BP Gulf of Mexico Neogene Astronomically-tuned Time Scale BP Gulf of Mexico Neogene Astronomically- tuned Time Scale (BP GNATTS)

J.A. Bergen1, S. Truax III2, E. de Kaenel3, S. Blair4, E. Browning5,†, J. Lundquist6, T. Boesiger7, M. Bolivar5, and K. Clark5 1Paleo at the Hill Country, Brenham, Texas 77833, USA 2Houston, Texas 77070, USA 3DeKaenel Paleo Research, Mont-sur-Rolle, Switzerland 4Blair Biostratigraphy, Cypress, Texas 77429, USA 5BP America, 200 Westlake Park Blvd., Houston, Texas 77079, USA 6Lundquist Stratigraphic, LLC, Houston, Texas 77065, USA 7Nebraska Oil and Gas Conservation Commission, Sidney, Nebraska 69162, USA

ABSTRACT This step change in Neogene resolution, now sponse to exploration focus (Martin, 2013). To- at the level of cyclostratigraphy (the orbital day, planktonic foraminifera and nannofossils This paper introduces an integrated Neo- periodicity­ of eccentricity) and the magneto- are the primary groups used for time correla- gene microfossil biostratigraphic chart de- stratigraphic chron, demonstrates the poten- tion in deep water wells and the construction of veloped within post-merger BP for the Gulf tial for calcareous microfossil biostratigraphy global Cenozoic timescales. Integrated Gulf of of Mexico Basin and is the first published to more consistently reinforce correlations of Mexico (GoM) industrial biostratigraphies and industrial framework “fully-tuned” to or- these time scale parameters. The integration published global biozonations utilizing these bital periodicities. Astronomical-tuning was of microfossil disciplines, consistent taxono- two planktonic groups date back half a century, accomplished through a 15-year research mies, and rigorous analytical methodologies near the inception of a research coring program program on the Ocean Drilling Program’s are all critical to obtaining and reproducing in the world’s deep-sea basins (Deep Sea Drill- (ODP) Leg 154 sediments (offshore NE Bra- this new level of biostratigraphic resolution. ing Project). During this time, many industrial zil) with sampling resolution for calcareous staffs dedicated to the GoM developed their own nannofossils and planktonic foraminifera INTRODUCTION internal Cenozoic biostratigraphic frameworks. ~20 k.y. and 40 k.y. (thousand year), respec- The Deep Sea Drilling Project (DSDP) was later tively. This framework extends from the Late Microfossils are an important, arguably inte- rebranded the Ocean Drilling Program (ODP) in Oligocene (25.05 Ma) to Recent at an aver- gral tool in subsurface petroleum exploration. 1983 and the Integrated Ocean Drilling Program age Chart Horizon resolution for the Neo- Conventional exploration has reached into new (IODP) from 2003 to 2013. gene of 144 k.y., approximately double that regions and basins, while further development Low oil prices from the mid-1980s through of published Gulf of Mexico biostratigraphic takes place in stratigraphically- and structurally- most of the 1990s impacted specialties such charts and a fivefold increase over the high- complicated fields with increased requirements as biostratigraphy. Maintenance of taxonomic est resolution global calcareous microfossil for finer correlation in reservoir intervals (i.e., concepts and methodologies were challenged biozonation. Such resolution approximates the need for increased resolution in the expanded in this business environment. Foraminiferal and that of fourth to fifth order parasequences sections that are typically targeted in offshore nannofossil taxonomic equivalency projects and is a critical component in the verification exploration). Application of published Cenozoic were formed through the Gulf Coast section of of seismic correlations between mini-basins global biozonations (Blow, 1969; Martini, 1971; the Society for Sedimentary Geology (SEPM) in the deep-water Gulf of Mexico. Its utility Okada and Bukry, 1980) in deep-water explora- amidst concerns about biostratigraphic data and in global time-scale construction and correla- tion was not ideal, especially with the combined terminologies (Picou et al., 1999). Around this tion has been proven, in part, by application effects produced by sediment dilution on micro- time, Shell (Styzen, 1996) and Texaco (Law- of the scheme in full to internal research for fossil recovery, different taxonomic concepts, less et al., 1997) published their GoM Ceno- the Oligocene–Miocene boundary interval and varied methodologies. This necessitated zoic charts. The post-Eocene Shell Offshore on the global boundary stratotype section improvement beyond published global bio­zona­ Inc. biozonation established separate enumera- and point (GSSP) in northern Italy and off- tions and stimulated petroleum companies to tions for surfaces represented by the tops of shore wells in the eastern Mediterranean Sea. support research that improved their biostrati- nannofossils and combined benthic-plank- graphic databases and frameworks. tonic foraminif­ era­ events (Neogene resolution †Corresponding author e-mail: emily​.browning@​ The first industrial applications of micro- 307 k.y.) and was related to the time scale of bp.com​ . Other: jbnanno@att​ .net​ , stephentruax@​ fossil biostratigraphy along the U.S. Gulf of Berggren et al. (1995a, 1995b). The Cenozoic comcast​.net, edekaenel@​bluewin​.ch, stacie​.blair81@​ gmail.com​ , JasonLundquist@comcast​ .net​ , tboesiger@​ Mexico Coast began with benthic foraminifera Texaco zonation utilized fossil bases and more nogcc​.ne​.gov, Maria​.Bolivar@​bp​.com, Kendra.​Clark@​ nearly a century ago (Loutit et al., 1988) and down-hole abundance increases in wells to en- bp​.com. progressed from onshore to deep-water in re- hance resolution (271 k.y. for the Neogene).

GSA Bulletin; November/December 2019; v. 131; no. 11/12; p. 1871–1888; https://doi.org/10.1130/B35062.1; 7 figures; 7 tables; Data Repository item 2018407; published online 16 April 2019.

Geological Society of America Bulletin, v. 131, no. 11/12 1871 © 2018 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.

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The Texaco chart referred to the Berggren et al. unified internal framework, completed in 2007, Ceará Rise in the western tropical Atlantic (1985) time scale for the Neogene, but did not aided exploration and development efforts Ocean during ODP Leg 154 recovered an im- specify ages for biostratigraphic markers. Both within the stratigraphically and structurally portant composite cyclostratigraphic reference charts were founded on sequence stratigraphy, complex GoM deep-water (DW). section. The age model derived from ODP showing comparisons to the coastal onlap curve It had long been realized that there were only a Leg 154 cores is based on the astronomically- of Haq et al. (1988), and related to global plank- limited number of published geologic ages avail- tuned cycles (Shackleton and Crowhurst, 1997; tonic foraminifera (Blow, 1969) and nannofossil able for bioevents in GoM industrial schemes. Shackleton et al., 1999; Pälike and Shackleton (Martini, 1971) biozonations. Coupled with the late twentieth century “cyclo­ 2000; Zachos et al., 2001) recalibrated to the Cenozoic stratigraphic research was in the stratigraphic revolution” and the availability of orbital solution of Laskar et al. (2004). This midst of a revolution during the 1990’s. Re- such reference sections, an internal research pro- composite section was sampled by de Kaenel search on, and formal ratification of, reference gram was initiated in 2002 with the goal to de- from the lower Oligocene (30.679 Ma) through outcrop sections known as global boundary rive astronomically-calibrated geologic ages for lower Pleistocene (1.595 Ma) for nannofossils stratotype section and point (GSSP) resulted the entire BP Neogene biostratigraphic frame- (1357 samples) and foraminifera (633 samples) in precise global definitions of stratotype work. Efforts culminated in the first “BP Gulf between 2003–2011. We realize continued boundaries (see stratigraphy​.org). The scaling of of Mexico Neogene Astronomically-tuned Time improvements of the ODP Leg 154 astronom- geologic time shifted from geomagnetic polar- Scale” (BP GNATTS) in early 2007. Subsequent ical-tuning have been published for the up- ity time scales (GPTS) with the first applications research through 2012 extended calibration into per Miocene to Pliocene since 2011 (Zeeden of astronomical “tuning” (Lourens et al.,1996; the lower Oligocene through sampling and study et al., 2013; Drury et al., 2017; Wilkens et al., Laskar et al., 2004) of sedimentary cycles in the of the base Neogene GSSP in northern Italy and 2017) and that problems remain with the or- construction of higher temporal resolution Late ODP Leg 154 cores, offshore NE Brazil (Fig. 1). bital tuning of the Early Miocene (see Hilgen Neogene timescales (see Hilgen et al., 1997). In 2016, efforts were refocused on publication et al., 2012; Ogg et al., 2016), both of which Today, Neogene calcareous microfossil bio­zona­ of BP GoM taxonomy and biostratigraphy, in- could affect age estimates for the ODP Leg 154 tions (e.g., Backman et al., 2012) are founded cluding new research on ODP Leg 154 materials samples by as much as 100 k.y. We have main- almost entirely by astronomical ages. Although to more thoroughly document biostratigraphic tained the integrity of the astronomically-tuned the accuracy and precision of ages for Neogene events for publication. age model used by de Kaenel, when he sampled planktonic microfossil events also improved by the ODP Leg 154 cores at the IODP repository an order of magnitude with these techniques, MATERIALS in Bremen, Germany. This makes direct corre- the resolution of global biozonations (~750– lation and comparison to Neogene nanno­fossil 1200 k.y.) are still coarser than the lower limits Localities (see Backman et al., 2012) and planktonic of astronomical tuning achieved by the dominant foraminifera (see Wade et al., 2011) bioevent 405 k.y. eccentricity cycle (see Hinnov, 2013). There are several thousand wells in the BP ages derived from these cores possible. It also Advances in timescale construction, com- GoM biostratigraphic database. The vast major- maintains synchronic­ ity­ with nannofossil bio- bined with the upswing in oil prices around the ity are located onshore and on the continental event ages published recently in the Journal of beginning of the twenty-first century, provided shelf; several hundred wells are located in deep the Nannoplankton­ Research (Bergen et al., new opportunities for industrial biostratigraphy water. Deep-water exploratory drilling began in 2017; Blair et al., 2017; Boesiger et al., 2017; in the GoM. BP America staff from the three the 1970s and encountered progressively older Browning et al., 2017; de Kaenel et al., 2017). heritage companies (BP, Amoco, and Arco section through time. By the 1990s, several ma- The ODP Leg 154 sites 925–929 were chosen Vastar) were charged with producing a single jor DW Miocene reservoirs had been discovered because of their geographic proximity to the Neogene GoM chart from three independently- in the GoM. GoM and because individual samples could be derived GoM biostratigraphic frameworks. Staff Age calibration of the GoM Neogene bio- equated to geologic time. They are referred to exchanged taxonomic concepts and method- stratigraphic framework was based on the study herein by their geologic age; individual sample ologies, which accounted for some differences of ODP core materials (Fig. 1) in the western information is given in the range charts (www​ between company schemes; remaining discrep- Atlantic Ocean (ODP Leg 154) and western .Pangaea.de​ ). The remainder of the Pleistocene ancies were solved through in-house analyses Mediterranean Sea (ODP Leg 161). Five sites is calibrated to the orbital time scale based on of well samples. The resulting improved and (925–929) drilled as a depth transect on the the nanno­fossil biostratigraphy (de Kaenel

120°0′0″W 90°0′0″W 60°0′0″W30°0′0″W 0°0′0″ 30°0′0″E

Lemme-Carrioso

Leg 161; Atlantic Sites 974-977, 979 30°0′0″N Figure 1. Locality map of mate- Ocean Gulf of Mexico: rials used in this publication. \

Leg 154; Sites 925-929

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et al., 1999) from ODP Leg 161 sites 974–977 because microfossil abundance estimates are The final critical factor to achieving our re- and site 979 in the western Mediterranean Sea. fundamental. ALS Ellington and Associates, sults was the setting. These innovations were The BP GNATTS framework has been ex- Inc. (Houston, Texas, USA) prepared all well possible because the biostratigraphy team tended to the Mediterranean for the Oligocene– samples and foraminifera ODP core samples, worked together daily in an integrated environ- Miocene boundary interval. The first Mediter- whereas ODP core samples taken for nanno­ ment with geologists and geophysicists. These ranean locality is the base Neogene GSSP of fossils were prepared by the research scientists. interactions gave biostratigraphers time to share Lemme-Carrosio in northern Italy (Bergen Historically, BP utilized microfossil abundance concepts, identify business needs, fully integrate et al., 2009; de Kaenel and Villa, 2010). Thirty- peaks in well correlation and the identification biostratigraphy with the description of the sub- nine samples were collected from this section of event horizons within these peaks for use in surface (geology), and provide essential one-on- in Fall 2008 with aid from the University of basin-wide and field scale schemes. This meth- one training for the next generation. Parma. Biostratigraphic research on the GSSP odology is outlined in Armentrout (1996). Biostratigraphic events derived from sample was completed in 2009 and the nannofossils re- Time is the most determinative factor in sam- analyses are often evaluated relative to their examined in late 2017 as part of this study. The ple analyses because fossils are very rare at the resolution, reliability, and synchronicity. Reso- second location in the eastern Mediterranean ends of their stratigraphic ranges. In clastic set- lution is defined herein by the number of events Sea are three exploration wells analyzed by the tings such as the GoM, analysis times are skewed per unit of geologic time. Sample resolution first two authors. toward samples within abundance peaks, which is the number of samples per unit of geologic maximizes results and makes it possible for an time. For ODP Leg 154, where samples are Data experienced analyst to average up to two sam- related to geologic time through cyclostrati- ples per hour. For pelagic and hemipelagic set- graphic methods, sample resolution equates to Foraminifera taxonomy is based on heritage tings, collecting accurate abundance estimates the precision of derived bioevents and estimates company concepts and supplemented with and range data for rare taxa from fossil-rich as- of error in their geologic age. Reliability refers the standard industry concepts in Picou et al. semblages is more time consuming. to bioevents either within a biostratigraphic (1999). The BP taxonomic concepts and bio- The primary ODP Leg 154 research was done scheme or an individual well or section. For stratigraphy for 204 Oligocene–Recent nanno- by Eric de Kaenel and Jim Bergen for nanno­ BP GNATTS, the reliability of biostratigraphic fossil species were recently published as a series fossils (1202 samples), Sheila Barnette and markers is evaluated relative to the number of of five papers in the Journal of Nannoplankton Steve Truax for foraminifera (618 samples). times a bioevent has been reproduced in se- Research (Bergen et al., 2017; Blair et al., 2017, The remaining authors re-examined selected quence between wells. For events used by all Boesiger et al., 2017; Browning et al., 2017; research samples in the months prior to comple- three heritage companies in the GoM, marker de Kaenel et al., 2017), including 70 new spe- tion of an internal 2007 GoM Neogene chart and events in these schemes have been tested in hun- cies. Photographic plates of the BP GNATTS again for this publication. For nannofossils, 45– dreds to possibly thousands of wells. For post- nannofossil markers species are included in the 60 minutes were typically needed to document merger BP, largely in the DW GoM, marker supplementary materials (Plates S1–S9)1. Also rare “marker” taxa, corresponding to ~1000 events in BP GNATTS have been tested in tens included in the Supplementary Materials are the fields-of-view at 1000× magnification. For to hundreds of wells. The reliability of a micro- following data tables: (1) the BP GNATTS cali- planktonic foraminifera, similar analysis times fossil top (highest occurrence) or base (lowest brations for chart horizons and events (Table S1; are recommended. Barnette examined 519 sam- occurrence) in an individual section (well, core, see footnote 1); (2) BP taxonomic equivalencies ples from the upper Oligocene (24.303 Ma) to or outcrop) is also related to its persistence in (Table S1); and (3) Pleistocene ODP Leg 161 lower Pliocene (4.128 Ma). BP staff examined occurrence. Taxa that are very rare and sporadic nannofossil events (Table S2; see footnote 1). 253 samples for the presence/absence of marker in occurrence at the ends of their stratigraphic All supplemental information (Plates S1–S9 and species, while also extending stratigraphic cov- ranges are considered less reliable. Such taxa Tables S1–S2) is available in the GSA Data Re- erage into the upper Oligocene (24.900 Ma) and are certainly less desirable as marker events pository, as well as a full-sized pdf of Figure 22 lower Pleistocene (1.720 Ma). in biostratigraphic schemes, especially if they (see footnote 1). All stratigraphic range chart Abundance estimates (total assemblage and are sporadic in occurrence in fossil-rich sec- data from the Italian GSSP for nannofossils­ and individual taxa) are routine for well and re- tions (e.g., ODP Leg 154 cores) not affected by foraminifera (Tables S3–S4) and ODP Leg 154 search analyses. For nannofossils, the cascading sediment dilution. Bioevents defined by signifi- (Tables S5–S23) are stored in the Pangaea web count system of Styzen (1997) is GoM industry cant abundance changes in taxa are determined database (www​.Pangaea​.de). standard (specimens/100 fields of view esti- more quickly in sample analyses, but must be mates) outside of BP. Within BP, a 0–100 based evaluated relative to facies changes. This is cer- METHODS counting system has been employed for decades tainly true in a large sedimentary basin such as for the sole practical purpose in having to work the GoM, where lateral changes in microfos- The preparation and examination of samples with hardcopy histogram data (estimates based sil abundances can occur between an original are two critical factors to results. Consistency on specimens per field-of-view at 1000×). For wellbore and its bypass or sidetrack hole. The is of primary importance in sample preparation foraminifera, relative abundance categories synchronicity of microfossil events used in BP (10 categories between Present to Flood, with GNATTS has been tested in a number of ways. 1GSA Data Repository item 2018407, Tables S1 quantitative values estimated within categories) First, is their reproducibility in sequence within and S2 and Plates S1–S9, is available at http://​www​ per BP standard were used in well analyses and an enumerated Neogene framework having an .geosociety​.org​/datarepository​/2018 or by request to the original research. The foraminifera research average resolution of 144 k.y. Second, is their editing@​geosociety​.org. Tables S3–S23 are stored in data was converted to presence/absence for this application within much higher resolution bio- the Pangaea web database (www​.Pangaea.de). 2Figure 2 is on a separate sheet accompanying this publication because it was not possible to nor- stratigraphic frameworks at field scale or indi- issue, and a PDF of the figure is also included in the malize all count data from different researchers vidual well bores, where correlations are fur- Data Repository. over a fifteen-year time span. ther constrained by geologic log correlations.

