper Cretaceous and Paleogene rocks of Los Palacios outcrop along a narrow belt parallel to the Pinar fault. These rocks, which generally dip towards the south and southeast, are also found in the exploratory wells drilled in different parts of the unit. The upper Campanian and Maastrichtian section, which outcrops on the southwestern flank of Los Palacios, consists of shallow water limestone interbedded with conglomerate composed of debris from Cretaceous igneous rocks (San Juán y Martínes Fm (Piotrowski, 1987)). These rocks yield an abundant late Campanian and Maastrichtian fossil assemblage including rudists, larger foraminifera and algae (Piotrowski, 1987; Alvares Sánchez, 1989a).
The exploratory wells drilled elsewhere in this tectonic unit penetrate upper Campanian-Maastrichtian arkosic sandstone which grades downwards into conglomerate and siltstone. The clastic component in these rocks is dominated by quartz and muscovite, but coarse-grained debris derived from a volcanic arc source is common near the base of the section (García et al., 1989). Planktonic and benthic foraminifera indicate an outer neritic environment (Fernández et al., 1988). The absence of shallow water limestone in this section suggests that the San Juán y Martínez Fm pinches out southeastward and grades into clastic rocks. The Paleogene section in Los Palacios unit is represented by the Vibora Group, and the Capdevila, Universidad and Loma Candela Fms Piotrowski, 1987; García et al., 1989). These rocks are slightly to moderately deformed, with deformation intensifying near the Pinar fault. The clastic component is derived from the erosion of the Cretaceous volcanic arc, and includes several types of siliceous plutonic and volcanic rocks (Echevarría et al., 1988). The lithology and age of Vibora Group and the Capdevila and Universidad Fms in this area are comparable with those in the Bahía Honda and La Habana-Matanzas areas (Piotrowski, 1987; Alvarez Sánchez, 1989a; García et al., 1989).
The La Coloma-Sabana Grande tectonic unit is a large depression located south of the Güanal structural high. The depression in probably filled with sedimentary rocks that overlie Cretaceous arc rocks. The volcanic arc rocks outcrop in the northwestern end of the Isle of Youth and have been documented by Furrazola et al. (1964) and Pushcharovski et al. (1989). This area is transected by E-W trending magnetic and gravity anomalies that correlate with the axial part of the deformed Cretaceous volcanic arc in central Cuba (Pardo et. al., 1990). We did not collect any samples from this tectonic unit. The Paleogene section in Los Palacios unit is represented by the Vibora Group, and the Capdevila, Universidad and Loma Candela Fms Piotrowski, 1987; García et al., 1989). These rocks are slightly to moderately deformed, with deformation intensifying near the Pinar fault. The clastic component is derived from the erosion of the Cretaceous volcanic arc, and includes several types of siliceous plutonic and volcanic rocks (Echevarría et al., 1988). The lithology and age of Vibora Group and the Capdevila and Universidad Fms in this area are comparable with those in the Bahía Honda and La Habana-Matanzas areas (Piotrowski, 1987; Alvarez Sánchez, 1989a; García et al., 1989).
The La Coloma-Sabana Grande tectonic unit is a large depression located south of the Güanal structural high. The depression in probably filled with sedimentary rocks that overlie Cretaceous arc rocks. The volcanic arc rocks outcrop in the northwestern end of the Isle of Youth and have been documented by Furrazola et al. (1964) and Pushcharovski et al. (1989). This area is transected by E-W trending magnetic and gravity anomalies that correlate with the axial part of the deformed Cretaceous volcanic arc in central Cuba (Pardo et. al., 1990). We did not collect any samples from this tectonic unit. Mesozoic metasiliciclastics and marbles of the Pinos tectonic unit indicative of medium grade barrovian metamorphism, outcrop in the unit. The internal structure of the unit is discordant with the structural trend of the Guaniguanico unit, as folds and faults are oriented NNW to SSE (Somin and Millán, 1981; Pardo, 1990. The lower part of the section generally correlates with Lower-Middle Jurassic rocks of the Guaniguanico unit, but overlying rocks show poor resemblance to any of the Guaniguanico belts (Somin and Millán, 1981). The only Tertiary rocks known from this area are Pliocene limestones that rest unconformably on the metamorphic rocks along the south of the island (Pushcharovski et al., 1989). According to Iturralde-Vinent (1994a, b), the Pinos tectonic unit is a terrane (Pinos Terrane) detached from the Yucatan borderland, and underthrust the Cuban fold belt sometime between the Campanian and the middle Eocene. The possibility that the crust underlying the Pinos unit continues SW to underlie the area between the Pinos unit and the Yucatan oceanic rift basin is in agreement with this hypothesis Rosencrantz, 1990).
