Non-marine Settings Research Articles

About this title ‐ Microbial Carbonates in Space and Time: Implications for Global Exploration and Production

Microbial carbonates (microbialites) are remarkable sedimentary deposits. They have the longest geological range of any type of biogenic limestones, form in the greatest range of different sedimentary environments, oxygenated the Earth's atmosphere and produce and, furthermore, store large volumes of hydrocarbons. This Special Publication provides significant contributions at a pivotal time in our understanding of microbial carbonates when their economic importance has become established and the results of many research programmes are coming to fruition. It is the first book to focus on the economic aspects of microbialites and in particular the giant pre-salt discoveries offshore Brazil. The volume contains papers on the processes involved in the formation of both ancient and modern microbialites and the diversity of style in microbial carbonate build-ups. Structures and fabrics from both marine and non-marine settings are discussed from throughout the geological record.

The role of climate and aeolian dust input in calcrete formation in volcanic islands (Lanzarote and Fuerteventura, Spain)

Calcretes are widely described in non-marine settings with carbonates in their catchment, or vicinity areas, but in volcanic islands without carbonates in their substrate, calcretes are not very common. In Lanzarote and Fuerteventura Canary Islands, characterized by impressive volcanic landscapes, the sedimentary carbonate rocks are rare except for some recent marine and aeolian deposits. In these settings very well-developed calcretes cover large areas of the present landscape. The source of calcium required for the formation of these calcretes has not been discussed in much detail till now, although its role is critical to an understanding of the climatic conditions in which calcium was transported and fixed and of the calcrete formation processes. The petrological and geochemical studies (87Sr/86Sr ratios, δ13C, δ18O, major, trace and REE) carried out in this paper do confirm the important role of aeolian dust input in the formation of these calcretes. Canarian calcretes were mainly generated by pedogenic processes and are composed of various irregular carbonate lamina interbedded with fine clastic deposits. Our study indicates that these interbeddings were the result of several stages in which, during dry periods, aeolian dust deposition alternated with leaching and calcite precipitation during wetter periods when plants, insects and bacteria played an important role in carbonate precipitation. The δ18O (−2.70 to +2.22‰ VPDB) and δ13C (−8.21 to +0.24‰ VPDB) values indicate that calcretes were formed by pedogenic processes. Comparison of calculated ∆18O values for the Canary calcretes with continental mid-latitude calcrete values reflects the more homogeneous temperature regimes of calcrete formation in island (oceanic) settings. Calcrete87Sr/86Sr ratios (0.706357 to 0.709208) show strong affinity with those obtained in aeolian carbonate dust and marine deposits, and are relatively different from those obtained in basalts. REE, major and trace element concentrations show that Ca-bearing minerals from volcanic host rock contributed little to calcrete formation and most of the calcium was supplied by aeolian deposits such as the aeolian dust coming from the Sahara and Sahel or sand dunes.

The role of Volcanic vs Seismic actions in ground deformations recorded in Oceanic Volcanic Islands: Examples from the Eastern Canary Islands (Spain)

Calcretes are widely described in non-marine settings with carbonates in their catchment, or vicinity areas, but in volcanic islands without carbonates in their substrate, calcretes are not very common. In Lanzarote and Fuerteventura Canary Islands, characterized by impressive volcanic landscapes, the sedimentary carbonate rocks are rare except for some recent marine and aeolian deposits. In these settings very well-developed calcretes cover large areas of the present landscape. The source of calcium required for the formation of these calcretes has not been discussed in much detail till now, although its role is critical to an understanding of the climatic conditions in which calcium was transported and fixed and of the calcrete formation processes. The petrological and geochemical studies (87Sr/86Sr ratios, δ13C, δ18O, major, trace and REE) carried out in this paper do confirm the important role of aeolian dust input in the formation of these calcretes. Canarian calcretes were mainly generated by pedogenic processes and are composed of various irregular carbonate lamina interbedded with fine clastic deposits. Our study indicates that these interbeddings were the result of several stages in which, during dry periods, aeolian dust deposition alternated with leaching and calcite precipitation during wetter periods when plants, insects and bacteria played an important role in carbonate precipitation. The δ18O (− 2.70 to + 2.22‰ VPDB) and δ13C (− 8.21 to + 0.24‰ VPDB) values indicate that calcretes were formed by pedogenic processes. Comparison of calculated ∆18O values for the Canary calcretes with continental mid-latitude calcrete values reflects the more homogeneous temperature regimes of calcrete formation in island (oceanic) settings. Calcrete87Sr/86Sr ratios (0.706357 to 0.709208) show strong affinity with those obtained in aeolian carbonate dust and marine deposits, and are relatively different from those obtained in basalts. REE, major and trace element concentrations show that Ca-bearing minerals from volcanic host rock contributed little to calcrete formation and most of the calcium was supplied by aeolian deposits such as the aeolian dust coming from the Sahara and Sahel or sand dunes.

