The following, who are listed in alphabetic order, are responsible for the given section:
Operations: Cobbs, Miller, SugarmanSea Girt was the tenth site drilled as part of the Coastal Plain Drilling Project (CPDP) and the seventh site drilled as part of Leg 174AX. Drilling at the National Guard Training Base, Sea Girt, New Jersey (40°07´12.698''N, 74°01´58.25''W; elevation = 9.8 ft [3.05 m]; Point Pleasant quadrangle, Monmouth County) targeted Upper Cretaceous sequences and aquifers with a 1500 ft (457.20 m) corehole drilled 24 September to 11 November 2003. At Sea Girt, we recovered 1215.76 ft (370.56 m); mean recovery was 77.9% for the 1600 ft (487.68 m) cored. Gamma ray logs were collected from the inside of the rods, and a full suite of multitool logs were obtained from the HQ hole (depth = 1070 ft; 326.14 m), but hole instability prevented further logging. A team of scientists from the New Jersey Geological Survey (NJGS), Rutgers University, the Delaware Geological Survey (DGS), and the U.S. Geological Survey (USGS) collaborated in drilling and stratigraphic studies of this corehole that was funded by the National Science Foundation (NSF; Earth Science Division, Continental Dynamics Program). Onsite and postdrilling studies of lithology, sequence stratigraphy, biostratigraphy, and Sr isotopic stratigraphy comprise the data sets on which this site report is based.
A thin paleosol, uniform massive medium sand, and medium sand with heavy mineral laminations (3.4–23.15 ft; 0.4–7.06 m) are provisionally assigned to the ?Holocene/Pleistocene Cape May Formation. These sediments were deposited in a nearshore setting in upper shoreface to foreshore environments.
The Miocene Kirkwood Formation consists of four sequences in the Sea Girt corehole. The uppermost Kirkwood Formation (23.15–45.5 ft; 7.06–13.87 m) consists of micaceous clays with silt laminations and uniform, tight, dark olive-green clays deposited in lagoonal or lower estuarine environments. These clays comprise a confining unit and probably correlate with one of the Kw2 sequences of Sugarman et al. (1993). The highstand systems tract (HST) of the Kirkwood 1b? sequence (45.5–106.4 ft; 13.87–37.46 m) consists of (1) medium to fine sands (45.5–63.6 ft; 13.87–19.39 m) deposited in lagoonal–estuarine or proximal upper shoreface environments, (2) interlaminated sand and sandy silt (63.6–76.7 ft; 19.39–23.38 m) interpreted to represent bay fill/estuarine environments, (3) heavily burrowed silty fine sand (80–91.6 ft; 24.38–27.92 m) representing shelf deposits influenced by a delta, and (4) delta front sands (91.6–106.4 ft; 27.92–32.43 m). The sequence from 45.5 to 106.4 ft (13.87 to 32.43 m) probably correlates to the Kw1b sequence. The underlying sequence (106.4–122.9 ft; 32.43–37.46 m) consists of interbedded fine–medium sand, clayey silt, and coarse sand deposited in delta front and prodelta environments and is probably correlative with the Kw1a sequence.
A sequence from 122.9 to 136.3 ft (37.46 to 41.54 m) may correlate to the Kw0 sequence of Miller et al. (1997). Coarser beds from 122.9 to 130.6 ft (37.46 to 39.81 m) comprise the upper HST sand, and finer beds from 130.6 to 134.4 ft (40.97 to 40.93 m) comprise the lower HST. The section from 134.4 to 136.6 ft (40.97to 41.64 m) may comprise the transgressive systems tract (TST). Alternatively, there may be a sequence boundary at 134.4 ft (40.97 m) and the sands below could be the HST of an underlying sequence.
The top of the upper Shark River Formation and the top of middle Eocene Sequence E8 is placed at the first downhole appearance of glauconite sand and a sharp gamma ray peak (~140 ft; 42.67 m). The HST consists of upper sands, deposited in lower shoreface environments and finer grained clays and silts deposited in inner–middle neritic environments (140–220 ft; 42.67–67.06 m). Glauconite increases downsection below 220 ft (67.06 m) to a maximum flooding surface (MFS) at 228 ft (69.49 m), a TST (228–236.2 ft; 69.49–71.96 m), and a burrowed sequence boundary at 236.1 ft (71.96 m).
