Lower Miocene through Pleistocene sediments were sampled at coarse and irregular intervals for palynological analysis (dinoflagellate cysts and pollen) (Table T2), concentrating around sequence boundaries identified in field studies. Unfortunately, few dinocysts were found in the highly terrigenous Pleistocene succession and none of these were useful for biostratigraphy. Dinocysts are useful for dating Miocene sediments at Ocean View using the zonation of de Verteuil and Norris (1996) (Fig. F1).
No biostratigraphically useful dinocysts were found in sediments above 108 ft (32.92 m). Dinocyst abundance and diversity are low from 108 to 150 ft (32.92 to 45.72 m). Palaeocystodinium golzowense (HO = top of Zone DN8) is found together with Trinovantedinium glorianum (lowest occurrence [LO] = DN6) in samples from 107.6 and 115 ft (32.80 and 35.05 m), suggesting an age of 8.6-13.2 Ma (DN6-DN8). A sample from 150 ft (45.72 m) can be assigned an age range of 7.5-13.2 Ma, based on the presence of Heteraulacacysta campanula (HO = DN9) and Selenopemphix dionaeacysta (LO = base of DN6); the age of the overlying samples constrains this level to >8.6 Ma. We can restrict the age of these sediments to either middle middle Miocene Zone DN6 (12.8-13.2 Ma) or to early late Miocene Zone DN8 (8.6-11.2 Ma). Zone DN7 appears to be missing (unless represented by the barren interval) because Cannosphaeropsis passio, the dinocyst that characterizes Zone DN7 (de Verteuil and Norris, 1996), was not found at Ocean View.
Eight samples examined from 156 to 243 ft (47.55 to 74.07 m) were barren of palynomorphs. We interpret that sea levels were very low for a prolonged interval during the late middle or early late Miocene, allowing nearly 100 ft (30.48 m) of sediment to be oxidized. Dinocyst abundance and diversity are relatively high from 250 to 629 ft (76.20 to 191.72 m). The presence of P. golzowense (HO = top of Zone DN8) in a dinocyst-rich sample at 250 ft (76.20 m) provides a minimum age of 8.6 Ma for this sample. There are no biostratigraphically useful dinocysts in sparse samples at 258 or 273 ft (78.64 or 83.21 m). The presence of P. golzowense, together with common S. dionaeacysta (LO = base of DN6), in a sample from 291 ft (88.70 m) provides an age range of 8.6-13.2 Ma. A sample from 362 ft (110.34 m) can be assigned to Zone DN6 based on the first appearance of T. glorianum, whose LO was revised to DN6 by de Verteuil (1997). This gives a maximum age of 13.2 Ma for these sediments. The presence of Cousteaudinium aubryae (HO = top of DN4) in this sample is attributed to reworking.
The presence of Apteodinium spiridoides and C. aubryae (HO = the top of Zone DN4) at 420 ft (128.02 m) supports an assignment of no younger than DN4 for this sample (>15.1 Ma). The first appearance of Labyrinthodinium truncatum truncatum at 450 ft (137.16 m) also suggests a middle Miocene age for this sample, because the LO of this dinocyst occurs near the base of Zone DN4 (de Verteuil and Norris, 1996). Samples at 490 ft and 523 ft (149.35 and 159.41 m) are no younger than ~15.1 Ma, based on the presence of A. spiridoides, whose HO occurs at the top of Zone DN4.
Samples at 534, 596, 621, and 629 ft (162.76, 181.66, 189.28, and 191.72 m) are lower Miocene, based on the presence of Sumatradinium hamulatum and Lingulodinium multivirgatum, whose HOs occur at the top of Zone DN3 (de Verteuil and Norris, 1996). The presence of Cribroperidinium tenuitabulatum, which was not found in sediments younger than upper Zone DN3 at Cape May and Atlantic City (de Verteuil, 1997), lends further support to an early Miocene age (dinocyst Zone DN2 or DN3; ~22.2-16.7 Ma).