Reassessment of the Early Cretaceous non-marine ostracod generaHourcqiaKrömmelbein, 1965 andPattersoncyprisBate, 1972 with the description of a new genus,Kroemmelbeincypris

The Early Cretaceous non-marine ostracod generaHourcqiaKrömmelbein andPattersoncyprisBate are reinstated. A previously published referral ofHourcqiatoCyprideaBosquet is rejected due to the absence of an anteroventral rostrum in the holotype of the type speciesHourcqia africanaKrömmelbein. The genusHourcqiais characterized by an “inverse” valve ratio (right valve larger than left) and the lack of an anteroventral rostrum, and the diagnosis of the genus is broadened to accommodate ornamented forms, resulting in the acceptance of five species:Hourcqia africana,H. confluens(Krömmelbein and Weber),H. kouilouensis(Grosdidier),H. bateke(Grosdidier) andH. sylvesterbradleyi(Bate). The previously published synonymy ofPattersoncypriswith the genusHarbiniaTsao is also rejected. The diagnosis ofPattersoncyprisis refined, meaning that three species are recognized:Pattersoncypris micropapillosaBate,P. salitrensis(Krömmelbein and Weber), andP. sinuata(Krömmelbein and Weber). The new genusKroemmelbeincyprisis erected for two species initially assigned toHourcqia, and subsequently toPattersoncyprisandHarbiniaby different authors:Kroemmelbeincypris symmetrica(Krömmelbein and Weber) andK. angulata(Krömmelbein and Weber). The genusHourcqiais diagnostic of latest Barremian non-marine settings, whilstPattersoncyprisandKroemmelbeincyprischaracterize Aptian saline lacustrine environments. The geographic ranges of all three genera are restricted to northeastern and eastern Brazil and northern and western Africa, though a species ofPattersoncypris(P. dakotaensisTibert and Colin) is also present in the United States.

Earth’s earliest non-marine eukaryotes

The existence of a terrestrial Precambrian (more than 542 Myr ago) biota has been largely inferred from indirect chemical and geological evidence associated with palaeosols, the weathering of clay minerals and microbially induced sedimentary structures in siliciclastic sediments. Direct evidence of fossils within rocks of non-marine origin in the Precambrian is exceedingly rare. The most widely cited example comprises a single report of morphologically simple mineralized tubes and spheres interpreted as cyanobacteria, obtained from 1,200-Myr-old palaeokarst in Arizona. Organic-walled microfossils were first described from the non-marine Torridonian (1.2-1.0 Gyr ago) sequence of northwest Scotland in 1907. Subsequent studies found few distinctive taxa-a century later, the Torridonian microflora is still being characterized as primarily nondescript "leiospheres". We have comprehensively sampled grey shales and phosphatic nodules throughout the Torridonian sequence. Here we report the recovery of large populations of diverse organic-walled microfossils extracted by acid maceration, complemented by studies using thin sections of phosphatic nodules that yield exceptionally detailed three-dimensional preservation. These assemblages contain multicellular structures, complex-walled cysts, asymmetric organic structures, and dorsiventral, compressed organic thalli, some approaching one millimetre in diameter. They offer direct evidence of eukaryotes living in freshwater aquatic and subaerially exposed habitats during the Proterozoic era. The apparent dominance of eukaryotes in non-marine settings by 1 Gyr ago indicates that eukaryotic evolution on land may have commenced far earlier than previously thought.

Spongeliomorpha in nonmarine settings: an ichnotaxonomic approach

ABSTRACTThe authors revise the occurrences of burrow networks with striated walls having dominantly transverse to oblique striae, which have been assigned to the ichnogeneraSpongeliomorphaSaporta, 1887, andSteinichnusBromley & Asgaard, 1979. The taxonomic status of the ichnogenusSteinichnusBromley & Asgaard, 1979 is examined and it is suggested that this ichnogenus is a subjective junior synonym ofSpongeliomorphaSaporta, 1887.Spongeliomorphais best reserved for an unlined network of burrows having distinct surface ridges or grooves of different orientation and massive filling. The diagnosis ofSpongeliomorphais emended accordingly and the proposed ichnospecies revised for consistency with the diagnostic features of the ichnogenus.Spongeliomorpha milfordensisMetz, 1993a is considered a subjective junior synonym ofSpongeliomorpha carlsbergi(Bromley & Asgaard, 1979) after a visual comparison and statistical analysis of the angle of striation with respect to the burrow midline in the type material. Nevertheless, the use of statistical techniques is not advocated for distinction of ichnotaxa, but may support observations.Spongeliomorpha carlsbergiis considered as an indicator of nonmarine settings and was probably produced by burrowing insects. Proposed ichnospecies ofSpongeliomorphathat fit the emended diagnosis includeS. sudolica(Zaręczny, 1878);S. ibericaSaporta, 1887;S. siculaD’Alessandro & Bromley, 1995;S. chevronensisMuñiz & Mayoral, 2001; andSpongeliomorphaisp. nov. aff.siculaLewy & Goldring, 2006.

