Palynology of the Upper Cretaceous \(Turonian\) Ferron Sandstone

Palynology, 2015 http://dx.doi.org/10.1080/01916122.2015.1014525

Palynology of the Upper Cretaceous (Turonian) Ferron Sandstone Member, Utah, USA: identification of marine flooding surfaces and Milankovitch cycles in subtropical, ever-wet, paralic to non-marine palaeoenvironments Isil Akyuza*, Sophie Warnya*, Oyebode Famubodeb and Janok P. Bhattacharyac aDepartment of Geology and Geophysics and Museum of Natural Science, Louisiana State University, E-235 Howe-Russell, Baton Rouge, Louisiana 70803, USA; bDepartment of Earth and Atmospheric Sciences, University of Houston, Science & Research, Building 1, Rm. 312, Houston, Texas 77204-5007, USA; cSchool of Geography and Earth Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada The Upper Cretaceous Ferron Sandstone Member of the Mancos Shale Formation in Utah includes coal and gas deposits and is an important outcrop analogue to study reservoir characterisation of fluvialÀdeltaic petroleum systems. Numerous sedimentological and sequence stratigraphic studies of the Notom fluvialÀdeltaic wedge have been conducted recently; however, palynological analyses had not previously been undertaken. Here, we present palynological data from 128 samples collected in the Notom wedge of the Ferron Sandstone Member outcropping in south-central Utah. The purpose of this study is to use palynological analysis to refine the broader depositional environments, evaluate the climatic setting, and to build a biostratigraphic palynological framework. The dominance of terrestrial palynomorphs, especially the high yield of moisture-loving cryptogam spores, indicates a primarily ever- wet depositional environment characteristic of hydromorphic floodplain palaeosols formed in subtropical to tropical climates. Although dinoflagellates are rare, four intervals with occurrences of marine cysts indicate periods of increased marine/tidal influence associated with previously identified flooding surfaces within Milankovitch-scale parasequences of the largely non-marine stratal succession. These flooding surfaces confirm correlations from regional high-resolution sequence stratigraphic studies and allow correlative marine parasequences and systems tracts to be extended within floodplain-dominated stratal successions. The presence of Nyssapollenites albertensis pollen places the interval studied within the Nyssapollenites albertensis Interval Zone (Nichols 1994), constraining the age of the Ferron Sandstone Member to the latter part of the Cenomanian and the early Coniacian. This largely agrees with the bentonite- and ammonite-derived Turonian age proposed in previous studies. Keywords: palynology; Upper Cretaceous (Turonian); Ferron Notom; Cretaceous Western Interior Seaway; sequence stratigraphy

1. Introduction successions suggests high-frequency sequences can also Studying fluvialÀdeltaic outcrops is fundamental to be recognised (Famubode 2014). understanding how such formations are formed and to The Ferron Sandstone Member was deposited apply the knowledge gained to the reservoir characteri- along the Cretaceous Western Interior Seaway (KWIS) sation of fluvialÀdeltaic petroleum systems. Here, we during the Turonian (Peterson & Ryder 1975, Cobban focus on the Upper Cretaceous Ferron Sandstone et al. 2006), a time interval known to be the warmest Member of the Mancos Shale Formation, a well-known period of the Cretaceous, as indicated by composite host of coal and gas deposits Bhattacharya & Tye oxygen isotopic records (e.g. Huber et al. 2002, (2004). Within the Ferron, three major deltaic wedges MacLeod et al. 2013). The Turonian age also marked have been defined, including the Notom, Last Chance the highest sea level seen during the Mesozoic and and Vernal sub-members. Recent high-resolution strati- Cenozoic. During the Turonian, the KWIS coastline graphical analysis of the Notom delta system (Li et al. ran through central Utah, and much of the western 2010; Zhu et al. 2012) demonstrates six 100,000-year- half of the state consisted of coastal environments duration Milankovitch-frequency sequences based (Figure 1). The Ferron Sandstone Member has been largely on outcrop correlation of marine parasequences informally divided into three separate clastic wedges. and overlying incised valley systems. Detailed pedostra- From oldest to youngest, these are the Notom delta, tigraphical analysis of the associated non-marine the Vernal delta and the Last Chance delta. But none

*Corresponding authors. Email: [email protected] and [email protected]

Ó 2015 AASP À The Palynological Society 2 I. Akyuz et al.

