SURFACE SURVEY OF THE ON THE NORTHWESTERN SLOPE OF CUBA, SOUTHERN OF FLORIDA

Luis A. Soto, Diego López-Veneroni, Cecilia López-Canovas, Ricardo Ruiz-Vázquez and Guadalupe de la Lanza Espino

SUMMARY

The seabed off the northwestern coast of Cuba was ex- had a coarse appearance and were impregnated with a plored to study the sedimentary and biological characteris- strong oil odor. Their external surface had a blackened tar tics of surface in three blocks leased to REPSOL- layer and an irregular -oxyhydroxide stain. Bulk sedi- YPF-Cuba S.A., at depths between 1600 and 2000m. Sub- ment isotopic analysis (δ13C: -25.7 to -18.5‰) revealed a coring of surficial sediments was conducted for stable iso- non-methanogenic carbon source, suggesting that oil seep- topic analysis, and nitrogen contents, age occurs localized. Source of sedimentary organic carbon and infauna description. Spatial heterogeneity in moder- was mainly oceanic (δ13C: -18.50 to -19.13‰; δ15N: +3.6 to ately laminated sediments was detected among blocks. Sur- +6.4‰; molar C:N ratios of 2.4 to 5). Bottom water condi- ‑1 face sediments consist of silty and materials, mainly tions were stable (5ml·l O2, 3-4ºC, 35.0psu) and infauna composed by calcite, were impoverished in was low due to reduced organic matter flux to deep and rich in hemipelagic components. From the northeastern sediments. This survey documents one of the deepest oil end of this area (Block III, 1640m) large limestone blocks seeps in the vicinity of the eastern . stained with were recovered. Rock fragments

n international multi- Straits of Florida. A previous geophysi- Associated to cold seeps disciplinary research cal survey of the area of study (Cesig- are carbonate mounds, coral reefs, group supported by ma, 2002) indicated the presence of pockmarks, mud volcanoes, and - REPSOL-YPF Cuba S.A. initiated in sediment mounds, sink holes and a mounts (Mazzini et al., 2003). Accord- 2002 a multibeam prospection of the complex of knolls on the slope seafloor ing to these authors, in conventional insular slope seabed, off the northwest- associated perhaps to collapsed karstic cold seeps fluids escape to the seafloor ern coast of Cuba, to describe the main structures that may potentially encom- through permeable fractures and faults. bathymetric features and the prevailing pass oil and seeps (see Wilson et These systems have been documented hydrographic conditions in the Southern al., 1974). with different approaches at numerous

KEYWORDS / Carbon and Nitrogen Stable Isotopes / Cold Seeps / Cuba NW Slope / Straits of Florida / Received: 03/11/2011. Modified: 11/06/2012. Accepted: 11/14/2012.

Luis A. Soto. M.S. in Marine Biology, Florida State University, USA. Ph.D. in Biological Oce- anography, RSMAS, University of Miami, USA. Address: Laboratorio de Ecología del Bentos, Instituto de Ciencias del Mar y Lim- nología, Universidad Nacional Autónoma de México (UNAM). Ciudad Universitaria, México D.F. 04510, México. e-mail: lasg@ cmarl.unam.mx Diego López Veneroni. Biochemical Engineer, Instituto Tecnológico y de Estudios Superiores de Monterrey, Mexico. M.S. in Marine Sciences, UNAM, Mexico. Ph. D. in Oceanogrphy, A&M University, USA. Resear- cher, Instituto Mexicano del Petróleo, Mexico. e-mail: [email protected] Cecilia López-Canovas. M.S. in Biology, Universidad de La Habana, Cuba. Researcher, Insti- tuto de Ecología y Sistemática, Havana, Cuba. Ricardo Ruíz Vázquez. M.S. in Marine Sciences, UNAM, Mexico. Guadalupe de la Lanza Espino. M.S. and Ph.D. in Biological and , UNAM, Mexico. Professor, UNAM, Mexico.