Vegetation and climate of the New Zealand Jurassic

New Zealand's Jurassic plant fossils are known from non-marine settings in two terranes: the Murihiku forearc basin and from a small area on the Rakaia Terrane, an accretionary prism. These terranes lay in relatively high latitudes along the Gondwana margin but their precise location, latitude and position with respect to each other is unclear. The flora was dominated by conifers, ferns, bennettitaleans, pentoxylaleans and locally equisetaleans, but it is relatively depauperate, perhaps reflecting a high latitude position. Most climate indicators suggest a warm temperate climate with rainfall that was not especially high and that might have been seasonal at times. Revision of the New Zealand Jurassic flora is overdue, and while new genera may be discovered, species numbers may well decrease.

AN EARLY CRETACEOUS (HAUTERIVIAN) SPORE-POLLEN ASSEMBLAGE FROM SOUTHERN CHILE

Abstract A single sample from the Springhill Group of well 2 at La Posesion in the Manantiales oilfield, southern Chile at 1752 m yielded a rich spore-pollen assemblage. The sample is from the base of approximately 32 m of medium- to coarse-grained sandstone with streaks of brown-gray clay and occasional carbonaceous streaks. Forty-nine species of pollen and spores in 36 genera are documented. On the basis of the occurrences of Aequitriradites plicatus, Appendicisporites jansonii, Contignisporites multimuratus, Cyclusphaera sp. A, Muricingulisporis annulatus, and Ornamentifera echinata, the age of the sample is considered to be Early Cretaceous (Hauterivian). The absence of marine palynomorphs indicates that the horizon sampled was deposited in a non-marine setting, close to araucarian and fern vegetation. The spore genus Sphagnites Cookson 1953 is emended, and the species Sphagnum antiquasporites Wilson & Webster 1946 is transferred to Sphagnites.

Augerinoichnus Helicoidalis, a new helical trace fossil from the nonmarine Permian of New Mexico

New Mexico contains a significant record of trace fossil assemblages, in terms of both abundance and ichnodiversity, from Lower Permian nonmarine depositional settings. Most notable amongst these are the trace fossil assemblages in the Robledo Mountains Formation of the Robledo Mountains in Doña Ana County, southern New Mexico, as recognized by the recent proposal to designate this area as a national monument. These trace fossil assemblages formed on a tidal flat under largely non-marine conditions (Mack and James, 1986; Hunt et al., 1993; Lucas et al., 1995a, 1998) and are dominated by the trackways of tetrapods and arthropods, yielding important information on the paleoecology, diversity and behavior of late Paleozoic arthropods (Braddy and Briggs, 2002; Minter and Braddy, 2006a), as well as evidence of specialized foraging strategies (Minter et al., 2006). Additional Lower Permian trace fossil assemblages occur at a number of localities in New Mexico and represent a variety of nonmarine depositional settings.

Application of Ostracoda and Charophyta from the Late Jurassic to Early Cretaceous Tendaguru formation at Tendaguru, Tanzania (East Africa) — Biostratigraphy, palaeobiogeography and palaeoecology

Revisitation of the famous Late Jurassic/Early Cretaceous dinosaur locality of Tendaguru by a German–Tanzanian expedition in summer 2000 resulted in a new standard section. Micropalaeontologic samples from this section yielded a marine and nonmarine, partially mixed ostracod fauna consisting of 40 taxa and some charophyte gyrogonites and utriculi. A few marine taxa provided biostratigraphic information, although comparable faunas from the West Indian–Madagascan–East African faunal province are stratigraphically older (Middle/Late Jurassic), fully marine and strongly endemic. An (Middle) Oxfordian age is suggested for the lower part of the Tendaguru formation. Nodosoclavatoroid utriculi (Charophyta) suggest that the Jurassic/Cretaceous boundary may be located lower in the section than supposed previously, i.e. in the Trigonia smeei member rather than in the Upper Saurian member. In biogeographical terms, the marine ostracod fauna is relatively endemic and has most similarities with that known from eastern Tanzania. Only a few faunal links to Madagascar, Northwest India and Somalia exist, and there are no links to South Africa. Ostracods and charophytes also provided palaeoecological data for specific horizons. In the lower part of the Middle Saurian member a regression is documented. While the nonmarine Late Jurassic/Early Cretaceous ostracods of Tendaguru are not applicable to biostratigraphy so far, they are important because the nonmarine setting is unique in this area of the Tethys.