Hard, occasionally porcellanitic, foraminiferal-rich, slightly glauconitic clay of the lower Shark River Formation is found from 236.1 to 255.5 ft (71.96 to 77.88 m). The section grades to a glauconitic sand below 261 ft (79.55 m). A surface at 265.8 ft (81.02 m) with indurated clay clasts associated with a major biostratigraphic break (Subzones NP15b at 261 ft [79.55 m] and NP14a at 266 ft [81.08 m]) is a sequence boundary separating Sequence E7 above from Sequence E5 of Browning et al. (1997) below. Clayey glauconite sand below the contact continues to a major irregular erosional contact at 271.75 ft (82.83 m) representing a sequence boundary separating Subzone NP14a and Sequence E5 of Browning et al. (1997) from the slightly glauconitic clay of Zone NP12 and Sequence E3 below. Sequence E4 is not represented at Sea Girt. Systems tracts are difficult to differentiate in the relatively deep paleodepths represented in middle Eocene Shark River Sequences E7 and E5 and lower Eocene Manasquan Sequences E3, E2, and E1.
Uniform clay assigned to the lower Eocene Manasquan Formation appears below the sequence boundary at 271.75 ft (82.83 m). The upper sequence (E3; 271.75–318 ft; 82.83–96.93 m) of the Manasquan Formation consists of (1) an upper, slightly sandy HST; (2) a heavily burrowed MFS at 288 ft (87.78 m); and (3) increasing quartz content in the TST. A tentative sequence boundary separating Sequence E3 from E2 is picked at 318 ft (96.93 m) based on a biostratigraphic break between nannofossil Zone NP12 above and NP11 below.
Quartz and glauconite sand increase below the 318 ft sequence boundary to a heavily burrowed irregular contact at 348.6 ft (106.25 m) that could be a sequence boundary or MFS. Below 348.6 ft (106.25 m), glauconite increases from trace at top to 80% above a contact at 358.8 ft (109.36 m). Nannofossil biostratigraphy suggests that the section above 358.8 ft (109.36 m) is equivalent to Sequence E2, and the contact at 358.8 ft (109.36 m) is a sequence boundary separating Sequence E2 above from E1 below. Sequence E1 consists of a glauconite sand that continues to a sequence boundary at 365.2 ft (111.31 m).
Below a burrowed contact (365.2 ft; 111.53 m) is a unique lithologic unit associated with the Paleocene/Eocene Thermal Maximum (PETM) (Zachos et al., 2001; Cramer et al., 1999). This green, brown, and reddish brown clay (365.2–384.7 ft; 111.31–117.26 m), though previously termed the "Vincentown equivalent" (Miller, et al., 1998), is lithologically distinct from the Vincentown Formation at outcrop and probably should be assigned unique member status.
The upper Paleocene Pa3 sequence first recognized at Island Beach, New Jersey (Liu et al., 1997) is uniform, micaceous, sandy, glauconitic clayey silt at Sea Girt (384.7–461.3 ft; 117.26–140.60 m). Glauconite increases below 452 ft (137.77 m) to clayey glauconite sand at 456 ft (138.99 m). An irregular contact at 461.3 ft (140.60 m) is interpreted as the lower sequence boundary. The base of the Vincentown Formation is placed at 465 ft (141.73 m), below which glauconite content consistently remains >50%. As at other sites, the formational boundary is offset from the sequence boundary.
The upper Hornerstown Formation consists of heavily bioturbated glauconitic sand deposited in lower shoreface to middle neritic environments. There are four sequence boundaries associated with the Hornerstown Formation: (1) below a brachiopod-rich shell hash at 469.8 ft (143.20 m) separating Sequence Pa2 of Liu et al. (1997) from Pa1b below, (2) at a hard zone at 482.4 ft (147.04 m), (3) in a coring gap (495.2–500.0 ft; 150.94–152.40 m) associated with a large gamma ray log kick and a biostratigraphic gap (Zone NP3/Subzone NP4a above and NP2 below) separating Sequence Pa1b of Liu et al. (1997) from Pa1a below, and (4) at the base of the Hornerstown Formation at 509.8 ft (155.39 m).
The Maastrichtian Navesink Formation consists of two different lithofacies that may represent two sequences. The upper Navesink Formation (509.65–535.8 ft; 155.34–163.31 m) consists of a black, clayey, massively burrowed glauconite sand interpreted as an inner neritic environment interfingering with lower shoreface environments. A lithologic contact at 535.8 ft (163.31 m) separates the sandier zone above from intensely burrowed silty glauconite sand with more common interbedded light gray clay. This may be a sequence boundary separating the Navesink I/II contact postulated by Miller et al. (2004). The lower Navesink lithofacies consists of interbedded glauconite silty sand and carbonate clay facies more typical of the Navesink Formation. This facies was deposited in middle–outer neritic environments. The contact zone (565.1–566.2 ft; 172.24–172.58 m) between the Navesink and Mount Laurel Formations is interpreted as a lowstand systems tract (LST). It consists of the glauconite clays above mixed together with the quartz sands below and includes shell and phosphate pellets deposited in nearshore to starved middle shelf environments.