812 0378-1844/12/11/812-08 $ 3.00/0 NOV 2012, VOL. 37 Nº 11 multibeam depth sub-bottom pro- filer (50kHz) was employed at wa- ter depths ranging 1600 to 2000m in the exploration of three blocks out of the 59 leased on the Exclu- sive Economic Zone of Cuba for oil and gas extraction. The blocks are referred henceforth as Blocks I, II, and III. The thermohaline structure and current velocity pro- files were obtained with a CTD coupled with an ADCP deployed from the surface down to 5-7m above the seafloor. A 2kHz echo- sounder was employed for the rec- ognition of the bottom structure. Near-surface sediments were sam- pled with a Reineck box-corer (sample area of 0.06m2). Recovered box cores were subcored with a 6cm diameter and 30cm long fi- berglass core-liner. Subcores were freeze-dried and later divided into standard sediment depth intervals; the resulting sediment fractions were lyophilized and ground to a fine powder. Total organic carbon (TOC) determinations were per- formed using Gaudette and Flight’s technique (Gaudette et al., 1974). Total nitrogen (TN) was de- termined following the procedure of Rodríguez-Medina (1989). The Figure 1. of the Southern Straits of Florida. Explored blocks I, II, and III are indicated concentrations of TOC and TN are from left to right; included in each block are the sites sampled. expressed in percent dry weight. C:N ratios were stoichiometrically calculated based on the respective sites both at passive and active margins cent initiatives of searching for fossil molecular weights. Bulk surficial sedi- in the Atlantic , Eastern and fuels in the sub-seafloor have re- ment samples were obtained for isoto- Western Pacific Ocean, and in the Med- newed interest in studying pic analysis (15N/14N and 13C/12C), and iterranean Sea (Paull et al., 1984, 1985; processes such as erosion of surficial fauna description. Sediment samples Kennicutt et al., 1985; Kulm et al., sediments, new sedimentological dep- for stable isotopic analysis were acidi- 1986; Sibuet and Olu, 1998; León et ositional models, and organic particle fied in a 1N HCl bath for 24h, washed al., 2007). seepage into fluxes (Gaumet and Letouzey, 2002; with distilled water and dried at 60oC the seabead also occurs in fore arc ba- Chambers et al., 2003; Magnier et al., to remove carbonates. The dried sam- sins in the Western Pacific (Schmidt et 2004; Piñón, 2006). This paper docu- ples were ground with a mortar and al., 2002) and in the Barbados accre- ments the presence of oil seeps in the pestle and analyzed in a Finnigan-MAT tionary wedge (Lance et al., 1998). Southern Straits of Florida and pro- 252 Stable Isotope Ratio Mass Spec- Sibuet and Olu (2003) summarized vides new data on the sedimentary trometer against air nitrogen and PDB current knowledge on the benthic com- features, the sources of organic car- standards, for N and C, respectively. munities associated to envi- bon an nitrogen based on stable iso- About 200g of the top 10cm of sedi- ronments. In the vicinity of the area of topes, the diversity and density of ments were sieved through 0.50 and study, cold seeps have been studied off surficial fauna, and the petrographic 0.25µm screens for qualitative infaunal the continental slope of Louisiana, in characteristics of seep-related authi- analysis. Quantitative analyses for mac- the northern Gulf of Mexico (Kennicutt genic carbonates. roinfauna and meiofauna were based on et al., 1985; Feng et al., 2009), and two replicate samples taken in each along the Florida Escarpment (Paull et Materials and Methods box-core with the aid of syringes of al., 1985), and new sites have recently 2.5cm diameter and 10cm penetration; been explored within the Gulf of Mexi- The area of study com- sediment replicates were then sieved co (Cordes et al., 2007). prises the insular slope seabead of the through 0.50 and 0.37µm screens. All The deep seafloor in southwestern channel of the Florida Straits, were counted and manually the studied area remained unexplored between 23º23'57''N, 83º06'47''W and sorted into major taxa after being for several decades. Echeverría-Rodrí- 23º27'39''N, 81º44'37''W, approximately stained with Rose Bengal. X-ray dif- guez et al. (1991) summarized much 68 and 39km off Bahía Honda and fraction (XRD) analyses of rock sub- of the oil exploration conducted in Puerto Escondido, in the Havana Prov- samples were conducted with a Phil- Cuba both inshore and offshore. Re- ince, Cuba, respectively (Figure 1). A ips 1130/96 diffractometer utilizing

NOV 2012, VOL. 37 Nº 11 813 Topographic features

The three studied blocks lie on the slope of the Southern Straits of Florida (Figure 1). The deeper sector (>2100m) consists of a trough- like feature, graded axial slope, with decreasing depths eastwards and north- wards, that separates Cuba, the Florida Peninsula and the Bahama Bank (Hur- ley, 1964; Malloy and Hurley, 1970). The insular margin (~200-1600m) is ex- tremely steep and rugged. Block I, lo- cated off Artemisa Province, Cuba, at a maximum depth of 2169m had a surface of 28.49km2, comprised a v-shaped val- ley oriented along the main axis of the channel, with faulting structures and small canyon on its western end. Block II (54.11km 2) had a maximum depth of 1640m depth showed a scarped surface faulting NE-SW. The distance between Figure 2. a: Large fragment of a limestone Blocks I and II was of 27.7km. Block rock recovered from block III at 1650m; III (174.32km2) at a maximum depth of the external surface of the rock is black- ened by a 2mm tart crust followed by 1650m included a ridged bottom with iron-oxyhydroxide stain. b: Microscopic prominent knoll-like structures protrud- image of carbonate rock showing rich fora- ing ~100m above the seabed. This area, minifera allochems (For) embedded in a positioned 70km east from the other fine-grained calcite matrix (CM). c: SEM two blocks, lies closer to the insular image of hexagonal calcite aggregate. shelf (<28km) just off Puerto Escondi- do, Mayabeque Province, Cuba. The predominant faunal constituents of the bottom sediments in the biofacie were planktonic foraminifers, pteropod Results shells, and coccolithophorids that ap- peared disseminated with a fine-grained Hydrographic setting carbonate mud. In spite of their relative proximity, the three blocks exhibited The Southern Straits of certain sediment heterogeneity. In the Florida lie under the influence of the deepest block (I) surficial sediments Cu Kα 1, 2 radiation directed toward ran- Florida Current, the Yucatan Current were classified as Globigerina clay de- domly oriented samples. Standard scans and the southerly-flowing surface Cu- void of an oxidized layer, whilst the ad- were recorded from 4° to 70° (2θ) at ban Counter-Current. Four water mass- jacent block (II) contained an assorted 2°/min. Field descriptions of rock color es can be recognized: a) the Surface biogenic hemipelagic biota (foramin- are given in accordance to the code Tropical water mass in the upper 100m, ifera, pteropods, scaphopods, micromol- numbers contained in the Rock-Color with an average temperature of 29ºC luscs, and echinoid and sponge spicules) Chart of the Geological Society of and 35.5psu; b) the Subtropical Subsur- and a discrete oxidized layer. Subcores America (Goddard et al., 1948). Non- face water mass down to 700m depth, obtained from this area revealed at 5cm parametric and parametric ANOVA with 22-26°C and 36.4-36.7psu; c) the sediment depth two dark horizons of tests (Friedman’s, Kruskal-Wallis with Subantarctic Intermediate water mass organic matter, of 1.3 and 2.0cm. Surfi- tied ranks) were applied to determine near 1000m, with ~7°C and ~34.8psu; cial sediment in Block III was dominat- differences in stable C and N isotope and d) the North Atlantic deep-water at ed by carbonate, highly cohesive due to ratios, TOC and TN, and infaunal den- depths exceeding 2000m, with ~7°C the predominance of clay and minor sity values among blocks. A multiple and 35.0psu. The thermohaline profiles hemipelagic constituents. At this site regression analysis was used to deter- revealed a stratified column with a 70m large fragments of limestone blocks mine the interrelationship between mixed layer and a permanent thermo- were recovered (Figure 2a). They were meio/macrofauna density (dependent cline extending to a depth of 700m, a coarse with sharp angles, and impreg- variable) and TOC and TN (indepen- temperature of 10ºC and 35.2psu. In the nated by a strong oil odor. Their exter- dent variables). A factorial analysis present study, a strong near-bottom nal surface was blackened by a 2mm was employed to generate a correlation flow had a SE-E direction and an aver- tar crust coated by an irregular iron- matrix of the parameters measured at age velocity of 4cm·s‑1, 30% higher than oxyhydroxides stained. the 12 sites sampled in the three blocks the 3cm·s‑1 known for abyssal basins The XRD analysis of explored. These sites were later (Munk et al., 1970). In contrast, the rock fragments revealed a mineral com- grouped according to the similarity of thermohaline structure at the bottom of position predominantly of calcite and their biogeochemical attributes with a the Southern Straits is stable with aragonite, with a minor proportion of cluster analysis. 5ml·l-1O2, 3-4ºC and 35.0psu. fluoroapatite. Allochems were bioclasts