Climate Change Across Continental Sequence Boundaries: Paleopedology and Lithofacies of Iglesia Basin, Northwestern Argentina

Subdivision of sedimentary rocks into genetically related sequences reflects the interaction between the extrinsic and intrinsic processes that affect a basin's accommodation potential as well as its environment. In nonmarine settings, sequence-bounding surfaces are often difficult to locate, and several causal mechanisms for sequences (e.g. tectonism, climate change, and autogenic variability) combine in complex and still poorly understood ways. Here we draw upon paleosols as sources of evidence for causes of sequence boundaries in the upper Miocene–lower Pliocene continental Iglesia wedgetop basin, San Juan Province, Argentina. Stable-isotope compositions (δ13C and δ18O), clay mineralogy, inorganic carbon weight percentages, and micromorphologic features of paleosols that span 9.0–4.6 Ma reveal environmental conditions concurrent with the development of ten continental stratigraphic sequences. Charaetcristics of compound pedofacies and regionally recognizable, abrupt vertical lithofacies changes suggest fluctuations in both accumulation rate and climate across sequence boundaries and between structural subbasins. We interpret that the Iglesia Basin strata accumulated under conditions that were generally semiarid with seasonal precipitation. Isotopic ratios and soil inorganic carbon weight percentages indicate increased aridity at 6.9 and 5.2 Ma, each a time of sedimentary hiatus. Notable enrichment of the δ13C signal at 6.9 Ma also suggests the onset of dominance of C4 plant biomass in northwestern Argentina. In combination with seismic data, we interpret that four of the ten sequence boundaries formed during intervals of marginal surface uplift concurrent with greater aridity, circumstances that led to erosion of proximal strata and starved the central basin of sediment input, resulting in hiatuses in sediment accumulation.

Plio-Pleistocene lacustrine evaporites of the Baza Basin (Betic Chain, SE Spain)

The Baza Basin (the eastern part of the Guadix–Baza Basin, in SE Spain) underwent a significant evaporitic sedimentation in non-marine settings during the Plio-Pleistocene. The largest of these settings developed in the central part of the basin as a shallow, saline lake system, where abundant gypsum deposits occur (Benamaurel and Galera Gypsum units). This paper studies these deposits from the cartographic, stratigraphic, sedimentologic, petrographic and isotopic points of view. All the gypsum has been preserved as primary enabling a good characterization of the environmental conditions of the original precipitates. Three interconnected subenvironments or zones –inner, intermediate and marginal– are differentiated in this saline lake system. In the inner zone (shallow to relatively deeper central lake), a regular alternation of gypsum and carbonate laminae accumulated suggesting a seasonal regime. Many of the gypsum laminae display size-gradation (both reverse and symmetrical) indicating free precipitation in a stable brine body. In the intermediate zone (mosaic of shallow lakes), carbonate (dolomitic) beds formed in association with dark lutite levels, gypsum beds, and gypsum nodules and micronodules. Moreover, anoxic conditions developed in this zone, which resulted in the formation of native sulphur occurrences of economic value. In the marginal zone, the evaporitic deposits are developed only locally (the Galera Gypsum unit, in particular). The various gypsum lithofacies in these marginal deposits suggest the presence of a number of shallow to exposed settings (saline mudflat, saline marsh and gypsiferous pond). The isotopic composition ( δ 34S, δ 18O) of the gypsum samples is consistent with a Triassic origin of the sulphate as a result of chemical recycling. These data also suggest that a similar recycling mechanism operated in the saline lake system, where the gypsum sediments from the margins were coevally recycled towards the inner part. Both the evaporitic mineralogy and the gypsum and carbonate lithofacies suggest that semiarid conditions prevailed in this basin during the accumulation of the evaporite units.

Non Marine Molluscs in the Injana Formation, Kand Anticline, NW of Mosul / Iraq

Monotypic shell beds of molluscan skeletal sand are contained in the non-marine, fluvial sequence of Injana Formation of Upper Miocene age-Kand Anticline, as yet undescribed previously. These carbonate beds are characterised only by abundant pelecypod, oyster with scarce and opportunists gastropods and smooth-shelled ostracods. This faunal assemblage is consignable with non-marine low salinity euryhaline fresh, brackish water. The sudden change in their composition and distribution has been influence by salinity variation. The exclusion of normal marine-stenohaline fauna point to their deposition in non-marine setting including interchannel lake initiated on distal floodplain and/or river dominated bay esturay, or fan delta lake-lagoon.