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Third, is that the large majority of events in BP has evolved somewhat haphazardly. Letter des- HO GNATTS (~86%) have been reproduced in se- ignations refer to the Pleistocene (PS), Pliocene quence from research on cores in the western (P), Miocene (M), and Oligocene (O) Epochs. tropical Atlantic Ocean (ODP Leg 154) and Horizons within each epoch are then numbered HRO western Mediterranean Sea (ODP Leg 161). bottoms-up, akin to global biozonations. Epoch HIO enumerations in the original BP framework HFO RESULTS ranged from 1 to 100, but this is no longer true e because epoch boundary criteria have changed HCO The BP Gulf of Mexico Neogene Astro- over the decades. Some Chart Horizons are sub- nomically-tuned Time Scale (BP GNATTS) is divided into upper (U) and lower (L) and/or sub- HAO presented in Figure 2 and a more detailed digi- divided by lettering (from A to D), both in a top- LAO tal version is available in the Supplementary down sense. Horizons not yet proven across the ’ abundanc Materials (Table S1). The chart extends into entire basin are referred to as “Locals.” For the the Paleogene, including ~2 m.y. of the Late Neogene, there are 160 Chart Horizons and 14 LCO Oligocene. The following summarize the BP Locals. Eight Oligocene Chart Horizons (O85- LFO GNATTS chart. O75) are also included on BP GNATTS. Species Historically, GoM microfossil events have LIO Terminology been limited to fossil tops (highest occurrences) LRO and abundance increases (in a down-hole or Stratigraphic Terminology drilling sense) because ditch-cuttings routinely In 2009, the International Union of Geo- “cave” down the well bore. Down-hole cav- LO logical Sciences (IUGS) ratified the Quater- ing is less problematic in modern DW GoM Figure 3. Idealized abundance distribution nary System (Period) as a formal stratigraphic wells relative to those drilled before the lat- of an individual species. HO—highest oc- unit (Gibbard and Head, 2010), truncating the ter part of the twentieth century. We speculate currence; LO—lowest occurrence; HRO— top of the Neogene System and abandoning that this could be due to the use of synthetic highest regular occurrence; LRO—lowest the informal term Tertiary. We have chosen a muds that do not break down the ditch-cutting regular occurrence; HIO—highest increase twofold division of the Cenozoic, referring the samples and by improved drilling parameters occurrence; LIO—lowest increase occur- Miocene through Holocene Series (Epochs) to and pressure predictions. Remobilization and rence; HFO—highest few occurrence; the Neogene, following decades of conventional redeposition of sediments, the latter referred LFO—lowest few occurrence; HCO—high- use in marine micropaleontology and that advo- to as reworking by microfossil specialists, are est common occurrence; LCO—lowest cated by Hilgen et al. (2012) for the Neogene more problematic in a terrigenoclastic basin common occurrence; HAO—highest abun- Period. To us, the terms Quaternary and Tertiary with salt tectonism such as the GoM. In the dant occurrence; LAO—lowest abundant should be paired and are an alternate way to sub­ GoM, the reworking of microfossils is most occurrence. divide the Cenozoic. For further clarification, often observed as sporadic occurrences of rare we also follow Hilgen et al. (2012) by placing specimens involving only a few species. Such the Pliocene–Pleistocene boundary at the top, processes are easier to recognize in wells when as opposed to the base, of the Gelasian Stage. applying a much higher resolution biostrati- section) are based on microfossil appearance We have maintained an age of 23.03 Ma for graphic scheme such as BP GNATTS, which or extinction events, including all zonal bio- the Oligo­cene–Miocene boundary, following then provides a foundation for still higher reso- events for planktonic foraminifera. For nanno­ both Hilgen et al. (2012) and Ogg et al. (2016). lution biostratigraphic schemes developed for fossils, age estimates in the Backman et al. Stadial terminology is not typically used in the expanded reservoir sections in the GoM. When (2012) biozonation were chiefly derived from GoM Basin, where Series/Epochs (e.g., Plio- all this is considered along with the consistency astronomically-tuned cyclostratigraphies using cene) are the basic stratigraphic units. provided in sample preparations, it is now pos- the semiquantitative methods of Backman and sible to more fully utilize the entire abundance Shackleton (1983). These counting methods Horizons and Event Terminology profile of individual species (Fig. 3) in correla- provide precise and reliable bioevents that are BP biostratigraphic Chart Horizons are both tion. Biostratigraphic resolution can be further easily determined; however, they emphasize chronostratigraphic terms and mappable sur- improved by utilizing non-standard marker taxa speed, which is counter-intuitive to document- faces in the GoM. In application, a Chart Hori­ and describing new species. ing the rare and sporadic occurrences that typify zon (Fig. 2) is a surface that includes section The documentation of fossil appearances the stratigraphic extremities of individual spe- down to the top of the next Chart Horizon (a top- (first occurrences) and extinctions (last occur- cies. We believe these semiquantitative methods down or drilling sense). A biozone is bounded rences) in a stratigraphic section is of primary actually have produced both initial and final by two surfaces and its application functions in importance, where they are expressed as low- abundance changes as proxies for nearly all of a similar manner. A BP biostratigraphic Chart est occurrences (bases) or highest occurrences the Neogene nannofossil appearance and extinc- Horizon is set apart from a biozone in that it (tops), respectively. Two-thirds of the micro- tion events in Backman et al. (2012). Thus, we is multidisciplinary (i.e., both nannofossil and fossil events used in BP GNATTS are lowest introduce two biostratigraphic events for these foraminifera events) and often utilizes multi­ or highest occurrences, with the latter being abundance changes: (1) the lowest increase oc- ple event criteria and intra-horizon (or intra- far more predominant. Ninety percent of the currence for the initial abundance increase; and zonal) events. bioevents utilized among the six Neogene cal- (2) the highest increase occurrence for the final The terminology of BP GoM Chart Horizons careous microfossil biozonations discussed abundance decrease. This fundamental differ- has a long history prior to the BP mergers and herein (see “Calibration, Global Biozonations” ence of opinion about the stratigraphic expres-

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sion of nannofossil appearances and extinctions Top-down Bottoms-up Top-Down Bottoms-Up explains why many of our geologic ages are outside those ages presented in Backman et al. S (2012), many of which were derived from the DEC same reference cores (ODP Leg 154). S D/S The following standard abbreviations (Figs. 3 INC HIO and 4) are used for bioevent terminology: LO (lowest occurrence) and HO (highest occur- S/D D rence); abundance modifiers are: R (regular or persistent) for LRO and HRO, I (increase) LIO INC D for LIO and HIO, F (few) for LFO and HFO, C (common) for LCO and HCO, A (abundant DEC RA Wells Outcrop or acme) for HAO and LAO, and Ab (absence) Drilling Core for LOAb and HOAb. Other paired terms uti- EXIT HOAb lized herein include EXIT and RE (re-entry), Figure 5. Planktonic foraminifera coiling disappearance (DA) and reappearance (RA), LOAb DA changes top-down and bottoms-up. S— and increase (INC) and decrease (DEC). For sinistral; d—dextral. planktonic foraminifera, coiling directions are RE abbreviated as S (sinistral) or D (dextral). Event terminology is in a “top-down” or “down-hole” type (e.g., HRO or HIO, respectively) in the sense because of its use in drilling (Figs. 4 and Wells Outcrop research. Associated ages are those assigned 5). These terms should not be confused with Drilling Core ages only through correlations established in those used in a “bottoms-up” or depositional the GoM framework; all benthic foraminifera sense for deep-sea research cores (DSDP, ODP, Figure 4. Top-down and bottoms-up event events fall into this category. Bioevent ages de- IODP) and outcrops (see Appendix). terminology. Inc—increase; Dec—decrease; rived from sampling of ODP Leg 154 and Leg Abundance categories for calcareous nan- RE—re-entry; HIO—highest increase oc- 161 are maintained at three decimal precision, nofossils (Fig. 3) are based on estimates of the currence; LIO—lowest increase occurrence; when expressed in mega-annums (Ma). Errors number of specimens per fields-of-view (FOV) LOAb—lowest occurrence of absence; for these ages are the differences in assigned at 1000× magnification, where from lowest HOAb—highest occurrence of absence; ages for the next sample analyzed upwards or to highest are: P (present) being 1 specimen DA—disappearance; RA—reappearance. downwards in the composite section (Supple- in >100 FOV; R (rare) then being 1 specimen mentary Materials; Tables S5–S16, S18–S23). in ≤100 FOV; F (few) then being 1 specimen in Most of the 174 Chart Horizons (includ- ≤10 FOV; C (common) then being ≥1 specimen ample, when stating “a well has penetrated the ing Locals) are defined by multiple events and per FOV; and A (abundant) then being ≥10 spec- Oligocene.” Various GoM microfossil events various combinations of events from each of the imens per FOV. that have been used to pick the top Oligocene three microfossil groups. The age for a Chart vary over 3.55 m.y. (Bergen et al., 2009), repre- Horizon is the youngest geologic age deter- Calibration senting the interval spanned by BP Horizons M4 mined for either a planktonic foraminiferal or to O79 (Fig. 2). Within BP, this boundary has calcareous nannofossil event associated with Stratigraphic Boundaries moved from a purely lithologic definition in the that Chart Horizon (Fig. 2; Table S1). Direct age We have used the ages for stage boundaries in twentieth century (M4/old O90), to a “global” calibrations to ODP Leg 154 have been made accordance with the most recent geologic time definition in 2001 (O80), to where it is now and for 86% of the Chart Horizons. An extreme scale of Ogg et al. (2016), who followed the calibrated internally to both the base Neogene example of an indirect calibration would be IUGS and positioned the base of the Pleistocene GSSP in northern Italy and the ODP Leg 154 Horizon­ M82, where the HO of the nannofossil Series—and Quaternary System—at the base of chronometer between Horizons LM3C and O85 Disco­aster bellus in the GoM has been tied to its the Gelasian Stage. However, we have chosen (old M2). HCO in the ODP Leg 154 research. to maintain a 3-fold subdivision of the Pliocene There are 468 Neogene events on BP and place the Pliocene-Pleistocene boundary at Horizons and Events GNATTS, which yielded an effective resolu- the top of the Gelasian. This conforms to place- The geologic ages for BP GNATTS were tion of 101 k.y. for nannofossil events, 397 k.y. ment within previous GoM charts (Shell and derived through orbital scaling of ODP Leg for planktonic foraminifera events, and 344 k.y. Texaco) and global planktonic foraminifera and 161 (Horizons PS107-LPS60) and ODP Leg for benthic foraminifera. About 60% of these nannofossil biozonations. 154 (Horizons PS50-O75) based on our inter- events are fossil tops. Chart Horizon resolution Industrial historic placement of Neogene nal research on these cores. The base Holocene is highest in the Pleistocene (67 k.y.) and lowest ­Epoch boundaries in the GoM Basin are litho- age is assigned to PS108. Direct ages are those in the Early Miocene (261 k.y.)—also typical of logic, corresponding to major mappable seismic based on the same type of event in both the re- global calcareous microfossil biozonations and surfaces. Placement of microfossil biostratigra- search and the GoM. For example, the highest other GoM frameworks. phy relative to these surfaces has varied among occurrence (HO) of the nannofossil Discoaster companies, partially caused by different global brouweri is used in both BP GNATTS and the Global Biozonations usages of boundary microfossil criteria. This research on the ODP Leg 154 cores. Ages are BP’s routine application of fossil bases in has sometimes caused confusion in communi- considered indirect when a GoM event (e.g., GoM wells enabled full calibration to global cation between companies and partners; for ex- HO or HCO) is sequenced to different event biozonations, which are weighted toward fossil