Palynofacies analysis provides a means of evaluating the character of stratal surfaces in sections. Palynomorphs are too scarce in the section above 156 ft (47.55 m) to aid in detailed palynofacies analysis, although their scarcity suggests high clastic input and/or a high degree of sediment oxidation in a very nearshore environment. The interval from 156 to 243 ft (47.55 to 74.07 m) was entirely barren of palynomorphs. Whereas this precludes palynofacies analysis to support lithologically proposed sequence boundaries within the interval, the absence of the palynomorphs indicates extreme oxidation (exposure) of almost 100 ft (30.48 m) of sediment. It is therefore likely that there are several sequence boundaries located within the barren interval, although they cannot be placed by palynofacies analysis. A sample from 250 ft (76.4 m) contains aquatic pollen, lending support to a prodelta/delta-front depositional environment at this level.
The sample at 273 ft (83.2 m), underlying the sequence boundary at 267 ft (81.4 m), is virtually barren of palynomorphs, containing only two pollen grains and two dinocysts, reflecting the extreme oxidation of the sediments at this level. The increase in dinocyst concentration and decrease in palynomorphs:dinocysts (P:D) from 258 to 250 ft (78.9 to 76.4 m) indicates an increase in the distance to the shoreline resulting from transgression due to rising sea level.
The highest dinocyst concentrations and one of the lowest P:D ratios in the sampled material is found at 291 ft (88.70 m). The diversity of dinocysts at this depth is moderate to high, whereas the diversity of pollen is relatively low, with high proportions of bisaccate pollen. These variables indicate deep-water and low sediment accumulation, and more specifically, to a condensed section.
The sequence boundary at 533 ft (162.03 m) is consistent with the palynofacies analysis. The sample from 534 ft (162.76 m) contains a palynomorph assemblage characteristic of the upper HST suggested in the lithology. The sample at 534 ft (162.76 m) has rather low dinocyst concentration, low dinocyst diversity, and very high pollen concentrations and diversity. This palynofacies is characteristic of upper HST deposits where the shoreline is regressing and environments are becoming increasingly shallow. The very high P:D ratio and the presence of aquatic pollen are further evidence that water levels were low and the Ocean View site was near the shoreline. Above the sequence boundary at 523 ft (159.6 m), we find the palynological signature of the TST with a lower P:D, lower pollen concentrations, and a reduction in pollen diversity, reflecting the increased distance to the shoreline. The sample at 490 ft (149.5 m) has remarkably similar pollen and dinocyst concentrations and proportions of bisaccate pollen to the sample at 523 ft (159.6 m), which was also taken from TST sediments deposited immediately above a sequence boundary.
The lithologically proposed MFS at 627 ft (191.11 m) is supported by the palynofacies found in the samples at 621 and 629 ft (189.28 and 191.72 m). In the lower sample, we see the characteristic TST palynofaciesa low P:D and a high abundance and diversity of dinocysts. Above the surface at 621 ft (189.28 m), the P:D ratio is higher, indicating deeper water at 629 ft (191.72 m) than at 621 ft (189.28 m). P:D ratios continue to increase up to the sequence boundary at 533 ft (162.03 m).
Like other Leg 150X and 174AX Oligocene-Miocene sections, planktonic foraminiferal assemblages at Ocean View suffer from low abundance, low diversity, rare occurrence of marker species, and the dominance of nonage-diagnostic planktonic taxa. However, the downdip location of Ocean View allows better Oligocene-Miocene foraminiferal biostratigraphic control vs. more updip locations (e.g., Ancora, Bass River, Island Beach, or Atlantic City). Eocene planktonic foraminiferal assemblages at Ocean View are common to abundant and contain marker taxa for several zones (Table T3). However, an admixture of lower Eocene and middle Eocene taxa below 521 ft (463.60 m), along with silica diagenesis of the section below 1480 ft (451.10 m), precludes a detailed zonation.