Figure 1. Palaeogeographical location map illustrating the three deltas that built the Ferron Sandstone Member; the Notom, Last Chance and Vernal deltas, along the Cretaceous Western Interior Seaway during the Turonian (base map ÓRon Blakey, Colorado Plateau Geosystems, Inc.). Palynology 3 of these units is an official stratigraphical or lithostrati- southÀcentral Utah (Figure 3). On the basis of litho- graphical unit. It is generally agreed that the Vernal, logical characteristics, the Ferron Sandstone Member Last Chance and Notom delta complexes were built as studied here was previously divided into two informal a consequence of northeast progradation of fluvial del- units, the Lower FerronÀNotom and the Upper Fer- taic deposits into the western margin of the seaway ronÀNotom Peterson & Ryder (1975). Shelf and shore- (Figure 1; Gardner 1995, Ryer & Anderson 2004). line sandstones and marine shale beds are common in Here, we will refer to the studied section as the Ferron the Lower FerronÀNotom unit, and fluvialÀdeltaic Sandstone Member, with the understanding that the deposits, including channel sandstones, floodplain work presented herein is on the oldest clastic wedge deposits and coals predominate in the Upper Ferron (the Notom delta informal unit) of the Ferron Sand- unit (Peterson & Ryder 1975, Ryer & Anderson 2004, stone Member. This section provides an ideal sequence Li et al. 2010). Zhu et al. (2012) subdivided the Notom for understanding coastal/deltaic deposition under into six sequences, 18 parasequence sets and 43 parase- extreme greenhouse climatic conditions. quences. The uppermost, and youngest, sequence 1 Other penecontemporaneous fluvialÀdeltaic clastic comprises a 5À25-m-thick compound incised valley wedges of the KWIS include the Upper Cretaceous system overlain by about 23 m of interbedded channel Cardium Formation in Alberta, Canada, the Frontier belt sandstones and muddy floodplain deposits, includ- Formation in Wyoming, and the Gallup Sandstone ing crevasse splays, coals, floodplain pond mudstones Formation in New Mexico (Gardner 1995, Li & Zhu and palaeosols (Famubode 2014, and Figure 4). These 2014). 23 m are the focus of this study. The sampled section The Ferron Sandstone Member was deposited above has been subdivided into nine fluvial aggradational the Late Cenomanian to Lower Turonian Tununk Shale cycle sets, based on analysis of pedostratigraphical Member of the Mancos Formation (Figure 2). Based on cycles and river channel deposits, and these have in ammonites, the Notom delta wedge of the Ferron Sand- turn been grouped into three higher-frequency sequen- stone Member has been estimated to be Middle to ces (Famubode 2014). These are designated from youn- Upper Turonian in age (Peterson & Ryder 1975,Cob- gest to oldest as 1A, 1B and 1C (Figure 5). The lowest ban et al. 2006). The Ferron Sandstone Member is dis- sequence 1C is the upper tidally influenced part of a 5- conformably overlain by the Santonian Blue Gate Shale m-thick sandy valley-margin fill. Several horizons have Member of the Mancos Shale Formation (Figure 2; also been identified as candidate flooding surfaces. Peterson & Ryder 1975,Fielding2010). Assuming that the entire sequence 1, including the The Ferron Sandstone Member outcrop sampled compound incised valley, represents about 100,000 for this study is exposed in the Henry Mountains in years’ duration, these 23 m likely represent around half that time, or about 50,000À60,000 years. Ma Period Stage Henry Basin - Utah The present study evaluates palynofacies and palynostratigraphy to search for evidence of marine Tarantula Mesa Sandstone incursions within floodplain stratal successions that Campanian could correlate with high-frequency marine flooding 80 surfaces, and to identify possible Milankovitch-style Masuk Formation palaeoclimatic controls on the origin of high-frequency

Muley Canyon Sandstone sequences.

S 83.50 Only a few studies have been conducted on the U Santonian Blue Gate Shale Member 85 O Upper Cretaceous terrestrial ﬂoras of Utah and adja-

85.85 n

i t

a cent areas. Orlansky (1971) described and illustrated m

A Coniacian r

o 124 palynomorph species from 20 samples from the

F Hiatus

E l

85.27 a Straight Cliffs Sandstone, Garﬁeld County, Utah.

90 s Gray et al. (1966) focused on the coal intervals and cor- o

c Ferron Sandstone Member n

Turonian a related coal zones using pollen and spore assemblages M Tununk Shale Member from Ferron Sandstones. Lohrengel (1969) and Nich- 93.55 ols (1995) described palynomorphs from the Kaiparo- À 95 Dakota Sandstone wits Plateau, in south central Utah. Several Cenomanian additional studies have been conducted to interpret the Upper Cretaceous terrestrial ﬂoras of North America Hiatus in adjacent areas. For example, Jameossanaie (1987) 99.60 reported on the palynology of South Hospah coal- Figure 2. Stratigraphic column showing the Upper Creta- bearing deposits, in McKinley County, New Mexico, ceous succession of the Henry Mountains (modiﬁed from and described some important Upper Cretaceous Fielding 2010). palynomorphs. 4 I. Akyuz et al.

Figure 3. Maps illustrating the Ferron Sandstone Member outcrop belt and the location of the study area (modiﬁed from Famubode 2014). Palynology 5

Figure 4. Stratigraphical cross section of the Ferron Sandstone Member outcrop in Sweetwater Creek (near Henry Mountains, Utah) showing channel and floodplain facies grouped into fluvial aggradation cycles, fluvial aggradation cycle sets, systems tracts and lower-order sequences in the uppermost compound sequence 1. The section studied for palynology is labeled 12-03 (second from left).

The new, detailed palynological study presented 2. Material and methods herein aims to refine the characterisation of the climatic One hundred and twenty eight palynological samples and depositional settings, and evaluate the nature of were taken from Sweetwater Creek, between the Henry high-frequency sequences formed during the middle to Mountains and Utah Highway 24. For each sample, upper Turonian of Utah. Dinoflagellate cysts should one kerogen slide and two > 10-mm fraction slides provide evidence for marine incursions, while spores and were studied. This location was selected because it is pollen provide information about the type of plants that well exposed, and both channel and floodplain deposits grew during this purported greenhouse-climate interval. outcrop extensively (Figure 3). Where possible, sam- Any drastic changes in plant composition observed ples were collected at approximately 10-cm intervals would indicate that climatic changes occurred during the from the floodplain mudstones and coal intervals in development of the Ferron sequences. The second focus the 23-m-thick section. Chemical processing was per- of this study is to develop a high-definition biostrati- formed on all samples and proceeded according to graphical framework for regional sequences contempo- techniques described in Brown (2008). Hydrochloric raneous to the Ferron Sandstone Member deposits. and hydrofluoric acids were used to digest the 6 I. Akyuz et al.