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appearances. Three nannofossil biozonations sil biozonations, the latter also within the GoM schemes. It doubles stratigraphic resolution are included on BP GNATTS. Emendations Basin. When operating ~100 k.y. resolution, relative to published industrial GoM Neogene of the NN zonation of Martini (1971) have re- it is necessary to more precisely define taxa. biostratigraphic charts (Styzen, 1996; Lawless sulted in additions of Neogene subzones (Rio For example, the total range of the nannofos- et al., 1997) and is distinguished from all other et al., 1990b; Raffi and Flores, 1995; Blair sil Discoaster hamatus­ defines an upper Mio- industrial schemes by being “fully-tuned” et al., 2017) and a new zone (NP26) at the cene zone used in all three Neogene schemes to orbital periodicities. Neogene resolution top of the Paleogene (de Kaenel et al., 2017). (NN9, CN7, CNM13). Our stratigraphic range for nannofossil events marking BP GNATTS These emendations yield 794 k.y. resolution for for larger specimens (>15µm) is 1.512 m.y. Chart Horizons is 142 k.y., whereas the effec- the Neogene. The CN zonation of Okada and (Browning et al., 2017), 0.67 m.y. longer than tive resolution for all nannofossil events on BP Bukry (1980) has comparable Neogene reso- reported by Backman et al. (2012). For even GNATTS is 101 k.y. These are five- and four- lution (853 k.y.) and shares many events with smaller specimens of Discoaster hamatus, the fold increases in resolution relative to the zonal Martini (1971). The CNM-CNPL zonation of total stratigraphic range is estimated around and event level resolution of the Backman et al. Backman et al. (2012), although no significant 2.280 m.y. in the ODP Leg 154 cores. (2012) global scheme. For planktonic forami­ improvement in zonal resolution (743 k.y.), Three planktonic foraminifera biozonations nifera, Neogene resolution on BP GNATTS made significant changes; they proposed 13 are included herein (Fig. 2). The emended N-P Chart Horizons is 435 k.y., doubling that of the new zonal markers for their 31 zones, but Blow (1969) zonation (Fig. 2) has 1152 k.y. res- highest resolution global biozonation of Berg- did not consider 11 historical markers in the olution for the Neogene. The M-Pl-Pt zonation gren et al. (1995a, 1995b). two aforementioned schemes. Backman et al. of Berggren et al. (1995a, 1995b), which has BP GNATTS has utility beyond a biostrati- (2012) presented geologic ages for 58 Neogene 886 k.y. resolution, listed 135 Neogene events graphic framework for the GoM Basin, where events (397 k.y. resolution) dated mostly by calibrated to the GPTS of Cande and Kent it has impacted the entire value chain in the cyclostratigraphic methods; all but four of their (1995). Wade et al. (2011) drew from many GoM from exploration to production and is the Neogene ages were derived from ODP Leg 154. sources, the ultimate being British Petroleum, foundation for yet higher resolution, reservoir Raffi et al. (2016) later combined the Backman and summarized the history of tropical and sub- biostratigraphic frameworks. BP GNATTS has et al. (2012) zonation with the Paleogene zona- tropical Neogene planktonic foraminifera zona- been tested in selected portions of the geologic tion of Agnini et al. (2014), which is applied to tions. They listed 108 Neogene events and their column outside the GoM Basin, in both research the Oligocene herein. sources alongside the ages of Berggren et al. and industrial settings. Extending this improved We have derived ages for all zonal and sub- (1995a, 1995b). The Wade et al. (2011) ages are resolution geographically has new found appli- zonal events in each of the three nannofossil used herein, in conjunction with those derived cation for the interpretation and correlation of biozonations shown on BP GNATTS from our from in-house research on ODP Leg 154 cores cyclostratigraphic, magnetostratigraphic, and internal research. This information is sum- (Table 2). The upper Oligocene zones (P22, O6, eustatic records. marized in Table 1, along with all remaining O7) on BP GNATTS are extensions of the three nannofossil­ events presented in Backman et al. aforementioned Cenozoic frameworks into the Within the GoM (2012). We share 47 dated events from ODP Paleogene. Significant differences in age deter- Per BP methodology, microfossil abun- Leg 154 sites (including the Oligocene) with minations for planktonic foraminifera bioevents dance peaks are the fundamental unit used in Backman et al. (2012), but have significant age between Wade et al. (2011) and our internal correlations. In theory, biostratigraphic reso- differences (>100 k.y.) for 22 events. As previ- research, as with the nannofossils, are best ex- lution is then only limited by the number of ously discussed, our methodology that under- plained by methodology and taxonomy. abundance cycles that can be uniquely defined pins BP GNATTS—investing significant sam- by their microfossil content and stratigraphic ple examination time to establish nannofossil Curves position. The influence of facies on microfos- appearances and extinctions—is responsible for Three columns outside biostratigraphy were sil recovery and preservation is usually a pri- our longer­ stratigraphic ranges. More restricted included for reference and calibration. The mary practical limitation on biostratigraphic taxonomic concepts can be invoked to explain Earth’s major orbital eccentricity periodici- resolution, affecting the abundances of spe- why we may have established shorter strati- ties (~100 k.y. and 405 k.y.) derived from the cies to entire microfossil groups, as well as graphic ranges. For example, Curry et al. (1995) Laskar et al. (2004) solution are shown near the number of taxa that may be utilized in dated the LO of the nannofossil Helicosphaera the left side of BP GNATTS. Geomagnetic correlations. This is less problematic in DW ampliaperta­ at 20.43 Ma in Hole 926B (ODP polarity appears to the left of the orbital scale GoM Neogene, although significant changes Leg 154), whereas our determination in Hole (from Ogg et al., 2016; Hilgen et al., 2012). The in facies affecting microfossil recovery and 926B for this event was 19.115 Ma (Boesiger eustatic sea level sequences and transgressive- diversity can exist between an original hole et al., 2017). However, we determined the LO regressive cycles at the right side of the chart and its sidetrack or bypass holes. One of the for a very similar species, Helicosphaera scis- are calibrated to BP GNATTS through Time­ most important influences on stratigraphy in sura, at 20.350 Ma and comparable to the age Scale Creator GTS 2016 by Purdue University, DW GoM is salt tectonism. This structural determined by Curry et al. (1995). Four nanno­ West Lafayette, Indiana, USA, (engineering​ component affects the placement, orienta- fossil bioevents have discrepancies greater .purdue.edu​ /stratigraphy​ /tscreator​ ) founded on tion, and continuity of stratigraphic section. than one million years between Backman et al. the SEPM Chart #2 by Hardenbol et al. (1998). The effects of salt can be dramatic, involv- (2012) and our study. We have suggested alter- ing thousands of feet of repeated, folded, native event types or taxonomic fixes for all such DISCUSSION or inverted section. The mixing of fossil as- discrepancies (Table 1). We believe only the semblages and remobilization of sediments HO of Helicosphaera recta (base Zone NN1) BP GNATTS is a step-change in strati- through salt movement must always be con- and the HO Triquetrorhabdulus­ carinatus­ (base graphic resolution (144 k.y.) relative to sidered in biostratigraphic analyses and inter- Zone NN3) are problematic in global nannofos- pub­lished Neogene calcareous microfossil pretations in the GoM.

1876 Geological Society of America Bulletin, v. 131, no. 11/12

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Br Br Br Br Br Br de K de K de K de K vised Br vised Br vised Br vised de K this study: this study: this study: this study: this study: re Boesiger et al. re re re .) or d d d Err (m.y 0.012 0.010 0.014 0.017 0.021 0.003 0.023 0.008 0.021 0.008 0.017 0.015 0.024 0.014 0.008 0.020 0.027 0.020 0.014 0.026 0.012 0.017 0.017 0.024 0.022 0.020 0.024 0.013 0.021 0.026 0.028 0.020 0.017 0.021 0.021 0.035 0.010 0.024 0.028 0.012 0.007 0.019 0.031 0.027 0.027 0.024 e/ Sit 977A 926A 926A 926B 926B 926B 926A 926C 926B 926B 926A 976A 926C 926C Hole 977A 926B 926A 926C 976 975B 926A 975 977 926A 926A 974 979 926B 926B 926C 926B 926B 926A 926B 926B 926C 926A 926B 926C 926A 926B 926B 926B 926C 926B 926B 926C 926A 926C 926A 926B 926B 926C 926C 926B e Ag (Ma ) 0.070 5.244 5.258 4.978 5.076 7.646 9.689 2.729 4.812 8.785 5.354 0.218 3.510 3.588 0.275 4.927 5.340 3.531 0.962 0.424 3.727 1.525 1.235 5.389 3.819 1.566 1.246 4.978 4.102 1.607 4.445 5.059 5.440 1.698 4.644 1.898 5.147 5.981 1.924 5.232 6.930 2.024 7.086 2.144 7.236 7.265 2.286 7.374 2.511 7.559 7.667 8.261 8.317 8.317 8.738 BP .) ence r TES 0.03 0.23 0.02 0.10 0.02 0.02 0.02 0.01 0.09 0.00 0.00 0.02 0.10 0.02 0.09 0.01 0.03 0.07 0.00 0.00 0.14 0.18 0.00 0.02 0.10 0.02 0.02 1.15 fe (m.y –0.02 –0.01 –0.06 –0.01 –0.06 –0.66 –0.11 –0.15 –0.17 –0.12 Dif TIMA 9 2 2 2 2 e . . . . . ig ig ig ig ig 2.76 5.04 5.33 3.61 0.29 5.36 0.43 3.82 5.39 1.59 1.06 1.14 0.91 5.08 1.25 1.24 4.04 1.60 5.53 1.71 1.93 5.22 5.98 4.58 5.23 2.16 6.82 5.26 7.09 2.39 2.53 7.39 8.20 8.80 Ag (Ma ) GE ES A 9 e/ . ig 607 Sit Hole 653A 926C 926B 926A 925B 926A 926C 926A 926A 926C 926B 926C 926C 926C 926C 926C 926C 926C 926B 926A 926A 926C 926A 926A 926B 926A 926B 926A 926C 926A 926B 926B/C i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) i (1997) f f f f f f f f f f f f f f f (2012 )F (2012 )F (2012 ) (2012 ) (2012 )F (2012 )F (2012 )F (2012 )F (1995 ) (1995 ) (1995 ) (1995 ) (1995 ) (1995 ) (1995 ) (1993) ce (1990a) i (2002) i (2002) i (2002) i (2002) i (2002) i (2002) i (2002) f f f f ff ff ff Sour af af af af i et al. y et al. y et al. y et al. y et al. y et al. y et al. y et al. f Ra Ra Ra af kman et al. kman et al. kman et al. kman et al. kman et al. kman et al. kman et al. kman et al. urr urr Rio et al. Curr Curr Curr Curr Curr kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf kman and Raf ac ac ac Bac Bac Bac Bac Bac ac ac Bac Bac Bac Bac Bac Bac Bac Bac Bac Bac Bac Bac Bac AL NEOGENE NANNOFOSSIL BIOEVENT OB kman GL et al. (2012) CNPL5 CNPL2 CNPL1 CNPL4 CNPL9 CNPL3 CNPL8 CNPL7 CNPL6 CNM20 CNM19 CNM18 CNM17 CNM16 CNM15 CNPL1 1B CNPL1 0R Bac y ABLE 1 . T ada CN15 CN8B CN9B CN9A CN9A CN8B (1980) Ok CN12B CN10B CN12 A CN14B CN12A CN14 A CN11B CN10A CN13 BR CN11 A CN13A CN11 AB CN10 BB CN10C CN10 CB CN10C CN12D CN12 CC and Bukr tini NN14 NN20 NN16 NN13 NN13 NN15 NN18 NN17 (1971) Mar NN19F NN21 B NN12B NN21A NN19 E NN19E NN19 ER NN12A NN19B NN19A NN19 A NN11B NN19 DR NN19 D NN11 A NN19C nt O O O O Ab s. Ab s. Ab s. ve LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO LIO LI O LF O LR LR LC OR LCO LC OC LC OB HFO HR HCO ODec. LO L HO HO HODec. 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ent ages ; s. CN2 CN4 CN3 CN6 O—lo CN4 CN4 CN1B CN1A CN7A CN8A CN5B CN5B CN7B CN5A CN1C (1980) Ok ABLE 1. L er O—highest ab T and Bukr HA der of ev tini nal ma rk minology: NN3 NN3 NN1 NN2 NN9 NN1 NN1 NN4 NN7 NN8 NN6 NN5 NP26 r NN10 (1971) Mar y zo nt te O) ve nt O O O ve LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO LI O LI O LI O pancy in the or HIO HIO HIO O (L HIO HIO LF O r LCO and HCO; LR LCO LC OB HA HCO HR HCO HCO HCO HCO CrOv r bioe LR e secondar disc re ar ey e used fo er i rt i i (Atlantic) a a i i C—common fo hus hus hus re re re re tis / ca a rinatus rinatus rinatus i at ensis ensis mo rp mo rp mo rp viations ar mis a r e ro ro ro scen s adiatu s ct ined ages indica te li fo ar llis a pseudoumbilicus emacin ty emacin ty scissu ra euph ra trunc ampliapert re ampliapert emacin ty emacin ty lyculu s lyculu s lyculu s abdulus ca abdulus ca abdulus ca ents shaded in light gr r druggii (≥15 µm) r signus r hamatu s r hamatu s r hamatu s r pe ta r druggii (≥10–15 µm) r pent r kugleri r kugleri r hamatu s r kugleri r neohamatus r bellu s r defland re Unde rl clus ni te r LFO and HFO; enestr rh rh rh wing abbr er ca er coalitus er coalitus er ca er coalitus er ca golithus abisectus golithus floridanu s golithus floridanu s golithus floridanu s fo : Ev llo ar ar ar ar no cy ided). ew ylitha con va ticulof clic clic clic clic No te ov riquet ro riquet ro riquet ro Helicosphae ra Helicosphae ra Sphenolithus belemnos Helicosphae ra Sphenolithus delphix Specie sE Sphenolithus belemnos T Discoas te Cy Helicosphae ra Sphenolithus delphix Coccolithus miopelagicus Discoas te T Discoas te Discoas te Sphenolithus cipe ro Min Discoas te T Sphenolithus delphix Discoas te Discoas te Sphenolithus cipe ro Discoas te Sphenolithus disbelemno s Calcidiscus pr Discoas te Calcidiscus pr Helicosphae ra Catinast pr Sphenolithus disbelemno s Sphenolithus he te Discoas te Catinast Discoas te Sphenolithus belemnos Discoas te Catinast The fo Catinast Cy F—f Cy Catinast Co ro Catinast Discoas te Calicidiscus pr Discoas te Calicidiscus pr Re Cy Sphenolithus he te Sphenolithus he te Helicosphae ra Discoas te

1878 Geological Society of America Bulletin, v. 131, no. 11/12

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(Ma ) 3.343 3.019 3.019 3.233 1.945 2.968 3.19 1.983 2.236 2.361 2.659 2.024 2.286 3.233 4.79 4.504 4.907 6.212 9.452 4.315 4.978 8.343 6.058 4.354 4.39 6.338 3.861 3.957 BP age 23.39 5 22.438 23.308 20.670 20.670 20.312 17.259 18.69 4 14.539 13.69 3 13.649 12.774 16.579 12.048 14.054 12.857 14.29 8 16.49 8 16.258 11.812 10.49 2 11.410 14.69 7 e/Hole .) TES ence west common occurr r 0.34 0.76 0.37 1.37 1.14 0.26 0.28 0.19 0.07 0.36 0.11 0.14 0.9 1 0.15 0.03 0.02 0.14 1.04 0.01 0.02 0.03 0.04 0.14 0.34 0.04 0.82 0.11 fe (m.y –1.00 –0.31 –0.09 –0.07 –0.31 –0.31 –0.50 –0.27 –0.18 –0.19 –0.06 –0.74 –0.10 –1.03 –0.01 –0.582 –0.11 –0.14 –0.02 –0.61 TIMA oiling change (S/D or D/S), disappearance (D Dif C e than one Sit . 0 LCO—lo e GE ES s; A Ag 0.61 3.51 1.30 0.08 3.41 1.93 1.88 3.13 3.16 2.99 2.10 3.33 2.60 1.99 3.76 3.76 2.26 2.39 5.48 5.63 9.79 4.60 8.52 4.36 6.0 5.80 5.95 6.20 6.40 3.84 4.07 4.30 (Ma ) 24.30 23.73 23.20 23.68 22.04 21.81 14.56 20.50 17.69 14.23 19.66 17.62 13.74 13.34 16.00 13.77 16.70 12.50 16.29 13.84 16.40 15.10 13.09 11.71 14.69 10.53 11.55 ent ages e/ 02C 849 Sit Hole 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 925B 10 Leg 15 4 Leg 154 Leg 154 Leg 154 Leg 15 4 es the use of mor der of ev ch.—chamber ence; (1999 ) (1999) (1999) (1999 ) (1999) (1999 ) (1999 ) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) son (1997) (2000) (1995b) (1995b) (1995b) (1995a) (1995b) (1995b) (1995b) (1995b) (1995a) (1995b) (1995b) (1995b) (1995a) (1995b) (1995b) G 154 indicat (2002 ) (2002) (2002) (2002 ) ce ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear ear (1995) epancy in the or gular occurr on et al. on et al. on et al. on et al. on et al. on et al. on et al. n et al. n et al. Sour on et al. o et al. o et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. en et al. discr co et al. co et al. rs rc rc klet klet klet klet klet klet klet ogram LE gr gr gr gr gr gr gr gr gr gr gr gr gr ur ur gg re Mix et al. gg re te ONIC FORAMINIFERAL BIOEVENT Tu Tu on and Chaisson (1997) er er son and Chaisson (1997) son and Chaisson (1997) son and Chaisson (1997) Pe Be rg Be rg Be rg Be rg Be rg Be rg Be rg Be rg Be rg Be rg Be rg Be rg Be rg Shac Shac Shac Shac Shac Shac Shac ar ar ar haisson and P haisson and P haisson and P haisson and P haisson and P haisson and P haisson and P haisson and P ea rs illing Pr Chaisson and P Chaisson and P Pe Chaisson and P Chaisson and P Pe Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P Pe Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P Chaisson and P O—highest re 3P 7T 1a 4a 5b 4b 5a 9b 10 14 L5 L4 L6 L1 L2 L3 13 aC lined ages indica te M2 M8 M6 M1 bB M9 aC M1 1T M1 2C de et al. PT1b PT1 aC M13b ence ; HR (2011) Wa en AL NEOGENE PLANKT n as just Ocean Dr bM 7M gr 1b 11 12 13 aM L1 aP (1995) OB M2 M3 M8 M6 PL 5P PL 4P PL 6P PL 2P PL 3P M1 aM M4 aM M9 aB M5 bM M4 bM M5 aM M9 M1 0M M1 4M PL1b PT1b PT1a M13b (2011) . Under Be rg GL et al. w 4a 11 12 13 de et al. N5 N6 N7 N8 N9 ABLE 2. N4 bM N1 0M N2 2C N1 4M N1 5M N1 8P N1 9C N1 6M Blo N17a N17b T (1969) N20/21 Wa ence ; HO—highest occurr nt O AC AC ON OM ON ON ve LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO LO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO HO S/D S/D LC ON HR e/Hole designations sh ow mined by r . Sit west occurr p” to O—lo m to to , this study )L age as de te xtral, L hs i (3 ch.) (4 ch.) “bot xtral) hs i , this study )L hs i , this study )H (“unhooded”) (“hooded”) (“hooded”) (“hooded”) fo l.

