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Home , Aalenian, Calpionellid, Early Cretaceous, Early Jurassic, Late Jurassic, Middle Jurassic

Sedimentology (2007) 54, 317–337 doi: 10.1111/j.1365-3091.2006.00837.x

The Late , a greenhouse phase in the –Early ‘cool’ mode: evidence from the cyclic Adriatic Platform, Croatia

ANTUN HUSINEC* and J. FRED READ *Croatian Geological Survey, Sachsova 2, HR-10000 Zagreb, Croatia Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061, USA (E-mail: [email protected])

ABSTRACT Well-exposed sections of the Bahama-like Adriatic Platform along the Dalmatian coast (southern Croatia) reveal the detailed stacking patterns of cyclic within the rapidly subsiding (Tithonian) shallow platform-interior (over 750 m thick, ca 5–6 Myr duration). Facies within parasequences include dasyclad-oncoid mudstone-wackestone-floatstone and skeletal-peloid wackestone-packstone (shallow lagoon), intraclast-peloid packstone and grainstone (shoal), radial-ooid grainstone (hypersaline shallow subtidal/intertidal shoals and ponds), lime mudstone (restricted lagoon), fenestral carbonates and microbial laminites (tidal flat). Parasequences in the overall transgressive Lower Tithonian sections are 1– 4Æ5 m thick, and dominated by subtidal facies, some of which are capped by very shallow-water grainstone-packstone or restricted lime mudstone; laminated tidal caps become common only towards the interior of the platform. Parasequences in the regressive Upper Tithonian are dominated by peritidal facies with distinctive basal oolite units and well-developed laminate caps. Maximum water depths of facies within parasequences (estimated from stratigraphic distance of the facies to the base of the tidal flat units capping parasequences) were generally <4 m, and facies show strongly overlapping depth ranges suggesting facies mosaics. Parasequences were formed by precessional (20 kyr) orbital forcing and form parasequence sets of 100 and 400 kyr eccentricity bundles. Parasequences are arranged in third-order sequences that lack significant bounding disconformities, and are evident on accommodation (Fischer) plots of cumulative departure from average cycle thickness plotted against cycle number or stratigraphic position. Modelling suggests that precessional sea-level changes were small (several metres) as were eccentricity sea-level changes (or precessional sea-level changes modulated by eccentricity), supporting a global, hot greenhouse climate for the Late Jurassic (Tithonian) within the overall ‘cool’ mode of the Middle Jurassic to . Keywords Adriatic Platform, Croatia, greenhouse, Late Jurassic, precession.

INTRODUCTION (Veizer et al., 2000) and by the pCO2 plots GEOCARB III of Berner & Kothavala (2001). At The Late Jurassic–Early Cretaceous has been the long-term scale, these climate proxies are in considered to lie in the Mesozoic ‘cool’ mode by agreement, but at shorter time scales, there is Frakes et al. (1992). Interpretation of this ‘cool’ some conflict both in degree of warming or mode is supported by oxygen isotope signals cooling and timing of the events (Veizer et al.,

