The integrated micropaleontological and palynological analyses of 17 wells from offshore Labrador... more The integrated micropaleontological and palynological analyses of 17 wells from offshore Labrador and southern Baffin Island allowed consistent assignments of biozones, ages, and depositional environments to the sections. Resolution attained is approximately at the stage level or finer. Interpretation of the foraminifera and palynomorphs from the Labrador Shelf indicates that the depositional environments were mainly neritic during the Early and
Palynological analyses of several subsurface sections in the autochthonous block in Northern Mona... more Palynological analyses of several subsurface sections in the autochthonous block in Northern Monagas, eastern Venezuela, show a Cretaceous-Oligocene unconformity. The Maastrichtian to Paleocene sandstones of the San Juan Formation unconformably underlie the Oligocene to Miocene sandstones of the Merecure Formation. Log analyses indicate two stratigraphic sequences within San Juan and two more within Merecure, and integration with paleontological data indicates changes which can be correlated with Haq et al.'s (1988) Sequence Chronostratigraphic Charts as follows: (1) The basal San Juan sandstones represent the late Maastrichtian (68 Ma) drop of seal level and the UZA-4.5/TA-1.1 Sequence Boundary (SB). The Maastrichtian or Maastrichtian to Paleocene San Juan sandstones represent either the TA-1.1 and the TA-1.2 Third-Order Cycles. (2) The late Oligocene sequence overlying the unconformity, represents the TB-1.3 Cycle starting at 26.5 Ma. Within this lower part of the Merecure sediments, an increase in the abundance and diversity of marine palynomorphs represents a maximum transgression correlatable with the 26 Ma Condensed Section contained in the Tb-1.3 Cycle. (3) The upper part of Merecure represents the Tb-1.4 Cycle starting at 25.5 Ma. Within this cycle, the lowermost (Oligocene) sandstones contain almost exclusively terrestrial palynomorphs, while the (Miocene) alternating sands and shales of themore » upper part contain diverse marine palynomorphs indicating a change from Low Stand Wedge to Transgressive deposits. This change is correlated with the Oligocene/Miocene limit at 25.2 Ma.« less
We present the results of the quantitative and qualitative study of dinoflagellate cysts in outcr... more We present the results of the quantitative and qualitative study of dinoflagellate cysts in outcrop samples from a section of the Snow Hill Island Formation (SHF) in James Ross Island, Antarctic. Dinoflagellate cysts assemblages are abundant and dominated by gonyaulacoid taxa. The last occurrence of the dinoflagellate cyst Kallosphaeridium? helbyi and Chatangiella granulifera, together with the first occurrence of Pterodinium cretaceum, indicates a probable late Campanian age (~76.4e~72.1 Ma) for the lower strata. Whereas the first occurrence of Manumiella bertodano and the last occurrence of Odontochitina operculata, Xenascus ceratioides, and Stiphrosphaeridium anthophorum indicate an early Maastrichtian (~72.1 e~70.0 Ma) age for the upper strata. Our results, combined with paleobotanical and palynological published data, indicate mediumehigh continental and marine productivity with temperate paleoclimate free of glaciers for this interval. Lithological and paleontological data indicate mainly inner neritic marine depositional environments. The predominance of shales in the lower part of the lower Maastrichtian interval indicates a slightly deeper environment. In contrast, in the middle part of the lower Maastrichtian, a shallower, transitional environment is marked by the presence of theropod dinosaurs and decapod crustaceans.
Journal of the Marine Biological Association of the United Kingdom, 2021
Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst a... more Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst abundance in sediments represents crucial information to understand and possibly predict Harmful Algae Blooms (HABs). Cyst distribution is related to the physical characteristics of the sediments and the hydrodynamics (circulation) of a particular region. In the northern Gulf of California (nGC) several Gymnodinium catenatum HABs have been recorded. However, the presence of resting cysts and the effect of hydrodynamics on their distribution in the nGC have not been investigated. This study evaluated cyst abundance, distribution and their relation to local circulation in surface sediments during two periods that coincided with a non-bloom year condition (July 2016) and after a major HAB registered in the nGC that occurred in January 2017. Also, a numerical ocean model was implemented to characterize the transport and relocation of cysts and sediments in the region. Gymnodinium catenatum cy...