814 NOV 2012, VOL. 37 Nº 11 Table I (Block III). Similarly, as in the case lowed by Block III (60ind/10cm2) and 13 2 Carbon and Nitrogen isotopic of N isotopes, equality of δ C values Block II (32ind/10cm ). These density values and MOLAR C:N ratio in among blocks was rejected (Kruskal- values seem heterogeneously distribut- surficial sediments at 12 sites Wallis test with tied ranks ed among sites and their apparent sampled in three Blocks on the 0.05

NOV 2012, VOL. 37 Nº 11 815 Discussion In reference to the iso- topic signature of the sampled sedi- The Straits of Florida ments, Macko et al. (1984) reported 15 is the region where the Florida Current- δ N values of +3.6 ±0.1‰ in the sedi- system forms. Local water ments from the of circulation in this area is influenced by South Florida, just north of the studied frontal eddies originated west of the area. The present values are relatively that propagates clockwise more enriched by ~1.8‰. Considering a anticyclones that impinge the west Flor- similar N isotope composition for coast- ida Continental Slope. In the Southern al and oceanic particulate matter, this Straits these anticyclones are called enrichment could reflect organic matter Tortugas eddies (Oey et al., 2005). Off decomposition of material sinking to western Cuba, southerly flows exist greater depths. The present δ15N aver- both at the surface and at depth (Shein- age falls within the range reported by baum et al., 2002). Deep flow above Macko et al. (1984) for the rugged topography had been sug- (+5.9±0.7‰), which emphasizes the in- gested by various authors (Hansen and corporation of pelagic POC into the Molinari, 1979; Gallegos et al., 1998) sediments without significant fraction- Figure 3. Cluster analysis (single linkage and was later confirmed by Ochoa et ation. The average δ13C value in surfi- Bray-Curtis similarity values) of δ13C, δ15N, al. (2001). These highly hydrodynamic cial sediments from the Southern Straits meiofauna and macroinfauna density, depth, conditions impose severe constrains on approaches those from the continental TOC, and TN values recorded at 12 sites sam- the particulate organic carbon (POC) shelf of South Florida (-18.5 ±0.7‰) re- pled in three blocks located on the northwest- flux to the seabed and may constitute a ported by Macko et al. (1984); such ern slope of Cuba. sediment transporting disturbance for value agrees with the autotrophic or- benthic dwellers. In the West Florida ganic carbon synthesized by phyto- slope, the Loop Current outlines the (-18.0 to -24.0‰) and has a 0.076, F= 0.37, d.f. =2, 9, p<0.7. As boundary between the shelf and slope, fairly constant average of -21.0‰ (Fry mentioned above, the insufficient or- winnows bottom sediments and stimu- and Sherr, 1984). The δ13C values ob- ganic matter input to the seabed of the lates pelagic production of calcium car- tained differ significantly from those insular slope clearly accounts for the bonate (Mullins et al., 1988). reported by Beazley (2003) at sites ex- low abundance and density of infaunal The three explored ceeding 2000m in the northern Gulf of organisms. In fact, the TOC in the top blocks are part of one of the twelve Mexico; this author recorded more de- 4cm of sediment from the three blocks major biofacies recognized in the Flori- pleted values (-20.6 to -30.0‰), which ranged from 0.19 to 0.80%, with aver- da-Bahamas area, namely the plankton- suggests both marine and hydrocarbon age values of 0.49, 0.60 and 0.34%, re- ic-foraminiferal one (Coogan, 1970). sources. spectively. Using the factorial analysis The two dark horizons of organic mate- In oceanic waters, sur- from which the correlation coefficient rial detected in the sediment subcores face productivity represents the main matrix was generated, the degree of in- possibly account for episodic events of source of organic matter that fuels ben- terdependence amongst the six parame- terrigeneous deposition of material ex- thic life throughout the rapid settling of ters was tested, including the depth at ported by surrounding environments large particles (>200µm). Suess (1980) each sampling site. The only cases of suggested by Malloy and Hurley (1970). postulated an empirical equation that positive covariation were the following Echeverría-Rodríguez et al. (1991) predicts Corg flux at any depth in the variables: δ13C, TOC, depth, and macro- pointed out that terrigeneous material ocean below the euphotic zone as a infauna density. The remaining comput- detected in offshore seismic lines may function of the rate ed correlation coefficients revealed act as a seal above hydrocarbon-gener- in surface waters and depth dependent moderate covariation, as in the case of ating Tertiary rocks. Interestingly, in consumption. Since surface waters in TOC, δ15N, and depth, or others had deep-cores obtained in the Straits of the area studied are oligotrophic, attain- clearly negative covariation and even Florida (eastern Gulf of Mexico; DSDP- ing values of 50-200mg C m3·d-1 in the scores of zero, indicating statistically Site 535) Herbin et al. (1984) correlated euphotic zone (Kabanova and López- independent variation. The above pa- lower cretaceous sediments (sub-bottom Baluja, 1973; Okolodkov, 2003), vertical rameters represent important attributes depth 582m), well-oxygenated environ- Corg flux to the sea floor must be kept for each site, whose interdependence ments, to light carbonate layers, where- to a minimum (<5%) applying may be the source of the observed het- as laminated darker sediments indicated Suess’empirical equation. This would erogeneity among the three blocks. The oxygen depletion events. explain the depletion in sedimentary or- exploratory cluster analysis of such at- The insular slope has ganic carbon in our subcore samples tributes in the 12 sites (Figure 3) re- characteristics of an erosional slope (TOC 0.66-0.81%). vealed remarkable similarity in three without significant sediment deposition. The type and source of groups encompassing sites 7-8, 9-10 and Unfortunately, no sedimentation rate organic matter may also be inferred 11-12, belonging to Block III, located at has been estimated in the Straits. Ac- from C:N ratios (Ruttenberg and Goñi, the slope rise. In contrast, sites includ- cording to Denny et al. (1994) the 1997). Normally, high (>10) C:N ratios ed in the other two blocks, near the Southern Straits of Florida evolved are indicative of refractory or non-de- channel axis, did not follow a defined from a shallow-water platform to a deep gradable organic matter, whereas ratios clustering pattern. This can be mainly trough. Due to rapid subsidence in the from 5 to 6 belong to relatively fresh attributed to the heterogeneity noted in Late Eocene the depositional regime labile organic matter. Export of alloch- the meiofauna and macroinfauna densi- shifted from a current-dominated to a thonous material from adjacent ty values recorded in these sites. pelagic/hemipelagic sedimentation. continental shelves to the slope and