Tectonic–palaeoenvironmental forcing of clay-mineral assemblages in nonmarine settings: the Oligocene–Miocene As Pontes Basin (Spain)

Two small, alluvial-lacustrine subbasins developed during the early restraining overstep stages of the Oligocene–Miocene As Pontes strike-slip Basin (NW Spain). Later, the basin evolved into a restraining bend stage and an alluvial-swamp-dominated depositional framework developed. The palaeobiological record demonstrates that the Oligocene–Miocene palaeoclimate in NW Spain was subtropical, warm and humid to subhumid. The metamorphic and igneous basin catchment yielded clay assemblages made up by kaolinite, illite and Al-smectite. Illite occurred as an original mineral in the source rock area, whereas kaolinite and Al-smectite resulted mainly from weathering of feldspar and clinochlore, respectively. This detrital primary clay assemblage remained preserved in the colluvial, alluvial fan and shallow lacustrine facies, whose early diagenesis was influenced by diluted, poorly evolved pore waters with neutral to slightly alkaline pH. The original clay assemblage was mildly to strongly transformed under early diagenetic conditions in the lacustrine and swampy environments where significant hydrochemical and Eh–pH changes took place. A fibrous magnesium-rich clay mineral-dominated assemblage (palygorskite and sepiolite) formed in shallow, saline lakes and palustrine zones under the influence of magnesium-rich, alkaline waters. Moreover, kaolinite-enriched assemblages formed in deep lacustrine, swamp and swamp-related alluvial zones under the influence of slightly to highly acidic pore waters. Pore water acidic conditions, characterising environments with organic matter accumulation, led to early diagenetic transformation of Al-smectite into kaolinite. This process was relatively limited in some environments such as organic matter-rich bottoms in meromictic lacustrine zones, whereas it was pervasive in peat-forming swamp zones. The stratigraphic relationships between the diverse clay mineral assemblages in the As Pontes Basin fill demonstrate the coeval development of rather diverse clay compositions. This clearly reflects the influence on clay assemblages of palaeoenvironmental changes forced by the morphological and tectonic evolution of the catchment–basin system. The interplay between climate and tectonic processes in the source areas did not result in major variations of the clay minerals fed into the basin. Conversely, this tectonic-sedimentation interplay influenced the evolution of the drainage and the water balance in the depositional zones, causing a complex environmental–hydrochemical evolution to occur. As a consequence, drastic early diagenetic changes affected the original clay mineral assemblages and resulted in a variety of early diagenetic assemblages. The As Pontes case study emphasises the major influence of palaeogeographical and tectonosedimentary evolution on the clay mineral record in nonmarine depositional systems. The depositional record in As Pontes Basin demonstrates that morphological and tectonically forced environmental and hydrochemical changes can result in variations similar to those forced by low-order climatic changes and that, in some cases, the role of climate can be negligible.

Stratigraphic and palaeoenvironmental significance of a Pennsylvanian (Upper Carboniferous) palynoflora from the Piaui Formation, Parnaiba Basin, northeastern Brazil

A well-preserved palynoflora is reported from within a cored interval of a coal-exploratory borehole (1-UN-23-PI of the Geological Survey of Brazil) in the southern part of the Parnaiba Basin, northeastern Brazil. The sample studied is from the lower portion of the Piaui Formation. Its palynoflora is characterized by particular abundance of the trilete cavate/pseudosaccate miospores Spelaeotriletes triangulus Neves and Owens, 1966 and S. arenaceus Neves and Owens, 1966, together with cingulizonate forms mainly attributable to Vallatisporites Hacquebard, 1957 and Cristatisporites R. Potonie and Kremp emend. Butterworth et al., 1964. Radially and bilaterally symmetrical monosaccate pollen grains are also well-represented, chiefly by Plicatipollenites Lele, 1964 and Potonieisporites Bhardwaj, 1954, respectively. Taeniate grains (i.e., monosaccates and bisaccates) are relatively minor constituents of the palynoflora; no marine microplankton were encountered. Several species are described in detail : the trilete apiculate spores Brevitriletes levis (Balme and Hennelly) Bharadwaj and Srivastava, 1969 and Horriditriletes uruguaiensis (Marques-Toigo) Archangelsky and Gamerro, 1979; and the taeniate pollen grains Meristocorpus ostentus sp. nov. and Lahirites segmentatus sp. nov. A Pennsylvanian (Late Carboniferous : late Westphalian) age is adduced for the palynoflora via its correlation with part of the Tapajos Group (specifically, the upper Itaituba Formation) of the Amazonas Basin in northern Brazil. The entirely land-derived palynomorphs, associated with abundant plant debris, corroborate previous suggestions that the lower part of the Piaui Formation accumulated in a nonmarine setting under conditions of aridity.