Here we present the raw data used in our study. In the first tab is the gross number of counts of... more Here we present the raw data used in our study. In the first tab is the gross number of counts of palinofacies. In the second flap is the gross number of dinofagellates cysts. In the third, the results of TOC and NT showed with the average age obtained.
Geochemical and palynological analyses of laminated sediments of samples corresponding to a core ... more Geochemical and palynological analyses of laminated sediments of samples corresponding to a core extracted at 745 m depth from La Paz Basin, allow recognition of centennial variations on rainfall and marine productivity from ~4487 to ~260 years BP. Concentrations of the paleoclimate proxies Ti and Fe (terrigenous input) and Mo (anoxia) were obtained by X-ray fluorescence analyses and total organic carbon concentrations (TOC, primary productivity) with a CO2 coulometer. Concentrations of marine (dinoflagellates) and continental palynomorphs (pollen and spores) indicate changes in marine productivity (PP) and rainfall (RF), with chemical results having significant statistical correlations and good graphic similarity with palynological data obtained from some of the same samples. Concentrations of TOC have a high statistical correlation with heterotrophic dinoflagellates and copepods, but only medium with continental palynomorphs, indicating the predominance of marine PP with an increa...
Abstract Changes in dinoflagellate assemblages indicate regional paleoceanographic events affecti... more Abstract Changes in dinoflagellate assemblages indicate regional paleoceanographic events affecting western Colombia. Integration of palynomorph, planktonic foraminifera, and calcareous nannoplankton data from a 616 m thick outcrop section in the Ladrilleros-Juan Chaco region allows the construction of a detailed and reliable chronological framework and identification of marine high-productivity intervals. Results indicate marine deposition from middle (~15 Ma) to late (~10 Ma) Miocene. Dinoflagellate cyst assemblages are consistent with known regional assemblages and include more warm water taxa than cold ones. Correlation of the palynomorphs with the other microfossils studied allows calibration of the biostratigraphic ranges of seven species of dinoflagellate cysts commonly reported from tropical zones. The ratio between autotrophic and heterotrophic dinoflagellate cysts indicates an overall increase of paleoproductivity at ~13.8 Ma. Gonyaulacoid taxa dominate the lower interval (15–13.8 Ma), while peridinioid taxa dominate the upper segment (~13.8–10.5 Ma). This change coincides with the global cooling related to the growth of the Antarctic ice sheet (~14 Ma) and presumably increased the recurrence of events like La Nina in the equatorial Pacific. These conditions increased the primary productivity in the Pacific coastal region of northwestern Colombia, and four high-productivity intervals are tentatively correlated to the Mi3a, Mi-3b, Mi-4, and Mi-5 isotope events.
Palynological data from offshore Costa Rica, allow us to investigate the relationship between din... more Palynological data from offshore Costa Rica, allow us to investigate the relationship between dinoflagellate cyst assemblages and changes in regional oceanic primary productivity. From Miocene to Pleistocene, productivity at ODP Site 1039 was influenced by tectonic drift, as Site 1039 approached the continent, from the Equator to its current position at ~10°N. In addition, dinoflagellate abundance is modulated by regional productivity events, which modified primary productivity, as also indicated by available data on calcareous nannofossils, diatoms, TOC, and CaCO3 content.Five palynomorph intervals are defined. The early-late Miocene one, dominated by Batiacasphaera, represents relatively stable, productive oceanic conditions before the closure of the Indonesian and Panama Seaways. The late Miocene decrease in palynomorph recovery is related to the Carbonate Crash Event. The high abundance and diversity of the assemblages at the end of the late Miocene to early Pliocene indicate in...