Miocene foraminifers are only sporadically abundant. Specimens are much more common at the base of the Miocene section (Sequence Kw1a) than in overlying sequences. Samples higher in the section, especially in Sequence Kw3, show signs of dissolution. Planktonic foraminifers are generally rare, and few age diagnostic specimens were found. A single planktonic specimen assigned to Globigerina bulloides was found in a sample at 401 ft (122.22 m). A sample at 601 ft (183.18 m) contained Globigerinitella insueta, Globigerinoides diminutus, and Globigerina labiacrassata. The first occurrence (FO) of G. insueta marks the base of Zone M3 (18.8 Ma) (Berggren et al., 1995); its last occurrence in Zone N9 indicates an age older than ~14.8 Ma. Common planktonic foraminifers were found in samples from 876 to 886 ft (267.00 to 270.05 m), near the base of the Kw1a sequence. Globigerinoides trilobus dominates the planktonic assemblage that also includes Dentoglobigerina globularis, Dentoglobigerina altispira, Catapsydrax unicavus, Globigerina praebulloides, Globigerina angustiumbilicata, and Globorotalia mayeri. The common occurrence of Globigerinoides may indicate that these samples should be assigned to Subzone M1b (Berggren et al., 1995). The sample at 891 ft (271.58 m) in Sequence Kw0 contains G. praebulloides and G. ciperoensis; the latter indicates assignment to Zone N4 or older (Zone M1 of Berggren et al., 1995).
Benthic foraminifers were found more commonly than planktonic foraminifers and are generally restricted to the TSTs. Most samples are dominated by Nonionellina pizarensis and can be assigned to the Nonionellina biofacies of Miller et al. (1997), indicating paleodepths of 25-50 m. However, elements of the Hanzawaia (10-25 m) and Uvigerina (>75 m) biofacies were also present:
Low abundance, low diversity, rare occurrences of marker species, and the dominance of nonage-diagnostic planktonic taxa characterize Oligocene planktonic foraminiferal assemblages. Benthic foraminifers dominate over planktonic foraminifers at Ocean View, representing inner to outer neritic faunas (e.g., Uvigerina spp., Trifarina spp., Cibicides spp., Bulimina gracilis, Epistominella pontoni, and Bolivina paula).
Planktonic foraminiferal Zone P18 extends from the base of the Oligocene (1171.5 ft; 357.1 m) to 1141.0 ft (347.8 m), based on the occurrence of Pseudohastigerina spp. at 1151 and 1141 ft (350.8 and 347.8 m). Planktonic foraminiferal Zone P19 possibly extends up to 1096.0 ft (334.1 m), based on the single occurrence of Turborotalia ampliapertura at 1096.0 ft (334.1 m). Chiloguembelina cubensis also occurs infrequently along with other nonage-diagnostic planktonic forms (Globigerina euapertura, Dentoglobigerina venezuelana, Subbotina spp., and Tenuitella spp.) from 1171 to 1096 ft (357.1 to 334.1 m). Samples from 1091 to 1011 ft (332.5 to 308.2 m) were either barren of planktonic foraminifers or contained undiagnostic marker species. The first occurrence of Globigerina angulisuturalis, at 1006.0 ft (306.6 m), marks the base of planktonic foraminiferal Zone P21. Paraglobigerina opima opima was not observed at Ocean View; thus, Zones P21 and P22 are undivided and extend up to the top of the Oligocene unit at 895.5 ft (272.9 m).
