Sediments recovered at Site 1196 consist of well-lithified, shallow-water carbonates (limestone and dolostone), which make up a significant carbonate edifice (SMP) that overlies a phosphatic-rich siliciclastic substrate. The surface of this carbonate platform is overlain by a variably thick veneer of hemipelagic sediments as seen on seafloor photographs taken during the precruise site survey (Fig. F6 in the "Leg Summary" chapter). In some places, the platform surface outcrops at the seafloor. The carbonate sediment succession was divided into four major units on the basis of carbonate mineralogy and the nature of constitutive particles (Fig. F4; Table T3). Unit I (Hole 1196A: 0.0-182.2 mbsf; Hole 1196B: 0.0-184.9 mbsf) is mainly composed of dolomitic floatstone and rudstone. Unit II (Hole 1194A: 182.2-345.8 mbsf; Hole 1196B: 184.9 mbsf-bottom of hole) consists of nondolomitized skeletal floatstone/grainstone characterized by the occurrence of shallow-water fauna. Within Subunit IIA, calcareous nannofossils indicate an age of 15.2 to 13.3 Ma (see "Biostratigraphy and Paleoenvironments"). Unit III (345.8-617.1 mbsf) is typically composed of variously colored, coarse crystalline dolostone. Unit IV (617.1-662.6 mbsf) also consists of dolostone, but in addition it contains a significant amount of siliciclastic particles. The underlying siliciclastic substrate, Unit V, is composed of dark sandstone, claystone, and phosphatic sands of late Oligocene age (see "Biostratigraphy and Paleoenvironments").
In Hole 1196A, the top of Unit I corresponds to a highly corrugated, iron-stained surface (Fig. F5), which was likely shaped by both subaerial (karstic dissolution) and submarine (bioerosion and currents) processes. This surface is partially overlain by a 1-cm-thick bed of skeletal wackestone that yielded a planktonic foraminiferal assemblage with a maximum age of 3.2 Ma (Fig. F6) (see "Biostratigraphy and Paleoenvironments"). Because this wackestone layer is so thin, it was not recorded as a separate lithologic unit. In Hole 1196B, the top of Unit I is capped by a 2-cm-thick stromatolitic crust (Figs. F7, F8). Unit I was divided into four subunits based on biotic assemblage. Subunits IA, IB, and ID are mostly dolomitic in composition, whereas Subunit IC is predominantly calcitic.
This subunit consists of dolomitic floatstone/rudstone characterized by the occurrence of centimeter-sized rhodoliths and coral fragments in a moderately sorted grainstone matrix (Fig. F9). This matrix contains larger benthic foraminifers, red algae, mollusks, and rare bryozoan fragments. Examination of one thin section from the uppermost part of Subunit IA, just below its corrugated upper surface, further revealed the occurrence of Halimeda debris (Fig. F10). Color varies downcore from pale yellow to pale brown. Both intergranular and moldic porosity occur. In the uppermost part of Subunit IA, pores are filled by a complex succession of cements and internal sediments, including early isopachous fibrous rims, vadose silt, blocky spar fringes, and micrite (Fig. F10). Dolomitization is not pervasive (calcitic horizons are preserved), and skeletal components are still identifiable. A single piece of skeletal wackestone with planktonic foraminifers, possibly an artifact related to drilling, was found between 20 and 30 cm in Section 194-1196A-1R-1. The base of Subunit IA is marked by the rapid disappearance of centimeter-sized rhodoliths at the bottom of Cores 194-1196A-13R and 194-1196B-16Z.