The upper Campanian (Zones CC21–CC22) Mount Laurel Formation is the upper HST of a sequence that includes the Wenonah (lower HST) and Marshalltown (TST) Formations. The Mount Laurel Formation (565.1–621 ft; 172.24–189.28 m) at Sea Girt consists of lower shoreface medium- to coarse-grained quartz sand that fines downsection to a silty, bioturbated fine sand. The contact with the sandy silts of the underlying middle–upper Campanian (Zones CC20–CC21) Wenonah Formation is gradational. Micaceous lignitic silt with very fine sand laminations between 621 and 675.7 ft (189.28 and 205.95 m) is placed in the Wenonah Formation. The Wenonah Formation at Sea Girt is coarser grained and has more physical structures than at either Ancora or Bass River, suggesting a shallower paleoenvironment (lower shoreface with a prodelta influence). An increase in glauconite content to >30% at 675.7 ft (205.97 m) marks the contact with the middle–upper Campanian (Zone CC20) Marshalltown Formation. The Marshalltown Formation consists of very glauconitic, slightly quartzose, massive to heavily burrowed silt and glauconite sand (675.7–687.2 ft; 205.95–209.46 m). The MFS of the sequence is placed at 676 ft (206.04 m), where clay is at a maximum, quartz sand is absent, and there are rare shells. The Marshalltown Formation was deposited in middle–outer neritic environments. The contact of the Marshalltown and Englishtown Formations is interpreted as a transgressive surface (687.2 ft; 209.46 m). The upper part of the Englishtown Formation (687.2–691.25; 209.46–210.68 m) is a LST consisting of a brown clay bed and very micaceous, silty medium–fine quartz sand containing phosphate pellets. An irregular surface at 691.25 ft (210.68 m) separates the quartz sands above from delta front sands below.
One of the major scientific achievements of drilling at Sea Girt is the recovery of a very thick upper sequence from the middle Campanian (Zones CC19–CC20) Englishtown Formation (691.25–837.6 ft; 210.68–255.30 m). There are three major lithofacies in the upper Englishtown sequence. On top, the sequence (691.25–757 ft; 210.68–230.73 m) consists of fine- to medium-grained micaceous sands with thin beds and laminae of silt, clay, and lignite deposited in delta front environments. The second lithofacies consists of slightly micaceous interbedded and interlaminated silt and clay with occasional very fine sand laminae, interpreted as prodelta deposits. A glauconitic clay between 780.05 and 784.8 ft (237.76 and 239.21) is a condensed section or flooding surface. We place the MFS at 829 ft (252.68 m) at a maximum in glauconite and the top of a zone with concretions and brown clay. The third lithofacies consists of glauconitic silty quartz sand with shells (below 829 ft; 252.68 m) that was deposited in lower shoreface environments and is interpreted as the TST. A thick indurated zone at 839.1 ft (255.76 m) marks a sequence boundary.
The upper Santonian–lower Campanian (Zones CC16–CC19) lower Englishtown–Woodbury–Merchantville sequence begins below the sandstone (839.15 ft; 255.77 m). The top of the lower Englishtown Formation consists of heavily burrowed, silty, fine–medium sand deposited in lower shoreface and delta front paleoenvironments and heavily bioturbated, micaceous, fossiliferous silt deposited in an offshore environment influenced by a delta. The lower Campanian (Zone CC18) Woodbury Formation (891–943.5 ft; 271.58–287.43 m) is a micaceous silty clay to clay. The top of the formation is moderately to heavily burrowed and represents offshore environments. The bottom of the formation is a laminated prodelta deposit. The upper Santonian–lower Campanian (Zones CC16–CC18) Merchantville Formation (943.5–1056 ft; 287.58–321.87 m) is a very clayey glauconite sand deposited in inner to middle neritic environments. A burrowed contact at 962.15 ft (293.26 m) and a major facies shift at 1000.9 ft (305.07 m) are interpreted as sequence boundaries within the Merchantville Formation. The lower Campanian (Zones CC18–CC19) sequence from 837.7 to 962.15 ft (255.33 to 293.26 m; lower Englishtown–Woodbury–upper Merchantville) is probably equivalent to the Merchantville III sequence of Miller et al. (2004). The uppermost Santonian (Zone CC17) sequence from 962.15 to 1000.9 ft (293.26 to 305.07 m) is probably equivalent the Merchantville II sequence of Miller et al. (2004). The upper Santonian (Zone CC16) sequence from 1000.9 to 1056 ft (305.07 to 321.87 m) correlates with the Merchantville I sequence of Miller et al. (2004).
Poor recovery from 1056 to 1070 ft (321.87 to 326.14 m) precludes definitive identification of the Santonian Cheesequake Formation and sequence.