Palynological events Sequence Stratigraphy Relative abundance of palynomorphs recovered in Ferron-Notom Section (this study) (Famubode, 2014)

Lithology Depth Yield Samples Biozones

Fluvial mudstone/siltstone FS: Flooding Surface Carbonaceous mudstone SB: Sequence Boundary Crevasse splay/channel MFS: Maximum Flooding Surface Levee deposit FADs TS: Transgressive Surface & ACME M Massive sandstone/mudstone FAC-SET: Fluvial Aggradation LADs Cycle Set * FAC- SET Number Other algae Angiosperms Spores Fungal spores Dinoflagellate cysts Unknown affinity Gymnosperms (m) Clay f. sand m. sand Silt vf. sand

23.15m 124 78 21 1 * 8 944 2 2 1 2 23.05m 16 FAC-SET BOUNDARY/ 23.00m 221 46 15 38 Top Appendicisporites unicus 23.00 23.05 22.95m 155 77 5 11 1 7 ACME of Cicatricosisporites MFS 22.85m 73 88 1 3 1 7 * 7 22.75m 21 83 10 7 crassiterminatus and 22.5 22.65m 95 67 5 24 5 Enzonalasporites bojatus 22.55m 36 90 5 2 1 1 22.42m 83 83 3 8 3 3 Top Appendicisporites auritus 22.35m 61 90 4 2 1 1 1 87 10 2 2 22.0 22.25m 40 83 8 3 8 22.15m 40 54 18 5 8 8 8 22.07m 93 68 11 1 13 7 22.05m 17 88 12 21.5 21.95m 29 90 10 21.85m 29 82 18 21.75 ACME of Alisporites spp. 21.75m 122 49 44 7 21.65m 149 Zone 4 59 36 3 1 1 21.58 21.0 21.58m 310 96 2 1 1 ACME of Triporoletes reticulatus, 21.00m 13 77 23 FAC-SET

20.90m 82 81 4 6 8 1 Foraminisporis simiscalaris, e c

20.80m 27 74 7 19 Laevigatosporites sp. BOUNDARY n 20.70m 12 233 54 232 e 20.5 u

20.65m 2 50 50 20.70 q

20.55m 27 65 12 23 e S

20.50m 61 49 2 16 18 15 Base Cicatricosisporites * 6 a

20.0 20.40m 34 6 9 15 35 32 3 crassiterminatus K

20.50

20.30m 76 29 9 36 19 5 1 0 4

M 20.20m 47 13 2 49 32 2 2

o t

20.10m 20 32 5 42 16 5 0

19.5 20.00m 51 64 2 2 30 2 Sequence 1A 2 19.90m 13 62 38 19.81m 44 82 7 5 7 19.30m 145 82 6 4 6 2 19.0 19.20m 231 89 5 3 <1 2 <1 19.10m 299 96 2 1 <1 <1 19.10 M 19.00m 62 79 2 3 7 10 ACME of Zlivisporis 18.5 18.90m 41 59 2 7 32 cenomanianus 18.80m 94 72 2 13 12 1 18.70m 37 49 8 11 32 18.60m 24 54 21 25 18.0 18.50m 5 40 40 20 18.40m 2 100 18.35m 7 57 43 17.5 17.55m 48 42 2 44 10 2 SEQUENCE 17.45m 180 64 2 6 6 22 17.45 ACME of Todisporites spp. BOUNDARY/TSE 17.35m 29 181 7 434 252 4 4 Zone 3 24 3 52 21 17.35 17.0 17.25m 29 17.20m 86 14 2 67 16 Top Cyathidites concavus * 5 17.10m 50 29 4 49 18 17.00m 26 8 12 8 58 15 16.5 16.90m 7 14 86 16.80m 8 100 16.70m 17 29 18 24 18 12 Base Enzonalasporites bojatus 16.0 16.60m 17 53 6 24 18 16.50m 42 43 7 5 43 2 16.40m 24 74 13 4 9 Base Tetrangulidinium spp. 15.5 16.30m 49 45 16 8 14 16 16.20m 35 60 14 17 3 6 16.10m 55 62 5 13 11 5 4 Base Triporoletes radiatus 15.0 16.00m 12 75 8 17 15.90m 6 33 67 15.80m 0 Base Appendicisporites auritus 59 25 7 3 4 1 Base Appendicisporites cristatus 15.70 14.5 15.70m 123 15.60m 24 17 46 29 8 Base Microreticulatisporites spp. ACME of Araucariacites sp. 13.00m 59 14 41 29 16 Base Appendicisporites unicus 12.90m 10 13.0 11 89 14.0 12.80m 28 4 89 4 4