This thin unit consists of light brown, well-lithified, dolomitized skeletal floatstone with a recrystallized grainstone matrix (Fig. F11). The coarse (>2 mm) fraction amounts to ~30% of the rock volume and predominantly includes elongated fragments of branching coralline algae and centimeter-sized mollusk shells. Numerous molds of flat, larger benthic foraminifers also occur. Faint, low-angle cross-bedding is visible in some intervals (Fig. F11). Dolomitization is more pervasive than in Subunit IA, but rock texture is still visible. The lower parts of Subunits IA and IB correspond to marked peaks in natural gamma ray (NGR) intensity, with increasing amplitude downcore (see "Core Physical Properties" and "Downhole Measurements"). The boundary between Subunits IB and IC is sharp and occurs near the base of Core 194-1196A-14R and within Core 194-1196B-20Z.
This poorly recovered, moderately lithified unit is characterized by light gray to white skeletal rudstone, floatstone, and boundstone rich in centimeter-sized hermatypic coral debris, mollusk shell fragments, and rhodoliths (Fig. F12). Coralline algae and bryozoan clasts, broken echinoid spines, and larger benthic foraminifers occur also in the finer-grained matrix. Both intergranular and moldic porosities are frequent throughout this interval, which, unlike overlying units, is essentially composed of calcium carbonate. In Hole 1196B, this reefal facies alternates with dolomitic floatstone containing molds of larger benthic foraminifers, coral, and bivalve fragments. The upper part of Subunit IC (Core 194-1196A-15R) correlates with low NGR values (see "Core Physical Properties" and "Downhole Measurements"). The boundary between Subunits IC and ID corresponds to a thin micritic crust near the top of Core 194-1196A-18R that was not recovered in Hole 1196B. The difference in thickness of this subunit in Hole 1196A and 1196B (14.5 vs. 36.9 m) exceeds the depth errors resulting from coring. This difference implies that Subunit IC is laterally variable in thickness.
The top of Subunit ID corresponds to marked peaks in resistivity and velocity in the downhole logs (see "Downhole Measurements"). Subunit ID is mostly composed of pale brown to brown dolomitic floatstone with a grainstone matrix. Main constituents include whitish, elongated fragments of branching coralline algae; small (<1 cm) rhodoliths; mollusk shells; rare bryozoan detritus; larger benthic foraminifers, which essentially occur as molds; and minor coral debris. The occurrence of rhodoliths and rare coral fragments is the main difference between this facies and that observed in Subunit IB. Overall sorting is poor in this subunit. A crude lamination generated by an abrupt change in grain size can be observed in some intervals (Fig. F13). Within this subunit, the grainstone matrix is pervasively dolomitized and with moldic porosity. Below the micritic crust forming the boundary with Subunit IC, the uppermost 15 cm of Subunit ID (Hole 1196A) is characterized by a dense, mottled dolomicrite with rare molds and no texture preserved. In the bottom of Core 194-1196A-18R, an interval of rhodalgal boundstone and rudstone was observed. The top of Core 194-1196A-19R contains a dense, brown, iron-stained, 1-cm-thick layer that may represent an exposure surface. The boundary between Units I and II occurs within Sample 194-1196A-20R-1, 27 cm, and at the top of Core 194-1196B-33Z. It corresponds to a sharp color and facies change in Unit I and to a thin dolomitic crust in Unit II (Fig. F14).
In Hole 1196A, the top of Unit II consists of a dense, dark brown dolomitic floatstone/rudstone interval (194-1196A-20R-1, 27-40 cm) (Fig. F14) containing abundant molds of branching coral and rare fragments of branching coralline algae. Pervasive dolomitization has removed much of the fine-grained matrix texture. Unit II was deposited in a shallow-water depositional setting (see "Biostratigraphy and Paleoenvironments"). This unit has been divided into two subunits on the basis of textural and biotic changes.