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2000; Royer et al., 2004). The cyclic Late Jurassic Cretaceous ‘cool’ mode (Frakes et al., 1992). record of the shallow Adriatic Carbonate Plat- Additionally, the parasequence stacking patterns form, Croatia, is used in this paper to provide on the platform record third-order relative sea- higher resolution palaeoclimate data to help level changes that can be evaluated against the resolve this. global (Haq et al., 1987) curve and the Arabian Stacking patterns of parasequences have been sea-level curve (Haq & Al-Qahtani, 2005). used to document precessional and eccentricity forcing in Tithonian- units in France (Strasser, 1994) and (Anderson, 2004a). GEOLOGIC AND TECTONIC SETTING OF These areas differ markedly from the Adriatic ADRIATIC PLATFORM Platform in that they were much more slowly subsiding and more humid. The high subsidence The Adriatic Platform (Fig. 1) was part of a rates of the Adriatic Platform should potentially regional to Early mega-platform yield a relatively complete record of eustatic that was attached to along the south- signals that affected the platform, given that it ern margin of Tethys. Following tended to be aggraded to near sea-level, and rifting, this mega-platform broke into large plat- probably had fewer missing beats than more forms that included the Adria microplate. The slowly subsiding areas elsewhere. Adria microplate then underwent subsequent Because shallow-water carbonate platforms lie rifting to form the Adriatic and close to sea-level, they are sensitive to the Italian Apulian and Apennine platforms (e.g. high-frequency global sea-level changes. Conse- Pamic´ et al., 1998; Bosellini, 2002; Jelaska, 2003; quently, sea-level changes in a purely green- Vlahovic´ et al., 2005). The Mesozoic Adriatic house, relatively ice-free world should leave a platform consists of an immense (up to 6 km different record within the platform thick) pile of shallow-water carbonates, punctu- than sea-level changes driven by small to ated by periods of subaerial exposure, palaeokarst moderate amounts of ice in a cooler, but non- and bauxites and by several pelagic (incipient ice-house world. Shallow interiors (<10 m) of drowning) episodes (Fig. 2). Intra-platform such platforms if formed under relatively ice- troughs were buried beneath syn-orogenic sedi- free greenhouse conditions are likely to contain ments and were deformed during the many small parasequences formed by preces- Alpine orogeny, when the Adriatic Platform sion-eccentricity driven or even sub-Milanko- became part of the peri-Adriatic mountain belt. vitch sea-level changes (Goldhammer et al., Subsidence history curves (Husinec & Read, 2005; 1990; Read, 1995; Zu¨ hlke et al., 2003) or if Husinec & Jelaska, 2006; Fig. 3) show that subsi- deposited in a few tens of metres, poorly cyclic dence rates on the Late Jurassic Adriatic platform ) shallow subtidal successions. In contrast, plat- were rapid, up to 15 cm kyr 1, slowing into the forms that develop under moderate amounts of -. Subsidence rates then increased global ice associated with a cooler (but not again into the with onset of icehouse) Earth (transitional eustasy of Read, collision. The relatively high subsidence rates (up 1995, and ‘doubthouse’ of Miller et al., 1998) to three times as fast as the Appalachian Cambro- appear to have distinctly different parasequence passive margin, USA; Koerschner & stacking, probably driven by obliquity and Read, 1989) favour a fairly complete stratigraphic short-term and long-term eccentricity, and also succession being preserved on the platform for show periodic emergence and palaeosol forma- the Tithonian. tion on the platform. In these platforms, only a few of the precessional beats flood the platform Biostratigraphic control and are preserved in the platform record, the remainder not being preserved on the platform The restricted shallow waters of the Late Jurassic top. These are end-member scenarios, and the Adriatic Platform interior precluded the occur- actual stratigraphic record may be a more rence of fully marine organisms, and carbonate complicated mix of the end-members. producers were limited predominantly to benthic Stacking patterns of the platform-interior para- and calcareous green algae. Conse- sequences of the Adriatic Platform of Croatia, quently, there was not an opportunity to recover which lie in the precessional band, suggest that stratigraphic records with high-resolution chro- the Late Jurassic Tithonian was hot green- nology provided by open-marine organisms house within the overall Middle Jurassic–Early such as ammonites, radiolarians or .

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Fig. 1. (A) General location map showing outline of the Mesozoic Adriatic Carbonate Platform within Croatia and environs (modified from Velic´ et al., 2002). Black rectangle outlines study area shown enlarged in (B). (B) Detailed map of study area showing location of sections LSL (Lastovo Island) and MSV (Mljet Island).

