Table of Contents
Figure F1. Location of topographic highs in the Western Pacific Basin.
Figure F2. Relief map of Shatsky Rise showing location of Leg 198 sites. Site 1207 is located on the Northern High, Site 1208 is on the Central High, and Sites 1209–1214 are on the Southern High.
Figure F3. Magnetic lineations across Shatsky Rise and trace of the hotspot from Nakanishi et al. (1989), showing previously drilled DSDP and ODP sites on the southern plateau.
Figure F4. Reconstruction of position of Shatsky Rise across the Pacific. After McNutt and Fischer (1987) and R.L. Larson (pers. comm., 2000).
Figure F5. Lithologic columns from previous DSDP and ODP sites on Shatsky Rise showing age, lithology, and prominent unconformities (after Sliter and Brown, 1993). Water depths for each site are listed beneath the site number. Bk = black.
Figure F6. Compilation of benthic foraminiferal oxygen isotopic composition from 34 DSDP and ODP sites plotted vs. age (from Zachos et al., 1993; J. Zachos et al., unpubl. data). MME = mid-Maastrichtian event, LPTM = late Paleocene thermal maximum, OAE = oceanic anoxic event.
Figure F7. Carbon and oxygen isotope values of planktonic and benthic foraminifers from the upper Paleocene of Sites 527 (closed squares), 690 (open circles, open diamonds), and 865 (closed circles, closed diamonds, crosses) (Kennett and Stott, 1991; Bralower et al., 1995; Thomas and Shackleton, 1996; J. Zachos and D. Rea, unpubl. data) plotted vs. age.
Figure F8. Compilation of DSDP/ODP isotope data from Albian to Maastrichtian (from Huber et al., 1995; Fassell and Bralower, 1999; Stott and Kennett, 1990; Barrera and Huber, 1990; Barrera, 1994; Barrera and Savin, 1999). Dashed lines connecting benthic foraminiferal data represent unconformities. CTBI = Cenomanian/Turonian boundary interval.
Figure F9. Mid-Cretaceous record of black shales and oceanic anoxic events (OAEs) in the context of the carbon isotopic record (Erbacher et al., 1996; Bralower et al., 1999), changing global sea level (Haq et al., 1988), seawater 87Sr/86Sr (Bralower et al., 1997a), LIP emplacement (Larson, 1991a), plankton evolution (Erbacher and Thurow, 1997; R.M. Leckie, et al., unpubl. data), and platform drowning (R.M. Leckie, et al., unpubl. data).
Figure F10. Worldwide volume of oceanic plateaus, seamount chains and continental flood basalts plotted as a function of geologic time according to Harland et al. (1990) (after Larson, 1991b).
Figure F11. Interpretation of seismic reflection profile across Site 1207. Mustard unit = middle Miocene to Holocene, light green = Campanian–Turonian, medium green = Cenomanian to Aptian, and dark green is Barremian to Valanginian. Eroded or slumped layers are seen on north and south ends of the Campanian–Turonian unit. Numbers across the figures are shotpoints. R = reflector.
Figure F12. Summary diagram of coring results for Hole 1207A plotted on the meters below seafloor (mbsf) scale. Maximum penetration measured with the drill pipe was 256.6 mbsf. The core recovery column is a graphic representation of the cored and recovered intervals for this hole. Large gaps in core recovery (<100% nominal recovery) near the base of the hole are primarily the result of coring problems that arose when chert was encountered. The graphic lithology column presents the major sediment types and defined lithologic units. The depth-age model is represented by calcareous nannofossil (red diamonds) and planktonic foraminiferal (black crosses) datum levels; dashed lines represent the boundaries between the Cretaceous/Paleocene and Oligocene/Miocene. Mass accumulation rates were calculated for total sediment (green open circles) and carbonate only (blue triangles). The color reflectance lightness parameter (L*) (purple points) was measured every 2.5 cm, and the percentage calcium carbonate (CaCO3) values are shown for comparison. Multisensor track (MST) magnetic susceptibility (brown points) and GRA wet bulk density (dark blue points) were measured every 2.5 cm, and index properties wet bulk density measurements (red circles) were completed on average once per section. MST P-wave velocity (light blue points) was determined every 2.5 cm, and discrete P-wave measurements (green circles) averaged at least one per section for comparison. Index properties determinations of porosity (blue squares) and percentage water content (red circles) were completed once per section on average.
Figure F13. Changes in ocean circulation that led to cycles in upper Miocene to Holocene section. A.ÝCirculation during warm/light cycle member. B. Circulation during cold/dark cycle member.