l. de ents by om s. s. s. G. ensis ensis

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a ae fo ae fo D—de a s. d fr at s. onda ” (= pr pr a a mis s. sa r oacu ta or ae ae agea e istulosa istulosa emus yeri hs i rit rit tulinoide s a eappearance )R .L amer der of ev nepenthe s nepenthe s nepenthe s nepenthe s xtr (= G. (= G. ensis ularis enui s enui s diu s (disappearance )D (sinistral to uosa or sp ae fo li s li ta li ta li ta li ta cheomenar bust assa fo saensis hs i hs i e indica te nu s nu s lia kugleri lia pseudokugler i lia kugleri lia bi rn lia ma xilis pr ta ta ta ta ella insuet ella ella insuet ta ta ta ta ta S—sinistral; x dissimili s ima ry lia pert lia to lia trun ca lia peripher lia “ lia fo lia e lia loba ta lia peripher lia ar lia mioceni ca lia pert lia multic lia ro lia mioceni ca lia plesiotumid a lia fo lia ma rga lia tumida lia plesiotumid a lia lenguaensis lia cibaoensis lia ma rga lia lenguaensis lia cr ra alia fl ex idinellopsis seminulin a idinellopsis seminulin a idinella dehiscens ta ta ta ta t ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ta ents ar yd : Pr ella cipe ro oglobigerina altispir ps nE globo ro globo ro globo ro globo ro globo ro nt lleniatin a sp p. lleniatina spp. (r lleniatina primalis lleniatin a sp p. ra minology: ra ra ra ra xo No te aeorbulina ci rc aeorbulina glome ro r rilobatus primor rilobatus si ca rilobatus si ca te (RA) ev T Pa Cipe ro Globoquadrina dehiscen s Pa Globigerinoides obliquus Pa Globo ro Globigerinoidesella f Globo ro Globigerinat Globigerinat T Sphae ro Pu Globo ro Globigerinoides altiaperturus Globo ro De Globigerinoidesella f Sphae ro Globo ro Globo ro Ca ta Globo ro Pa Globo ro Pr Globo ro Globo ro Globigerinat Pr Globo ro T Globo ro Globo ro Globo ro Globo ro Globigerinoides e Pu Globo ro Globo ro Globoturbo ro Globoturbo ro Globo ro Pa Ta Orbulina sutu ra Globo ro Globoquadrina dehiscen s Globo ro Sphae ro Globo ro Neogloboquadrina acos ta Globo ro Neogloboquadrina acos ta Globoturbo ro Globoturbo ro Globo ro Globo ro Pu Globo ro Pu Globo ro

Geological Society of America Bulletin, v. 131, no. 11/12 1879

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Salt tectonism and redeposition can cause event marked the M68 Horizon; none were di- bores. We have observed that down-hole cav- discontinuities in the sequence of biostrati- rectly calibrated to geologic time. One of these ing is not generally problematic in DW GoM graphic events. The effects of such geologic four events could not be proven in post-merger wells drilled since the turn of the century. processes are better detected by higher resolu- BP through analyses of DW GoM wells, nor by At first pass, this brings into play the use of tion schemes utilized in well-to-well correla- research on ODP Leg 154 cores (the HO of the fossil bases (LOs) and down-hole abundance tion (see Denne, 2009). Detection of “out-of- nannofossil Helicosphaera walbersdorfensis is deceases (DECs); this effectively doubles bio- sequence” events such as reworking, down-hole one of only two Neogene nannofossil events stratigraphic resolution and makes full calibra- caving of drill cuttings, faulting, and repeated in heritage company schemes that could not tion to published academic biozonations pos- stratigraphic section is much more likely with be confirmed post-merger). A new microfossil sible. The use of multiple events for a single improved resolution. Higher resolution biostra- abundance cycle (i.e., Local), observed in sev- taxon has been taken to the extreme for the tigraphy increases the number of correlations eral wells across DW GoM, has been included nannofossil Reticulofenestra pseudoumbili- between sections, which in turn, improves the on BP GNATTS. Six calcareous microfossil cus (Table 4). Here, twenty events recognized precision and accuracy of these correlations. events, all calibrated to geologic age through among DW GoM wells have been calibrated ­Errors in correlation are not always obvious ODP Leg 154 research, now marked two Chart either directly through the ODP Leg 154 re- when lower resolution biostratigraphic schemes Horizons and one Local on BP GNATTS. Four search or by “association”­ with marker events are applied to expanded GoM sections. In such additional microfossil events for Chart Horizon on BP GNATTS through well analyses. Ten of settings, biostratigraphic events can appear to be M70, three of which have been tied to geologic the more proven events mark Chart Horizons in sequence, but in reality, there may be ­errors of age in our research, have been observed in a lim- on BP GNATTS. Four events are related to the hundreds to more than a thousand feet because ited number of DW GoM wells and were not exit and re-entry (RE) of R. pseudoumbilicus of a combination of high sedimentation rates, included on BP GNATTS (Table 3). from the GoM Basin during the early Middle reduced microfossil recoveries, and the low The use of multiple types of biostratigraphic Miocene and early Late Miocene. The timing number of events. events, as in Chart Horizon M70, provides ad- for three of these four events involving the The BP GNATTS chart has been built upon ditional benefits. Using multiple microfossil two disappearances of R. pseudoumbilicus is a succession of BP heritage GoM Neogene groups for confirmation is standard practice different between the GoM and the ODP Leg biostratigraphic charts. These heritage charts in the GoM. Abundance changes of individual 154 sites near the equator (see Table 4). The have never been static frameworks. Efforts in taxa or taxa groups have practical utility in their disappearance of R. pseudoumbilicus in the twenty-first century post-merger BP focused on speed of recognition, but must be evaluated early Late Miocene has long been studied and improving both the reliability and resolution of relative to lateral changes in facies in the GoM considered by some to represent a significant GoM Chart Horizons, which are integrated into that can affect microfossil abundances. The se- reorganization in the Neogene carbonate pro- subsurface mapping and wells. BP GNATTS quencing of fossil bases (lowest occurrences) ducing community (Rio et al., 1990b; Young, is strengthened by the next level of biostrati- into the biostratigraphic framework has proven 1990; Takayama, 1993; Raffi and Flores, graphic data, whose entire detail is beyond the critical to interpretations of redeposition in DW 1995; Backman and Raffi, 1997; Kameo and scope of this publication. However, three ex- GoM wells. Bralower, 2000; Krammer et al., 2006). For amples are presented below. A second way to illustrate the use of differ- the planktonic foraminifera Catapsydrax dis- Both the resolution and reliability of Chart ent types of events and biostratigraphic resolu- similis, two of the five events recognized in Horizons are enhanced by the addition of bio- tion beyond BP GNATTS is through the lens GoM wells have been incorporated into BP stratigraphic events through well analyses. The of an individual taxon (Table 4). Standard in- GNATTS (Table 4). evolution in the definition and recognition of two dustrial biostratigraphic schemes are founded A third example of biostratigraphic resolu- upper Miocene Chart Horizons (M70 and M68) on microfossil tops (HOs), supplemented by tion beyond BP GNATTS is related to geo- is presented in Table 3. In pre-merger BP, three down-hole abundance increases in taxa, due to graphic proximity. Extension of BP GNATTS events marked the M70 Horizon and a ­single concerns about the caving of materials in well to field scale and individual well correlations

TABLE 3. EVOLUTION IN THE DEFINITION, RECOGNITION, AND CALIBRATION OF TWO BP CHART HORIZONS ODP Leg ODP Leg GoM event 154 event 154 Age Error Depth Chart horizonPre-merger BP GNATTSFossil type Taxon type type (Ma) (m.y.)* Hole (rmcd)† NN Discoaster calcaris LO LO 10.513 0.045926A249.60 M70 PF Paragloborotalia mayeri HROHIO 10.525 0.033926A249.71 NN Helicosphaera walbersdorfensis HO ------PF Paragloborotalia continuosa HO HIO 10.567 0.042926A250.11 NN Calcidiscus premacintyrei HO ------NN Discoaster brouweri LCOLCO 10.606 0.022926A250.50 NN Reticulofenestra gelida DEC DEC 10.606 0.022926A250.50 NN Discoaster neohamatus INC PULSE 10.628 0.022926A250.75 LOCAL NN Total Abundance HIO HIO10.716 0.014926A251.84 NN Discoaster bollii LO LO 10.716 0.016926A251.84 NN Catinaster coalitus LFOLCO 10.732 0.020926A252.03 M68 NN Coccolithus pliopelagicus (>11) HO HO 10.800 0.025926A252.83 NN Discoaster neohamatus LO LO 10.800 0.033926A252.83 Notes: Fossil type: NN—nannofossil; PF—planktonic foraminifera. GNATTS—Gulf of Mexico Neogene Astronomically-tuned Time Scale; GoM—Gulf of Mexico; ODP— Ocean Drilling Program; LO—lowest occurrence; HO—highest occurrence; HRO—highest regular occurrence; LCO—lowest common occurrence; DEC—decrease (top- down); INC—increase (top-down); HIO—highest increase occurrence; LFO—lowest few occurrence. *Error is age of next sample. †Revised meters composite depth.

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TABLE 4. INCREASED BIOSTRATIGRAPHIC RESOLUTION: TWO EXAMPLES OF MULTIPLE EVENTS FOR A SINGLE TAXON Top down Age Error Depth event BP Horizon (Ma) (m.y.)* Hole (rmcd)† CalibrationCalibration/Comments Nannofossil Reticulofenestra pseudoumbilicus - 20 events - ≥8 µm unless otherwise noted HO P55A 3.727 0.020 926A 115.70 Direct HRO P55B 3.819 0.020 926A 118.50 Direct HIO P50 3.933 0.024 926C 122.06 Direct1st downhole increase in GoM ≥10 µm HO P45A 4.032 0.021 926C 125.53 Direct HIO P45B-Loc (in) 4.177 0.034 926B 130.70 Direct1st strong downhole increase in GoM ≥10 µm HIO LP45 4.244 0.023 926C 133.39 Associated HO D. pansulus (LP45 marker bioevent) LCO P40 4.445 0.019 926B 138.91 Direct LFO LP40-Loc 4.596 0.028 926C 142.89 Direct LCOM102 (in) 6.533 0.017 926B 185.95 Associated Abundance Peak in M102 (GoM & Leg 154) LFO LM102 (in) 6.638 0.027 926B 187.60 Associated Abundance Peak in LM102 (GoM & Leg 154) HIO M100 6.801 0.022 926C 190.65 Direct LRO M95 (in) 7.065 0.021 926B 195.01 Direct EXITM89 7.438 0.030 926A 200.82 Associated HO D. hexaramus (M89 marker bioevent) RE M86 7.667 0.021 926B 203.61 Direct HIO M81B 8.670 0.020 926C 223.81 Directweak abundance pulse in Leg 154 ≥10 µm HAOM78 (in) 9.377 0.023 926A 234.33 Directtop acme ≥10 µm LO M56 (in) 13.341 0.009 926A 290.30 Associated 2nd Abundance Peak in M56 (GoM & Leg 154) EXITM54A 13.637 0.011 926A 296.95 Associated HO D. petaliformis (M54A marker bioevent) RE M48A 14.897 0.021 925D 367.64 Associated HO H. ampliaperta (M48A marker bioevent) LO M10 19.171 0.021 926B 387.06 Direct Planktonic Foraminifera Catapsydrax dissimilis - 5 events C. cf. dissimilis HO M42 (in) 16.749 0.136 925A 410.43 Direct C. dissimilis HO LM40 17.259 0.042 928B 269.66 Direct RE M25 17.831 0.020 928B 281.32 Associated with the top of M25 HROM8 19.392 0.038 926C 393.81 Associated with the top of M8 HAOLM5B 20.350 0.038 926B 418.77 Direct Note: BP horizon markers are in boldface. Direct/indirect calibrations are relative to Ocean Drilling Program Leg 154; associated calibrations are relativeto BP Gulf of Mexico (GoM) events. Increased Resolution: Multiple Events per Taxon. HO—highest occurrence; HRO—highest regular occurrence; HIO—highest increase occurrence; LCO—lowest common occurrence; LFO—lowest few occurrence; LRO—lowest regular occurrence; RE—re-entry; HAO—highest abundant occurrence; LO—lowest occurrence. *Error is age of next sample. †Revised meters composite depth.

involves the increased use of microfossil abun- increased sampling beyond the normal 30-foot and dated by ODP Leg 154 research (­Table 5). A dance events, but the number of abundance ditch-cutting sample intervals. Most profound total of 21 events were established in sequence cycles are often greatly increased in expanded are the reduction and elimination of errors in between the GSSP and ODP Leg 154, includ- DW GoM reservoir sections. This strengthens correlation in expanded Neogene reservoir sec- ing 13 correlations involving 15 GoM events the reliability of events on BP GNATTS by tions in the GoM, where new standards have (135 k.y. resolution). From this triangulation, testing their synchronicity in higher resolu- been obtained for resolution in depth correla- the calcareous microfossil event closest to the tion local schemes, which are then reinforced tions (~100 feet). Neogene/Paleogene boundary is the HO of the by log correlations among closely-spaced nannofossil Sphenolithus capricornutus, dated wells. These abundance peaks range from the Extending outside of the GoM at 22.998 Ma and 0.5–0.9 m above boundary highest taxonomic categories of entire fossil All the research ages used to ground BP in the GSSP (Aubry and Villa, 1996; Bergen groups down to individual species. Interpreta- GNATTS are from sections outside the GoM et al., 2017). The base of planktonic forami­ tion is simplest and most effective when using Basin. Pleistocene ages for Chart Horizons nifera Paragloborotalia kugleri helps bracket histogram range charts of semiquantitative above PS50 were derived directly from nanno­ the boundary interval in both ODP Leg 154 and data. Statistical treatment of well data is not fossil research on ODP Leg 161 sites in the the Italian GSSP (Table 5). appropriate until biases from sampling, meth- western Mediterranean Sea (de Kaenel et al., BP GNATTS was applied to a broader Oligo- odologies, taxonomic concepts, and individual 1999; this study). While maintaining consis- cene/Miocene boundary interval through analy- researchers are addressed. Within the GoM tency in both methods and taxonomy, as de ses of ditch-cutting samples from three explo- Basin, resolution in correlation comparable Kaenel was the primary researcher on both the ration wells in the eastern Mediterranean Sea. to the orbital periodicity associated with the ODP Leg 161 and Leg 154 cores, these data All 30 BP GNATTS Chart Horizons from the Earth’s obliquity (41 k.y.) has been obtained also contained the requisite resolution and de- upper lower Miocene (M35) down into the up- for field-scale (i.e., reservoir) biostratigraphic tail to constrain all but two of these 24 Pleisto­ per Oligocene (O75) were established in these schemes, whereas biostratigraphic resolution cene Chart Horizons (Fig. 2; Tables S1–S2). offshore wells by the first two authors, including in well-to-well correlations in expanded reser- Late Oligocene to earliest Pleistocene ages for the sequencing of 57 bioevents on BP GNATTS voir sections can be comparable to the orbital nannofossil and planktonic foraminifera bio- at 131 k.y. resolution. periodic­ities of precession (19 k.y. and 23 k.y.). events were based on our own research on ODP Although somewhat limited by reduced micro- Leg 154 sites in the western tropical Atlantic New Applications in Correlation fossil recoveries from sands, biostratigraphic Ocean (Tables S5–S23). Initial geographic extension of the BP resolution and the associated number of micro- BP GNATTS was fully applied to the base GNATTS framework into the western tropical fossil abundance cycles within reservoir sec- Neogene GSSP in northern Italy, where all seven Atlantic Ocean and Mediterranean Sea is en- tions are aided by high sedimentation rates and Chart Horizons (LM3B-O79) were recognized couraging for its potential application in other

