14. EARLY TO MIDDLE MIOCENE SEQUENCES, SYSTEMS TRACTS,...Kenneth G. Miller, Scott Rufolo, Peter J. Sugarman, Stephen F. Pekar, James V. Browning, and David W. GwynnABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONCONCLUSIONACKNOWLEDGMENTSREFERENCESAPPENDIXFIGURESFigure 1. New Jersey location map showing Leg 150X...Figure 2. Age-depth diagram, Atlantic City borehole...Figure 3. Age-depth diagram, Cape May borehole. ...Figure 4. Lithofacies interpretation of the Island...Figure 5. Lithofacies, paleoenvironments, and ...Figure 6. Lithofacies, paleoenvironments, systems ...Figure 7. Benthic foraminiferal biofacies results,...Figure 8. Lithofacies, paleoenvironments, systems ...Figure 9. Benthic foraminiferal biofacies results,...Figure 10. Comparison of the stacked Atlantic benthic...TABLESTable 1. Rotated loading values and cluster ...Miller, K.G., and Snyder, S.W. (Eds.), 1997Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 150X16914. EARLY TO MIDDLE MIOCENE SEQUENCES, SYSTEMS TRACTS,AND BENTHIC FORAMINIFERAL BIOFACIES, NEW JERSEY COASTAL PLAIN1Kenneth G. Miller,2,3 Scott Rufolo,2 Peter J. Sugarman,4 Stephen F. Pekar,2 James V. Browning,2 and David W. Gwynn2ABSTRACTWe identified and dated nine lower to middle Miocene sequences at the Island Beach, Atlantic City, and Cape May, NewJersey boreholes, integrating Sr-isotopic, lithofacies, log, and benthic foraminiferal biofacies data in a sequence stratigraphicframework. Miocene sequences typically shallow upsection, representing three major lithofacies: (1) thin, shelly, glauconitesands of the Transgressive Systems Tracts deposited in inner–middle (0- to 100-m paleodepth) neritic environments; (2) medialsilty clays of the lower Highstand Systems Tracts deposited in neritic prodelta environments; and (3) upper quartz sands of theupper Highstand Systems Tracts, deposited in inner neritic, near-shore, and delta front environments. Sedimentation rates werelow–moderate in the earliest Miocene (5−24 m/m.y.), increased to 40−90 m/m.y. at about 22 Ma as deltaic sedimentationbegan, and remained high and uniform through the middle Miocene. We develop a benthic foraminiferal biofacies model forthe inner to middle neritic zones (0- to 100-m paleodepth) and show that these biofacies follow a predictable succession in thesetransgressive/regressive sequences. The nomenclature and usage of the Kirkwood Formation is discussed, and the BrigantineMember is formally named.Onshore sequences result from a complex interplay of changes in eustasy, tectonics, and sediment supply. Correlation ofsequence boundaries onshore with offshore and Exxon records indicate that they represent global lowerings of baselevel. Cor-relation of the sequence boundaries with δ18O increases show that they were formed during glacioeustatic lowerings. Althougheustasy controls the timing of sequences, the preservation of sequences is also controlled by local tectonic effects while theirarchitecture is strongly influenced by changes in sediment supply and provenance. For example, differences in preservation ofsequences is attributed to differential tectonic subsidence due to changes in sediment loading. The depositional patterns onshoreallow prediction of offshore sequence architecture, including a progressive progradational change to deltaic sedimentation inthe early to middle Miocene; in addition, the absence of lowstand deposits onshore during an interval of high sediment supplymay indicate the presence of substantial lowstand systems tracts offshore.INTRODUCTIONPrimary goals of the New Jersey Sea-level Transect were to re-cover and date Oligocene to Holocene sequences, to compare them toglobal deep-sea δ18O records, and to evaluate sequence stratigraphicmodels (see Miller, Chapter 1, this volume for summary). It is partic-ularly critical to evaluate the early and middle Miocene, becausethere are at least eight well-defined δ18O increases that reflect gla-cioeustatic lowerings (Miller et al., 1991, 1996c). In addition, se-quences of this age are particularly well developed both onshore andoffshore of New Jersey (Miller and Mountain, 1994). Thus, studies ofthe Miocene onshore strata should allow evaluation of the responseof sedimentation to glacioeustatic lowerings (e.g., Miller et al.,1996c; Sugarman et al., Chapter 12, this volume) and the architectureof facies changes within sequences.Offshore, lower to middle Miocene sequences beneath the mod-ern inner and middle shelf are thick (often hundreds of meters per se-quence) and consist of prograding clinoforms that have clear reflectorterminations (Greenlee et al., 1992; see “Discussion”). Onshore, thelower to middle Miocene Kirkwood Formation comprises a thickrecord (up to 216-m total thickness and up to 47 m per sequence)record of near-shore and shelf (neritic) quartz sands and silty clays in-fluenced by deltaic sedimentation (see Appendix for discussion ofKirkwood Formation nomenclature). Sugarman et al. (1993) recog-nized five Kirkwood sequences: Kw1a, Kw1b, Kw2a, Kw2b, andKw3, from oldest to youngest, and used Sr isotopes to correlate thesesequences to the Berggren et al. (1985) time scale. Because only twocontinuously cored Miocene sections were available (ACGS#4 andBelleplain; Fig. 1), their study did not address fully the nature andtiming of Miocene sequences. As part of the New Jersey Sea LevelTransect, researchers on Leg 150X (a collaboration of ContinentalScientific Drilling and the Ocean Drilling Program) drilled three con-tinuously cored boreholes at Island Beach, Atlantic City, and CapeMay, NJ (Miller, et al., 1994, 1996a; Fig. 1), which recovered thickerand more complete Miocene sequences than were previously avail-able. Preliminary descriptions of the sequences were provided in theInitial Reports (Miller, et al., 1994, 1996a), where at least nine lowerto middle Miocene sequences were recognized: Kw0, Kw1a, Kw1b,Kw1c, Kw2a, Kw2b, Kw2c, Kw3, and Kw-Cohansey (Figs. 2, 3).These sections allow us to date the Miocene sequences and to devel-op a sequence stratigraphic model for onshore deposition.Previous studies of the Miocene sequences in these boreholeshave addressed either their relationship to the δ18O record (Miller andSugarman, 1995; Miller et al., 1996c; and Sugarman et al., Chapter12, this volume) or the facies succession at individual sites (Miller, etal., 1994, 1996a; Owens et al., Chapter 2, this volume; Sugarman andMiller, 1997). This study reconstructs lower to middle Miocene