Samples between 1172.1 and 1401 ft (357.26 and 427.02 m) are placed in the upper Eocene, and samples between 1411 (430.07 m) and TD are placed in the middle Eocene. The HO of Hantkenina alabamensis is at 1172.1 ft (357.3 m) (Fig. F7; Table T3), and the HOs of Turborotalia cerroazulensis and Turborotalia cocoaensis are at 1181 ft (359.97 m). A sharp change in benthic and planktonic assemblages takes place between 1401 and 1411 ft (427.02 and 430.07 m). Planktonic foraminifers are very abundant through this section but are represented by diagnostic middle Eocene species (Acarinina bullbrooki, Acarinina pentacamerata, Acarinina rohri, Acarinina topilensis, Globigerinatheka kugleri, Morozovella lehneri, Morozovella spinulosa, Subbotina frontosa, and Turborotalia possagnoensis) below and upper Eocene species (Dentoglobigerina galavisi and Globigerinatheka semiinvoluta) above. The middle Eocene species place the section below 1141 ft (430.07 m) in Zone P12 (M. lehneri Zone), whereas the upper Eocene species identify Zone P15 (Globigerinatheka semiinvoluta Zone) above. Zones P13 and P14 are not represented, suggesting that an unconformity and hiatus of ~2 m.y. separates the middle and upper Eocene. Species of the genera Bolivina, Cibicides, Cibicidoides, Gyroidinoides, and Uvigerina suggest an outer-neritic environment of deposition for this middle Eocene transgressive systems tract (Table T4). The upper Eocene environment of deposition ranges from outer neritic in the basal part to inner-mid neritic in the upper part. However, it is probable that two systems tracts and possibly more parasequences are present in the upper Eocene, based on the distribution of benthic and planktonic species. A rather sharp change in benthic assemblages occurs between 1241 and 1251 ft (378.26 and 381.30 m). Planktonic foraminifers are rare in the upper interval, whereas below, planktonic foraminifers are common to abundant, suggesting that a hiatus or flooding surface may be present between these two samples. Above 1251 ft (381.30 m), the planktonic assemblage, although sparse, contains species more common in the upper part of the upper Eocene (Globigerina officinalis, Globoturborotalia ouachitatensis, Paragloborotalia nana) in addition to Turborotalia pseudoampliapertura, which appears in Zone P16 (Turborotalia cunialensis-Cribrohantkenina inflata Zone). Although the zonal species are absent at Ocean View, the section above 1241 ft (378.35 m) is placed in Zone P16 based on the presence of T. pseudoampliapertura and Turborotalia pomeroli. The last occurrence of T. pomeroli is at the base of Zone P16 according to Berggren et al. (1995). This species is quite common in the section below 1241 ft (378.35 m) but is absent above. The section from 1401 to 1251 ft (427.02 to 381.30 m) is placed in Zone P15 (G. semiinvoluta Zone), although the occurrence of this species is sporadic. It is not present in samples between 1251 and 1281 ft (381.30 and 390.45 m).
Recovery of foraminifers was poor in samples at 1502.5 and 1512.5 ft (457.96 and 461.01 m) because of difficulty in disaggregating the samples. The planktonic species Subbotina eocaena, S. frontosa, and Pseudohastigerina micra indicate either upper lower Eocene or lower middle Eocene. Abundant early Eocene planktonic foraminifers are in samples from 1522 to 1542 ft (463.91 to 442.57 m): Acarinina quetra, M. gracilis, M. formosa, M. subbotina, S. frontosa, and S. senni. These taxa would normally place this section in Zones P6b/P7 of Berggren et al. (1995). The sample at 1552 ft (473.05 m), the lowermost sample in the section, contained poorly preserved lower Eocene foraminifers including Acarinina soldadoensis. However, middle Eocene planktonic foraminifers found in this section suggest assignment to Zone P10 or younger: Globigerinatheka subconglobata, S. frontosa, and Hantkenina nuttalli (LO = 1545.6 ft; 471.10 m). As discussed above, nannofossil biostratigraphy, benthic foraminiferal biostratigraphy, and sequence and log stratigraphic correlations suggest that the borehole bottomed at the base of the middle Eocene and that the lower Eocene planktonic foraminifers are reworked. Species of the benthic genera Cibicidoides, Melonis, Alabamina, and Gyroidinoides and the abundance of planktonic foraminifers suggest a middle to outer-shelf environment of deposition for this section.