816 NOV 2012, VOL. 37 Nº 11 abyssal is a major Corg source in polychaete density is around 100-150 Conclusions the Gulf of Mexico (Pequegnat et al., times smaller (0.04 vs 4-6ind/10cm 2) for 1983; Soto et al., 1998) and off North the same depth (Thistle et al., 1985 and Although the three Carolina (Rowe and Menzies, 1968). references therein). The data obtained sampled blocks on the NW insular According to Rasheed et al. (2006) C:N in the present study was deemed insuf- slope of Cuba were within a 100km ra- ratios >10 indicate an aged non-degrad- ficient to resolve the factors account- dius, topographic features and sediment able organic matter. Our estimated able for the atypical trend described be- characteristics revealed significant dif- mean molar C:N ratios support this tween meio/macrofauna abundance and ferences among them. Block I was lo- contention and are consistent with the density and TOC/TN. In addition to the cated within a v-shaped valley with depleted δ13C value here reported that small organic matter input to the deep faulting structures and small canyons. are similar to the isotopic signature for sediments in the Florida Straits Chan- Its surficial sediment was dominated by marine organic matter (-21.0‰) in nel, the exclusion effect upon surficial Globigerina clay. Block II had a Southern Florida (Macko et al., 1984). fauna caused by the box corer employed scarped surface and a faulting region Our estimated meiofau- cannot be overruled. and the sediment was constituted by an na density values are exceeded by al- The petrographic char- assortment of biogenic hemipelagic bio- most two-fold by those reported by acteristics of the limestone rock recov- ta; a discrete oxidized horizon suggests Beazley (2003). This author recorded ered from Block III are similar to that this site receives episodic terrige- densities of 70.0 to 50.8ind/10cm2 in the those described by Canet et al. (2006) neous influence. Block III was charac- Sigsbee abyssal plain of the Gulf of for carbonate rocks extracted from the terized by a ridged bottom with promi- Mexico at depths of 2050 and 3527m, Chapopote Knoll in the abyssal plain nent knolls. In spite of its proximity to respectively. Our macroinfauna density near the Campeche Bank in the south- the insular coast, sediment was domi- values are impoverished nearly three- eastern Gulf of Mexico, described as a nated by carbonate with evidence of in- fold when compared to those given by wackestone micrite with δ13C ranging termittent hydrocarbon seepage, produc- Beazley (2003) from the Sigsbee abys- between -23.0 and -23.5‰. The δ13C ing in authigenic deposits whose isoto- sal plain: 0.354 and 0.143ind/10cm2. values obtained from the recovered pic signature approaches that known for The pressure wave created by the limestone fragment in Block III fall oils in deep reservoirs of the Gulf of Reineck box-corer has been invoked as within the range of relatively depleted Mexico. Calcite was predominant in a factor for excluding surficial faunal δ13C range of seep carbonates (-29.4 to sediments of the three blocks. Stable groups (Bett et al., 1994) and, there- -15.1‰) recorded by Feng et al. (2009) carbon isotope in bulk sediment sam- fore, these values should be viewed from porous limestone slabs from Bush ples indicated a dominance of marine with caution. Conceding such a sam- Hill (GC 185) in the northern Gulf of organic matter deposition, with no evi- pling bias, the meiofauna and macrofau- Mexico. According to these authors, dence of thermogenic or biogenic isoto- na total density values estimated in the values above -20.0‰ indicate non- pic signatures. The low TOC within the 12 sites studied herein (32 to hydrocarbons being incorpo- cores and terrestrial plant remains in a 132ind/10cm 2) fall within the range of rated during seep carbonate-precipita- sample, along with the δ13C and δ15N those reported by Robinson et al. tion. It is feasible that Block III consti- values of sediments, suggests that an (2004) for cold seep habitats in the tutes a that allows the important carbon source to benthic fau- northern Gulf of Mexico and the Blake migration mature hydrocarbons. The na is pellet sinking rather than the rain- Ridge in the . These au- δ13C value of -25.7‰ approaches the fall from suspended particulate matter thors indicated that metazoan meiofauna isotopic range (-26 to -28 ‰) known generated within the . In density seems to be enhanced by the for oils in deep reservoirs of the Gulf this highly hydrodynamic energy sys- presence of microbial mats. Nonethe- of Mexico (Kennicutt et al., 1988) tem, surface particulate matter may be less, Shirayama and Otha (1990) and which are mainly produced by marine trapped above the and ad- later Levine et al. (2003) have acknowl- type II kerogen (Andrusevich et al., vected out of the region before reaching edged the lack of significant differences 2000). Possible variations in the make- the bottom, thus precluding benthic in density between seep and non-seep up of kerogen assemblage can alter the community complexity. Future research habitats in Sagami Bay, Japan, and at carbon isotopic relationship of oil-labile in this region must seriously consider the continental slope of northern Cali- components (Burwood et al., 1988). conducting direct observa- fornia, respectively. The two average Such variations may be caused by dia- tions to examine local fluid chemistry values of TOC recorded in surficial genesis that promotes the incorporation and seep community composition in sediments of Blocks I and II were simi- of humic carbon in the kerogen struc- one of the deepest seep sites near the lar to the values reported by Beazley ture. Humic carbon is normally more Gulf of Mexico. (2003) in the Sigsbee abyssal plain enriched in the 12C isotope, which (0.49 and 0.55% OC). In contrast, Block could account for the significant en- Acknowledgments III had low TOC values from a pre- richment in δ13C of -18.7‰ herein re- dominantly calcareous sedimentary en- corded, relative to the pelagic carbon The authors express vironment near the base of the Cuban source of -22.7‰. The specific site in their gratitude to the Cuban Authorities, northwestern insular slope. These aver- the northeastern corner of Block III at to the participating experts in the REP- ages are similar to those from the Nova the base of the NW Cuba’s slope from SOL campaign, and to the R/V “Justo Scotia (0.46 and 0.47%; which limestone rocks impregnated Sierra” crew for their invaluable assis- Thistle et al., 1985) at 4600m depth, with hydrocarbons were recovered, tance, R. Pereira (CESIGMA), J. Romo where polychaetes were the most abun- conforms to the conventional type of (UNAM) and I. Fernández (CICESE) dant macrofaunal group and nematodes cold seeps in which fluids escape from for their operative and logistic support. the most abundant meiofaunal group. hydrocarbon reservoirs through perme- C. Illescas, S. Hernández, C. Loyola Although TOC concentrations are simi- able fractures and faults (Mazzini et and C. Ilhicatzi were responsible for the lar to those from Nova Scotia rise, al.,2003). edition and illustrations of the text.