Figure F14. Hypothesized sequence of events that produced major Campanian–Miocene unconformity on the Northern High of Shatsky Rise.
Figure F15. Interpretation of seismic reflection profile across Site 1208. Mustard unit = middle Miocene to Holocene, light brown = lower Miocene and Paleogene, light green = Campanian, and medium green = Albian.
Figure F16. Summary diagram of coring results for Hole 1208A plotted on the meters below seafloor (mbsf) scale. The maximum penetration measured with the drill pipe was 392.3 mbsf. For details about figure symbols and descriptions see Figure F12.
Figure F17. Change in circulation in North Pacific associated with the closure of the Indonesian Seaway. The size of arrows indicates intensity of currents (after Kennett et al., 1985).
Figure F18. Interpretation of the evolution of stratigraphic section at Site 1208 based on drilling results and seismic section.
Figure F19. Interpretation of seismic reflection profile across Site 1209. Mustard unit = Miocene to Holocene, light brown = Paleogene, and light green = Maastrichtian.
Figure F20. Summary diagram of coring results at Site 1209 plotted on the meters composite depth (mcd) scale. Maximum penetration measured with the drill pipe was 307.5 mbsf. Small gaps (typically 0.5–2.0 m) in core recovery, revealed by hole-to-hole correlation, occur even when nominal core recovery is 100% or more. For details about figure symbols and descriptions see Figure F12.
Figure F21. Summary of stratigraphy and lithological succession from Sites 1207 to 1214. Lithology is plotted against time to show duration of periods of deposition and location of unconformities. Southern High Sites 1211 through 1214 are ordered by present-day water depth.
Figure F22. Paleontological summary of the LPTM interval in Section 198-1209B-22H-1. The LO of Morozovella velascoensis, which defines the boundary between Zone P5 and Subzone P6a, lies between Samples 198-1209B-22H-1, 74–75 cm and 9–10 cm, probably close to the latter sample. Depths listed along the lithology column are in meters below seafloor (mbsf). FO = first occurrence.
Figure F23. Paleontological summary of the Cretaceous/Paleocene boundary in Holes 1209A and 1209C. Samples described include planktonic foraminifers (F) and nannofossils (N).
Figure F24. Cores that contain the appearance and sudden disappearance of prisms of Inoceramus. In Sections 198-1209C-21H-1 through 198-1209C-21H-21H-3, and 198-1210B-28H-5 and 1209B-28H-6. The interval shown lies in the same biostratigraphic interval as the extinction in the deep sea. The small arrows indicate positions of prisms in cores, and large arrows show the disappearance level.
Figure F25. Interpretation of seismic reflection profile across Site 1210. Mustard unit = Miocene to Holocene, light brown = Paleogene, light green = Maastrichtian. CPD = common depth point.
Figure F26. Summary diagram of coring results at Site 1210 plotted on the meters composite depth (mcd) scale. The maximum penetration measured with the drill pipe was 377.0 mbsf. Multisensor track (MST) magnetic susceptibility (brown points) and GRA wet bulk density (dark blue points) were measured every 3.0 cm. For details about figure symbols and descriptions see Figure F12.
Figure F27. Comparison of magnetic susceptibility records for Holes 1210A (black) and 1210B (blue). The data show the location of critical events (LPTM = late Paleocene thermal maximum, E/O = Eocene/Oligocene boundary, and K/T = Cretaceous/Tertiary boundary) as well as significant gaps in the records of individual holes.
Figure F28. Total reflectance (L*) records for the Eocene/Oligocene (E/O) boundary interval at four sites (Holes 1209A, 1210A, 1211A and 1208A) in a depth transect across Shatsky Rise. Reflectance (L*) is a rough indicator of CaCO3 content as demonstrated in the Hole 1210A plot where CaCO3 is plotted as well. These records suggest that CaCO3 increased across the Eocene–Oligocene transition, possibly because of a deepening of the lysocline and calcite compensation depth (CCD). Note that the deepest record (Site 1208) has the lowest L* values and highest amplitude of variation of all, probably because it is near the lysocline depth. Water depths are indicated at the bottom of each plot.
Figure F29. Interpretation of seismic reflection profile across Site 1211 based on coring results as well as results of Sliter (1992) and Sliter and Brown (1993). Mustard unit = Miocene to Holocene, light brown = Paleogene, light green = Maastrichtian–Campanian, medium green = Cenomanian through Aptian; dark green is Neocomian. CDP = common depth point.