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TABLE 5. OLIGOCENE–MIOCENE BOUNDARY CORRELATIONS GoM-ODP LEG 154-GSSP ODP Leg 154 age BP depths GSSP depths Chart horizonFossil type TaxonEvent type Correlation #GoM event (Ma) (m) (m)* LM3B NN Triquetrorhabdulus carinatus HCO 22.126 N/O NN Sphenolithus disbelemnos LIO 13 22.498 12.9 PF Globoquadrina dehiscens LO 22.438 24.9 23.0 NN Sphenolithus dissimilis LO 12 22.658 24.9 NN Discoaster druggii (>15) LO 22.757 22.0 NN Sphenolithus disbelemnos LRO11 22.757 26.8 7.3 LM3C NN Sphenolithus capricornutus HO 10 22.998 34.6 34.1 NN Sphenolithus moriformis HAO 10 22.998 34.6 BASE MIOCENE 23.030 35.0 35.0 NN Discoaster druggii (10–15) LO 23.038 30.7 NN Calcidiscus tropicus (<6) LO 23.072 37.4 O85 NN Sphenolithus delphix HO 9 23.072 38.5 31.4 NN Sphenolithus delphix HIO 23.134 40.1 NN Discoaster druggii (<10) LO 8 23.155 40.1 NN Discoaster shumnykii LO 23.253 41.2 O83 NN Sphenolithus conicus (>7) HIO 7 23.253 42.3 NN Reticuofenestra amplus HOAb 23.253 42.3 NN Sphenolithus disbelemnos LO 6 23.274 44.4 12.2 NN Sphenolithus paratintinnabulum LO 5 23.308 47.7 NN Sphenolithus delphix Group LIO 5 23.308 47.7 PF Paragloborotalia kugleri LO 23.395 37.4 33.0 O82 NN Clausicoccus fenestratus HIO 4 23.594 52.3 NN Sphenolithus calyculus ACME 23.594 52.3 NN Cyclicargolithus abisectus HIO 23.834 54.3 O80 NN Dictyococcites bisectus-stavensis HIO - - - -56.2 NN Cyclicargolithus abisectus HCO† 3 23.854 56.2 O79 NN Sphenolithus ciperoensis HO 2 24.215 60.0 59.0 NN Cyclicargolithus abisectus HAO§ 1 24.254 61.9 PF Ciperoella ciperoensis HRO 24.275 N/O NN Sphenolithus capricornutus LO 24.281 61.9 34.1 O78 (in) NN Sphenolithus delphix LO 24.664 61.9 35.8 O78 (in) NN Sphenolithus calyculus LO 24.683 61.9 47.0 Note: BP top sample 9.0 m and bottom sample 61.9 m. ODP—Ocean Drilling Program; GoM—Gulf of Mexico; LIO—lowest increase occurrence;LO—lowest occurrence. LRO—lowest regular occurrence; HO—highest occurrence; HOAb—highest occurrence of absence; HRO—highest regular occurrence; N/O—not observed. *Global boundary stratotype section and point (GSSP) depths: Aubry and Villa (1996); Steininger et al. (1997). †Highest common occurrence (HCO) is a maximum value in GSSP because of low abundance. §Highest abundant occurrence (HAO) is highest increase occurrence (HIO) in GSSP because of low abundance. Underlined events are out of sequence in GSSP and ODP Leg 154.

geographic locations. The ability to establish sea level curve. One of the future applications Tcherepanov et al., 2008; Fielding et al., 2011; correlations at ~130 k.y. resolution has new for the BP GNATTS, with resolution com- Passchier et al., 2011), effects of changes in re- found applications—provided taxonomic and parable to that of fourth and fifth order para- gional tectonics (Browning et al., 2006; Moucha methodologic rigor are maintained. Impact on sequences, could be its utilization in sea level et al., 2008; Raymo et al., 2011), glacial isotopic the calibration and correlation of interpreted eu- studies to help better calibrate global records. adjustments associated with continental margins static records, bridging industry and academia, Additionally, microfossils are also a tool in de- (Raymo et al., 2011), and far field sea level am- is obvious. It may now be possible that cal- ciphering facies and the magnitude of sea level plification (Mitrovica et al., 2009). Poor age careous microfossil biostratigraphy be utilized changes in outcrop, core, and the well bore. The control in many studies has generally led to the to evaluate and correlate Neogene cyclostrati- construction of far more accurate age-depth assumptions of incomplete records of Miocene graphic and magnetostratigraphic records, the profiles based on biostratigraphy equates to eustasy (Isern et al., 2002; Eberli et al., 2010) latter previously used to assess the synchronic- better estimates of sedimentation rates, hence and has made it difficult to compare records ity of biostratigraphic events. identification of condensed sections and hiatal among various sites (Miller et al., 2005; Kominz Eustasy (change in global sea level) was surfaces fundamental to sequence stratigraphic et al., 2008). Conversely, certain high-resolution initially inferred from observations of distinct, interpretations. biostratigraphies (John et al., 2011), when ap- relatively synchronous intervals of deposition Advances in sequence and seismic stra- plied to records previously considered to record and erosion throughout the geologic record. tigraphy during the last three decades of the stratigraphic discontinuities (e.g.; Marion Pla- One of the foundations for deciphering records twentieth century provided a template for bet- teau, Australia ODP Leg 194 sites 1192–1195; of eustasy involves determining the timing ter understanding of global sea level change Isern et al., 2002; Eberli et al., 2010) have not and magnitude of sea level events, and often and the creation of a global sea curve for the recognized similar hiatal surfaces within the the basis for these age models is biostratigra- Phanerozoic (e.g., Vail et al., 1977; Vail and section, and then calibrated them to other sites phy. To investigate sea level on time scales of Hardenbol, 1979; Haq et al., 1987; Hardenbol and global sea level curves. 105–104 k.y., a standardized high-resolution et al., 1998). Subsequently, both curves have Late twentieth century Cenozoic geologic biostratigraphic zonation scheme is crucial. undergone intense scrutiny with studies focused time scales (e.g., Berggren et al., 1995a, 1995b) Without an adequate age model, it is difficult on improving methodology, as well as testing were scaled on magnetostratigraphy, which has to determine sedimentation rates, compare sea and finding inconsistencies in both the timing been used to test the geographic synchronicity level proxies to global events, and to correlate and magnitude of sea level change (e.g.; Miller of biostratigraphic events (e.g., Berggren et al., sequence boundaries and flooding surfaces et al., 1998, 2005; Zachos et al., 2001, 2008; 1985; Backman and Shackleton, 1983). The ages within a specific study area and to the global John et al., 2004, 2011; Kominz et al., 2008; and durations of most Neogene polarity chrons

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TABLE 6. NEOGENE CHRONOSTRATIGRAPHIC RESOLUTION: POLARITY CHRONS IN ATNTS2012 demonstration of a significant jump in resolu- Duration Resolution BP GNATTS Resolution Resolution tion in the most researched part of the geologic (m.y.) #Chrons (k.y.) #Horizons (k.y.) # Locals (k.y. w/Locals) column for these two planktonic microfossil­ Pleistocene 1.81 4.2 431 27 67 067 Pliocene 3.52 14.9 236 28 126 2 117 groups contradicts the assessment of the disci- Miocene 17.70 73.9 240 105 169 12 151 pline’s maturity. Our experience has shown that Late 6.30 31.4 201 53 119 6 107 Middle 4.34 21.5 202 26 167 5 140 biostratigraphic frameworks are not static; they Early 7.06 31.0 228 26 272 1 261 improve with each repetition in both the research Neogene 23.03 93 248 160 144 14 132 and well analyses. Technical transfer and the Note: (# Chrons = # Normals + Reversals) versus BP GNATTS Chart Horizons (w/Locals). Base Pleistocene = base Calabrian Stage (1.81 Ma). GNATTS—Global Neogene Astronomically-tuned Time Scale; ability to reproduce results are best done with ATNTS2012—2012 Astronomically-tuned Neogene Time Scale (Hilgen et al., 2012). daily contact over a period measured in weeks, months, or years. This is a challenge for biostra- tigraphy, which has become a scarce specialty in are now adjusted to cyclostratigraphic calibra- CONCLUSIONS both industry and academics. Yet methodologies, tions (Ogg et al., 2016) and were presented in such as those presented, can be applied outside the 2012 Neogene Time Scale (ATNTS2012) by The twenty-first century BP post-merger bio- of the GoM and certainly outside of industry, as Hilgen et al. (2012). In general, global micro- stratigraphy research program has resulted in the need for better calibration of geologic and fossil biozones can be subdivided by at least two the first published astronomically-tuned indus- climatic events has become of paramount in- polarity chrons (Ogg et al., 2008). Conversely, trial biostratigraphic chart (BP GNATTS). This terest in the academic community (Pälike and the stratigraphic resolution of Chart Horizons BP Neogene GoM chart represents dec­ades of Hilgen, 2008). Results presented here lend con- on BP GNATTS (144 k.y.) nearly double the contributions from numerous biostratigraphers viction to the promise that microfossil biostra- resolution of geomagnetic polarity chrons and a step-change in biostratigraphic resolution tigraphy is far from the end of its constructive (248 k.y.) for the Middle Miocene to Recent, al- and calibration. Consistent methodology and growth, rather it is a discipline with great current though their resolution is roughly equivalent for uniform taxonomic concepts have minimized utility and with a realistic expectation for devel- the Early Miocene (Table 6). There is an overall two factors that can plague biostratigraphic res- oping new and exciting applications. decrease in biostratigraphic resolution on BP olution and correlation, as exemplified by dis- GNATTS with geologic age. This suggests the crepancies in age estimates of bioevents from APPENDIX potential for increasing biostratigraphic resolu- the astronomical chronometer of ODP Leg 154 Three topics are presented in the Appendix: (1) re- tion in the GoM lower Miocene. sites in the BP research relative to most recent vised estimates in geologic ages for selected calcare- BP GNATTS is scaled through sampling and published ages (e.g., Wade et al., 2011; Back- ous nannofossil events; (2) two zonal emendations for analyses of cyclostratigraphic reference sec- man et al., 2012). Geologic setting, coupled the Miocene portion of the Backman et al. (2012) cal- careous nannofossil biozonation; and (3) more discus- tions. Miocene to Pliocene section from ODP with the high number of wells, has eliminated sion on the directional sense of bioevents. Leg 154 was sampled at 18 k.y. resolution for poor preservation and recovery as factors. The nannofossils and 32 k.y. for foraminifera. The use of multiple events for Chart Horizons has Revised Geologic Age Estimates for Select sampling intervals from ODP Leg 154 equate enhanced their reliability, but also the ability Calcareous Nannofossil Bioevents to errors in geologic age determinations that to determine when an individual microfossil The BP taxonomic concepts and biostratigraphy are comparable to the orbital periodicities of event—or “pick”—is out of sequence in a well. for over 200 Oligocene–Recent nannofossil species precession (19 k.y. and 23 k.y.) and obliquity For the GoM Basin, a more reliable and were recently published as a series of five papers in (41 k.y.). Stratigraphic resolution of the nanno­ higher resolution framework translates into the Journal of Nannoplankton Research (Bergen et al., fossil and planktonic foraminifera events on BP enhanced detection of stratigraphic disconti- 2017; Blair et al., 2017, Boesiger et al., 2017; Brown- ing et al., 2017; de Kaenel et al., 2017). Since their GNATTS are comparable to the ­major periodic­ nuities, such as redeposition, slumps, uncon- publication in November 2017, subsequent research ities of eccentricity (~100 k.y. and 405 k.y.). formities, and faults. Geographic proximity of on Ocean Drilling Program (ODP) Leg 154 cores led The stratigraphic resolution and precision of wells within the basin translates to still higher to revisions of the geologic age estimates for a lim- BP GNATTS can be improved by sampling resolution and ability to correlate individual ited number of bioevents presented in four of these and analyses of: (1) ODP Leg 154 cores to sands in expanded sections. The resolution of five manuscripts (Table 7). Data from the base Neo- gene global boundary stratotype section and point reduce error in age determinations; (2) other the integrated BP GNATTS at the level of Chart (GSSP) near Lemme-Carrosio in northern Italy was cyclostratigraphic reference sections in the Horizons (with Locals) is five to eight times also revised to reinforce correlations to ODP Leg circum-North Atlantic Basin; and (3) modern greater than that of stand-alone global calcare- 154 (Table 5). Our range chart data for the GSSP is GoM wells in targeted portions of the geologic ous microfossil biozonations. Although only introduced here for the first time (Table S3). For the Oligocene/Miocene boundary interval, the base of column, such as the lower Miocene. Two factors portions of BP GNATTS have been tested in the medium-sized Discoaster druggii and the correspond- are key to improved accuracies of derived geo- Mediterranean Sea, we hope that this new reso- ing base of Zone NN1 has been adjusted down one logic ages herein: (1) the astronomical “retun- lution can be extended both stratigraphically sample in ODP Hole 926B from that presented by de ing” of the cyclostratigraphic record preserved and geographically to enhance correlation of Kaenel et al. (2017) and is now dated at 23.038 Ma in the ODP Leg 154 cores; and (2) full astro- other time scale parameters, as well as eustatic (versus 23.030 Ma). For the genus Sphenolithus, the top of Sphenolithus delphix has been adjusted up one nomical tuning in continuous overlapping sec- records. For example, BP GNATTS nannofossil sample in Hole 926B and the base of Sphenolithus tions with magnetic polarity for the lower Mio- and planktonic microfossil resolution are com- paratintinnabulum down two samples in the same cene to uppermost Oligocene (Ogg et al., 2016). parable to the major periodicities in eccentricity hole section. The remaining 19 revisions were the re- In its present form, BP GNATTS has sufficient of ~100 k.y. and 405 k.y., respectively. sult of focused “marker hunts” and abundance counts (500 fields-of-view at 1000×), in order to complete BP biostratigraphic resolution to evaluate the com- The use of the term “high resolution” is quality control on the ODP Leg 154 research for the pleteness and correlation of cyclostratigraphic ubiquitous­ in biostratigraphy and suggests tech- upper Miocene to basal Pleistocene between BP Chart records at the level of eccentricity. nical limit and a mature state of the science. The Horizons M103 to PS42.

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TABLE 7. REVISED GEOLOGIC AGES FOR SELECTED NANNOFOSSIL EVENTS FROM NEW RESEARCH ON ODP LEG 154* Age Leg 154 Revised age Error Species Event (Ma) Source event (Ma) (m.y.) ODP Leg 154 sample Ceratolithus separatus HO 1.855 Blair et al. (2017) HO 1.8100.014 926C-6H-3, 4–5 cm Discoaster brouweri HO 1.924 Browning et al. (2017) HO 1.8980.024 926C-6H-4, 130–131 cm Discoaster asymmetricus HO 2.165 Browning et al. (2017) HO 1.9240.026 926C-6H-5, 64–65 cm Discoaster blackstockae HO 1.957 Browning et al. (2017) HO 1.9450.021 926C-6H-5, 129–130 cm Discoaster asymmetricus HRO 2.236 Browning et al. (2017) HRO1.957 0.012926C-6H-6, 19–20 cm Discoaster pentaradiatus HO 2.327 Browning et al. (2017) HO 2.2860.024 926C-7H-6, 114–116 cm Discoaster pliostellulus HO 2.686 Browning et al. (2017) HO 2.6340.020 926A-9H-2, 89–90 cm Discoaster tamalis HO 2.752 Browning et al. (2017) HO 2.7290.023 926C-9H-1, 144–145 cm Discoaster variabilis HO 2.968 Browning et al. (2017) HO 2.9240.022 926C-9H-5, 99–101 cm Discoaster asymmetricus INC 3.019 Browning et al. (2017) HO Acme 3.0820.018 926C-10H-2, 3–4 cm Discoaster tamalis INC 3.019 Browning et al. (2017) HO Acme 3.0820.018 926C-10H-2, 3–4 cm Discoaster berggrenii HO 5.772 Blair et al. (2017) HO 5.6770.015 926C-16H-5; 124–125 cm Discoaster neorectus HO 5.932 Browning et al. (2017) HO 5.8870.024 926B-17H-4; 34–35 cm Discoaster quinqueramus (>15µm)HRO 5.932 Blair et al. (2017) HRO5.909 0.022926B-17H-4; 82–83 cm Discoaster vinsonii HO 6.120 Blair et al. (2017) HO 6.0960.018 926C-17H-4; 130–131 cm Discoaster compactus HRO 6.325 Blair et al. (2017) HRO6.338 0.013926B-18H-3; 28–29 cm Discoaster newellii HRO 6.423 Blair et al. (2017) HIO 6.4450.022 926B-18H-4; 73–74 cm Amaurolithus amplificus HRO/HIO 6.445 Blair et al. (2017) HAO6.445 0.022926B-18H-4; 73–74 cm Discoaster neorectus HRO 6.445 Browning et al. (2017) HIO 6.4450.022 926B-18H-4; 73–74 cm Discoaster druggii (>10-15µm)LO 23.030 de Kaenel et al. (2017)LO23.038 0.016926B-50X-5, 45–46 cm Sphenolithus delphix HO 23.093 Bergen et al. (2017) HO 23.072 0.018926B-50X-5, 140–142 cm Sphenolithus paratintinnabulum LO 23.274 Bergen et al. (2017) LO 23.308 0.025926B-51X-3, 130–132 cm Note: ODP—Ocean Drilling Program; HO—highest occurrence; HRO—highest regular occurrence; INC—increase (top-down); HIO—highest increase occurrence; LO— lowest occurrence; HAO—highest abundant occurrence. *Since Journal of Nannoplankton Research, 2017, v. 37, no. 2-3.