70 Ma nonmarine diatoms from northern Mexico

Research Article| March 01, 2002 70 Ma nonmarine diatoms from northern Mexico Elizabeth Chacón-Baca; Elizabeth Chacón-Baca 1Instituto de Geología, Universidad Autónoma de México, Circuito de la Investigación Científica, México D.F. 04510, México Search for other works by this author on: GSW Google Scholar H. Beraldi-Campesi; H. Beraldi-Campesi 1Instituto de Geología, Universidad Autónoma de México, Circuito de la Investigación Científica, México D.F. 04510, México Search for other works by this author on: GSW Google Scholar S.R.S. Cevallos-Ferriz; S.R.S. Cevallos-Ferriz 1Instituto de Geología, Universidad Autónoma de México, Circuito de la Investigación Científica, México D.F. 04510, México Search for other works by this author on: GSW Google Scholar A.H. Knoll; A.H. Knoll 2Botanical Museum, Harvard University, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar S. Golubic S. Golubic 3Department of Biology, Boston University, Boston, Massachusetts 02215, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Elizabeth Chacón-Baca 1Instituto de Geología, Universidad Autónoma de México, Circuito de la Investigación Científica, México D.F. 04510, México H. Beraldi-Campesi 1Instituto de Geología, Universidad Autónoma de México, Circuito de la Investigación Científica, México D.F. 04510, México S.R.S. Cevallos-Ferriz 1Instituto de Geología, Universidad Autónoma de México, Circuito de la Investigación Científica, México D.F. 04510, México A.H. Knoll 2Botanical Museum, Harvard University, Cambridge, Massachusetts 02138, USA S. Golubic 3Department of Biology, Boston University, Boston, Massachusetts 02215, USA Publisher: Geological Society of America Received: 12 Jul 2001 Revision Received: 01 Nov 2001 Accepted: 19 Nov 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (3): 279–281. https://doi.org/10.1130/0091-7613(2002)030<0279:MNDFNM>2.0.CO;2 Article history Received: 12 Jul 2001 Revision Received: 01 Nov 2001 Accepted: 19 Nov 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Elizabeth Chacón-Baca, H. Beraldi-Campesi, S.R.S. Cevallos-Ferriz, A.H. Knoll, S. Golubic; 70 Ma nonmarine diatoms from northern Mexico. Geology 2002;; 30 (3): 279–281. doi: https://doi.org/10.1130/0091-7613(2002)030<0279:MNDFNM>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Carbonaceous cherts of the Tarahumara Formation, exposed near Huepac, Sonora, Mexico, contain abundant diatom frustules occurring as benthic filamentous colonies. Stratigraphic and paleontological observations indicate that Tarahumara sediments accumulated in a nonmarine setting; radiometric ages on encompassing volcanic rocks delimit their depositional age to ca. 70 Ma. Tarahumara fossils therefore extend the paleontological record of nonmarine diatoms from middle Eocene to Late Cretaceous. Preserved populations include forms similar to species of the extant genera Amphora and Melosira, as well as filament-forming araphid pennates comparable to species of Fragilaria and Tabellaria. Tarahumara fossils indicate that by 70 Ma, nonmarine diatoms had achieved considerable environmental as well as taxonomic diversity. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Geomorphology, facies architecture, and high-resolution, non-marine sequence stratigraphy in avulsion deposits, Cumberland Marshes, Saskatchewan