Calcareous nannofossil analyses were performed on samples taken at ~3-ft (0.91 m) intervals from the lowermost part of the Kirkwood Formation (basal Kw1a sequence) through the Shark River Formation (890.4 ft-1574 ft; 271.39-479.9 m). The abundance, preservation, and diversity of coccoliths and nannoliths (particularly discoasters) vary considerably through the section, resulting in uneven success at establishing biostratigraphic subdivisions for the successive lithostratigraphic units.
Three biostratigraphic intervals are exceptionally well represented in the Ocean View Borehole. The NP23-NP25 zonal interval, although poorly differentiated, is at least 264.2 ft (79.98 m) thick and corresponds to the Atlantic City and Sewell Point Formations. As elsewhere on the New Jersey margin, the NP19-NP20 zonal interval is thick (202 ft; 61.59 m) from ~1388 to ~1403 ft (~423.20 to ~427.77 m) and its base (between 1388 and 1403 ft; 423.20 and 427.77 m) is characterized by abnormal intercalations of layers assignable to Zone NP18, a likely signature of the Chesapeake Bay impact. The greater part of the Absecon Inlet Formation belongs to this zone. The NP15-NP16 zonal interval is 139 ft (42.38 m) thick and constitutes the lower part of the upper Shark River Formation and the lower Shark River Formation (1445-1575 ft; 440.58-480.22 m). In contrast, all other biozonal intervals (Zones NP22, NP21, NP18, and NP17) identified in the Ocean View borehole are extremely thin, ranging from <5 ft (1.52 m) (Zone NP22) to <30 ft (9.15 m) (Zone NP18).
Four outstanding features concern the calcareous nannofossil assemblages preserved in the Paleogene section recovered at Ocean View. First, the occurrence of Braarudosphaera-rich horizons in the NP23-NP25 zonal interval is reminiscent of the Oligocene deep sea Braarudosphaera-rich oozes reported from the North Atlantic Ocean (e.g., Parker et al., 1985). Second, calcareous nannofossil assemblages preserved in the Absecon Inlet Formation (Zone NP19) are rich and well preserved. Third, and in stark contrast with above, the calcareous nannofossil assemblages are generally scarce and extremely poorly preserved in the Shark River Formation. And fourth, we note that tiny placoliths (2-5 µm) are abundant, particularly in NP15-NP16 and NP23-NP25 zonal intervals. This may be indicative of high productivity.
The zonal scheme used below is that of Martini (1971) and Martini and Müller (1976). Determination of the zones is based on the recognition of the zonal markers. The age estimates are from Berggren et al. (1995).
Only three samples (890.4, 893.0, and 895.9 ft; 271.48, 272.27, and 273.16 m) were examined from the Kirkwood Formation. No zonal markers were found, but a Miocene age is attested by the co-occurrence of Coccolithus miopelagicus, Discoaster deflandrei, Helicosphaera carteri, and Reticulofenestra floridana.
This formation strictly belongs to Zones NP23-NP25 undifferentiated. However, the occurrence of Reticulofenestra abisecta between 1086 and 967 ft (331.12 and 294.84 m) allows a restricted assignment to Zones NP24-NP25. In addition, a single well-preserved typical specimen of Sphenolithus distentus indicates that level 1074.01 ft (327.46 m) cannot be younger than the NP24/NP25 zonal boundary (~27.5 Ma).
Two datum levels that are used to approximate the Oligocene/Miocene boundary were recorded at 906.1 ft (276.27 m) (HO of Reticulofenestra bisecta) and 909 ft (277.15 m) (HO of Zygrhablithus bijugatus). The upper bounding surface of the Atlantic City Formation may thus be slightly younger than the NP25/NN1 chronal boundary (~23.9 Ma).