Emendations to CNM Zonation of belemnos and Sphenolithus delphix in Gulf of Mexico (Fig. 6) is instead more congruent with the age deter- Backman et al. (2012) (GoM) deep-water wells, as well as our research refer- mined for its LO by Backman et al. (2012), differing ence sites on the Ceará Rise offshore Brazil (ODP Leg by only 90 k.y. (Table 1). The Oligocene–Miocene The results from our research showed it necessary 154) and the base Miocene GSSP section in northern boundary section of Lemme-Carrosio in northern Italy to emend two Miocene zonal events in the Backman Italy (Table 5). Both of these bioevents actually fall provides a solution to this discrepancy. Fornaciari and et al. (2012) nannofossil biozonation; both involve within the terminal Oligocene in Gulf of Mexico wells Rio (1996) placed the LO of Sphenolithus disbelem- significant differences in age determinations for the and these two reference sections (Zone NP26). nos at 57 m in this section (subjacent sample 55 m), lowest occurrences (LO and LO absence) of two spe- Backman et al. (2012) gave on age of 23.06 Ma twenty-two meters above the base of the Miocene. cies in this biozonation. Instead, the placement of for the extinction of Sphenolithus delphix based on We placed its LIO in this section at 22.1 m (subjacent these two events in published studies appear to rep- ODP Site 1218B, which is within sampling error sample 20.2 m) above the base of the Miocene, but resent abundance changes of the two species. Such (0.021 Ma) for our age of 23.072 Ma at Site 926B observed the actual base of Sphenolithus disbelemnos discrepancies can occur when taxa are extremely rare (Table 1). However, Backman et al. (2012) also de- 9.4 m below the base of the Miocene (Table 5). and sporadic at the ends of their stratigraphic ranges, termined an age of 22.41 Ma for the appearance (base Although the upper Oligocene base for Spheno- in combination insufficient analyses times. Specimen or lowest occurrence [LO]) of Sphenolithus disbelem- lithus disbelemnos can be explained by its very rare counts of the relevant taxa were done on smear slide nos in ODP Hole 1218A. We have dated the base of occurrences in the lower part of its stratigraphic range, preparations for 500 fields-of-view at 1000× magni- Sphenolithus disbelemnos at 23.274 Ma in ODP Hole taxonomy must also be considered. Our concept of fication to document these abundance shifts. A total 926B, nearly one million years older (Table 1). The Sphenolithus disbelemnos is more restricted than of 1000 fields-of-view were examined to document LIO of Sphenolithus disbelemnos in ODP Hole 926B other authors, likely including Sphenolithus paratin- these rare occurrences. Emendations to the Cenozoic nannofossil­ biozonation of Martini (1971) were done by Blair et al. (2017) and de Kaenel­ et al. (2017). 22.3 o CNM1—Sphenolithus conicus Partial Range o Zone—emended o Original definition: Interval from top ofSphenolithus o delphix to the base of Sphenolithus disbelemnos. o Emended definition: Interval from top of Sphenolithus 22.4 o LFO (22.358 Ma) delphix to the lowest increase occurrence (LIO) of o Sphenolithus disbelemnos. Figure 6. Total abundance counts Authors: Backman, Raffi, Rio, Fornaciari, and Pälike o of Sphenolithus disbelemnos (2012). ved from ODP Leg 154 o Original Reference Section: ODP Hole 1218A, cen- from Ocean Drilling Program tral tropical Pacific Ocean. o (ODP) Hole 926B offshore NE Additional Reference Sections: ODP Hole 926B, 22.5 o Brazil. LIO—lowest increase Lemme-Carrosio (northern Italy). o LIO (22.498 Ma) occurrence; LFO—lowest few Remarks: This zone was first defined in the Medi- occurrence. terranean Sea (Italy) zonation by Fornaciari and Rio o (1996) as the Sphenolithus delphix–Sphenolithus o

disbelemnos Interval Subzone (MNN1c). The top of Geologic ages (Ma) deri o this zone was constrained by the base (LO) of Sphe- o nolithus disbelemnos by Fornaciari and Rio (1996) 22.6 and later extended into the Pacific Ocean by Backman o et al. (2012) in their low to middle latitude Neogene 0 biozonation. In contrast, we have observed significant 10 20 30 40 50 60 overlap in the stratigraphic ranges of Sphenolithus dis-

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AB

R. pseudoumbilicus (>7um) o 1210 8.7 6.9 o o R. pseudoumbilicus (>8um) o LFO >8um (6.930 Ma) 650 o o g 154 oo eg 154 Le o o o LO of decrease (8.785 Ma) o o o o 7.0 o o 8.8 o o ed from ODP L

ed from ODP o o o o o o o o oo o o LFO >7um (7.065 Ma) ooo o o o o oo o o oo o HFO (8.929 Ma) 7.1 8.9 o o HO of decrease R. pseudoumbilicus (>7um) o o o o (7.086 Ma) o o o o R. pseudoumbilicus (>8um) 64 126 Geologic ages (Ma) deriv 0

Geologic ages (Ma) deriv scale 0 10 20 30 change 40 80 120 160 10 20 30 40 50 60 70

Figure 7. (A) Total abundance count plot showing base “paracme” (LO of decrease) of Reticulofenestra pseudoumbilicus in Ocean Drilling Program (ODP) Holes 926A/B offshore NE Brazil. LO—lowest occurrence; HFO—highest few occurrence. (B) Total abundance count plot showing top “paracme” (HO of decrease) of Reticulofenestra pseudoumbilicus in ODP Hole 926B. HO—highest occurrence; LFO—lowest few occurrence.

tinnabulum Bergen and de Kaenel, 2017, in Bergen species, as the age of Reticulofenestra events clearly Directional Sense of Bioevents et al. (2017). The lowest increase occurrences of both vary with size. A general rule is that smaller specimens species are the same in ODP Hole 926B. Sphenolithus­ have longer stratigraphic ranges; this is true both for Some terminology is in a “top-down” or “down- paratintinnabulum has both an older appearance Paleogene and Neogene reticulofenestrids. We were hole” sense when referring to wells and drilling and (Table ­ 5) and younger extinction than Sphenolithus unable to determine an interval either absent or al- must be distinguished when using in a “bottoms- disbelemnos (Bergen et al., 2017). most entirely absent of specimens of Reticulofenestra up” sense for outcrops and deep-sea research cores pseudo­umbilicus (>7 µm) in upper Miocene sediments (Fig. 4). Two associated paired terms and abbrevia- CNM14—Reticulofenestra pseudoumbilicus Partial of ODP Leg 154 cores (Table S7, S8). In the GoM, tions are: DEC (decrease) and INC (increase), DA Range Zone—emended we refer specimens ≥8 µm to R. pseudoumbilicus and (disappearance) and RA (reappearance). Increase Original definition: Interval from the top ofDisco ­ those ≥ 5µm to < 8µm to Reticulofenestra amplus. The (INC) and decrease (DEC) are used herein only in a aster hamatus to the base of the interval of absence of upper Miocene down-hole re-entry of Reticulo­fenestra top-down sense. They are avoided in a bottoms-up Reticulofenestra pseudoumbilicus. pseudo­umbilicus (Horizon M86) has been utilized in sense and the terms highest increase occurrence (HIO) Emended definition: Interval from the top ofDisco ­ GoM wells since the 1980s and the first downhole and lowest increase occurrence (LIO) are preferred for aster hamatus to the base of the interval with decreased increase below this (Horizon M81B) later established outcrop and cores. The use of various terms to describe numbers of Reticulofenestra pseudoumbilicus. in deep-water wells around the turn of the century. Fi- the exit and re-entry of an individual species from a Authors: Backman, Raffi, Rio, Fornaciari, and Pälike nally, we reason that the ages of these Late Miocene stratigraphic section are necessary so that ages can be (2012). “paracmes” should vary with latitude, once taxonomy related to published studies. Otherwise, the ages can Reference Section: ODP Site 926 (western tropical and methods have been normalized. For example, the be offset a single sample (see Fig. 4). For example, Atlantic Ocean) top paracme or down-hole exit of R. pseudo­umbilicus Wade et al. (2011) used the terms disappearance (DA) Remarks: Backman et al. (2012) defined the top of (≥8 µm) in ODP Hole 926B in the western tropical and reappearance (RA) when referring to certain this zone as “the base of the interval of absence of Atlantic Ocean has been dated at 7.236 Ma (Sample planktonic foraminifera events, whereas nannofossil­ Reticulofenestra pseudoumbilicus.” This definition 926B-19-5, 100-101; error 0.035 Ma) within BP studies (Backman et al., 2012; Agnini et al., 2014) is highly problematic for several reasons. First is the GoM Chart Horizon LM94. In the GoM, the exit of prefer the use of the term “absence.” Events are also precise definition of this event. Backman et al. (2012) R. pseudo­umbilicus appears much older and has been offset one sample when referring to changes in plank- also referred to “the interval of almost total absence of correlated within BP Horizon M89 in ten deep-water tonic foraminifera coiling directions (Fig. 5) in either R. pseudoumbilicus in upper Miocene sediments (the wells (top M89 dated at 7.438 Ma). a “top-down” or “bottoms-up” sense; the terminology so-called “R. pseudoumbilicus paracme”)” in their re- The original Discoaster bellus Subzone of Bukry is also reversed dextral to sinistral (D/S) versus sinis- marks on assemblages in the description of this zone. (1973) was defined from the highest occurrence of tral to dextral (S/D). None of these three terms are synonymous: interval of Discoaster hamatus up to the lowest occurrence of absence, interval of almost total absence, or paracme. Discoaster neorectus. Bukry (1975) later added the ACKNOWLEDGMENTS Backman and Raffi (1997) dated the paracme of lowest occurrence of Discoaster loeblichii as a second R. pseudoumbilicus in ODP Hole 926B from 7.09 Ma event to mark the top of this Subzone. The Discoaster We thank many people in BP Gulf of Mexico to 8.80 Ma, using a size of >7 µm for the species. bellus Subzone was later codified (CN8a) by Okada (GoM) Exploration and Production for their support These ages are confirmed by our counts of specimens and Bukry (1980). Backman et al. (2012) illustrated and encouragement over the years—and Graham­ of R. pseudoumbilicus from Hole 926B (Table 1), but the lowest occurrences (bases) of both Discoaster Vinson, Liz Jolley, Tim Hill, and John Farrelly for are constrained by abundance increases that in neither loeblichii and Discoaster neorectus (their figure 2) in permission to publish. We are grateful to all the GoM instance represent common occurrences or acmes the uppermost portion of Zone CNM14. The base of biostratigraphers from each of the three heritage (Figs. 7A, 7B). A second consideration is methods— Discoaster loeblichii is a very reliable event in GoM companies whose efforts spanning decades contrib- specifically the time spent searching for rare speci- deep-water wells, in addition to the ODP Leg 154 re- uted to this work. Appreciation is extended to our mens—which directly affect whether the “paracme” search materials. This event is dated at 8.738 Ma in Egyptian colleagues in BP Cairo for helping to cali- interval appears entirely devoid or almost entirely de- Hole 926B (Table 1) and is suggested as a secondary brate the Early Miocene to Late Oligocene and Inte- void of specimens. Third is the size used to define the marker for the top of Zone CNM14. grated Ocean Drilling Program staff at the Bremen

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Core Repository in Bremen, Germany. We extend Berggren, W.A., Kent, D.V., Swisher, C.C., III, and Aubry, Denne, R., 2009, Assemblage-based bio-zonations: A key special gratitude to Sheila Barnette and Jim Newell M.-P., 1995b, A revised Cenozoic geochronology and tool in the detection of reworked calcareous nanno- for their contributions to the GoM and the original chronostratigraphy, in Berggren, W.A., Kent, D.V., fossils, in Demchuk, T.D., and Gary, A.C., eds., Geo- foraminiferal Ocean Drilling Program Leg 154 BP Aubry, M-P., and Hardenbol, J., eds., Geochronology logic problem solving with microfossils: Society for Time Scales and Global Stratigraphic Correlation: So- Sedimentary Geology (SEPM) Special Publication 93, research. Thank you to the authors’ families, as ef- ciety for Sedimentary Geology (SEPM) Special Pub- p. 41–55. forts to get this work into publication along with the lication, p. 129–212, https://​doi​.org​/10​.2110​/pec​.95​.04​ Drury, A.J., Westerhold, T., Frederichs, T., Tian, J., Wilkens, proceeding five taxonomic nannofossil papers took .0129​. R., Channell, J.E.T., Evans, H., John, C.M., Lyle, M., untold time and dedication to the science in effort to Blair, S., Bergen, J., de Kaenel, E., Browning, E., and and Rohl, U., 2017, Late Miocene climate and time pass this stratigraphy to the next generations. Special Boesiger, T., 2017, Upper Miocene-Lower Pliocene scale reconciliation: Accurate orbital calibration from thanks to the two reviewers and Geological Soci- taxonomy and stratigraphy in the circum North At- a deep-sea perspective: Earth and Planetary Science ety of America editors for their many helpful sug- lantic Basin: Radiation and extinction of Amauroliths, Letters, v. 475, p. 254–266, https://​doi​.org​/10​.1016​/j​ gestions to improve the quality of this manuscript. Ceratoliths, and the D. quinqueramus lineage: Journal .epsl​.2017​.07​.038​. of Nannoplankton Research, v. 37, no. 2-3, p. 113–144. 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1888 Geological Society of America Bulletin, v. 131, no. 11/12

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Gulf of Mexico Neogene Astronomically Tuned Time Scale 2018 with Ceara Neogene Chronostratigraphic Chart 2018 Rise-Western Equatorial Atlantic, ODP Leg 154, Shackelton and Crowhurst