12.70m 20 100 e c

12.60m 27 4 11 4 63 19 n 13.5 e

12.50m 46 87 7 7 TRUNCATED u q

12.40m 46 39 28 22 11 e

FAC-SET BOUNDARY S 12.30m 67 151 1 1 181 3 585 3 8 92 12.30 a

13.0 12.20m 12 K

12.05m 3 67 33 * 4 0 4 50 50

12.00m 4 o

12.5 11.90m 0 0 Sequence 1B 11.80m 1 100 2 11.70m 0 12.0 11.60m 4 25 50 25 FAC-SET BOUNDARY/ 11.50m 15 27 73 MFS 11.40m 22 5 919 5 11.30m 5 100 11.40 11.5 11.20m 2 100 11.10m 12 100 11.00m 2 100 * 3 11.0 10.90m 1 Zone 2 100 10.80m 2 50 50 10.70m 1 100 10.02m 28 19 7 4 63 7 10.5 9.99m 16 6 94 9.50m 2 50 50 9.25m 3 100 10.0 9.20m 7 14 29 14 14 29 9.10m 2 100 9.00m 6 83 17 8.95m 1 100 9.5 8.85m 0 8.80m 0 8.70m 1 100 8.60m 0 9.0 8.50m 1 100 8.40m 11 27 9 55 9 8.30m 6 83 17 8.20m 6 83 17 8.5 8.10m 23 35 9 4 48 4 8.00m 76 61 17 4 17 1 M 7.90m 124 77 15 4 4 7.90 ACME of Cyathidites spp. 7.80m 90 56 22 5 14 5 8.0 7.70m 79 48 27 8 11 1 5 FAC-SET BOUNDARY M 7.60m 2 7.70 100 7.50m 10 60 10 20 10 / FS 7.40m 11 646 18 9 9 7.30m 5 80 20 7.40 7.5 7.20m 18 71 12 6 6 6 7.00 7.10m 20 35 35 15 15 Base Cyathidites concavus ACME of Taxodiaceaepollenites 7.00m 194 36 12 22 2 5 15 8 sp. 6.90m 309 31 5 10 <1 29 25 Zone of marine/tide 7.0 6.79m 135 68 6 11 1 14 2 Base Nyssapollenites 6.70m 24 71 21 8 albertensis 6.90 influence on fluvial 6.60m 7 100 ACME of Schizosporis spp.,

Zone 1 33 67 6.50m 3 Schizophacus spp. deposition fluvial 6.5 6.40m 1 100 6.30m 2 50 50 6.18m 14 7 29 14 29 21

6.07m 19 72 22 6 * 2 Sequence 1C 6.00m 39 6 41 24 16 5 8 5 60

Figure 5. Stratigraphical distribution chart displaying the lithostratigraphy, the relative abundance of the seven palynological assemblages and the key palynostratigraphical events identified in the Ferron Sandstone Member studied. These are graphed against the sequence stratigraphical interpretation proposed by Famubode (2014). Notes: FAD stands for First Appearance Datum and LAD stands for Last Appearance Datum. Palynology 7 sediments. After the residues were rinsed to neutrality, species recovered and the changes in abundance of a heavy liquid (Zinc bromide [ZnBr2]) was used to sep- seven main palynomorph groups (Figure 5). The four arate the organics from the fine mineral fractions. We zones are described below. expected to count up to 300 palynomorphs per sample, Zone 1 spans between 6.0 and 7.70 m from the base but this was rarely possible. The samples were quite of the section. It is characterised by the most continu- poor and all three microscope slides were scanned for ous presence of dinoflagellate cysts, and the first occur- each sample to help increase the number of palyno- rences of Nyssapollenites albertensis and Cyathidites morphs recovered. Identification and description of the concavus. The common occurrence of Schizoporis sp., palynomorphs was conducted using an Olympus BX Schizophacus sp. and Taxodiaceaepollenites sp. also 41 transmitted-light microscope at the Center for marks this zone. Excellence in Palynology (CENEX), Louisiana State Zone 2 ranges from 7.70 to 13.00 m and its base is University. All palynomorphs recovered were tabu- characterised by an acme in Cyathidites spp., and lated. The StrataBugsÓ biostratigraphical data man- abundant fungal spores. agement software was used to create distribution and Zone 3 ranges from 13.00 to 20.50 m and is marked range charts. by the first occurrence of Appendicisporites unicus, Tri- poroletes radiatus, Enzonalasporites bojatus and Tetran- gulidinium sp., and the last occurrence of Cyathidites 3. Ferron Sandstone Member palynological results concavus. In addition to these events, common occur- 3.1. Overall palynomorph recovery rences of Zlivisporis cenomanianus, Araucariacites sp. A total of 5789 palynomorphs were counted from the and Todisporites spp. are identified. 128 samples collected. Palynomorph recovery varied Finally, the uppermost Zone 4 is characterised by from very poor to good with several samples essentially the first occurrence of Cicatricosisporites crassitermina- barren. For each of these samples, several slides had to tus, and the last occurrences of Appendicisporites unicus be scanned to increase the number of palynomorphs and Appendicisporites auritus. Additionally, the com- observed. Regarding the barren samples, palyno- mon occurrence of Laevigatosporites sp., Triporoletes morphs may have been oxidised by natural processes reticulatus, Cicatricosisporites crassiterminatus and and destroyed, especially in the lower part of the sec- Foraminisporis simiscalaris is also noted in Zone 4. tion. The difficulty of working with such a poor yield might explain why very few palynological analyses 3.3. Palynomorphs recovered from the Ferron Sand- have been performed on this important sequence. stone Member and their environmental significance Despite these time-consuming, low-yield analyses, important palaeo environmental information was gath- Among the fern spores, Schizaeaceae species resem- ered from this study. The morphotypes recovered bling the living Anemia are one of the most prominent include 82 species of pollen and spores, six species of forms recovered. The genera Appendicisporites and dinoflagellate cysts and other algae, and two palyno- Cicatricosisporites collectively represent 13% of the morphs of unknown affinity. The average relative total specimens counted. An acme of Cicatricosispor- abundance of Ferron palynomorphs consists of 61.7% ites crassiterminatus occurred from 23.0 to 23.05 m. cryptogam spores, 9.5% gymnosperm pollen, 9.0% The abundance and variety of schizaceous spores (schi- angiosperm pollen and 19.8% other palynomorphs, zaeaceans) is similar to those recovered from Upper including mostly fungal spores, algae and palyno- Cretaceous rocks throughout the KWIS (Agasie 1969, morphs of unknown affinity. Clearly, the depositional Jameossanaie 1987, Nichols 1995, Ludvigson et al. environment is dominated by ferns and bryophytes, 2010). such as mosses, liverworts and hornworts, all indicative Another abundant spore genus recovered is Zlivis- of very moist environments. poris, a genus belonging to the Hepaticae or liverworts. Relative abundances of significant palynomorph Note that in many previous studies, these spores have groups, biozones and events are summarised in been assigned to the genera Rouseisporites, Triporoletes Figure 5. These data are presented in relation to or Inaperturopollenites (Braman 2001). These small changes in lithology and other outcrop measurements. bryophytes require moist environments and grow in a Some of the most abundant taxa recovered are illus- prostrate manner on stable surfaces Braman & trated in Plates 1 and 2. Koppelhus (2005). Relative abundances of Zlivisporis average approximately 12.7% of the total specimens counted. An acme of Zlivisporis cenomanianus has 3.2. Palynostratigraphy been identified from 19.10 to 19.20 m. The abundance Four palynological assemblage zones were defined for and variety of Zlivisporis cenomanianus recovered this data set. These are based on the distribution of along the KWIS in other studies have varied from rare 8 I. Akyuz et al. Palynology 9