Before middle Miocene times, Baja California was attached to the rest of the North American conti... more Before middle Miocene times, Baja California was attached to the rest of the North American continent. Consequently, most of the terrestrial fauna and flora of the peninsula had its origins in mainland Mexico. However, the separation of the peninsula and its northwestward displacement resulted in a variety of distribution patterns, isolations, extinctions, origins and ultimate evolution of fauna and flora in several ways. The islands in the Gulf of California have been colonized by species from Baja California and mainland Mexico. Some workers (Soulé and Sloan 1966; Wilcox 1978) consider that many of these islands originated as landbridges. Geographically, most of the islands are closer to the peninsula than to the mainland. Therefore, it has been assumed that the Baja California Peninsula was the origin of most of the organisms inhabiting them (Murphy 1983). Islands separated by depths of 110 m or less from the peninsula or mainland Mexico apparently owe their current insular exist...
Biennial variations of marine palynomorph concentrations mirrored oceanographic conditions in the... more Biennial variations of marine palynomorph concentrations mirrored oceanographic conditions in the Magdalena Basin, Baja California Sur (Mexico), in the period from 1811 to 1907 (common era, CE), for which the sea surface temperature index (SSTI) showed predominantly negative anomalies. We analyzed 49 samples of laminated sediments taken from a core extracted at a water depth of 520 m. Changes in dinoflagellate assemblages and copepod egg abundances were compared to SSTI records and to El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) reconstructions. Copepods were the most abundant and showed a significant correlation with SSTI. Among the dinoflagellates, heterotrophs were the most abundant and did not correlate with SSTI. The lowest concentration of autotrophs showed a significant and inverse correlation with SSTI. The canonical correlation analysis also indicated that copepods and autotrophs were modulated by variations in SSTI. Dinoflagellate richness and ...
The integrated micropaleontological and palynological analyses of 17 wells from offshore Labrador... more The integrated micropaleontological and palynological analyses of 17 wells from offshore Labrador and southern Baffin Island allowed consistent assignments of biozones, ages, and depositional environments to the sections. Resolution attained is approximately at the stage level or finer. Interpretation of the foraminifera and palynomorphs from the Labrador Shelf indicates that the depositional environments were mainly neritic during the Early and
Palynological analyses of several subsurface sections in the autochthonous block in Northern Mona... more Palynological analyses of several subsurface sections in the autochthonous block in Northern Monagas, eastern Venezuela, show a Cretaceous-Oligocene unconformity. The Maastrichtian to Paleocene sandstones of the San Juan Formation unconformably underlie the Oligocene to Miocene sandstones of the Merecure Formation. Log analyses indicate two stratigraphic sequences within San Juan and two more within Merecure, and integration with paleontological data indicates changes which can be correlated with Haq et al.'s (1988) Sequence Chronostratigraphic Charts as follows: (1) The basal San Juan sandstones represent the late Maastrichtian (68 Ma) drop of seal level and the UZA-4.5/TA-1.1 Sequence Boundary (SB). The Maastrichtian or Maastrichtian to Paleocene San Juan sandstones represent either the TA-1.1 and the TA-1.2 Third-Order Cycles. (2) The late Oligocene sequence overlying the unconformity, represents the TB-1.3 Cycle starting at 26.5 Ma. Within this lower part of the Merecure sediments, an increase in the abundance and diversity of marine palynomorphs represents a maximum transgression correlatable with the 26 Ma Condensed Section contained in the Tb-1.3 Cycle. (3) The upper part of Merecure represents the Tb-1.4 Cycle starting at 25.5 Ma. Within this cycle, the lowermost (Oligocene) sandstones contain almost exclusively terrestrial palynomorphs, while the (Miocene) alternating sands and shales of themore » upper part contain diverse marine palynomorphs indicating a change from Low Stand Wedge to Transgressive deposits. This change is correlated with the Oligocene/Miocene limit at 25.2 Ma.« less