Figure F30. Summary diagram of coring results at Site 1211 plotted on the meters composite depth (mcd) scale. The maximum penetration measured with the drill pipe was 169.9 mbsf. Multisensor track (MST) magnetic susceptibility (brown points) and GRA wet bulk density (dark blue points) were measured every 3.0 cm. For details about figure symbols and descriptions see Figure F12.
Figure F31. Age-depth curves for Sites 1209, 1210, 1211, and 1212 based on shipboard biostratigraphy. Circles = planktonic foraminiferal datums, squares = nannofossil datums, P. = Pleistocene, Pl. = Pliocene.
Figure F32. Lithology of the Eocene/Oligocene boundary interval in Core 198-1211C-9H. Arrow points to the last observed occurrence of Hantkenina sp., the planktonic foraminiferal datum that defines the boundary.
Figure F33. Correlation of LPTM sections recovered in Holes 1211A, 1211B, and 1211C.
Figure F34. Summary diagram of coring results at Site 1212 plotted on the meters composite depth (mcd) scale. The maximum penetration measured with the drill pipe was 207.6 mbsf. Multisensor track (MST) magnetic susceptibility (brown points) and GRA wet bulk density (dark blue points) were measured every 3.0 cm. For details about figure symbols and descriptions see Figure F12.
Figure F35. Interpretation of seismic reflection profile across Site 1213 based on coring results. Mustard unit = Pliocene to Holocene, medium green = Albian through Aptian, dark green =ÝNeocomian, and brown = igneous sill unit (Unit IV) and basement. Lithologic units and subunits and depths (in meters below seafloor [mbsf]) are indicated.
Figure F36. Summary of lithostratigraphy for Sites 1207–1214. TD = total depth.
Figure F37. Summary of generalized chert color by age for the Cretaceous at ODP Leg 198 and DSDP Leg 32 sites on Shatsky Rise. Red represents oxidized hues of brown, orange, red and pink, whereas black represents reduced hues of olive-green, gray and black. Note the similar regional temporal trends in chert color.
Figure F38. Lithology and carbonate, organic carbon and pyrolysis hydrogen indices for lower Aptian sedimentary rocks recovered at Sites 1207, 1213, and 1214 on Shatsky Rise. Note that Sites 1207 and 1213 recovered very organic Corg-rich intervals representing OAE1a. Homog. clayst. = homogeneous claystone.
Figure F39. Total reflectance (L*) records for the Paleocene/Eocene boundary interval at four sites (Holes 1209C, 1210A, 1212A, and 1211A) in a depth transect across Shatsky Rise. Reflectance (L*) is a rough indicator of CaCO3 content as demonstrated in the Hole 1210A plot where CaCO3 is plotted as well. The abrupt decrease in L* denoted between the ages of 58.95 and 54.83 Ma represents an hypothesized shoaling of the lysocline associated with the LPTM event. Water depths are indicated at the bottom of each plot.
Figure F40. Percentage estimates of biosiliceous material of late Neogene to Quaternary sediments from smear slides plotted vs. depth in meters below seafloor (mbsf) for Sites 1207–1213. Site 1214 has been excluded on the basis that only 1.32 m of late Neogene–Quaternary sediments were recovered. This figure illustrates that biosiliceous material is more abundant within the late Neogene–Quaternary sections on the Northern and Central High than on the Southern High of Shatsky Rise. The expanded Pleistocene to Miocene sedimentary sections at Sites 1207 and 1208 can partly be attributed to relatively high sea-surface productivity inferred from the higher occurrence of diatoms, radiolarians, and silicoflagellates relative to the other sites further south. The trends in biogenic silica abundance correlate strongly with sedimentation rate, as the more southerly Sites 1209 through 1212 were characterized by lower sedimentation rates.
Figure F41. Photomicrographs from sediment containing diagenetic "green bands." (A) Plane-polarized light and (B) cross-polarized light images of clayey nannofossil ooze with foraminiferal tests (arrow) containing authigenic smectite clays (note that black dendritic areas are epoxy used to impregnate the soft sediment); the bottom half of each image is within a "green band." (C) plane and (D) polarized light photomicrograph of a burrow in clayey nannofossil ooze filled with volcanic glass. Burrow (arrow; glass is isotropic) shows authigenic smectite (saponite) filling pore spaces and part of foraminifer test.
Figure F42. Age-depth plots for Sites 1207–1214 based on calcareous nannofossil and planktonic foraminiferal datums. Horizontal lines represent unconformities in the sections. Critical events are marked by thin gray vertical bands. Widespread unconformities are indicated by the wide blue vertical bands.