During the field trip will be visited most of the stratigraphic units of the Los Organos and Rosario belts, in order to have an overview of the transition from Pangaea into the pasive continental margin of the Caribbean basin, and the Early Tertiary destruction and deformation of the former continental margin.
Geology and Tectonics of Western Cuba: Description of the Stops. Scenic view. Observation of the Abra del Ancón From Viñales town, toward Valle de San Vicente, stop at the intersection with the road to Laguna de Piedra. On the slopes of Abra del Ancón were found the first Jurassic fossils reported from Cuba, late in the XIX century, by Manuel Fernández de Castro and shortly after by Carlos de la Torre y Huerta. Stop 1. Exposures just south of Mogote La Mina (San Cayetano Fm) This stop is reached by driving along the road to Laguna de Piedra from Viñales, and turning to the east, at the first intersection after the entrance to República de Chile. Drive 1.5 km from the intersection. The San Cayetano Formation is exposed just after the intersection about 2 km. This unit is the oldest known in Guaniguanico mountains. It represents a siliciclastic shelf and coastal plain environment, with sedimentary features typical for these facies. Metamorphism is present from very low grade up to mid grade high-P locally. Terrestrial deposits occur in Sierra de los Organos with dry-land and brackish-water coastal planes (Areces, 1990). Shallow marine incursions are also found as intercalations that yield bivalves. The age of the unit is identified as Lower? To Upper Jurassic (early Oxfordian) (Pszczolkowski, 1978, 1994). The San Cayetano Fm probably represents a sedimentary unit coeval with the breakup of Pangea in the Mesoameridan area. Hence, it is locally cut by dikes and sills of basic igneous rocks. In western Cuba, as in some sections of the Gulf coast, the siliciclastic deposits (Eagle Mills) are directly overlain by marine clays and limestones (Smackover), but evaporites are not present. Only isolated gypsum veins have been recorded in some deep wells drilled in Guaniguanico. Present in the outcrops are some of the sedimentary facies of San Cayetano, which consist here of well-bedded reddish and yellowish fine- to medium-grained sandstones with shales. The sandstones yield muscovite derived from Grenville and Pan African terranes. Above San Cayetano the Jagua Formation poorly outcrop at the base of the Mogote la Mina. The Jagua Vieja Member of the Jagua Formation is represented by dark shales and thin-bedded limestone, with embedded laminated calcareous concretions. The concretions are of different sizes and are named “jicoteas” or “quesos” in the local vernacular and are highly fossiliferous. The only Jurassic vertebrates known from the Caribbean have been recovered from the carbonate concretions in this member, and yield fossil fishes, plesiosaurs, pliosaurs, metriorhynchus crocodiles, pterosaur and ammonites. Uphill the Jagua Fm is covered by the San Vicente member of the Guasasa Formation. Stop 2 and 3. Observations along the walls of Valle de San Vicente, Jagua-Guasasa Fms. This section is reached by driving southwestward from Viñales Town in the direction of Motel Rancho San Vicente. Just at the intersection to Laguna de Piedra, looking northward, begins the Abra del Ancón.
At the gentle slope of the “mogote” hill on both sides of El Abra is found the Oxfordian Jagua Fm, represented by well-bedded shales with laminated fossiliferous limestone concretions (Jagua Vieja member), followed by well-bedded limestones (Pimienta member) exposed on the walls of the mogotes (Pszczolkowski, 1978). At the top of the well-bedded limestones is located the base of the Guasasa Formation, containing well developed karstic features (Figure 5). The base of Guasasa Fm is a limestone breccia that can be observed on the wall just left of the Cueva de Viñales bar. Some geologists in the past saw in this breccia a tectonic unit, but most probably it is a sedimentary bed deposited during an onlap event. Above the breccia, the massive limestones of the San Vicente Member (Guasasa Fm) are found. These limestones are latest Oxfordian to earlest Tithonian in age, and represent a carbonate platform known only in the Los Organos mountains area of western Cuba. The limestones are massive to thick-bedded, gray to black, totally or partially dolomitized. Micritic limestones dominate the lower section, whereas calcarenites are more common upward (Pszczolkowski, 1978). These lithologies can be observed at the mogote wall on the right side of the Cueva de Viñales bar, and on the other side of the valley, near Cueva del Indio. Unfortunately, combined recristalization, karstification and weathering obscure details of the carbonate bank facies.