NOV 2012, VOL. 37 Nº 11 817 This study was sponsored by REPSOL- gas vent and hydrate site of the Gulf of Magnier C, Moretti I, López JO, Gaumet F, YPF-Cuba through a contract granted Mexico. Mar. Petrol. Geol. 26: 1190-1198. López JG, Letouzey J (2004) Geochemical to CESIGMA (Cuba). Fry B, Sherr EB (1984) δ13C measurements as characterization of source rocks, crude oils indicators of carbon flow in marine and and of Northwest Cuba. Mar. Petrol. freshwater . Contrib. Mar. Sci. Geol. 21: 195-214. References 27: 13-47. Malloy RJ, Hurley RJ (1970) Geomorphology Gallegos A, Victoria I, Zavala J, Fernández M, and geological structure: Straits of Florida. Andrusevich VE, Engel MH, Zumberge JE Penié I (1998) Hidrología de los estrechos Geol. Soc. Am. Bull. 81: 1947-1972. (2000) Effects of paleolatitude on the sta- del Mar Caribe Noroccidental. Rev. Invest. Mazzini A, Jonk R, Duranti D, Parnell J, Cro- ble carbon isotope composition of crude Mar. 19: 1-35. nin B, Hurst A (2003) Fluid escape from oils. Geology 28: 847-850. Gaudette HE, Flight WR, Toner L, Folger DW reservoirs: implications from cold seeps, Beazley MJ (2003) The Significance of Organic (1974) An inexpensive titration method for fractures and injected sands Part I. The flu- Carbon and Sediment Surface Area to the the determination of organic carbon in re- id flow system. J. Geochem .Explor. 78-79: Benthic Biochemistry of the Slope and Deep cent sediments. J. Sedim. Res. Petrol. 44: 293-296. Water Environments of the Northern Gulf of 249-253. Mullins HT, Gardulski AF, Hinchey EJ, Hine Mexico. Thesis. Texas A&M University. AC (1988) The modern carbonate ramp College Station, TX, USA. 94 pp. Gaumet F, Letouzey J (2002) Northwestern Cu- ba’s deep-water potential. Offshore Mag. slope of central West Florida. J. Sedim. Bett B, Vanreusel A, Vincx M, Soltwedel T, 62(9): 5. Res. 58: 273-290. Pfannkuche O, Lambshead PJD, Gooday AJ, Ferrero T, Dinet A (1994) Sampler bias in Goddard EN, Trask PD, De Ford RK, Rove ON, Munk W, Snograss F, Wimbush M (1970) the quantitative study of deep-sea meioben- Singewald JT, Overbeck RM (1948) Rock- off-shore: transition from California coastal thos. Mar. Ecol. Prog. Ser. 104: 197-203. Color Chart. Geological Society of Ameri- to deep-sea waters. Geophys. Fluid Dyn. 1: ca. Boulder, CO, USA. 116 pp. 161-235. Burwood R, Drozd RJ, Halpern HI, Sedivy RA (1988) Carbon isotopic variations of Hansen DV, Molinari RL (1979) Deep currents Ochoa J, Sheinbaum J, Badan A, Candela J, kerogen pyrolyzates. Org. Geochem. 12: in the Yucatan Straits. J. Geophys. Res. 84: WSilson D (2001) Geostrophy via potential 195-205. 359-362. vorticity inversion in the Yucatan Channel. J. Mar. Res. 59: 725-747. Canet C, Prol-Ledesma RM, Escobar-Briones Herbin JP, Deroo G, Roucaché J (1984) Organic E, Mortera-Gutiérrez C, Cienfuegos E, geochemistry of lower cretaceous sediments Oey LY, Ezer T, Lee HC (2005) Loop current, Morales-Puente P (2006) Mineralogical from Site 535, Leg 77, Florida Straits No. rings and related circulation in the Gulf of geochemical characterization of hydrocar- 13 (Vol. LXXVII) In Initial Reports of the Mexico: A review of numerical models and bon seep sediments from the Gulf of Mex- Deep Sea Drilling Project. pp. 459-475. future challenges. In Sturges W, Lugo- ico. Mar. Petrol. Geol. 23: 605-619. Fernández A (Eds.) Circulation in the Gulf Hurley RJ (1964) Bathymetry of the Straits of of Mexico: Observations and Models. Cesigma (2002) Estudio de Línea Base Ambi- Florida and the Bahamas Islands, part 3. Monograph Nº 161. American Geographical ental en Dos Áreas Marinas de la Zona de Southern Straits of Florida. Bull. Mar. Sci. Union. Washington, DC, USA. pp. 31-56. Exploración Petrolera que se Encuentran Gulf Carib. Fish Inst. 14: 373-380. Limitadas por las Coordenadas Escritas Okolodkov YB (2003) A review of russian Kabanova Y, López-Baluja L (1973) Producción plankton research in the Gulf of Mexico en el Anexo 1. Reporte Técnico. Cesigma, primaria en la región meridional del Golfo S.A. La Habana, Cuba. 239 pp. and the Caribbean Sea in the 1960-1980’s. de México y cerca de la costa noroccidental Hidrobiólogica 13: 207-221. Chambers AF, Lukito P, Solla Hach C, Torres- de Cuba. Ser. Oceanol. 