This subunit consists of light gray to pale brown, well-lithified, poorly sorted, skeletal floatstone with a silt-sized grainstone matrix (Fig. F15). Predominant constituents are porcellaneous larger benthic foraminifers (alveolinids and soritids) and centimeter-sized, disarticulated but unbroken mollusk shells. Coral, bryozoan, and rare Halimeda debris were also observed. The fine grainstone matrix mostly contains abraded coralline-algae clasts and small benthic foraminifers (miliolids) in a sparry calcite cement (Fig. F16). Thread-like dark patches up to 1 cm long are interpreted as preserved seagrass roots. Organic matter and clays also occur in this subunit (See "Geochemistry"). Bioturbation is visible in some intervals. Within this subunit, moldic porosity is common and fenestral porosity is observed in Section 194-1196A-22R-1. Well-sorted, coarser grainstone intervals, about 0.2-0.4 m thick, occur near 230 mbsf (Cores 194-1196A-25R and 194-1196B-45Z) and at 317 mbsf (Core 194-1196A-34R). Rare nannofossils yielded an early to middle Miocene age (13.6-18.2 Ma) (316.0 mbsf [Core 194-1196A-34R] and 218.0 mbsf [Core 194-1196B-40Z]). Benthic foraminiferal data further constrain the age of Subunit IIA to between 15.2 and 13.3 Ma (see "Biostratigraphy and Paleoenvironments"). The lower part of Subunit IIA is characterized by thin horizons with dark brown, dense micrite mottles. One of these horizons (Section 194-1196A-33R-1, 42-88 cm; 307.4 mbsf) corresponds to exceptionally high values in NGR, resistivity, and sonic velocity in the downhole logging record (see "Downhole Measurements"). The facies change between Subunit IIA and IIB occurs between Cores 194-1196A-35R and 36R; the boundary itself was not recovered.
This thin subunit is represented by a pale beige to white, well-lithified, poorly sorted skeletal rudstone/boundstone. The very coarse (>1 cm) fraction includes colonial hermatypic corals, red algae, and mollusk (gastropod and bivalve) fragments. The matrix of Subunit IIB is dominated by micrite. Lithophaga borings are common, as is moldic porosity. A possible oolitic grainstone occurs at the top of Core 194-1196A-36R. The boundary with underlying Unit III occurs at Sample 194-1196A-37R-1, 30 cm (345.8 mbsf) (Fig. F17), and is characterized by a marked change in rock composition from pure calcite to mixed calcite and dolomite mineralogy (Fig. F4). This boundary corresponds to the downhole transition in NGR values, which decrease from a maximum at 306.0 mbsf near the base of Unit II to minimum values at the top of Unit III (see "Downhole Measurements").
This ~270-m-thick unit consists of coarse crystalline dolostone. Depositional textures have, for the most part, been erased by pervasive dolomitization, and only the ghosts or molds of original rock constituents can be observed. Four subunits have been determined on the basis of color; trace minerals; the presence or absence of molds; and, in one case, the identification of primary rock components.
This subunit consists of a mottled, pinkish white to light brown, recrystallized, dolomitic rudstone with a grainstone matrix (Fig. F17). Ghosts of rhodoliths, branching and massive corals, and dissolved mollusk fragments were identified.
Only 0.22 m of sediment was recovered from this ~60 m interval. These sediments consist of cream-white dolomitic floatstone, including centimeter-sized rhodoliths and coralline algae fragments in a grainstone matrix. Because of their similarity to the facies of Subunit IA, these rocks were first interpreted to have fallen down the hole. However, there are also similarities to lithologic intervals recovered from Subunit IIB, between 285 and 410 mbsf, at Site 1199.
This core interval is characterized by a brilliant white, sucrosic dolostone ("snowstone") (Fig. F18). Rare relicts of centimeter-sized rhodoliths and branching coralline algae are preserved along with scattered, millimeter-sized, lenticular molds of larger benthic foraminifers. Dolomite content is close to 100% (Fig. F4), except in the upper part of Core 194-1196A-44R where a weak reaction to HCl occurs. This subunit is visually homogenous despite the presence of several peaks in sonic velocity between 450 and 460 mbsf (see "Downhole Measurements") that likely correspond to unrecovered horizons of different lithologic composition. The lower boundary of Subunit IIIB corresponds to a reddish interval at the top of Core 194-1196A-50R.