The San Vicente carbonate bank evolved upward into more open marine carbonates and cherts of the El Americano, Tumbadero and Tumbitas members, representing drowning and extinction of the carbonate platform. They are well stratified limestones with calpionellids, radiolaria and other nannofossils, occasionally ammonites (Pszczolkowski, 1978). The Jurassic-Cretaceous boundary here is within the El Americano-Tumbadero contact, which shows a minor unconformity. El Americano Member: Is the lower part of the section above the San Vicente thick bedded limestones, represented by well-bedded, dark-gray to black limestones with some dolomites, up to 45 m thick. Minor unconformity between El Americano and Tumbadero. Tumbadero Member: Thin-bedded to laminated limestones with black chert intercalations, which reach 20 to 50 m thick. Tumbitas Member: Thick-bedded, compact, light-grey micritic limestones with some thin Intercalations of darker limestones, ranging from 40 to 50 m thiick. The last three members are exposed at the mogote wall facing southeast, near the parking area of Cafeteria Cueva del Indio, walking northward toward the International Post Office.
Stop 4. Moncada Section From Viñales Town, drive 18 km to the west, just after the intersection to Moncada (southward). The section contains excellent examples of the Guaniguanico Tertiary deposits, with the transition from continental passive margin deposits is represented by the Pons-Moncada-Ancón: The Albian-Cenomanian Pons Fm consists of well-bedded black micritic and biomicritic limestone and cherts. It is overlain by the Moncada Fm represented by a 2 m thick layer of thin-bedded, fine-grained calcarenites located below the Ancón Fm. The Ancón limestone consists of about 18 m of well-bedded, light reddish-violet-green micritic, slaty to sublithographic limestone with interbedded shales. The overlying foreland deposits are represented by the Manacas Fm which is subdivided into the Pica Pica siliciclastics and the Vieja Olistostrome. Pica Pica siliciclastics are represented by 15 m of thin-bedded claystone and fine- to medium-grained arkosic and lithoclastic sandstone. The section is capped by more than 30 m of olistostrome, composed of large blocks embedded in a strongly deformed sandy-claystone matrix. The blocks, which consist of limestone, chert, basalt, diabase, gabbro and serpentinite, are up to 3 or 4 m in diameter and coarsen toward the top of the outcrop.
Moncada Formation is an approximately 2-m-thick weakly metamorphosed complex characterized by repetition of calcareous sandstone units that show overall upward fining and thinning. The Moncada Formation contains abundant shocked quartz, altered vesicular impact-melt fragments, and altered and deformed greenish grains of possible impact glass origin. In addition, a high iridium (ca. 0.8 ppb) peak is identified at the top of the formation. Together with the biostratigraphically estimated age between late Maastrichtian and early Paleocene, this evidence supports a Cretaceous-Tertiary (K/T) boundary origin of the deposit. The Moncada Formation bears ripple cross-laminations at several horizons that indicate N-S trending paleocurrent directions with reversals. In addition, the maximum grain-size variation within each unit suggests the presence of higher frequency waves superimposed on the lower frequency waves. Thus, suggest that K/T impact tsunami waves had a complex rhythm that was caused either by reflections and diffractions of waves or by multiple tsunami waves created by multiple gravity-flows triggered by seismic shocks of the impact.
Not far is located the Santo Tomas Cave System. You reach this place taking the road to Moncada village and following the signs. This is a wonderfull cave with several superimpossed levels of alluvial origin communicated by vertical sinks. It has been maped more than 30 kilometers. Parts of the Cave can be visited by tourists depending on their skills. Stop 5. Río Piedra section From the stop 3, drive to Pons, but turn to the south in the intersection: the first small bridge.