In addition, the long-distance sequence strati- Kurnubia palastiniensis, Pseudocyclammina lit- graphic correlation with coeval Tethyan succes- uus and Valvulina lugeoni. The Late Kimmerid- sions is hampered because the platform-interior gian is in agreement with the data from the succession does not contain sediments deposited , where FAD of C. jurassica is in a spectrum of settings, but instead are mainly reported in the ammonite euxodus Zone (Bernier, shallow peritidal carbonates. Biostratigraphic 1984). The beginning of Tithonian is character- control for Upper Jurassic Tithonian platform- ized by more frequent findings of C. jurassica in interior strata consists of two dasycladacean association with Pseudoclypeina distomensis,an (Early Tithonian Clypeina jurassica alga whose FAD in the Dinarides is at the s.str., and Late Tithonian Clypeina jurassica and –Tithonian boundary. The upper Campbelliella milesi), which have been described part of Tithonian is characterized by abundant in detail by Velic´ (1977) and Velic´ & Sokacˇ findings of the alga Campbelliella. Following the (1978). Numerous references on Late Jurassic disappearance of Campbelliella and several for- of both benthic foraminifera and aminiferan species that are restricted to Late calcareous algae from this region show that there Jurassic (e.g. Parurgonina caelinensis), the begin- is a reasonable correlation with other Mediterra- ning of Berriasian is characterized by FADs of nean localities where benthic biozones are calib- several index species of calcareous algae in the rated with the established ammonite and area investigated, including Otternstella lemmen- schemes (De Castro, 1993; and refer- sis, Clypeina isabelae, Clypeina parasolkani, ences therein). The determined local stratigraph- Clypeina catinula, Humiella sardiniensis, Humi- ical ranges of individual benthic species, if ella catenaeformis and Salpingoporella katzeri studied in the context of the stratigraphic ranges (Husinec & Sokacˇ, 2006). Magnetostratigraphic or of the entire association, seem to strontium-isotope chemostratigraphic dating remain constant at a regional, platform-wide techniques are needed in the future to improve scale. The strata underlying the studied Titho- the chronostratigraphic correlation. nian succession are characterized by the scarce Tisˇljar et al. (2002) suggested that the begin- alga Clypeina jurassica [its first appearance ning of Berriasian is characterized by a regional datum (FAD) is registered just above the strata regression, as evidenced by peritidal , with last recorded occurrence of foraminifera black-pebble breccia, emersion breccia, residual Praekurnubia crusei], associated with foramini- clays, swamp deposits and palaeosols, sporad- fera of longer stratigraphic ranges, including ically even with bauxites. In the study area,

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Fig. 2. (A) Generalized strati- graphic column of Mesozoic Adriatic Platform showing major units and geological events (Jelaska, 2003). The Late Jurassic (Tithonian) interval of study is shown by black bar alongside column. (B) Schematic columns of sections used in the study showing regional facies relations. Correlation is inferred based on facies stacking patterns and unconformity surfaces (basal Berriasian). The MSV section is located ca 40 km inboard from the platform margin. Heavy black vertical bars mark measured sections. several emersion breccia and/or residual clay METHODS horizons have been reported from the basal Berriasian of Lastovo (Husinec, 2002). In the Data in this paper are based on detailed sections wider Tethyan realm, the overall regression measured by Husinec et al. at the Croatian characterized the Tithonian, and it was marked Geological Survey (see Husinec, 2002). The sec- by continuous-exposure conditions on the peri- tions used are detailed bed-by-bed logs recording Tethys margins, and by the associated long-term stratigraphic position, sedimentary structures, forced regression and gravitational deposits in textures, Dunham rock types and fossils inclu- basinal areas (Jacquin et al., 1998, and refer- ding age-diagnostic . These were ences therein). reformatted to provide colour-coded computer-