This subunit is characterized by a mottled, recrystallized, well-lithified dolostone showing various colors from white to pinkish to brown. Ghosts of rhodoliths, mollusk shells, and coralline algal fragments are visible in hand specimens. Fragments of echinoid spines and plates surrounded by a rim of syntaxial cement can be seen in thin section (Fig. F19). A small algal or coral buildup is present near the bottom of Core 194-1196A-53R. Intercrystalline, shelter, moldic, and possibly fenestral porosities were observed (Fig. F20). Moldic porosity results from the dissolution of larger benthic foraminifers. Dolomitization is pervasive in this subunit and euhedral dolomite rhombs up to 200 µm in size were observed in thin section (Fig. F19). The lower portion of Subunit IIIC contains several millimeter- to centimeter-thick, dense, brown or red-colored layers (Fig. F20) interpreted as exposure surfaces. The occurrence of several veins filled by dark-red, fine-grained dolostone (e.g., interval 194-1196A-51R-1, 128-147 cm) suggests that this interval is fractured. This interpretation is corroborated by FMS data (see "Downhole Measurements"). The base of this subunit has been placed immediately above a 6-cm-thick, dense dolomicrite zone at the top of Core 194-1196A-57R.
The lowermost portion of Unit III is characterized by very pale brown to olive-brown, well-lithified dolostone with abundant centimeter-sized molds resulting from the dissolution of benthic foraminifers (Fig. F21). Some molds are horizontally aligned, and there is an overall fining-upward trend, suggesting that the original sediment was laminated and graded. Other important constituents, most of which are barely visible, include rhodoliths, coralline algae, and mollusk fragments. Original rock texture has been lost. Two decimeter-thick intervals of light gray, dolomitic, skeletal packstone/grainstone with abundant larger benthic foraminifers occur in Samples 194-1196A-63R-1, 62 and 134 cm. The boundary between Units III and IV, corresponds to a 5-cm-thick, dense dolomicrite crust found in Core 194-1196A-65R.
This lowermost lithologic unit includes various dolostone facies, all of which contain siliciclastic material, such as quartz and lithoclasts. Glauconite is also present in certain intervals. These facies occur in meter-scale sequences separated by iron-stained zones interpreted as exposure surfaces. The following lithologies were distinguished on the basis of color, sedimentary structure, and noncarbonate mineral content:
Unit IV preserves a strong remanent magnetization, possibly linked to the occurrence of magnetite (see "Paleomagnetism"). The lower limit of this unit occurs at the base of Core 194-1196A-68R. No material was recovered from Core 194-1196A-69R.
Core 194-1196A-70R contains dark rocks (Fig. F23) of late Oligocene age (see "Biostratigraphy and Paleoenvironments"), which form the substrate for the carbonate platform described above. These rocks were described at macroscopic scale as sandstone and claystone. However, examination of two thin sections indicates the presence of phosphatic sands.
Paleodepositional environments, essentially determined from petrographic and sedimentological data, are proposed for each lithologic unit at Site 1196. Additional paleoenvironmental interpretation based on microfossil assemblages can be found in "Biostratigraphy and Paleoenvironments".
Rhodolith-bearing dolomitic floatstones, similar to those occurring in Subunit IA, were recovered from Leg 133, Sites 816 and 826, on the northern margin of the Marion Plateau (Shipboard Scientific Party, 1991). The coralline algae species and associations found in these rocks suggest that they accumulated in a neritic, storm-influenced, open-platform environment, at a water depth estimated between 30 and 80 m (Martín et al., 1993). This depth estimate is corroborated by the study of larger foraminiferal assemblages (Chaproniere and Betzler, 1993), which further indicate normal-salinity waters. Finer grain size, occurrence of delicate fragments of branching red algae, and the lack of centimeter-sized rhodoliths in Subunits IB and ID suggest a lower-energy, possibly deeper (up to 100 m) depositional setting for these lithologies. By contrast, the floatstone/boundstone facies rich in centimeter-sized hermatypic coral debris typical of Subunit IC probably corresponds to an in situ, shallow (< 30 m) reefal buildup.