to dominant. For example, Ravn & Witzke (1994) of 5.8% of the total yield. The association of Taxodia- reported that Zlivisporis cenomanianus was recovered ceae, Araucariaceae and Pinaceae has been reported in almost every sample throughout the Dakota Forma- from moist upland areas near water, and in temperate tion; however, in other formations, it was very rare. to subtropical environments (Orlansky 1971). The reason for this variability may be local palaeoeco- Taxodiaceaepollenites pollen was produced by trees logical effects such as changes in moisture availability. that are the principal component of swamp-forest vege- Liverworts and hornworts favour soil with high mois- tation (Nichols 1995) and are most likely similar to ture, and tolerate minor flooding, but these plants Taxodium species such as the swamp cypress found would die if fully submerged (Warny et al. 2012). On today. the other hand, soils that are too dry would prevent the Angiosperm pollen grains represent only 9.0% of reproduction of these bryophytes. the total yield. The assemblage of angiosperm pollen Other cryptogam spore groups recovered include includes the following species: Aquilapollenites psilatus, spores of fern genera Cyathidites, Gleicheniidites, Lae- Cupanieidites spp., Cupuliferoidaepollenites spp., vigatosporites and Todisporites, and spores of the bryo- Foveotricolporites spp., Liliacidites spp., Margocolpor- phyte Aequitriradites. Collectively, these represent an ites spp., Monosulcites spinosus, Nyssapollenites spp., average of 20.1% of the specimens recovered. Gleichen- Nyssapollenites albertensis, Retitricolpites spp., Tricol- niidites is a terrestrial fern that is mostly found in tropi- pites spp, Rousea sp. and Stellatopollis spp. cal and temperate environments. Todisporites is Cupanieidites spp. is related to some of the Cupanieae interesting as it belongs to the family Osmundaceae or from tropical and subtropical regions of America, Cinnamon ferns, a group that has three living genera Madagascar and Australia. These species occur in a including terrestrial and subaquatic ferns. It is mostly wide range of humid tropical to subtropical environ- found in temperate to tropical swampy regions (Law- ments Coetzee & Muller (1984). The gymnosperm rence 1951, Braman & Koppelhus 2005). Aequitrira- Cycadopites and angiosperm Monosulcites are palm- dites is believed to be the spore of some unknown like pollen found in subtropical and tropical lowland liverwort. Archangelsky & Archangelsky (2005) com- swamp areas (Braman & Koppelhus 2005, Mann pared Aequitriradites they recovered from Cretaceous 2007). The most predominant genus of angiosperm is sections in Patagonia to the spores of the aquatic genus Tricolpites, representing 5.1% of the total specimens Riella. They noted that the genus was characteristic of counted. Other angiosperm genera are rare or only temperate to warm and humid environmental occur intermittently. conditions. Two other species, Enzonalasporites bojatus and Many other cryptogam spore genera have a relative Aquilapollenites psilatus, were recovered in the upper abundance lower than 1% of the total. The abundance section of sequence 1. Aquilapollenites psilatus has been and variety of spore specimens increase progressively reported in several studies, including from the Campa- from the lower to the upper part of the section. nianÀMaastrichtian Edmond Group of Alberta, Can- Pollen grains from gymnosperms and angiosperms ada Srivastava & Braman (2013). These authors are less abundant than the spores recovered; however, suggested that this species was actually a trilete spore the diversity of these forms is interesting. Gymnosperm in equatorial view and proposed it be included in the assemblages average 9.5% in relative abundance. Schizaeaceae, Cyathidites or Deltoidospora. Here we Among the gymnosperms recovered, bisaccate grains keep with the traditional view that this is actually a are prevalent, with 3.7% of the total palynomorphs pollen (not a spore) that displays a unique triprojectate recovered. The assemblage of bisaccate pollen includes morphology. Although it is not abundant, the occur- the following species: Abiespollenites sp., Alisporites rence of this species is noteworthy because it is the only sp., Parvisaccites sp., Piceapollenites sp., Pityosporites triprojectate pollen recovered along the section. Enzo- alatipollenites, Pityosporites sp., Pristinuspollenites sp., nalasporites bojatus, which has an uncertain affinity Rugubivesculites sp. and Vitreisporites sp. Other gym- Currie & Koppelhus (2005), was recovered previously nosperm pollen, including Araucariacites, Taxodia- in the Upper SantonianÀLower Campanian Milk ceaepollenites, Ephedripites, Zonalopollenites, River Formation in southern Alberta, Canada Cycadopites spp. and Classopollis, made up an average (Braman 2001). J Plate 1. Light photomicrographs of terrestrial palynomorphs with spores (1À10) and gymnosperm pollen (11À12). All specimens are at the same magnification (see 20-mm scale bar on plate). Each species is followed by the sample number and England Finder coordinates. 1. Cicatricosisporites crassiterminatus (S-119 L16/1), 2. Deltoidospora sp. (S-102 T16/0), 3. Triporoletes reticulatus (S-10 G11/4), 4. Gleicheniidites senonicus (S-68 W14/3), 5. Appendicisporites unicus (S-111 V19/4), 6. Foraminisporis sp. (S-92 S28/4), 7. Aequitriradites sp. (S-11 N20/0), 8. Zlivisporis cenomanianus (S-91 G43/2), 9. Laevigatosporis sp. (S-103 O50/1), 10. Echinatisporis sp. (S-99 N17/2), 11. Pinaceae (S-104 P44/2), 12.Classopollis sp. (S-20 O15/3). 10 I. Akyuz et al. Palynology 11