The outcrop along the river, starting from the road bridge upstream includes the Pons (Albian-Cenomanian-Turonian?), Peñas (Campanian-Maastrichtian) and Ancón (Paleocene) Fms. The oldest unit is represented by micritic and biomicritic well-bedded black to dark gray limestones with interbedded cherts as nodules and layers. It contains planktonic foraminifera, radiolaria and calcispherulids. It is covered by limestones and cherts of the younger Peñas Fm, richer inchert intercalations. The contact is a non-evident parallel unconformity. The section is capped by the beige and pink limestones of the Ancón Fm and the Pica Pica siliciclastics. Peculiar to this section and typical of the Cretaceous in Sierra de los Órganos is the absence of siliciclastic intercalations, common to the isochronous units of the Rosario mountains. The Pons-Peñas hiatus is probably isochronous to the so called mid-Cretaceous unconformity. Stops in the Sierra del Rosario and Bahía Honda belts Following the Carretera de Montaña from Mogote La Mina heading east. Drive up to the road intersection located 2 km SE of La Palma, driving east toward Mil Cumbres and Niceto Pérez Stop 6. Exotic serpentinite blocks in Paleocene-Eocene Manacas Fm Exposures of Manacas Fm from 2.5 to 8.2 km. These outcrops yield large exotic blocks of serpentinites and other ophiolites Following the road: • Exposures of San Cayetano Fm near 7.8 km. • Exposures of Manacas Fm from 9.7 to 11.5 km. Stop 7. Allochthonous thrust sheet of ophiolites After 12 km, the contact between Guaniguanico terrane and Bahía Honda allochthon is visible. This is a large thrust fault that superimposed the Cajálvana ophiolites and Bahía Honda volcanic arc rocks above the Guaniguanico terrane. Following outcrops of serpentinites and laterites from 14 to 20 km. Stop 8. KTB Cacarajicara Fm and view of the Guajaibón Aptian-Cenomanian platform
At 24 km near Mameyal, scenic view of the Pan de Guajaibón, looking north. The Guajaibón Fm is an Albian to Cenomanian carbonate bank, which is part of a section located north in Sierra del Rosario. This bank is interpreted in different manners, as an old knol within the western Caribbean offshore Yucatan, or as a fragment of the Yucatan platform (Iturralde-Vinent, 1998). • Albian Santa Teresa cherts thrust onto lower Eocene Vieja olistostrome from 32 to 33 km, 4 km before Niceto Pérez/ • Niceto Pérez. Turn in the intersection to the left; it is the road to Soroa and Las Terrazas. • Scenic view looking north 7.4 km from Niceto Pérez. The coastal plain north of the mountains is the Bahía Honda tectonic unit. • San Cayetano-Artemisa Fms contact 8.7 km after Niceto Pérez. • Artemisa Fm from 9.4 to 10 km after Niceto Pérez. Stop 9. Cretaceous deep-water deposits in the Rosario mountains, Polier-Roble-Santa Teresa-Carmita. Exposure on the left side of the road, 10.3 km after Niceto Pérez. Four units are present in this exposure: the Polier Fm limestones and shales, the Roble sandstone member of the Polier, the Santa Teresa cherts and the Carmita limestones and cherts. They represent the Lower Cretaceous Hauterivian? To Turonian? basinal marine section, probably facing the Caribbean sea (Iturralde-Vinent, 1994). A similar pattern of Lower Cretaceous facies development is found at the southern slope of the Bahamas platform (exposed in north-central Cuba). In contrast to the isochronous section in Sierra de los Organos, this section yields clastic sediments from a deeper water environment. The outcrop is deformed, but still the units preserve the original superposition. From oldest to youngest are: The Polier Fm is composed of thin-bedded, gray, micritic limestones intercalated with sandstones and shales. The sandstones are yellow-brown, fine- to medium-grained, with some calcareous cement. They display flute casts, groove casts, cross and horizontal lamination and graded bedding. The clastic component is dominated by quartz with plagioclase and muscovite. The Roble member (of the Polier Fm) is composed of thick-bedded, medium-grained quartz sandstones, with few clayey shale intercalations. They display graded bedding, and abundant sole casts. The Santa Teresa Fm is composed of well-bedded turbidite silicified sandstones, red to greenish-brown ribbon cheerts and a few green shale intercalations. Sedimentary features typical of deep-water deposition are visible. The cherts are usually strongly folded. The Carmita Fm is light grey, well-bedded micritic limestone with interbedded radiolarian cherts and shales (Pszczolkowski, 1978, 1994). Step10. Exposures of Artemisa Formation.