16: 46-68. cusa Villaverde C, Molina R, Bachmann Paull CK, Hecker B, Commeau R, Freeman- Kennicutt II MC, Brooks JM, Bidigare RR, Fay Lynde RP, Neumann C, Corso WP, Golubic H (2003) Structural controls on the hydro- RA, Wade TL, McDonald TJ (1985) Vent carbons prospectivity of Blocks 25- S, Hook JE, Sikes E, Curray J (1984) Bio- type taxa in a hydrocarbon seep region on logical communities at the Florida Escarp- 29&36, offshore northern Cuba. AAPG the Louisiana slope. Nature 317: 351-353. International Conference. Barcelona, ment resemble taxa. Sci- Kennicutt II MC, Brooks JM, Bidigare RR, ence 226: 965-967. Spain. (Abstract) Denoux GJ (1988) Gulf of Mexico hydro- Paull CK, Jull AJT, Toolin LJ, Linick T (1985) Coogan AH (1970) Bahamian and Floridian carbon seep communities-I. Regional dis- Stable isotope evidence for biofacies. In Gray-Multer H (Ed.) Field tribution of hydrocarbon seepage and asso- in an abyssal seep community. Nature 317: Guide To Some Carbonate Rock Environ- ciated fauna. Deep-Sea Res. 35:1639-1651. 709-711. ments. Florida Keys and Western Baha- Kulm LD, Suess E, Moore JC, Carson B et Pequegnat WE, Pequegnat LH, Kleypas JA, mas. Fairleigh Dickinson University. Mad- al. (1986) Oregon zone: vent- James BM, Kennedy EA, Hubbard GF ison, NJ, USA. pp 141-153. ing fauna and carbonates. Science 231: (1983) The Ecological Communities of the Cordes EE, Carney SL, Hourdez S (2007) Cold 561-566. Continental Slope and Adjacent Regimes of seeps of the Gulf of Mexico: Community Lance P, Henry P, Le Pichon X (1998) Submers- structure and biogeographic comparisons to the Northern Gulf of Mexico. Minerals ible study of mud volcanoes seaward of the Management Service. Gulf of Mexico OCS Atlantic equatorial belt seep communities. Barbados accretionary wedge: sedimentolo- Deep-Sea Res. I 54: 637-653. Regional Office. US Department of the In- gy, structure and rheology. Mar. Geol. 145: terior. Metairie, LA, USA. 398 pp. Coull BC, Ellison RL, Fleeger JW, Higgins 255-292. RP, Hope WD, Hummon WD, Rieger RM, Piñón JR (2006) Cuba’s energy crisis: Part III León R, Somoza L, Medialdea T, González FJ, Cuba Focus. Issue 72. Sterrer WE, Thiel H, Tietjen JH (1977) Díaz-del-Río V, Fernández-Puga C, Maestro Quantitative estimates of the meiofauna A, Mata MO (2007) Sea-floor features re- Rachor E (1975) Quantitative untersuchangen über from deep-sea off North Carolina. Mar. lated to hydrocarbon seeps in deepwater meiobenthos der nordosatlantschen Tiefsee. Biol. 39: 233-240. carbonate-mud mounds of the Gulf of Meteor. Forschungs. Ser. 21: 317-329. Denny W, Austin JA, Buffler RT (1994) Seis- Cádiz: from mud flows to carbonate precip- Rasheed M, Al-Rousan S, Manasrah R, Al-Ho- mic startigraphy and geologic history of itates. Geo-Mar. Lett. 27: 237-247. rani F (2006) Nutrient fluxes from deep se- the middle cretaceous through Cenozoic Levin LA, Ziebis W, Mendoza GF, Growney diments support nutrient budget in the oli- rocks, southern Straits of Florida. AAPG VA, Mahn C, Gieskes JM, Tryon MD, gotrophic waters of the Gulf of Aqaba. J. Bull 78: 461-487. Brown KM, Ratbhun AE (2003) Spatial Oceanogr. 62: 83-89. Echeverría-Rodríguez G, Hernández-Pérez G, heterogeneity of macrofauna at northern Robinson CA, Bernhard JM, Levin LA, Mendo- López-Quintero J, López-Rivera J, Rodrí- California methane seeps: the influence of za GF, Blanks JK (2004) Surficial hydro- guez-Hernández R, Sánchez-Arango J, So- sulfide concentration and fluid flow. Mar. carbon seep infauna from the Blake Ridge corro-Trujillo R, Tenreyro-Pérez R, Ypar- Ecol. Prog. Ser. 265: 123-139. (Atlantic Ocean 2150 m) and the Gulf of raguire-Pena (1991) Oil and gas explora- Macko SA, Entzeroth L, Parker PL (1984) Re- Mexico (690-2240). Mar. Ecol. 25: 313-336. tion in Cuba. J. Petrol. Geol. 14: 259-274. gional differences in the nitrogen and car- Rodríguez-Medina MA (1989) Estudio in situ Feng D, Chen D, Roberts HH (2009) Petro- bon isotopes on the continental shelf of the de la Degradación de la Halofita Salicornia graphic and geochemical characterization Gulf of Mexico. Naturwissenschaften 71: Subterminalis y su Relación con los Me- of seep carbonate from Bush Hill (GC 185) 374-375. canismos de Movilización de Nutrimentos a