The occurrence of seagrass (roots and rare blades) and the larger foraminiferal assemblage (see "Biostratigraphy and Paleoenvironments") shows that the nondolomitized skeletal floatstone characterizing Subunit IIA was deposited in a shallow-water (10 to 30 m) setting. This shallow-water setting is further suggested by the occurrence of fenestrae (Core 194-1196A-22R); a well-sorted grainstone interpreted as former shoal, or even coastal sand (Cores 194-1196A-25R and 34R); and micritic crusts and mottled zones reminiscent of pedogenic calcrete profiles (Cores 194-1196A-33R and 35R) (see Tucker and Wright, 1990). The presence of rare coccoliths in this succession (Cores 194-1196A-34R and 40Z) does not contradict this interpretation, as coccoliths may be distributed from the open ocean to inshore lagoonal settings and even estuaries (Haq, 1978). The energy level during deposition of Subunit IIA was relatively high, possibly because of current action, as indicated by the lack of mud in the silt-sized floatstone matrix (Fig. F16). The skeletal rudstone/boundstone at the base of Unit II (Subunit IIB) likely corresponds to a shallow (patch) reef facies.
Pervasive dolomitization precludes accurate reconstruction of the paleodepositional setting of the lowermost two carbonate units encountered at Site 1196. For each subunit, however, the following scenarios can be suggested:
Determining the magnitude and timing of eustatic sea level variations during the Miocene, particularly during the middle Miocene (Zones N12-N14), was one of the prime objectives of Leg 194. As such, the following points can be made regarding sea level variations over the platform at Site 1196:
Site 1199 is located 5 km to the east of Site 1196, slightly more proximal to the platform edge. The sedimentary succession was subdivided into three major units on the basis of carbonate mineralogy and nature of constituent particles (Fig. F24; Table T4). Unit I (0.0-159.8 mbsf) is characterized by dolomitic floatstone, rudstone, and a thin reefal interval. Unit II (159.8-410.0 mbsf) consists of nondolomitized skeletal floatstone/grainstone with shallow-water fauna. Unit III (410.0 mbsf- bottom of hole) was recovered in the core catcher of the last core and is represented by 15 cm of sucrosic dolostone. These units were further subdivided into subunits as described in the following sections.
Subunit IA (0.0-106.6 mbsf). This subunit is identical to the one found at the same level at Site 1196. It consists of whitish to pale brown dolomitic floatstone/rudstone, characterized by the occurrence of centimeter-sized rhodoliths and coral fragments in a moderately sorted grainstone matrix. This matrix contains small benthic foraminifers, coralline algae, mollusk shells, and rare bryozoan fragments. Whole echinoids are preserved locally, and bioturbation is common in these intervals (Cores 194-1199A-12R and 13R). The top 50 cm of Subunit IA includes a reddish horizon with pronounced moldic porosity, grading to a dense, nonporous whitish zone, and then to unaltered rock. This succession could represent a pedogenic profile. Increased recovery at Site 1199, as compared to Site 1196, provided the following new information:
The transition between Subunits IA and IB occurs at 106.6 mbsf in Core 194-1199A-13R and is marked by the sharp disappearance of centimeter-sized rhodoliths.
Subunit IB (106.6-114.1 mbsf). This thin subunit consists of very pale brown, well-lithified, dolomitized skeletal floatstone with a recrystallized grainstone matrix (Fig. F27). The coarse (>2 mm) fraction predominantly includes elongated fragments of branching coralline algae and centimeter-sized mollusk shells. Numerous molds of flat, larger benthic foraminifers also occur. This lithology is very similar to that observed at Site 1196, between 117.2 and 125.9 mbsf (Hole 1196A), and 122.9 and 130.5 mbsf (Hole 1196B). As in Hole 1196A, the base of Subunit IB corresponds to a marked peak in NGR intensity (see "Core Physical Properties" and "Downhole Measurements"). The boundary between Subunits IB and IC is sharp and occurs at 114.1 mbsf within Core 194-1199A-14R (Fig. F27).