We present the results of the quantitative and qualitative study of dinoflagellate cysts in outcr... more We present the results of the quantitative and qualitative study of dinoflagellate cysts in outcrop samples from a section of the Snow Hill Island Formation (SHF) in James Ross Island, Antarctic. Dinoflagellate cysts assemblages are abundant and dominated by gonyaulacoid taxa. The last occurrence of the dinoflagellate cyst Kallosphaeridium? helbyi and Chatangiella granulifera, together with the first occurrence of Pterodinium cretaceum, indicates a probable late Campanian age (~76.4e~72.1 Ma) for the lower strata. Whereas the first occurrence of Manumiella bertodano and the last occurrence of Odontochitina operculata, Xenascus ceratioides, and Stiphrosphaeridium anthophorum indicate an early Maastrichtian (~72.1 e~70.0 Ma) age for the upper strata. Our results, combined with paleobotanical and palynological published data, indicate mediumehigh continental and marine productivity with temperate paleoclimate free of glaciers for this interval. Lithological and paleontological data indicate mainly inner neritic marine depositional environments. The predominance of shales in the lower part of the lower Maastrichtian interval indicates a slightly deeper environment. In contrast, in the middle part of the lower Maastrichtian, a shallower, transitional environment is marked by the presence of theropod dinosaurs and decapod crustaceans.
Journal of the Marine Biological Association of the United Kingdom, 2021
Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst a... more Germination of cysts serves as inoculum for the proliferation of some dinoflagellates, and cyst abundance in sediments represents crucial information to understand and possibly predict Harmful Algae Blooms (HABs). Cyst distribution is related to the physical characteristics of the sediments and the hydrodynamics (circulation) of a particular region. In the northern Gulf of California (nGC) several Gymnodinium catenatum HABs have been recorded. However, the presence of resting cysts and the effect of hydrodynamics on their distribution in the nGC have not been investigated. This study evaluated cyst abundance, distribution and their relation to local circulation in surface sediments during two periods that coincided with a non-bloom year condition (July 2016) and after a major HAB registered in the nGC that occurred in January 2017. Also, a numerical ocean model was implemented to characterize the transport and relocation of cysts and sediments in the region. Gymnodinium catenatum cy...
Here we present the raw data used in our study. In the first tab is the gross number of counts of... more Here we present the raw data used in our study. In the first tab is the gross number of counts of palinofacies. In the second flap is the gross number of dinofagellates cysts. In the third, the results of TOC and NT showed with the average age obtained.
Geochemical and palynological analyses of laminated sediments of samples corresponding to a core ... more Geochemical and palynological analyses of laminated sediments of samples corresponding to a core extracted at 745 m depth from La Paz Basin, allow recognition of centennial variations on rainfall and marine productivity from ~4487 to ~260 years BP. Concentrations of the paleoclimate proxies Ti and Fe (terrigenous input) and Mo (anoxia) were obtained by X-ray fluorescence analyses and total organic carbon concentrations (TOC, primary productivity) with a CO2 coulometer. Concentrations of marine (dinoflagellates) and continental palynomorphs (pollen and spores) indicate changes in marine productivity (PP) and rainfall (RF), with chemical results having significant statistical correlations and good graphic similarity with palynological data obtained from some of the same samples. Concentrations of TOC have a high statistical correlation with heterotrophic dinoflagellates and copepods, but only medium with continental palynomorphs, indicating the predominance of marine PP with an increa...