818 NOV 2012, VOL. 37 Nº 11 Través de la Interfase Sedimento Agua en Sheinbaum J, Candela J, Badan A, Ochoa J Soto LA, Manickhand-Heileman S, Flores E, el Sistema Lagunar Huizache y Caimanero, (2002) Flow structure and transport in the Licea S (1998) Processes that promote de- Sin. México. Tesis. Universidad Nacional Yucatan Channel. Geophys. Res. Lett. 29: capod diversity and abundance on the upper Autónoma de México. 86 pp. 1029/2001 GL013990 continental slope of the southwestern Gulf Rowe GT, Menzies RJ (1968) Deep bottom cur- Shirayama Y, Otha S (1990) Meiofauna in a of Mexico. Issues (2) 4th Int. rents off the coast of North Carolina. cold seep community off Hatsushima, Crustacean Congr. Amsterdam, Nether- Deep-Sea Res 15: 711-729. Central Japan. J. Oceanogr. Soc. Jap. 46: lands. pp 385-400. Ruttenberg KC, Goñi MA (1997) Depth trends 118-124. Suess E (1980) Particulate organic carbon flux in phosphorus distribution and C:N:P ratios Sibuet M, Olu K (1998) , biodiver- of organic matter in Amazon fan sedi- sity and fluid dependence of deep-sea cold- in the ocean-surface productivity and oxy- ments: indices of organic matter source and seep communities at active and passive gen utilization. Nature 288: 260-262. burial history. In Flood RD, Klaus DJW, margins. Deep-Sea Res II 45: 517-567. Thistle D, Yingst, JY, Fauchald, K (1985) A Petersen LC (Eds.) Proc. of Ocean Drilling Sibuet M, Olu-LeRoy K (2003) Cold seep com- deep-sea benthic community exposed to Program, Scientific Results 155: 505-518. munities on costal margins. Structure and strong near-bottom currents on the Scotian Schmidt M, Botz R, Winn K, Stoffers P, Thies- quantitative distribution relative to geologi- Rise (Western Atlantic). Mar. Geol. 66: sen O, Herzig P (2002) Seeping hydrocar- cal fluid venting patterns. In Wefer G, Bil- 91-112. bons and related carbonate mineralisations let D, Hebbeln D, Jorgensen BB, Schlüter in sediments south of Lihir Island (New M, Van Weering TCE (Eds.) Ocean Margin Wilson RD, Monaghan PH, Osanik A, Price Ireland fore arc basin, Papua New Guinea). Systems. Springer. Berlin, Getrmany. pp LC, Rogers MA (1974) Natural marine oil Chem. Geol. 186: 249-264. 235-254. seepage. Science 184: 857-865.