Other palynomorphs recovered include dinoflagel- fluvial deposition under low-salinity sea-surface condi- late cysts, other algae and fungal spores, together mak- tions. A similar lack of dinoflagellate cysts is observed ing an average of 19.8% of the total specimens today in samples of sediments taken in various areas of tabulated. Fungal spores are the most prominent, with the Mississippi Delta, along the Gulf of Mexico, where 9.5% of the total. They are present throughout the sec- salinity ranges from 0 to 20 psu. The presence of tion. This is significant because most modern studies diverse freshwater algae recovered from sequence 1 of done in hospitals or aerobiology laboratories on air- the Ferron Sandstone Member supports this hypothe- sample quality show that peaks in some fungal spores sis. Although they are rare, the four occurrences are often occur during hot, humid, rainy weather and dur- potentially quite important because they might indicate ing harvest seasons (Emberlin 2000). As harvest is not brief episodes of increased marine influence or flooding a consideration in the Cretaceous, the abundance of surfaces with associated increase in salinity. The lower fungal spores has significant implications for the cli- part of the section, up to 7.70 m, shows the almost con- matic conditions during the time of deposition. Several tinuous presence of dinoflagellate cysts. These proba- freshwater algal spores were also recovered, accounting bly represent the time in the section with the most for up to 6.5% of the total assemblage. Spores of fresh- marine influence and correlate with deposition within a water algae include Schizophacus parvus, Schizophacus brackish and tidally influenced valley fill. Following sp., Schizosporis sp., Tetranguladinium sp., Chomotri- this period, dinoflagellates appeared mostly at three letes minor and spores of Zygnemataceae. The green main levels: at 11.40 m (5%), at 12.30 m (3%) and at algae family Zygnemataceae is known as a palaeo 17.35 m (4%). Each of these occurrences correlates climatological and palaeoenvironmental indicator (van with previously defined flooding surfaces that were Geel et al. 1989,Yi1997, Warny et al. 2009, Lindsrom€ based on sequence stratigraphic analysis by Famubode 2013). For instance, Tetranguladinium have been (2014). This strongly supports the interpretation of reported in sediments of humid warm temperate to flooding surface-capped fluvial aggradation cycle sets subtropicalÀtropical regions that have a dry season and high-frequency sequences in this largely non- (van Geel et al. 1989, Davis 1992,Yi1997, Lindstrom€ marine succession. 2013). Tetrangulidinium has also been reported from Most of the spore and pollen species recovered are Upper Cretaceous non-marine sediments along the mostly indicative of warm, moist to marine environ- KWIS (Braman 2001, Lucas et al. 2003, Bercovici et al. ments, indicating that the deposition occurred under 2009). Tetranguladinium was regarded as a dinoflagel- the influence of a tropical climate in a floodplain to late cyst or acritarch in previous studies (Batten & paralic setting. Although mangrove pollen was Lister 1988, Fensome et al. 1990); however, according expected to be recovered in these sequences, it was not to more recent studies, it has been reported as zygo- found. The lack of mangrove pollen in the section is spores of cyanobacteria or Zygnemataceae (Yi 1997, remarkable, and the reason for this absence is Fensome & Williams 2004). The spores of Zygnemata- unknown. Traverse (2007), who observed a similar ceae are an excellent indicator of a freshwater realm, lack of mangrove in other Cretaceous sections, and and their presence has been reported as an indicator of proposed a possible explanation in that Classopollis- freshwater ponds in Antarctica during the Mid-Mio- producing plants may have occupied the mangrove cene Climatic Optimum (Warny et al. 2009). Their habitat. Srivastava (1976) indicated that plants produc- presence here might be indicative of floodplain ponds ing Classopollis have an affinity with araucarian and/or or lake-fill deposits. Taxa of freshwater algae, similar gnetalean conifers. They occupied environments such to those recovered from the Ferron Sandstone Mem- as the well-drained soils of lowland coastal areas, and ber, have also been reported in several formations preferred a warm climate, although some modern throughout the KWIS (Orlansky 1971, Jameossanaie Araucarian species extend today to the tree line in 1987, Nichols 1997, Braman & Sweet 2012). modern southern Chile and Argentina (Bowman et al. Dinoflagellate cysts, although very rare in the sec- 2014 and references therein). Other studies (Orlansky tion, were recovered in four main intervals of sequence 1971, Heimhofer et al. 2008) suggest that Classopollis 1 in the Ferron Sandstone Member. The overall lack of indicates warm, semi-arid to arid coastal palaeoenvir- dinoflagellate cysts might be indicative of dominant onments, with pollen thought to be produced by