(1997) emended * 1) * *

EARTH'S s * ORBITAL Eustatic Sea

ECCENTRICITY Level cycles: y 100 & 405 k.y. Sequences de et al. (201 LASKAR Epoch/ CALCAREOUS Horizons PLANKTONIC BENTHIC after R Cycles SOLUTION Blow (1969) Wa Agnini et al. (2016)* Martini (1971) Okada and Bukry (1980)* Backman et al. (2012) Age(Ma) Hardenbol et al., Age (Ma ) La2004 T- Horizons Age (Ma ) Geomagnetic Polarit Chron/ Subchron min max Horizon Stage Zone Zone Zone NANNOFOSSILS FORAMINIFERA Zone Zone FORAMINIFERA (1998) PS108 PS108 PS108 PS107 Holocene Gephyrocapsa omega (<4) 0.029 PS107 Globoconella inflata (GoM-local) PS107 0.0117 NN21b 0.02 QLGM QLGM PS105 Emiliania huxleyi (LIO) G. caribbeanica A1/Gephyrocapsa spp. (<3) (inc) 0.080 PS105 PS105 PS101 0.070 PS101 Globorotalia flexuosa PS101 PS100 LATE G. caribbeanica A2/G. caribbeanica (>3) (inc) 0.088 PS100 PS100 CN Globorotalia flexuosa (HRO) 0.13 0.130 PS95 NN 15 GO assemblage/Gephyrocapsa omega (<4) (inc) 0.166 PS95 Ehrenbergina trigona PS95 0.14 QMIS6 PS93 21a CN Emiliania huxleyi (LRO) Umbilicosphaera rotula 0.218 PS93 (GoM-local) PS93 PS92 GS assemblage/Gephyrocapsa spp. (<3) (inc) 0.275 PL 0.238 PS92 PS92 0.24 LPS92 Emiliania huxleyi (LO) QMIS8 11 lower GS assemblage/G. caribbeanica (inc) 0.275 LPS92 Pt1 LPS92 0.27 NN CN b C1n 20 14b Pseudoemiliania lacunosa "1”(delicate) PS90 0.424 0.406 PS90 Globorotalia truncatulinoides D/S PS90 0.42 LPS90 lower Pseudoemiliania lacunosa "1" 0.424 LPS90 LPS90 PS85 Pseudoemiliania lac. lacunosa (cir) Pseudoemiliania lacunosa "1.5" 0.439 PS85 Globorotalia hessi Trimosina denticulata PS85 0.44 QMIS12 LPS85 lower Pseudoemiliania lacunosa "1.5" (inc) 0.527 LPS85 LPS85 MIDDLE PS83 Gephyrocapsa omega (>4) 0.584 Stilostomella antillea PS83 PS83 Globorotalia tosaensis 0.61 0.62 QMIS16 NN CN 0.64 CN PS82 19f 14a Pseudoemiliania lacunosa "1.5" (inc) 0.742 PS82 0.773 PL PS82 PS80 10 P. lacunosa "2"/Crenalithus japonicus 0.781 PS80 2nd Trimosina denticulata PS80 PS79 P. lacunosa "2 large"/Crenalithus asanoi 0.825 PS79 (local) PS79 0.84 Sphaeroidinella dehiscens (1st acme) / 0.86 QMIS22 C1r.1r PS70A OCEN E P. lacunosa "3"/Crenalithus doronicoides (HRO) 0.905 PS70A Globigerina incisa PS70A 0.962 PS70B Gephyrocapsa omega (>4) (LO) 0.962 PS70B N22 PS70B 0.95 1 LPS70 P. lacunosa "3"/Crenalithus doronicoides (inc) 0.990 LPS70 Trifarina reussi LPS70 1 C1r.1n 1.06 Gephyrocapsa spp. (>4) (HO Ab) NN CN C1r.2r 19e PL Crenalithus asanoi (>6.5) (LO) C1r.2n 9

PLEIST Gephyrocapsa caribbeanica "B" (>6.5) PS68 1.246 1.25 1.235 PS68 Pt1 Hyalinea balthica PS68 PS65 Gephyrocapsa oceanica (>5.5) Helicosphaera sellii (cf. sellii) 1.246 PS65 PS65 CN (GoM-local) PS60 PS60 13b Helicosphaera sellii (lrg holes) 1.276 PS60 a

LPS60 EAR LY Helicosphaera sellii (inc) 1.357 LPS60 Sphaeroidinella dehiscens (2nd acme) Trifarina holcki / LPS60 NN Uvigerina hispida (local) 19d CN PL C1r.3r 8 QCala2 1.566 Gephyrocapsa oceanica (>5.5) (LO) 1.54 PS50 NN19c Calcidiscus macintyrei 1.607 PS50 PS50 1.607 Calcidiscus macintyrei (inc) 1.634 1.61 LPS50 NN19b LPS50 LPS50 QCala1 Gephyrocapsa caribbeanica (>4) (LO) 1.65 1.698 Lenticulina wallacei var. PS42 1.698 Gephyrocapsa oceanica (>4) (LO) Dictyococcites productellus (inc) 1.698 PS42 PS42 CN CN 1.806 NN 13a 1.76 PL Globorotalia crassula (inc) C2n 19a 7 (1.810) 1.898 P140 Discoaster brouweri 1.898 P140 Globorotalia menardii S/D Lenticulina wallacei var. (HRO) P140 Discoaster asymmetricus / Discoaster triradiatus 1.945 Globigerinoidesella fistulosa

2 Crenalithus doronicoides (1st acme) / Globorotalia truncatulinoides (LO) 2.024 2 n Discoaster dennei 2.024 Textularia sica (GoM-local) C2r.1r P135 Discoaster triradiatus (LCO) P135 Globorotalia exilis P135 NN CN CN (GoM) PL C2r.1n 18 12d PL6

TE 6 2.16 QGe2 LA P130 2.286 Discoaster pentaradiatus 2.286 P130 Bolivina imporcata P130 C2r.2r Gelasia 2.361 (local) Globorotalia miocenica NN CN 2.39 17 12c 2.511 CN Lenticulina lacrimata / P120 Discoaster surculus 2.511 P120 Textularia crassisepta / P120 2.5 QGe1 PL Bolivina imporcata (HRO) 2.588 5 2.59 LP120 CN Discoaster pliostellulus 2.634 Ceratobulimina pacifica LP120 12b LP120 Globorotalia pertenuis PL4 (2.659) 2.729 / P110 Discoaster tamalis 2.729 P110 Saracenaria nuttalli P110 PL5 2.76 NPia2 C2An.1n

2.89 P102 Discoaster variabilis 2.924 P102 P102 Globorotalia multicamerata (2.968) 3 P90 3.019 P90 Dentoglobigerina altispira / 3.019 Alvarezina sinuata ("large") / P90 3 NN Dentoglobigerina venezuelana / Cibicorbis herricki C2An.1r 16 Crenalithus doronicoides (2nd acme) / Discoaster asymmetricus (inc) / 3.082 Sphaeroidinellopsis seminulina N20 Discoaster tamalis (inc) (3 ch.) (GoM) C2An.2n / MIDDL E N21 Piacenzian CN CN C2An.2r PL 12a 3.27 NPia1 P75 4 Dictyococcites productellus (inc) 3.305 P75 P75

C2An.3n Sphaeroidinellopsis seminulina (4 ch.) PL3 P60 Sphenolithus spp. 3.510 P60 (GoM) / Sphaeroidinellopsis seminulina P60 (3 ch.) (GoM) (HRO) 3.600 LP60 Pontosphaera multipora (GoM) 3.631 LP60 Textularia 25 / LP60 LOCAL Gephyrocapsa spp. (<3) (inc) / Sphenolithus abies (GoM) 3.666 LOCAL Cibicides pseudocarstensi / LOCAL 3.727 Discorbis P P55A Reticulofenestra pseudoumbilicus 3.727 P55A Globorotalia margaritae (GoM) P55A

P55B Reticulofenestra pseudoumbilicus (HRO) 3.819 P55B P55B 3.861 3.82 C2Ar P53 Reticulofenestra gelida (>8) / Sphenolithus spp. (inc) 3.861 P53 Globorotalia margaritae (Leg 154) P53 CN CN Globoturborotalita nepenthes ("unhooded") P50 11b PL Amaurolithus delicatus Reticulofenestra pseudoumbilicus (inc) 3.933 P50 (GoM) / Globorotalia margaritae (GoM) Buccella hannai (local) P50 3 (HRO) 4 Reticulofenestra pseudoumbilicus (>10) / Scyphosphaera globulata (GoM) Globoturborotalita nepenthes (”hooded”) NZa2 4 P45A NN 4.032 P45A Uvigerina rustica P45A 4.01 P45B Discoaster toralus / Helicosphaera zeta 4.069 (GoM) P45B PLIOCEN E 4.102 P45B PL2 15 Discoaster asymmetricus (LCO) Helicosphaera intermedia (4.102) LOCAL Reticulofenestra pseudoumbilicus (acme) / Sphenolithus moriformis (acme) 4.143 LOCAL LOCAL 4.16

C3n.1n LP45 CN Reticulofenestra pseudoumbilicus (>10) (inc) / Discoaster pansulus 4.244 LP45 LP45 4.315 11a Globorturborotalita nepenthes (Leg 154) P42 Amaurolithus delicatus (HRO) 4.379 P42 P42 C3n.1r P40 4.395 P40 Globoturborotalita nepenthes (”hooded”) Buliminella basispinata (HRO) / P40 4.445 CN Amaurolithus tricorniculatus / Reticulofenestra amplus (acme) / (inc) Siphotextularia jugosa PL Reticulofenestra pseudoumbilicus (LCO) (4.445) LP40 2 4.503 LP40 Globorotalia plesiotumida LP40 EAR LY C3n.2n LOCAL Zanclean CN Amaurolithus tricorniculatus (HRO) Reticulofenestra pseudoumbilicus (LFO) 4.596 LOCAL LOCAL NZa1 NN 10c 4.62 P32 14 Ceratolithus cornulum Ceratolithus armatus 4.666 P32 P32 C3n.2r P30 Dictyococcites antarcticus (HRO) 4.747 P30 P30 4.790 4.812 Globorotalia miocenica (LO) P29 Ceratolithus acutus Ceratolithus acutus / Reticulofenestra spp. (<3) (flood) 4.812 P29 P29 C3n.3n

4.927 Globorotalia crassaformis (LO) Discoaster asymmetricus (LRO) PL1 C3n.3r P28 NN Dictyococcites antarcticus (inc) 4.951 P28 Sphaeroidinellopsis kochi (5 ch.) P28 5 13 CN 5 5.059 CN P26 Ceratolithus cristatus (LO) 5.059 P26 Globigerinoides seigliei (GoM) Sigmoilopsis schlumbergeri var. P26 10b PL C3n.4n 1 Dictyococcites antarcticus (HCO) (5.107) N19 (inc) P25 Ceratolithus atlanticus 5.147 P25 P25 NN 12b Triquetrorhabdulus rugosus (5.232) 1st Globorotalia menardii D/S Bolivina M P24 Ceratolithus apiculus 5.258 P24 (5.233) P24 5.333 5.340 Ceratolithus acutus (LO) M122 NN CN CN Ceratolithus apiculus (LO) Discoaster quintatus 5.365 M122 M122 12a 10a M20 M120 Discoaster quinqueramus 5.440 M120 2nd Globorotalia menardii D/S M120 5.440 5.48 5.45 (5.457) Sphaeroidinella dehiscens s.l. (LO) N18 C3r Globorotalia tumida (LO) 5.63 M110 CN Discoaster berggrenii 5.667 M110 M110 M19 Globorotalia primitiva (HRO) NMe2 NMe2 (5.759) 5.76 M109 5.840 M109 M14 M109 M108 Discoaster quinqueramus (>15) 5.909 M108 Textularia X M108 5.981 Amaurolithus amplificus 6.00 6 Globorotalia lenguaensis 6 Globorotalia juanai N17 6.03 n M105 Discoaster vinsonii 6.096 M105 (6.058) b Textularia 6 M105 C3An.1n

Discoaster compactus (6.233)

C3An.1r M104 Discoaster compactus (HRO) / Reticulofenestra rotaria (>5) 6.338 M104 M104 6.40

Messinia Pulleniatina primalis (LO) M103 Discoaster newellii (HRO) 6.423 M103 M103 M102 Discoaster extensus / Discoaster subsurculus / Discoaster pseudovariabilis 6.457 M102 M102 CN Textularia MR NN CN Discoaster tristellifer Neogloboquadrina acostaensis D/S (HRO) LM102 11B 9B M18 Coccolithus pelagicus (inc) 6.550 (6.497) LM102 C3An.2n LM102

M101 Discoaster abrachiatus / Discoaster compactus (inc) 6.710 M101 Textularia M M101

M100 Discoaster bergenii / Discoaster calcaris / Discoaster loeblichii 6.801 M100 Lenticulina vaughni var. M100 M98 Discoaster icarus (HRO) 6.832 M98 Tritaxilina atlantica M98 M96 Dictyococcites productellus (inc) 6.879 M96 M96 C3Ar 6.930 Amaurolithus amplificus (LO) M95 Dictyococcites productellus (acme) 6.950 M95 M95 7 LOCAL Discoaster compactus (acme) 6.994 LOCAL LOCAL 7 M13 Bigenerina floridana var. / M94 Discoaster neohamatus / Reticulofenestra spp. (<3) (bloom) 7.086 M94 M94 b Textularia 16 C3Bn LM94 CN Discoaster prolixus 7.201 LM94 LM94 7.2 NMe1 C3Br.1r 7.246 M17 C3Br.1n M92 Minylitha convallis 7.265 M92 M92 Discoaster abrachiatus (inc) (7.305) M90 Amaurolithus delicatus (LO) Discoaster pachyloeblichii 7.332 M90 M90 C3Br.2r LM90 Discoaster breviloeblichii 7.374 LM90 LM90 M89 Discoaster hexaramus 7.438 M89 M89 C3Br.2n N17 C3Br.3r a Cristellaria K / 1st Miocene LOCAL 7.559 Discoaster abrachiatus (dec) 7.542 Melonis pompilioides (GoM) LOCAL Amaurolithus primus (LO) LOCAL M88 Catinaster mexicanus 7.566 M88 C4n.1n M88 Amphistegina lessoni var. 2nd Cristellaria K (local) C4n.1r Reticulofenestra pseudoumbilicus (re-entry) 7.667 M86 M86 Cyclammina 3 / M86 7.67 Uvigerina carapitana

LM86 7.800 LM86 Cibicides floridanus var. LM86 M84 Helicosphaera orientalis / Minylitha convallis (HRO) 7.848 M84 M84 C4n.2n NN CN CN Discoaster astellaris (7.912) 11A 9A M16 8 8 LM84 Discoaster gemmulatus 8.025 LM84 2nd Miocene Melonis LM84 pompilioides (GoM)

C4r.1r Catinaster mexicanus (LO) (8.204) 8.261 C4r.1n M83 M83 M83 8.317 Discoaster berggrenii (LO) / Discoaster quinqueramus (LO) M82 Discoaster bellus 8.343 M82 Globorotalia lenguaensis (GoM) M82

M81A Discoaster prepentaradiatus prepentaradiatus 8.449 M81A M81A C4r.2r TE Discoaster neohamatus (HRO) (8.484) 8.52 CN Globorotalia plesiotumida (LO) CN LA 8B M15

C4r.2r-1 M81B Reticulofenestra pseudoumbilicus (inc) 8.670 M81B M81B 8.738 Discoaster loeblichii (LO) 8.785 R. amplus (>7) / R. pseudoumbilicus (LO Dec) M81C Discoaster prepentaradiatus plautus 8.806 M81C Globorotalia lenguaensis (GoM) (HRO) M81C Bolivina thalmanni / Lenticulina wallacei var. / M81D NN Discoaster styzenii 8.902 M81D M81D 10 Textularia 23 / C4An LM81A Discoaster prepentaradiatus (HCO) 8.929 LM81A Globoquadrina dehiscens s.s. (GoM) N16 M13 Textularia G LM81A 9 a 9

LM81B CN CN Discoaster prepentaradiatus (LCO) 9.095 LM81B LM81B

MIOCEN E 8A M14 LM81C Reticulofenestra gelida (>8) (inc) 9.161 LM81C LM81C 9.202 Discorbis dissona (HRO) / C4Ar.1r M80 Discoaster bollii M80 M80 M79 Discoaster hamatus (<15) 9.229 M79 Bigenerina B M79 Lenticulina 15 9.29 NTor2 M78 Minylitha cancellata 9.326 M78 M78 C4Ar.1n Discoaster pentabollii (9.377) 9.451 9.452

rtonia n Discoaster hamatus (>15) (HO) (ODP) Neogloboquadrina acostaensis (LO)

C4Ar.2r M77 To Discoaster neorectus (>20) (LRO) Discoaster caulifloris 9.542 M77 “Listerella-Schenckiella” M77 fauna / Cibicides K / M75 Discoaster hamatus (>15) (GoM) 9.618 M75 Bolivina floridana / M75 Cibicidoides crebbsi C4Ar.2n LM75 Discoaster bollii (2nd acme) / Discoaster hamatus (inc) 9.727 LM75 C4Ar.3r LM75 LOCAL Discoaster caulifloris (inc) 9.781 LOCAL LOCAL M72 Catinaster coalitus 9.826 M72 M72 C5n.1n Spiroplectammina barrowi / Bolivina L C5n.1r N15 M12 10 10 NN CN CN 9 7B M13

Cibicides inflata / LM72 Catinaster coalitus (inc) / Catinaster coalitus (>10) 10.403 LM72 Gyroidina scalata LM72 LOCAL Discoaster gozoensis 10.451 LOCAL LOCAL M71 Discoaster exilis 10.490 M71 Paragloborotalia mayeri 10.492 Bigenerina directa / M71 10.525 Cibicides carstensi (HRO) / C5n.2n M70 M70 Paragloborotalia mayeri (HRO) M70 10.53 Gyroidina scalata (HRO) Reticulofenestra gelida (>8) (dec) (10.606)