Abstract This paper demonstrates field relationships between landforms, facies, and high-resolution sequences in avulsion deposits. It defines the building blocks of a prograding avulsion sequence from a high-resolution sequence stratigraphy perspective, proposes concepts in non-marine sequence stratigraphy and flood basin evolution, and defines the continental equivalent to a parasequence. The geomorphic features investigated include a distributary channel and its levee, the Stage I crevasse splay of Smith et al. (Sedimentology, vol. 36 (1989) 1), and the local backswamp. Levees and splays have been poorly studied in the past, and three-dimensional (3D) studies are rare. In this study, stratigraphy is defined from the finest scale upward and facies are mapped in 3D. Genetically related successions are identified by defining a hierarchy of bounding surfaces. The genesis, architecture, geometry, and connectivity of facies are explored in 3D. The approach used here reveals that avulsion deposits are comparable in process, landform, facies, bounding surfaces, and scale to interdistributary bayfill, i.e. delta lobe deposits. Even a simple Stage I splay is a complex landform, composed of several geomorphic components, several facies and many depositional events. As in bayfill, an alluvial ridge forms as the feeder crevasse and its levees advance basinward through their own distributary mouth bar deposits to form a Stage I splay. This produces a shoestring-shaped concentration of disconnected sandbodies that is flanked by wings of heterolithic strata, that join beneath the terminal mouth bar. The proposed results challenge current paradigms. Defining a crevasse splay as a discrete sandbody potentially ignores 70% of the landform's volume. An individual sandbody is likely only a small part of a crevasse splay complex. The thickest sandbody is a terminal, channel associated feature, not a sheet that thins in the direction of propagation. The three stage model of splay evolution proposed by Smith et al. (Sedimentology, vol. 36 (1989) 1) is revised to include facies and geometries consistent with a bayfill model. By analogy with delta lobes, the avulsion sequence is a parasequence, provided that its definition is modified to be independent from sea level. In non-marine settings, facies contacts at the tops of regional peats, coals, and paleosols are analogous to marine flooding surfaces. A parasequence is redefined here as a relatively conformable succession of genetically related strata or landforms that is bounded by regional flooding surfaces or their correlative surfaces. This broader definition incorporates the concept of landscape evolution between regional flooding surfaces in a variety of depositional settings. With respect to landscape evolution, accommodation space has three spatial dimensions — vertical (x), lateral (y), and down-the-basin (z). A flood basin fills in as landforms vertically (x) and laterally accrete (y), and prograde down-the-basin (z). Vertical aggradation is limited by the elevation of maximum flood stage (local base level). Differential tectonism and geomorphology control the slope of the flood basin floor and the direction of landscape evolution. These processes produce parasequences that include inclined stratal surfaces and oriented, stacked macroforms (clinoforms) that show the magnitude and direction of landscape evolution.

Deposition and early alteration of evaporites

SummaryThe depositional settings for primary and early diagenetic evaporite deposits generally fall into three categories: marginal (mixed shallow‐subaqueous and subaerial), shallow and deep subaqueous. These three environmental groupings hold for both marine and nonmarine settings, although the details of continental evaporites may be far more complex than in most marine‐fed water bodies. The primary evaporite morphologies from many continental (playa), hypersaline marine and marine‐marginal depositional settings are reasonably well understood, because of the numerous detailed studies of recent, Holocene and Cenozoic deposits that serve as models for sedimentary interpretation. The sedimentological features that develop in deeper water settings are inferred, based on examination of unaltered Cenozoic deposits. Each environmental setting develops characteristic depositional features and patterns, and one facies grades into the next. Because there may be significant physiochemical changes in water composition during deposition as well as sudden change(s) in both water depth and basinal circulation, description and interpretation of evaporative rocks should not be based on mineralogy alone, but on the distinct sedimentary characteristics of each part of a deposit. In cases where sediments still reflect their primary mineralogy and morphology, most of the environments can now be recognized; however, geochemical studies are commonly required to determine the source(s) of the original water. The determinative geochemical techniques that presently serve as a support to sedimentologic study include studies of fluid inclusions, bromine content of chloride salts, and the stable isotopes of strontium, sulphur, carbon and oxygen. Only after these and perhaps other chemical analyses are considered can the full depositional history of a region be reasonably unravelled.

Sedimentology of Ancient Saline Pans: An Example from the Permian Opeche Shale, Williston Basin, North Dakota, U.S.A.

ABSTRACT The mid-Permian Opeche Shale of North Dakota consists of bedded evaporites and red-bed siliciclastics. Detailed core and petrographic study has documented sedimentary and early diagenetic features in order to develop a depositional model, and to refine paleoclimatic data and paleogeographic setting for the late Paleozoic of the U.S. midcontinent. Lithologies and sedimentary features indicate lacustrine, distal alluvial, and minor eolian deposition, subaerial exposure, and soil formation. Bedded halites consisting of chevron and cumulate crystals, dissolution surfaces and pipes, and mudcracked microcrystalline salt crusts were deposited in a saline pan dominated by flooding, evaporative concentration, and desiccation. Bedded halites containing chevron and cumulate crystals but lacking any dissolution or desiccation features formed in perennial saline lakes. Chaotic halite, composed of red mudstone and siltstone with displacive halite crystals, represents saline mudflat deposits. Red mudstone and siltstone with little or no displacive halite but with abundant cracks and root features suggest deposition in a dry mudflat. Red-bed sandstones and conglomerates, composed of poorly sorted, subrounded quartz grains cemented with halite indicate distal alluvial deposition with possible transport by ephemeral streams, sheet floods, and debris flows. Most deposition took place in halite-dominated shallow perennial and ephemeral saline lakes surrounded by saline and dry mudflats. Evaporation, desiccation, flooding, and wind played significant roles in this environment. Therefore, the Opeche evaporites and red beds are representative of an ancient saline pan system. An inland playa setting is favored as a depositional model for the Opeche Shale. The abundance of soil features and halite dominance, as well as lack of nearshore carbonates and lack of restricted marine fossils, suggest a closed-basin nonmarine setting for the mid Permian of the U.S. midcontinent.