Subunit IC (114.1-121.9 mbsf). This subunit is characterized by beige to pink rudstone/boundstone (Fig. F27) that contains centimeter-sized hermatypic coral debris, branching coralline algae fragments, and larger benthic foraminifers. Except for rare molds, this lithology is massive and, unlike the corresponding interval at Site 1196, pervasively dolomitized. In addition, this subunit is locally leached and infiltrated by reddish silt (Fig. F28). The boundary between Subunits IC and ID occurs at 121.9 mbsf in Core 194-1199A-15R (Fig. F29).
Subunit ID (121.9-159.8 mbsf). The top of this subunit corresponds to a 3-cm-thick red layer rich in silt-sized quartz grains (Fig. F29). Below this layer, Subunit ID is mostly composed of whitish to brown dolomitic floatstone with a grainstone matrix. Primary constituents include elongated fragments of branching coralline algae, small (<1 cm) rhodoliths, mollusk shells, rare bryozoan detritus, larger benthic foraminifers that essentially occur as molds, and rare coral debris. The grainstone matrix is pervasively dolomitized with moldic porosity. Dense, dark brown dolomicrite zones, with rare molds but no texture preserved, are found in the lower part of the unit. This lithology is identical to that of Subunit ID at Site 1196, which occurs between 162.8 and 182.2 mbsf in Hole 1196A, and 145.0 and 184.9 mbsf in Hole 1196B. The boundary between Subunit ID and Unit II occurs between Cores 194-1199A-18R and 19R; it was not recovered.
The lack of exposure or hardground horizons at the top of Core 194-1199A-19R suggests that the uppermost portion of Unit II has not been recovered. The dolomitic coral framestone occurring at this level in Hole 1196A was not found at this site. The uppermost interval of Unit II corresponds to low values in resistivity, density, and NGR intensity in the downhole physical property record (see "Downhole Measurements"). Unit II can be partitioned into two subunits (IIA and IIB).
Subunit IIA (159.8-285.0 mbsf). This unit consists of pale brown to beige, well-lithified, slightly dolomitized skeletal floatstone with a silt-sized grainstone matrix (Fig. F30). Millimeter-sized constituents include larger benthic foraminifers (alveolinids), thin mollusk shells, which commonly appear as molds, and rare coral fragments. The fine grainstone matrix possibly contains red-algae clasts. Subunit IIA is also characterized by thin horizons with dark brown, dense micrite mottles and dark centimeter-thick crusts. It corresponds to an interval of relatively high NGR values in the downhole logging record (see "Downhole Measurements"). Contrary to its lateral equivalent at Site 1196, Subunit IIA is slightly dolomitized and more lithified. The boundary between Subunits IIA and IIB occurs at 285.0 mbsf in Core 194-1199-32R.
Subunit IIB (285.0-410.0 mbsf). This highly porous, friable limestone unit is characterized by two facies that form meter-scale alternations. The first facies is a white to pale yellow, well-sorted, skeletal grainstone (Fig. F31). Grains have been leached and bioclast identification is difficult. Small benthic foraminifers, echinoid spine fragments, coralline algae and possibly Halimeda detritus have been recognized. Rare, meter-thick, more lithified, dolomitized intervals occur within this lithology. The second facies is slightly darker and includes centimeter-sized rhodoliths. In Hole 1196A, rare pieces of similar petrographic composition have been recovered from Cores 194-1196A-41R and 42R. Because of their rarity, small size, and similarity with shallower units at that site, they were assumed to have fallen down the hole. Hole 1196A further includes, at this level, a partly dolomitic coral rudstone facies that was recovered at Site 1199.