Abstract Changes in dinoflagellate assemblages indicate regional paleoceanographic events affecti... more Abstract Changes in dinoflagellate assemblages indicate regional paleoceanographic events affecting western Colombia. Integration of palynomorph, planktonic foraminifera, and calcareous nannoplankton data from a 616 m thick outcrop section in the Ladrilleros-Juan Chaco region allows the construction of a detailed and reliable chronological framework and identification of marine high-productivity intervals. Results indicate marine deposition from middle (~15 Ma) to late (~10 Ma) Miocene. Dinoflagellate cyst assemblages are consistent with known regional assemblages and include more warm water taxa than cold ones. Correlation of the palynomorphs with the other microfossils studied allows calibration of the biostratigraphic ranges of seven species of dinoflagellate cysts commonly reported from tropical zones. The ratio between autotrophic and heterotrophic dinoflagellate cysts indicates an overall increase of paleoproductivity at ~13.8 Ma. Gonyaulacoid taxa dominate the lower interval (15–13.8 Ma), while peridinioid taxa dominate the upper segment (~13.8–10.5 Ma). This change coincides with the global cooling related to the growth of the Antarctic ice sheet (~14 Ma) and presumably increased the recurrence of events like La Nina in the equatorial Pacific. These conditions increased the primary productivity in the Pacific coastal region of northwestern Colombia, and four high-productivity intervals are tentatively correlated to the Mi3a, Mi-3b, Mi-4, and Mi-5 isotope events.
Palynological data from offshore Costa Rica, allow us to investigate the relationship between din... more Palynological data from offshore Costa Rica, allow us to investigate the relationship between dinoflagellate cyst assemblages and changes in regional oceanic primary productivity. From Miocene to Pleistocene, productivity at ODP Site 1039 was influenced by tectonic drift, as Site 1039 approached the continent, from the Equator to its current position at ~10°N. In addition, dinoflagellate abundance is modulated by regional productivity events, which modified primary productivity, as also indicated by available data on calcareous nannofossils, diatoms, TOC, and CaCO3 content.Five palynomorph intervals are defined. The early-late Miocene one, dominated by Batiacasphaera, represents relatively stable, productive oceanic conditions before the closure of the Indonesian and Panama Seaways. The late Miocene decrease in palynomorph recovery is related to the Carbonate Crash Event. The high abundance and diversity of the assemblages at the end of the late Miocene to early Pliocene indicate in...
Before middle Miocene times, Baja California was attached to the rest of the North American conti... more Before middle Miocene times, Baja California was attached to the rest of the North American continent. Consequently, most of the terrestrial fauna and flora of the peninsula had its origins in mainland Mexico. However, the separation of the peninsula and its northwestward displacement resulted in a variety of distribution patterns, isolations, extinctions, origins and ultimate evolution of fauna and flora in several ways. The islands in the Gulf of California have been colonized by species from Baja California and mainland Mexico. Some workers (Soulé and Sloan 1966; Wilcox 1978) consider that many of these islands originated as landbridges. Geographically, most of the islands are closer to the peninsula than to the mainland. Therefore, it has been assumed that the Baja California Peninsula was the origin of most of the organisms inhabiting them (Murphy 1983). Islands separated by depths of 110 m or less from the peninsula or mainland Mexico apparently owe their current insular exist...
Biennial variations of marine palynomorph concentrations mirrored oceanographic conditions in the... more Biennial variations of marine palynomorph concentrations mirrored oceanographic conditions in the Magdalena Basin, Baja California Sur (Mexico), in the period from 1811 to 1907 (common era, CE), for which the sea surface temperature index (SSTI) showed predominantly negative anomalies. We analyzed 49 samples of laminated sediments taken from a core extracted at a water depth of 520 m. Changes in dinoflagellate assemblages and copepod egg abundances were compared to SSTI records and to El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) reconstructions. Copepods were the most abundant and showed a significant correlation with SSTI. Among the dinoflagellates, heterotrophs were the most abundant and did not correlate with SSTI. The lowest concentration of autotrophs showed a significant and inverse correlation with SSTI. The canonical correlation analysis also indicated that copepods and autotrophs were modulated by variations in SSTI. Dinoflagellate richness and ...
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Papers by Javier Helenes