Figure F43. Mass accumulation rates for bulk sediment and carbonate fraction for Sites 1207–1212. Mass accumulation rates were determined using dry bulk density and carbonate content data through linear sedimentation rate segments. No rates were determined at Sites 1213 and 1214.
Figure F44. Downhole gamma radiation and resistivity logs from Holes 1207B and 1213B illustrating the form and setting of the OAE1a black shale.
Figure F45. Chert layers in Hole 1207B as observed in FMS resistivity images.
Figure F46. Magnetic susceptibility data for the uppermost Cretaceous to lower Eocene interval at Sites 1209–1212 showing the position of critical events as well as cycles. LPTM = late Paleocene thermal maximum, K/T = Cretaceous/Tertiary boundary.
Figure F47. Spliced magnetic susceptibility data covering the Eocene/Oligocene boundary and Eocene interval of Sites 1211, 1210, and 1209 vs. meters composite depth (mcd). Systematic changes in cycle amplitude and frequency are consistent from site to site suggesting that these changes reflect regional paleoceanographic processes. The cycle packages are distinct enough to allow for detailed correlation between sites.
Figure F48. Total color reflectance data on a timescale for Holes 1208A and 1209A plotted along with orbital obliquity and eccentricity for the (A) 0- to 2-Ma and (B) 3- to 5-Ma time intervals. These data suggest that the dominant cycle frequency over the last 0.7 m.y. is near that of the 100-k.y. eccentricity cycle. From 0.7 to 2.6 Ma, the dominant period shifts toward a higher frequency close to that associated with the 40-k.y. obliquity cycle. A long wavelength oscillation with a period of roughly 1.0 to 1.25 m.y. appears in the total color reflectance record from Site 1209 over the period 3 to 5 Ma. Comparison with the orbital curves suggest that this cycle may be in phase with the long period 1.25-m.y. cycle of obliquity.
Figure F49. Relationship between (A) sedimentation rate, (B) mass accumulation rate (MAR), (C) SO42– reduction, (D) NH4+ production, and (E) CH4 generation on Shatsky Rise.
Figure F50. Oxygen and hydrogen indices for samples from lower Aptian organic-rich horizons (OAE1a; Table T3) plotted on a modified van Krevelen diagram. The characteristics of organic-rich samples from Holes 1207B and 1213B, and from the Aptian at Holes 463 and 866A in the mid-Pacific are also shown. Data for Sites 463 and 866A are compiled from Dean et al. (1981), Mélières et al. (1981), and Baudin et al. (1995). The size of the data points is proportional to organic carbon contents. The lines designated I, II and III represent the evolutionary trends with thermal maturation of the three major kerogen types (Tissot et al., 1974). OI = oxygen index.
Figure F51. GC-MS traces of aliphatic hydrocarbons and ketones for representative samples from Holes 1207B, 1213B and 1214A. For the aliphatic hydrocarbon traces, the numbers refer to n-alkanes; other peak assignments and identities are given in the lists.
Figure F52. Plots of coring rate vs. depth for three Cretaceous sections on Shatsky Rise. Coring rate may be a function of the frequency of hard chert layers in the section.
Figure F53. Cretaceous/Tertiary boundary on Shatsky Rise in Sections 198-1209A-25H-6, 198-1209C-15H-3, 198-1210A-24H-4, 198-1210B-24H-1, 198-1211A-15H-4, 198-1211B-15H-3, 198-1211C-15H-3, 198-1212A-12H-7, and 198-1212B-11H-7.
Figure F54. LPTM on Shatsky Rise in Sections 198-1209A-21H-7, 198-1209B-22H-1, 198-1209C-11H-3, 198-1210A-20H-6, 198-1210B-20H-3, 198-1211A-13H-6, and 198-1211A-13H-5, 198-1211B-13H-4 (unconformity above clay-rich seam), 198-1211C-13H-2, and 198-1211C-13H-3, 198-1212A-10H-1, 198-1212B-9H-5.
Figure F55. Age vs. depth plots for Leg 198 sites constructed from magnetic stratigraphy using the timescale of Cande and Kent (1995). Only Neogene sediment cores produced an interpretable magnetic stratigraphy.
Figure F56. Stratigraphy of Cretaceous sections on Shatsky Rise showing recovered intervals in blue and nonrecovered intervals in white. Purple intervals indicate widespread unconformities on Shatsky Rise. Water depths are listed in parentheses for each site. KS = zonation of Sliter (1992).
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