J Plate 2. Light photomicrographs of selected palynomorphs with gymnosperm pollen (1À2), angiosperm pollen (3À6) and freshwater algae (7À8). All specimens are at the same magniﬁcation (see 20-mm scale bar on plate). Each species is followed by the sample number and England Finder coordinates. 1. Cycadopites sp. (S-90 O24/4), 2. Taxodiaceaepollenites hiatus (S-10 P23/2), 3. Monosulcites sp. (S-97E R28/4), 4. Aquilapollenites psilatus (S-10 M33/4), 5. Aquilapollenites psilatus (S-10 G16/4), 6. Margocol- porites sp. (S-119 T32/1), 7. Chomotriletes minor (S-110 J42/2), 8. Tetranguladinium sp. (S-72 S20/0). 12 I. Akyuz et al.

Cheirolepidiaceae, an extinct group of thermophilous (Dyman et al. 1988, Nichols 1994). The palynostratigra- conifers. Heimhofer et al. (2008) indicated that this phy thus supports the bentonite age but does not species can be found in tidally influenced, shallow- improve the resolution. water deposits, and that these plants could thus indicate the vicinity of the palaeo-shoreline. In the section studied herein, the co-occurrence of Classopollis at lev- 5. Summary of the environmental significance of the els where dinoflagellate cysts are found tends to con- assemblage recovered firm Traverse’s theory and broadly reinforces our The dominance of spores of ferns, hornworts and liver- paralic environmental interpretation. worts characterises the entire section studied. Crypto- gams require soil with high moisture content to produce gametophytes. Hence, the high abundance of 4. Age of the Ferron Sandstone Member spores suggests deposition in wetlands or hydromor- Previous ammonite and inoceramid biostratigraphical phic floodplain palaeosols, as also suggested by the studies constrained a middle Turonian age for the Fer- sedimentological analysis (Famubode 2014). The ron Sandstone Member (e.g. Peterson & Ryder 1975, occurrence of freshwater algal spores, including Schiz- Cobban et al. 2006). Because of an erosional unconfor- ophacus parvus, Schizophacus sp., Schizosporis sp., Tet- mity between the Ferron Sandstone Member and the ranguladinium sp., Chomotriletes minor and Blue Gate Shale Member above, several ammonite Zygnemataceae, in this section indicates freshwater zones representing late Turonian to late Coniacian input into the depositional environment, most likely time are missing. Additional work performed by Zhu from a fluvial source. The abundance of fungal spores et al. (2012) on bentonite beds refined the age of the also supports a continuously wet tropical climate, espe- Ferron Sandstone Member deposition to between cially in times of peaks in fungal spores. Gymnosperms 91.25 and 90.63 Ma, confirming the existence of an such as Taxodiaceae (including the swamp cypress) important unconformity between the Ferron Sand- and swamp palms are found throughout the Ferron stone Member and the Blue Gate Shale members of the Sandstone Member and are indicative of swamp envi- Mancos Shale Formation. ronments, similar to those found today in South Loui- Several palynostratigraphical events (acmes, FADs, siana, USA. and LADs) are noted in Figure 5. These might prove Gymnosperm pollen, such as Araucariaceae and useful to correlate this section to cuttings, but no paly- Pinaceae that might have inhabited upland areas nological markers allow us to refine the 91.25 to 90.63 (Orlansky 1971, Nichols & Brown 1992), were proba- Ma bentonite age. The recovered gymnosperm and bly transported by wind or/and water to the floodplain. spore taxa, such as species of Cicatricosisporites, Del- The two types of vegetation recovered most likely toidospora and Appendicisporites, have little biostrati- reflect the local floodplain or broader river valley graphical significance due to their long age ranges. The topography, with gymnosperms (other than Taxodia- best palynostratigraphical marker in the Ferron Sand- ceae) being abundant in moist upland areas while cryp- stone Member is the tricolporate angiosperm species togams and angiosperms were growing in relatively Nyssapollenites albertensis. This pollen taxon defines low-lying or swampy areas. the Nyssapollenites albertensis Interval Zone (Nichols There are four main stratigraphical levels marked by 1994, Nichols 1997). The presence of Nyssapollenites occurrences of dinoflagellate cysts, indicating increased albertensis in the studied section thus places it within marine influence and higher sea-surface salinity. These the interval zone indicating a late Cenomanian to early occurrences correspond perfectly to transgressive events Coniacian age. Other species known to be associated defined on the basis of sequence stratigraphic analysis, with the Nyssapollenites albertensis Interval Zone were palaeosol typing (pedostratigraphy) and stacking pat- also identified throughout the section, including Cicatri- terns of fluvial aggradational cycles defined by Famu- cosisporites spp., Classopollis sp., Cupuliferoidaepollen- bode (2014). These most likely indicate transgressive ites sp., Deltoidospora minor, Echinatisporis