ESTUDIO DEL SEDIMENTO SUPERFICIAL DEL LECHO MARINO FRENTE A LA COSTA NOROCCIDENTAL DE CUBA, EN EL ESTRECHO DE LA FLORIDA Luis A. Soto, Diego López-Veneroni, Cecilia López-Canovas, Ricardo Ruiz-Vázquez y Guadalupe de la Lanza Espino

RESUMEN

El lecho marino frente a la costa noroccidental de Cuba fue Su superficie externa estaba cubierta por una capa ennegre- explorado con el propósito de estudiar las características biogeo- cida de brea y manchas irregulares de oxihidróxido de hierro. 13 0 químicas de los sedimentos superficiales en tres Bloques asigna- El análisis isotópico de sedimentos totales (δ C -25,7 a -18,5 /00) dos a REPSOL-YPF-Cuba, S.A., entre los 1600 y 2000m de pro- reveló una fuente de carbono no-metanogénica, procedente de fundidad. Se analizaron isótopos estables y el contenido de car- un sitio de filtración de petróleo puntual. Se estableció que la bono y nitrógeno total, así como los componentes infaunales en fuente principal de carbono orgánico sedimentario es de origen 13 0 15 sedimentos superficiales. Los sedimentos de los tres bloques es- oceánico (δ C: -18,50 a -19,13 /00; δ N: +3,6 a +6,4‰; propor- tudiados son moderadamente laminados y exhiben una cierta het- ción molar de C:N de 2,4 a 5). Los parámetros fisicoquímicos de -1 erogeneidad espacial. Estos son de tipo limo-arcilloso con pre- las aguas profundas fueron estables (5ml·l O2, 3-4°C, 35,0ups) dominancia de calcita, empobrecidos en materia orgánica, pero y la densidad de la infauna fue baja debido al aporte limitado con depósitos hemipelágicos significativos. En el extremo noreste de materiales orgánicos a los sedimentos profundos. Este estudio del área estudiada (Bloque III, 1640m) se recuperó un fragmento documenta uno de los sitios de filtración de petróleo de mayor grande de roca caliza impregnada de hidrocarburo. La superficie profundidad en el este del Golfo de México. del fragmento era áspera y presentaba un fuerte olor a petróleo.

ESTUDO DO SEDIMENTO SUPERFICIAL DO LEITO MARINHO EM FRENTE DA COSTA NOROESTE DE CUBA, NO ESTREITO DA FLORIDA Luis A. Soto, Diego López-Veneroni, Cecilia López-Canovas, Ricardo Ruiz-Vázquez e Guadalupe de la Lanza Espino

RESUMO

O leito marinho em frente à costa noroeste de Cuba foi ex- de petróleo. Sua superfície externa estava coberta por uma ca- plorado com o propósito de estudar as características biogeo- mada escura de alcatrão e manchas irregulares de oxi-hidróxi- químicas dos sedimentos superficiais em três Blocos designados do de ferro. A análise isotópica de sedimentos totais (δ13C -25,7 0 a REPSOL-YPF-Cuba, S.A., entre os 1600 e 2000m de profun- a -18,5 /00) revelou uma fonte de carbono não metanogênica, didade. Analisaram-se isótopos estáveis e o conteúdo de carbo- procedente de um local pontual de filtração de petróleo. Esta- no e nitrogênio total, assim como os componentes infaunais em beleceu-se que a fonte principal de carbono orgânico sedimen- 13 0 15 sedimentos superficiais. Os sedimentos dos três blocos estuda- tário é de origem oceânica (δ C: -18,50 a -19,13 /00; δ N: +3,6 dos são moderadamente laminados e exibem certa heterogenei- a +6,4‰; proporção molar de C:N de 2,4 a 5). Os parâmet- dade espacial. Estes são de tipo limo-argiloso com predominân- ros físico-químicos das águas profundas foram estáveis (5ml·l-1 cia de calcita, empobrecidos em matéria orgânica, mas com O2, 3-4°C, 35,0ups) e a densidade da infauna foi baixa devido depósitos hemipelágicos significativos. No extremo noreste da ao aporte limitado de materiais orgânicos aos sedimentos pro- área estudada (Bloco III, 1640m) se recuperou um fragmento fundos. Este estudo documenta um dos locais de filtração de grande de rocha caliça impregnada de hidrocarboneto. A su- petróleo de maior profundidade no leste do Golfo do México. perfície do fragmento era áspera e apresentava um forte cheiro

NOV 2012, VOL. 37 Nº 11 819