From Jurassic shores to Cretaceous plutons: Geochemical evidence for paleoalteration environments of metavolcanic rocks, eastern California

Research Article| March 01, 1998 From Jurassic shores to Cretaceous plutons: Geochemical evidence for paleoalteration environments of metavolcanic rocks, eastern California Sorena S. Sorensen; Sorena S. Sorensen 1Department of Mineral Sciences, NHB-119, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560 Search for other works by this author on: GSW Google Scholar George C. Dunne; George C. Dunne 2Department of Geological Sciences, California State University, Northridge, Northridge, California 91330-8266 Search for other works by this author on: GSW Google Scholar R. Brooks Hanson; R. Brooks Hanson 3Science, 1200 New York Avenue, N.W., Washington, D.C. 20005 Search for other works by this author on: GSW Google Scholar Mark D. Barton; Mark D. Barton 4Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Jennifer Becker; Jennifer Becker 4Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Othmar T. Tobisch; Othmar T. Tobisch 5Earth Science Board, University of California, Santa Cruz, California 95604 Search for other works by this author on: GSW Google Scholar Richard S. Fiske Richard S. Fiske 6Department of Mineral Sciences, NHB-119, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560 Search for other works by this author on: GSW Google Scholar Author and Article Information Sorena S. Sorensen 1Department of Mineral Sciences, NHB-119, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560 George C. Dunne 2Department of Geological Sciences, California State University, Northridge, Northridge, California 91330-8266 R. Brooks Hanson 3Science, 1200 New York Avenue, N.W., Washington, D.C. 20005 Mark D. Barton 4Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Jennifer Becker 4Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Othmar T. Tobisch 5Earth Science Board, University of California, Santa Cruz, California 95604 Richard S. Fiske 6Department of Mineral Sciences, NHB-119, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1998) 110 (3): 326–343. https://doi.org/10.1130/0016-7606(1998)110<0326:FJSTCP>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Sorena S. Sorensen, George C. Dunne, R. Brooks Hanson, Mark D. Barton, Jennifer Becker, Othmar T. Tobisch, Richard S. Fiske; From Jurassic shores to Cretaceous plutons: Geochemical evidence for paleoalteration environments of metavolcanic rocks, eastern California. GSA Bulletin 1998;; 110 (3): 326–343. doi: https://doi.org/10.1130/0016-7606(1998)110<0326:FJSTCP>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Volcanic and plutonic rocks exposed in east-central California record a long history of metasomatism and/or metamorphism within the Mesozoic Cordilleran continental arc. We use whole-rock and mineral elemental compositions, along with standard and cathodoluminescence petrography to characterize alteration histories of Late Triassic to Middle Jurassic metavolcanic rocks in the Ritter Range, White-Inyo Mountains, and Alabama Hills. Although alkali-metasomatism is widespread and pervasive, ratios and abundances of Ce, Th, Tb, and Ta suggest that mafic protoliths from the White-Inyo Mountains were shoshonitic, whereas those from the Ritter Range were calc-alkaline. Alkali exchange apparently modified the compositions of many metavolcanic rocks. Much of this metasomatism may have occurred at low-temperature (T) conditions, and attended or shortly postdated deposition of the volcanic protoliths. High δ18O values for K-rich metatuffs from the Ritter Range suggest that the K-metasomatizing fluid was low-T seawater. In contrast, low δ18O values for K-rich metatuffs from the Alabama Hills and Inyo Mountains seem to reflect rock interaction with meteoric water prior to contact metamorphism. Jurassic metatuffs deposited in marine (Ritter Range) and nonmarine (Alabama Hills, Inyo Mountains) settings display similar degrees of K for Na (or Ca) exchange that were affected by isotopically distinct fluids. Some alkali-metasomatism of Jurassic metavolcanic rocks is related to Cretaceous plutonism. In the Ritter Range and Alabama Hills, these effects are localized around pluton contacts, appear to be more vein related than pervasive, and overprint K-metasomatized assemblages. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.