Calcareous nannofossils are common at most levels, but preservation is moderate to poor (dissolution) and a few levels were barren. We note the (minor) reworking of late Eocene-early Oligocene species (e.g., Reticulofenestra reticulata and Isthmolithus recurvus) at 920.1 and 980.1 ft (280.54 and 298.83 m). Braarudosphaera-rich assemblages occur at 938.1, 950.1, and 959.0 ft (286.03, 289.69, and 292.40 m).
This formation is assigned to Zones NP24-NP23 at Ocean View. The LO of R. abisecta at an indefinite level between 1093 and 1120 ft (333.26 and 341.49 m) can be taken to approximate the Zone NP23/NP24 boundary. The imprecision in this determination reflects the scarcity of the coccoliths in the uncertainty interval. The (unexplained) common occurrence of I. recurvus in samples from 1140.0 and 1143.0 ft (347.59 and 348.50 m) is noteworthy. A striking change in composition of the calcareous nannofossil assemblages occurs between 1162.0 and 1174.2 ft (354.29 and 358.01 m) (a sample taken at 1170.3 ft [356.82 m] was essentially barren).
This formation encompasses Zones NP21, NP19-NP20, and NP18 at Ocean View, but its major thickness belongs to Zones NP19-NP20. Zone NP21 extends from 1174.2 to 1198 ft (358.01 to 365.27 m). As in other complete upper Eocene sequences, we observe the sequential HOs of Discoaster saipanensis (1201.0 ft; 366.16 m), Discoaster barbadiensis (1213.0 ft; 369.84 m) and R. reticulata (1235.0 ft; 376.55 m). Zones NP19-NP20 extend down to 1403 ft (427.77 m). The intercalation of an interval (1388-1397 ft; 423.20-425.95 m) assignable to Zone NP18 (toward the base of the zone) reflects impact-related displacement of sediments at the beginning of Biochron NP19-NP20 (Poag and Aubry, 1995).
This formation comprises Zones NP18, NP17, an undifferentiated NP15-NP16 zonal interval, and Subzones NP15a and NP15b. Calcareous nannofossil assemblages are common to abundant in the upper part (1403 and 1470 ft; 427.77 and 488.20 m) of the formation, and preservation varies between moderate and good. Below 1470 ft (488.20 m), preservation deteriorates rapidly and assemblages, scarce at many levels, are dominated by diagenesis-resistant placoliths. Discoasters are few and strongly overgrown; they are not identifiable at the species level. Curiously, many levels yield abundant tiny placoliths.
Zone NP18 is well characterized between 1406 and 1418 ft (428.69 and 432.35), but its lower boundary is ambiguous. Chiasmolithus oamaruensis does not occur at 1421 ft (433.26 m) but occurs at 1430 (typical) and 1433 ft (436.01 and 436.92 m), whereas Chiasmolithus grandis (with an HO just slightly older than the LO of C. oamaruensis) occurs at 1421 ft (433.26 m). Zone NP17, bracketed by the LO of C. oamaruensis and the HO of Chiasmolithus solitus, constitutes a thin sliver extending from 1436 to 1442 ft (437.84 to 439.67 m). The undifferentiated NP15-NP16 zonal interval is delineated between the HO of C. solitus (1445 ft; 440.58 m) and the LO of Nannotetrina quadrata at 1571 ft (479.00 m). A sample at 1574.5 ft (480.07 m) was barren. In this interval we note (1) the occurrence of Cruciplacolithus staurion at 1559 ft (475.34 m), suggestive of Subzone NP15a; (2) the HO and LO of Chiasmolithus gigas (at, respectively, 1547 and 1556 ft; 471.68 and 474.42 m), indicative of Subzone NP15b; (3) the LO of large morphotypes of Reticulofenestra umbilicus at 1511 ft (460.70 m), used by some authors to delineate the NP15/NP16 zonal boundary; (4) the presence of R. reticulata at 1470 ft (448.20 m), indicative of a level in the upper part of Zone NP16; and (5) the LO of R. bisecta at 1445 ft (440.58 m), indicative of a level close to the NP16/NP17 zonal boundary.