LOCAL 10.732 Discoaster bollii (LO) 10.716 LOCAL LOCAL Catinaster calyculus (LRO) Catinaster coalitus (LFO) (10.732) M68 Coccolithus pliopelagicus (>11) / Discoaster neohamatus (LO) 10.800 M68 M68 LM68 CN Helicosphaera bownii 10.850 LM68 LM68 7A 10.963 Discoaster hamatus (>15) (LO) M67 Coccolithus miopelagicus (>14) 10.996 M67 Uvigerina basirotunda M67 11 LOCAL 11.017 LOCAL LOCAL 11 LM67A Discoaster cuspidatus / Discoaster emblematicus / Discoaster ulnatus 11.037 LM67A N14 M11 Nodosaria angularis (local) LM67A C5r.1r Globorotalia robusta C5r.1n LM67B Discoaster hexapleuros (knb) 11.155 LM67B LM67B (11.145) NN CN CN C5r.2r-1 8 6 M12

11.410 C5r.2r Globoturborotalita nepenthes (”hooded”) (LO) Lenticulina 5 (local) Discoaster kugleri / Discoaster patulus M66 11.531 Discoaster hamatus (<10) (LO) 11.509 M66 Catinaster coalitus (LO) Discoaster hexapleuros (11.531) M66 Globorotalia robusta (HRO) Textularia stapperi CNM11 M65 Discoaster kugleri (HCO) Discoaster deflandrei (HO/HRO) 11.575 M65 (11.529) M65 11.625 11.575 C5r.2n N13 M10 LM65 CN Dictyococcites productellus (inc) / Reticulofenestra haqii (<3) (inc) 11.665 LM65 Globorotalia lobata LM65 M10 (11.657) NN CN 11.760 7 5B Discoaster kugleri (LCO) 11.812 NTor1 NTor1 M63 11.812 M63 Globorotalia praefohsi M63 11.78

C5r.3r n Discoaster sanmiguelensis (11.849) 11.910 M62 Discoaster kugleri (LO) 11.925 M62 Globorotalia fohsi M62 Cyclicargolithus floridanus (<6) (11.962) M9b 12 12 12.048 LOCAL CN Dictyococcites antarcticus (inc) 12.046 LOCAL Globorotalia robusta (LO) LOCAL C5An.1n M9 Umbilicosphaera jafari (bloom) (12.125) N12 Bigenerina humblei M60 MIDDL E Discoaster sanmiguelensis (HRO) 12.173 M60 M60 C5An.1r

Serravallia NN CN M9 Gyroidina 6 (local) 12.24 M58 6 5A Calcidiscus spp. (inc) 12.321 M58 a M58 C5An.2n Calcidiscus premacintyrei (12.368)

C5Ar.1r *ALL SIX BIOZONATIONS ARE EMENDED FROM THE ORIGINAL PUBLICATIONS version 6.3/November 2018

Figure 2. 2018 BP Gulf of Mexico Neogene Astronomically-tuned Chronostratigraphic Chart. ODP—Ocean Drilling Program, Dec—decrease; inc—increase; GoM—Gulf of Mexico; S—sinistral; D—dextral; ch.—chambers; Q— Quaternary; N—Neogene; LGM—Last Glacial Maximum; MIS—Marine Isotope Stage; Cala—Calabrian. The following abbreviations are used for bioevent terminology: LO (lowest occurrence) and HO (highest occurrence); abundance modifiers are: R (regular or persistent) for LRO and HRO, I (increase) for LIO and HIO, F (few) for LFO and HFO, C (common) for LCO and HCO, and Ab (absence) for HO Ab.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/131/11-12/1871/4861016/1871.pdf by guest on 27 September 2021 GNATTS2018 12.5-25.1Ma BP Gulf of Mexico

Gulf of Mexico Neogene Astronomically Tuned Time Scale 2018 with Ceara Neogene Chronostratigraphic Chart 2018 Rise-Western Equatorial Atlantic, ODP Leg 154, Shackelton and Crowhurst

(1997) emended * 1) * *

EARTH'S s * ORBITAL Eustatic Sea ECCENTRICITY Level cycles: 100 & 405 k.y. Sequences LASKAR Epoch/ CALCAREOUS Horizons PLANKTONIC ade et al. (201 BENTHIC after R Cycles SOLUTION Blow (1969) W Agnini et al. (2016)* Martini (1971) Okada and Bukry (1980)* Backman et al. (2012) Age(Ma) Hardenbol et al., Age (Ma ) La2004 T- Horizon Age (Ma ) Geomagnetic Polarit y Chron/ Subchron min max Horizons Stage Zone Zone Zone NANNOFOSSILS FORAMINIFERA Zone Zone FORAMINIFERA (1998) Calcidiscus premacintyrei (HRO) 12.534 C5Ar.1r NN CN CN N12 6 5A M8 12.71 NSer3 C5Ar.1n Globorotalia lobata (LO) Globorotalia peripheroacuta (12.774) M9 C5Ar.2r M57A Cyclicargolithus floridanus (HRO) 12.821 M57A Globorotalia peripheroacuta (HRO) a Lenticulina cristi M57A C5Ar.2n Globorotalia peripheroronda (12.857) Helicosphaera rhomba (HRO) M57B 12.930 M57B M57B C5Ar.3r M57C Discoaster cuspidatus (LRO) 12.968 M57C M57C 13 LM57A Cyclicargolithus bukryi 12.989 LM57A LM57A 13 LM57B Dictyococcites antarcticus (inc) / Sphenolithus spp. (inc) 12.999 LM57B LM57B LM57C Discoaster musicus / Reticulofenestra kahniae (<8) 13.067 LM57C LM57C C5AAn LOCAL Umbilicosphaera jafari (bloom) 13.122 LOCAL LOCAL 13.12

M56 Triquetrorhabdulus millowii (HRO) 13.215 M56 Globorotalia peripheroronda (HRO) M56 C5AAr Serravallian

13.408 M55 Sphenolithus heteromorphus 13.408 M55 M55

C5ABn

13.53 NSer2

Cibicides opima / 13.649 M54A Discoaster petaliformis 13.637 M54A Globorotalia praefohsi (LO) Lenticulina 49 M54A C5ABr M54B Cyclicargolithus bukryi (HRO) 13.706 M54B M54B 13.68 M54C Reticulofenestra amplus (inc) 13.782 M54C M54C 13.82 NSer1 LM54A Discoaster druggii (<10) 13.856 LM54A N11 M8 LM54A 13.82 Reticulofenestra pospichalii 13.885 C5ACn LM54C LM54C LM54C

Helicosphaera californiana (HRO) (13.988) 14 14 M53 Helicosphaera scissura 14.022 M53 14.054 Lenticulina chambersi (local) M53 Cyclicargolithus bukryi (inc) Globorotalia fohsi (LO) LOCAL Discoaster arneyi 14.091 LOCAL LOCAL C5ACr NN CN Praeorbulina circularis / M51 Discoaster premicros 14.189 Praeorbulina curva / Lenticulina 53 M51 5 4 M51 Praeorbulina glomerosa Trilobatus sicanus (14.298) / Helicosphaera perch-nielseniae (HRO) (14.280) M7 M50 Discoaster deflandrei (inc) 14.320 M50 Globigerinatella insueta (local) N10 Amphistegina chipolensis M50 Trilobatus bisphericus

LOCAL MIDDLE Cyclicargolithus bukryi (HO Acme) 14.378 LOCAL C5ADn Discoaster premicros (inc) LOCAL (14.337)

LOCAL CN Cyclicargolithus bukryi (LO Acme) 14.539 LOCAL Globorotalia peripheroacuta (LO) 14.539 LOCAL M7 LM50 Discoaster petaliformis (HO Acme) 14.617 LM50 LM50

C5ADr Globigerinatella insueta (HRO) (14.697)

C5Bn.1n N9 M6 M48A 14.897 Helicosphaera ampliaperta 14.897 M48A M48A C5Bn.1r

15 Langhian 15

15.10 C5Bn.2n M48B Discoaster salomonii 15.098 M48B Orbulina suturalis (LO) M48B

15.2

M48C Discoaster leroyi (HRO) 15.379 M48C M48C

Globigerinatella insueta (inc) C5Br (15.498) 15.578 Discoaster signus (LO)

M48D Dictyococcites albitectus 15.657 M48D M48D M5 Discoaster petaliformis (LO) b M46 Reticulofenestra amplus (inc) 15.818 M46 M46 N8

15.97 Discorbis crosbiei / 16 M44 Coronocyclus nitescens (>9) / Dictyococcites onustus 16.018 M44 Lenticulina macomberi / M44 16 Globigerinoides diminutus (HRO) Lenticulina mayeri var. (16.058) (“non-beaded keel”) C5Cn.1n

Praeorbulina glomerosa s.s. (LO) 16.258 C5Cn.1r NN 4 CN 3 Calcidiscus premacintyrei (LRO) Cibicides opima var. (local) NLan1 C5Cn.2n M5 16.38 a C5Cn.2r CN Praeorbulina circularis (LO) M42 Cyclicargolithus floridanus (HO acme) 16.537 M42 M42 M6 Trilobatus sicanus (LO) 16.579

C5Cn.3n M4b 16.70 Paragloborotalia birnageae (LO) Eponides ornatus / Lenticulina M40 Helicosphaera ampliaperta (inc) / Helicosphaera ampliaperta (>12) 16.802 M40 mayeri var. (“beaded keel”) / M40 Operculinoides sp.

C5Cr N7 M4 16.96 17 a 17 Calcidiscus premacintyrei (LO)

17.259 LM40 Discoaster shumnykii (HRO) 17.258 LM40 Catapsydrax dissimilis LM40

Sphenolithus heteromorphus (LCO) C5Dn Discoaster exilis (LO) (17.393) Saracenaria senni / M35 Helicosphaera mediterranea / Sphenolithus apoxis 17.425 M35 Saracenaria schencki M35 Discoaster deflandrei (HO acme) Gyroidina K 17.54 NBur4 Discoaster druggii (>15) C5Dr.1r Sphenolithus heteromorphus (LFO) / Triquetrorhabdulus carinatus 17.683 Sphenolithus belemnos (HO) C5Dr.1n M30 Reticulofenestra spp. (<3) (flood) 17.713 M30 Lenticulina chambersi (HRO) M30 17.791 Sphenolithus heteromorphus (LO) M25 Sphenolithus belemnos (HRO) 17.831 M25 Catapsydrax dissimilis (re-entry) M25 C5Dr.2r Globigerinoides altiaperturus Sphenolithus belemnos (inc) (17.893) N6 MIOCEN E 18 n 18

Discorbis bolivarensis 18.05 M20 Discoaster calculosus s.s. 18.132 Dentoglobigerina binaiensis Marginulina ascensionensis / M20 M20 Bolivina tenuistriata (local)

C5En Burdigalia M3 “Discorbis B consistent 1” “Discorbis B consistent 2”

NBur3 CN 18.56 LM20A NN CN Sphenolithus paratintinnabulum / Sphenolithus procerus 18.612 LM20A LM20A C5Er 3 2 M5 “Discorbis B consistent 3” 18.694 Globigerinatella insueta s.s. (LO) Sphenolithus disbelemnos / LM20B Helicosphaera ampliaperta (>12) (LO) Sphenolithus dissimilis 18.768 LM20B LM20B M15 Discoaster saundersii 18.852 M15 Trilobatus primordius Siphonina davisi M15

Triquetrorhabdulus carinatus (HRO) LM15 18.991 LM15 18.98 19 "Dictyococcites" filewiczii (19.011) LM15 Planulina palmerae 19 M12 Dictyococcites albitectus (inc) 19.072 M12 M12 Helicosphaera ampliaperta (LO) M10 Reticulofenestra pseudoumbilicus (LO) 19.171 M10 C6n M10

N5 M8 19.414 Cyclicargolithus floridanus (<6) (inc) 19.392 M8 Sphenolithus belemnos (LO) M8 19.4 NBur2

Cyclicargolithus floridanus (<6) (HCO) / M5 EAR LY 19.552 M5 M5 Helicosphaera euphratis

Globigerinatella sp. (LO) 19.66 Ilselithina fusa

LOCAL Sphenolithus cometa (HRO) 19.832 LOCAL LOCAL C6r 19.91

20 20

C6An.1n CN M2 LM5A M4 Helicosphaera recta 20.170 LM5A Lenticulina hanseni LM5A Cyclicargolithus floridanus (>9) (inc) Textularia panamensis / LM5B Sphenolithus conicus (>7) 20.291 LM5B LM5B C6An.1r Liebusella extans (local) Cyclicargolithus abisectus (>11) / Helicosphaera scissura (LO) (re-entry)

20.44 20.43 NBur1

C6An.2n LM5C Cyclicargolithus abisectus (>12) 20.550 LM5C LM5C

M4 20.670 M4 Cyclicargolithus abisectus (inc) 20.670 M4 Paragloborotalia kugleri Lenticulina jeffersonensis (O90) (O90) (O90)

C6Ar LM4A Triquetrorhabdulus carinatus (inc) 20.891 LM4 LM4 20.932 Helicosphaera euphratis/H. carteri (cross over) 20.94 21 Ciperoella ciperoensis / 21 M3A Helicosphaera truncata 21.041 M3A Dentoglobigerina sellii Discorbis gravelli M3A NN CN C6AAn 2 1c M3B Clausicoccus fenestratus (HRO) / Helicosphaera disrupta 21.161 M3B M3B

C6AA1.1r Sphenolithus microdelphix / LM3A 21.362 LM3A Heterostegina texana LM3A Camuralithus pelliculathus (HRO) Dentoglobigerina sellii (HRO) C6AAr.1n (21.402) 21.44 NAq2 CN N4 M1 M3 b b C6AAr.2r

C6AAr.2n C6AAr.3r

C6Bn.1n Aquitanian

C6Bn.1r 22 22

22.126 C6Bn.2n LM3B Triquetrorhabdulus carinatus (HCO) 22.126 LM3B Cibicides jeffersonensis LM3B

CN 22.24 M2 Sphenolithus disbelemnos (LO Acme)

C6Br 22.438 Globoquadrina dehiscens (LO) 22.498 Sphenolithus disbelemnos (LIO)

C6Cn.1n Sphenolithus dissimilis (LO) (22.658) 22.757 CN Discoaster druggii (>15) (LO) M1 C6Cn.1r NN M1 1 a C6Cn.2n LM3C Sphenolithus capricornutus s.s. / Sphenolithus spp. (flood) 22.998 LM3C 23 23.030 23.038 LM3C 23 Discoaster druggii (10-15) (LO) NAq1 NAq1 23.072 23.03 O85 Sphenolithus delphix 23.072 O85 Ciperoella angulisuturalis Bolivina perca O85 (M2) (M2) C6Cn.2r (M2)

O83 O83 Sphenolithus conicus (inc) 23.253 O83 N4 C6Cn.3n (LM2) CN Sphenolithus disbelemnos (LO) (LM2) 1b (LM2) a

Paragloborotalia kugleri (LO) 23.395

O82 NP CN Clausicoccus fenestratus (inc) 23.594 O82 O82 06 C6Cr 26

23.854 Cyclicargolithus abisectus (acme) / Dictyococcites bisectus (inc) / O80 23.854 Marginulina idiomorpha O80 Dictyococcites stavensis (HRO) O80

C7n.1n 23.96 24 CN 24 TE C7n.1r 1a

LA O7

Chattian 24.215 O79 Sphenolithus ciperoensis 24.215 O79 O79 Ciperoella ciperoensis (HRO) C7n.2n Sphenolithus capricornutus s.s. (LO) 24.30 (24.275) Trilobatus primordius (LCO) O78 24.346 Marginulina vaginata O78 OLIGOCEN E Sphenolithus bulbulus O78 Paragloborotalia nana (HRO) (24.365) Sphenolithus ciperoensis (inc) (24.456)

NP CP CN C7r 25 19b 05 Sphenolithus peartiae P22 O77 Sphenolithus triangularis 24.700 O77 O77 Ciperoella angulisuturalis (HRO) Sphenolithus ciperoensis (>6) (24.759) (24.800) C7An O75 Helicosphaera bramlettei 24.870 O75 Marginulina howei O75 24.89 PaCh3 Sphenolithus tawfikii 25 C7Ar 28.1 26.126 26.126 26.926 (25.047) *ALL SIX BIOZONATIONS ARE EMENDED FROM THE ORIGINAL PUBLICATIONS version 6.3/November 2018 Figure 2 (continued).

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