These limestones are exposed 13.5 to 14.5 km from Niceto Pérez, 2.5 km before the intersection with the road to Soroa. Section of Late Jurassic (late Oxfordian) to Early Cretaceous well-bedded micritic, dark gray to black limestones and some black calcareous shales, with a few intercalations of coarse grained calcarenites. Sometimes aptychi are found in the limestones. The calcarenites in the lower (Kimmeridgian) part of the section are probably derived from the coeval carbonate platform in Los Organos (San Vicente mb of Guasasa Fm). Bioclastic limestones and coquinas composed of ammonite shells and aptychi are found near the top, as are some biomicritic limestones with radiolaria, calpionellids and other micrifossils. In the late Tithonian, as elsewere in Cuba, the fitst intercalations of cherts are found suggesting a general deepening of the sea floor (Pszczolkowski, 1978).
• After this stop is exposed the San Cayetano Fm up to the intersection with the road to Bahía Honda. Drive across it and follow the road to Las Terrazas.
Stop 11. The Early to Late (early Oxfordian) Jurassic San Cayetano Fm in Rosario mountains. The formation crops out from 800 m to 1.5 km after the intersection with the Road to Bahía Honda. Exposures of the San Cayetano Fm in Sierra del Rosario are interpreted as been more dominated by marine facies than their isochroous in Los Organos (Haczewsky 1978). This outcrop has thin-bedded to slaty shales with bitumen, and thin to coarse-grained sandstones to conglomerates, often with small fragments of plant remains. The rocks are rich in quartz and mica. • Manacas Fm 4.5 km after the intersection. • Exposures of Late Cretaceous units from 5 to 7.5 km. Stop 12. Oxfordian-early Kimmeridgian El Sábalo basalts.
These exposures are found 7.5 to 10.5 km after the intersection with the road to Bahía Honda. The El Sábalo Fm is a thick volcano-sedimentary unit deposited at the continental margin, during extension (and thinning) of the sialic crust. Because this continental margins was probably facing the Caribbean sea, the thick basaltic extrusives suggest an active event of ocean spreading (drifting) in the basin (Iturralde-Vinent, 1994). The El Sábalo underlies the Artemisa Fm in this area as can be observed in several places where the limestone cap the elevations built up by basalts. The El Sábalo is composed of massive or pillow basalts and hialoclastites with thin intercalations of laminated limestones and shales. These intercalations contain microfossils (Globochaete alpina, Colomisphaera spp. and spicules of Didemnidae) (Pszczolkowski, 1994). According to their rare elements this salts are geochemically different to those found in the ophiolitic sections (oceanic crust) of Cuba (Iturralde-Vinent, 1989). The unit es usually strongly brecciated but the character of the folding in the sedimentary intercalations shows that the deformation is not very strong. • After this stop is the road to Soroa. Turn left and about 1 km later turn right and drive toward Las Terrazas. Outcrops of the
Manacas Fm tectonically covered by slivers of Polier Fm lead up to the following stop.