sp., phases in times of maximum flooding or enhanced tidal Foraminisporis simiscalaris, Gleicheniidites senonicus, influence. Laevigatosporites sp., and Taxodiaceaepollenites hiatus. The absence of the triporate angiosperm pollen Protea- cidites is another indication of the Nyssapollenites alber- 6. Conclusions tensis Interval Zone (Nichols 1994,Braman&Sweet A detailed palynological analysis of the Upper Creta- 2012), suggesting that the age of the section cannot be ceous Ferron Sandstone Member of the Mancos Shale younger than Coniacian. This interval zone has been Formation in Utah was conducted. Palynostratigraphy reported in several formations in Utah and adjacent places the age of the section within the Nyssapollenites areas, including the Frontier Formation in Montana albertensis Interval Zone (Nichols 1994), indicating Palynology 13 that the section is no younger than mid-Coniacian and Batten DJ, Lister JK. 1988. Early Cretaceous dinoflagellate not older than mid-Cenomanian. This supports the cysts and chlorococcalean algae from freshwater and low 91.25À90.63 Ma bentonite-derived ages reported by salinity palynofacies in the English Wealden. Cretaceous Res. 9:337À367. Zhu et al. (2012). Based on the palynomorphs recov- Bercovici A, Pearson D, Nichols D, Wood J. 2009. Biostratig- ered, precise information concerning the depositional raphy of selected K/T boundary sections in southwestern environments and the vegetation that covered the del- North Dakota, USA: toward a refinement of palynological taic area during the middle Turonian was acquired. identification criteria. Cretaceous Res. 30:632À658. Vegetation was dominated by ferns, hornworts and liv- Bhattacharya JP, Tye RS. 2004. Searching for modern Fer- ron analogs and application to subsurface interpretation. erworts, which shared the swamp/floodplain with Regional to wellbore analog for fluvial-deltaic reservoir swamp cypress, cycads and other palm-like trees. modeling: The Ferron Sandstone of Utah. AAPG Studies Abundant freshwater algae and river-bank-indicative in Geology. 50:39À57. species confirmed deposition in hydromorphic flood- Braman DR. 2001. Terrestrial palynomorphs of the upper plain palaeoenvironments. Mangroves were absent Santonian-?lowest Campanian Milk River Formation, southern Alberta, Canada. Palynology 25:57À107. from the assemblage, but their ecological niche was Braman DR, Koppelhus EB. 2005. Campanian palynomorphs. most likely occupied by an extinct species producing In: Dinosaur provincial park: a spectacular ancient ecosys- Classopollis, known to favour lowland coastal areas, tem revealed. Indiana University Press, Bloomington, IN. and the warm climate of transgressive seas. This inter- p. 101À130. pretation is reinforced by the abundance of fungal Braman DR, Sweet AR. 2012. Biostratigraphically useful Late CretaceousÀPaleocene Terrestrial palynomorphs spores, whose high abundance in the air today is often from the Canadian Western Interior Sedimentary Basin. associated with a warm, humid climate. This climatic Palynology 36:8À35. trend, a continuously wet tropical to subtropical cli- Bowman VC, Francis JE, Askin RA, Riding JB, Swindles mate, characterised the entire interval studied. If an GT. 2014. Latest CretaceousÀearliest Paleogene vegeta- important Late Turonian cooling event (as suggested tion and climate change at the high southern latitudes: palynological evidence from Seymour Island, Antarctic from oxygen-isotopic records; e.g.Voigt & Wiese 2000) Peninsula. Palaeogeography, Palaeogeography, Palaeo- impacted the region, it occurred after the deposition of climatology 408:26À47. the interval studied. This time interval might be charac- Brown C. 2008. Palynological techniques. Edited by James terised by a zone of non-deposition, possibly time- Riding (U.K.) and Sophie Warny (LSU). AASP Special equivalent to the hiatus identified between the Ferron Publications; ISBN# 9780931871078. p. 137. Cobban WA, Mckinney K, Obradovich J, Walaszczyk I. Sandstone and Blue Gate Members of the Mancos 2006. USGS Zonal Table for the Upper Cretaceous Mid- Shale Formation. Four episodes of dinoflagellate cyst dle Cenomanian-Maastrichtian of the Western Interior occurrences indicate increased marine influence and of the United States Based on Ammonites, Inoceramids, correlate with previously identified flooding surfaces. and Radiometric Ages. U.S. Geological Survey Open File Report 2006-1250: 1À46. Coetzee J, Muller J. 1984. The phytogeographic significance Acknowledgements of some extinct Gondwana pollen types from the Tertiary of the southwestern Cape (South Africa). Ann Mo Bot Thanks are extended to the Turkish Petroleum Corporation Gard. 71:1088À1099. for providing a scholarship to Isil Akyuz and allowing her to Currie PJ, Koppelhus EB. 2005. Dinosaur Provincial Park: a conduct this Master of Science research project. spectacular ancient ecosystem revealed. Indiana Univer- sity Press, Bloomington, IN; p. 116. Davis OK. 1992. 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