The core catcher of the last core retrieved from Hole 1199A contains 5 cm of brilliant white, sucrosic dolostone similar to that found in Hole 1196A. Thus, it is concluded that this interval formed as an independent unit, although we can not totally exclude that it represents a dolomitized interval within Subunit IIB.
Paleodepositional environments, as outlined below, have been determined from petrographic and sedimentological data and are proposed for each lithologic unit from Site 1199.
The rhodolith-bearing dolomitic floatstone found in Subunit IA suggests deposition on an open-platform at water depths estimated to be between 30 and 100 m (middle neritic; see "Biostratigraphy and Paleoenvironments"). The occurrence of wackestone with planktonic foraminifers in intraparticle voids reinforces the validity of these depth estimates. Varying hydrodynamic energy, likely related to storm action, is supported by the presence of distinctive facies (floatstone with large rhodoliths and rudstone with small rhodoliths) and crude coarse-tail grading in some sediment intervals. Further study is required to determine whether the dense pink-colored zones correspond to exposure horizons or, more likely, to submarine hardgrounds. As discussed for Site 1196, the dolomitic floatstones rich in coralline algae fragments characterizing Subunit IB were also deposited in an open-platform setting, possibly at slightly deeper water depths. The dolomitic coral-rich rudstone of Subunit IC represents a shallow reefal facies. These rocks overlie, and are overlain by, reddish crusts interpreted as exposure surfaces. Widespread vuggy porosity and the presence of internal sediment consisting of reddish silt further support this interpretation. Downhole logging data (see "Downhole Measurements"), as well as these diagenetic features suggest that Subunit IC has been pervasively karstified. As with Subunit IB, Subunit ID was deposited in a low-energy open-platform setting.
The slightly dolomitic floatstone, rich in porcellaneous benthic foraminifers (alveolinids), mollusk shells, and rare coral fragments characterizing Subunit IIA, was probably deposited in an inner-platform setting at shallow-water (<30 m) depths. In contrast to its lateral equivalent at Site 1196, no evidence of seagrass roots or blades was found in Subunit IIA to support this paleoenvironmental interpretation. Shallow-water deposition is supported by the presence of several horizons with centimeter-thick brown crusts, interpreted as calcretes, and brown mottles possibly corresponding to rhizoliths. The well-washed, whitish, skeletal grainstone found in Subunit IIB could represent high-energy shoal deposits laid down in relatively shallow water. By contrast, the alternating rhodolith-rich, skeletal floatstone could represent a slightly deeper depositional setting analogous to that of Subunit IA.
Limited recovery and pervasive dolomitization prevent accurate reconstruction of the paleodepositional setting of this sucrosic dolostone.
The stratigraphic succession recovered at Hole 1199A consists of diverse carbonate facies that reflect variations in accommodation space during the middle, and possibly the late Miocene. A progressive shallowing-up trend is recorded from the high-energy shoal facies of Subunit IIB to the lower-energy, shallow inner-platform or lagoonal sediments typical of Subunit IIA. The presence of several potential exposure horizons in this interval suggests that water depth may have been comparable to the amplitude of middle Miocene high-frequency sea level changes. In contrast to Site 1196, no exposure surface was recovered from the top of Unit II. A rapid sea level fall must have occurred after deposition of Subunit ID, as shown by the direct superposition of an exposure surface on this open-platform facies. Marked reddening and the presence of quartz silt of possible eolian origin further indicate an important hiatus at this level, which could correspond to the middle/upper Miocene boundary. Accommodation space was limited during deposition of the Subunit IC reefal unit, which is karstified and framed by exposure surfaces. Following a transgression and a deepening-upward trend during most of Subunit IB deposition, conditions became shallower again throughout Subunit IA, leading to subaerial exposure and pedogenesis at the end of this last phase of carbonate platform growth.