The Bahía Honda allochthon: Example of synorogenic sedimentation in piggyback basins. The Bahía Honda allocation is represented by a lower deformed ophiolite sheet, overhrusted by Cretaceous volcano-sedimentary deposit of ?Albian to Campanian age. This volcanic arc section is unconformably overlain by upper Campanian- Maastrichtian deep-water sandstone, claystone, and conglomerate of the Vía Blanca Fm. The clastics are mostly derived from the erosion of the extinct volcanic arc. KTB deposits iin the area is represented by a calcareous megaturbidite (Peñalver Fm) as in La Habana-Matanzas area (Takayama, 2000). The lower Tertiary section was deposited in piggyback basins, partially during the tectonic emplacement of the Bahía Honda allochthon above Guaniguanico. Therefore, the Tertiary section of the piggyback basins is less deformed than the section of the foreland basin. In some localities (such as near Las Terrazas), the deposits of the piggyback basins directly overlie Guaniguanico, but the contact is tectonic (Iturralde-Vinent, 1994; Bralower and Iturralde-Vinent, 1997). The lower Tertiary section has been divided into the Víbora Group (well-stratified conglomerates, sandstones, siltstones and claystones, usually with slumping and olistostromic-like intercalations), the Capdevila Fm (well-bedded sandstone, claystone and siltstone, with minor intercalations of conglomerate), and the Universidad Fm (hemipelagic marls, marly limestone, and radiolarian marls, with rare intercalations of fine clastic rocks toward de base). These clastic rocks were deposited during the thrusting of Bahía Honda onto Guaniguanico, so abundant slumping and thick conglomerates developed. The transition between the clastics and the marls (Capdevila-Universidad) is coincidental with the end of the tectonic transport of Bahía Honda units above Guaniguanico (Bralower and Iturralde-Vinent 1997). During the field trip, some sections of the Tertiary piggyback deposits will be observed.
DESCRIPTION OF THE STOPS Informative stop. Exposures of the Guaniguanico-Bahía Honda contact (after a long wet season, these exposures are covered by grass) 10 km from the road to Soroa, just after the intersection to Las Terrazas. Low exposures on the road’s southern side. In this locality the Bahía Honda sediments are exposed directly on the deformed Guaniguanico. From base to stop: 1) strongly-deformed Lower Cretaceous Guaniguanico sedimentary rocks (Polier Fm); 2) a deformed contact, probably a thrust plane; 3) blocks and silvers of deformed Polier Fm mixed with deformed Paleocene sandstone; 4) foliated serpentinite dipping eastward probably along a thrust plane; 5) deformed Paleocene sandstone with inclusions of blocks of foliated serpentinite, chert and red stuff similar to those of the Cretaceous volcanic arc, and isolated small blocks of the Polier Fm. This contact is tectonic, because: 1) Paleocene sediments at this locality are of the same age or older than those of the underlying Guaniguanico Tertiary rocks, so they cannot rest transgressively on Guaniguanico; 2) sedimentary rocks in these sites are more deformed than the Capdevila deposits elsewhere in the Bahía Honda Basin; and 3) slivers of allochthonous foliated serpentinite and blocks of Guaniguanico deposits are observed intercalated in the section, as in other locations along the same contact (Bralower and Iturralde-Vinent, 1997). Stop 13. Deformed Víbora-Capdevila-Universidad Fm at La Pastora Low exposures on the north side of the road, near the exit to Mirador and to Autopista (highway). In this locality, known as La pastora, a Paleocene to Middle Eocene section of synorogenic piggyback deposits of the so-called Bahía Honda allochthon, is exposed. According to Bralower and Iturralde-Vinent (1997) the Lower Paleocene (Víbora Group) is represented by about 20-25 m of well-stratified, medium-to-coarse-grained sandstone and siltstone. This unit contains a lowermost Paleocene (Zone NPI) nannofossil assemblage. Above this unit are found, probably in tectonic contact, 30 m of folded medium- to coarse-grained sandy claystone and sandstone. These lithologies, partially produced by slumping, are also Paleocene. The Lower Eocene Capdevila-Universidad transitional lithologies unconformably overlie the deformed deposits. This unit is represented by a 15 m thick well-stratified marlstone and marly limestone intercalated with sandstone, sandy claystone, siltstone and a few conglomeratic beds. The base of the Universidad Fm crops out on the other side of the road above the previous section and consists of marlstone and marly limestone. These formations were also described by Bronnimann and Rigassi (1963) and Albear et al. (1985) in the Havana area. • 1 km toward Cayajabos Lower Eocene marls and marly limestones (Universidad Fm) are exposed.
Stop 14 Near Cabañas town, Bahia Honda Unit KTB Peñalver Fm.
Stop 15 Road Soroa-San Diego de Nuñez The Rosario belt transect, the Cajalbana mafic-ultramafic complex and the Cretaceous volcanic arc and its sedimentary Campanian and younger coverture Stop 16 Road San Cristóbal-Bahia Honda The Rosario belt transect , the Cajalbana mafic-ultramafic complex and the Cretaceous volcanic arc and its sedimentary Campanian and younger coverture