Several sequences are recognized in the upper Turonian–lower Santonian Magothy Formation (1063–1286.5/1289 ft; 324.00–392.13/392.89 m) and most can be tentatively correlated to the members at outcrop.
The Cenomanian–lower Turonian (Subzone CC10a through Zone CC1) Bass River Formation at Sea Girt is represented by at least three sequences. An uppermost Cenomanian–Turonian (Subzone CC10b through Zone CC11) sequence from 1289.0 to 1418.95 ft (392.89 to 432.50 m) consists of nearshore and delta front sands and silts on top and fines downsection to laminated silty clays deposited in proximal to distal prodelta environments. Very dark gray to black clays from 1370.15 to 1379.5 ft (417.62 to 420.79 m) may correlate to global ocean anoxic Event 2 (OAE2). This sequence correlates to the Bass River III sequence of Miller et al. (2004).
The sequence from 1418.95 to 1457.7 ft (432.50 to 444.31 m) consists of silt and sand deposited below wave base on a shelf overlying prodelta clays and silts. The upper part of this sequence contains calcareous nannofossils assigned to middle Cenomanian Subzone CC10a and it could correlate to either the Bass River II (Subzones CC10a–CC10b) or Bass River I (Zone CC9 through Subzone CC10a) sequence at Ancora (Miller et al., 2004). Based on superposition, we favor correlation to the Bass River II sequence.
A sequence from 1457.7 to 1494.95 ft (444.31 to 455.66 m) consists of prodelta clays on top, clayey very fine sand deposited in a delta front in the middle, and prodelta silts at the base. The sediments from 1480.15 to 1494.95 ft (451.15 to 455.66 m) contain distinct bands of light and dark colors, suggesting an environment alternating between organic-poor and organic-rich deposits. These organic-rich bands may represent changes controlled by Milankovitch cyclicity. The organic-rich sediments clearly predate OAE2. We tentatively correlate this sequence with the Bass River I sequence of Miller et al. (2004), though this is largely based on superposition because diagnostic fossils are absent from this sequence at Sea Girt.
The sequence from 1494.95 to 1520.2 ft (455.66 to 463.36 m) has a distinct blocky gamma ray log signature typical of the Potomac Formation. However, the upsection change from prodelta silts to delta front sands is typical of Upper Cretaceous marginal marine to marine sequences, and is not typical of the Potomac Formation. We tentatively term the sequence from 1494.95 to 1520.2 ft (455.66 to 463.36 m) the "Bass River 0.5" sequence and correlate it with the upper Potomac sequence at Ancora.
The top of the sequence deposited between 1520.2 and 1563 (463.36 and 476.40 m) consists of micaceous, lignitic, fine sands deposited in lower delta plain environments that may be the downdip equivalent to the Farrington Sand of the Raritan Formation. We tentatively term the sequence the "Bass River 0" sequence, though it could correlate to a Potomac sequence. The bottom of the sequence is a micaceous clay with subordinate interbedded very fine sand deposited in lower delta plain environments with oxbow and interfluvial marsh subenvironments. These sediments are notable for containing common leaf fossils.
The ?Albian–lower Cenomanian Potomac Formation (total depth [TD] = 1563–1600 ft; 476.40–487.68 m) contains mottled red and white clay and silt with sphaerosiderite and root casts representing paleosols that accumulated as overbank/interfluvial deposits. These probably correlate with Potomac Unit 3. Thus, the Sea Girt corehole penetrated the marine Bass River Formation, the marginal marine Bass River Formation–uppermost Potomac Formation undifferentiated, and the terrestrial Potomac Formation.
One of the major scientific achievements of drilling at Sea Girt is the recovery of very thick Upper Cretaceous sequences that were poorly or moderately represented in previous coastal plain coreholes. In particular, we targeted and recovered sequences from the middle Campanian upper Englishtown Formation, the lower Campanian Merchantville Formation (cryptic sequences Merchantville I and II), the upper Turonian–Coniacian Magothy Formation, and the Cenomanian–Turonian Bass River Formation.
1Miller, K.G., Sugarman, P.J., Browning, J.V., Aubry, M.-P., Brenner, G.J., Cobbs, G., III, de Romero, L., Feigenson, M.D., Harris, A., Katz, M.E., Kulpecz, A., McLaughlin, P.P., Jr., Misintseva, S., Monteverde, D.H., Olsson, R.K., Patrick, L., Pekar, S.J., and Uptegrove, J., 2006. Sea Girt site. In Miller, K.G., Sugarman, P.J., Browning, J.V., et al., Proc. ODP, Init. Repts., 174AX (Suppl.): College Station, TX (Ocean Drilling Program), 1–104. doi:10.2973/odp.proc.ir.174axs.107.2006
Ms 174AXSIR-107