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Fig. 3. Accommodation history plot using base of Jurassic as reference horizon, for Jurassic-Cretaceous interval, Adriatic Platform (from Husinec & Jelaska, 2006). The Jurassic to Late Cretaceous is the passive margin stage of the ) Adria Microplate. The Tithonian interval has the highest subsidence rate (12–15 cm kyr 1) of any of the stages, including the Late Cretaceous collisional event. drafted columns emphasizing Dunham rock types changes. This is because not all parasequences and dominant grain types. This simplified the shallow to each highstand of sea-level, thus not picking of parasequences and parasequence sets. all accommodation was filled during shallowing Accommodation (Fischer) plots were generated (Boss & Rasmussen, 1995). The estimates of by graphing cumulative departure from mean amplitudes of relative sea-level cycles are likely cycle thickness vs. either cycle number or strati- to be minimum estimates. Modelling was done graphic position in the section (Fischer, 1964; using PhilÒ 1Æ5 developed by Scott Bowman Read & Goldhammer, 1988; Sadler et al., 1993; (Petrodynamics, Houston, TX, USA). For the Day, 1997). These accommodation plots show modelling, precessional and obliquity sea-level periods of increased accommodation as rising cycles were convolved with eccentricity sea-level limbs and decreased accommodation as falling cycles, as in the deep sea isotope limbs on the graphs. Note that plotting cumul- record. Another way to model these, would be to ative departure vs. stratigraphic position does not have precessional sea-level amplitudes modula- affect the relative amplitudes of the plots, but ted by eccentricity. The main difference between only the steepness of the rising or falling limbs the approaches would be in the effect on the (Day, 1997). Fourth-order (0Æ1–0Æ5 Myr) and third- deeper water platform facies during sea-level low order (0Æ5–5 Myr) relative sea-level cycles were stands. As we are modelling the shallow-water picked from the accommodation plots. Effects of stratigraphy, it is probable that either approach compaction were neglected because much of the would yield a similar stacking of cyclic facies. dewatering in carbonates is assumed to be early and occurring during deposition of a cycle; sub- sequent burial compaction is difficult to access FACIES AND ENVIRONMENTS given the variable timing of cementation in car- bonates. It should be stressed that the Fischer Facies within the interior of the Late Jurassic plots only provide a relative measure of sea-level portion of the Adriatic Platform are summarized

Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 54, 317–337 322 A. Husinec and J. F. Read in Table 1; an idealized parasequence is shown genized these sediments obliterating any sedi- in Fig. 4, and the facies are illustrated in Fig. 5. mentary structures. The detailed stacking patterns are shown in Figs 6 and 7. Minimum estimates of water Skeletal-peloid wackestone-packstone depths of each facies were determined by (shallow lagoon) measuring the stratigraphic distance from the base of each facies to the base of the capping These facies (described in Table 1) are light tidal flat facies. The estimate is too small if brown, thin-bedded to thick-bedded wackestone- compaction is significant, or if sea-level was packstone (Fig. 5B) composed of peloids and falling as the parasequence shallowed (Koersch- skeletal fragments of dasyclad algae, benthic fora- ner & Read, 1989). Estimates of water depths minifera and hydrozoans (?), oncoids, and sparse would be too high if there was significant ooids and intraclasts. They formed in water depths load-induced subsidence during deposition of from 0 to 3 m (Fig. 8) in low-energy settings. each parasequence. These estimates of water Waters were moderately restricted and poss- depths using fenestral/microbial carbonate as a ibly metahaline, and hence lack open-marine sea-level datum (Fig. 8) are thus relative meas- oceanic assemblages, although the presence of ures, and show that the subtidal facies had hydrozoans (?) suggests near-normal salinities. overlapping depth ranges, implying mosaic-like facies patterns. The facies identified in this Intraclast-peloid packstone and grainstone study are outlined below (from deepest to (shoal-water) shallowest). These facies (described in Table 1) are light brown thin-bedded to thick-bedded packstone- Dasyclad-oncoid mudstone-wackestone- grainstone (Fig. 5C) composed of intraclasts, floatstone (‘deeper’ lagoon) peloids, and locally, minor ooids; in a few beds, These facies (described in Table 1) are light there are common dasyclad algae, benthic fora- brown, massive to thick-bedded mudstone- minifera, hydrozoan fragments and less common wackestone-floatstone (Fig. 5A) composed of oncoids and molluscs. These formed in shallow- variable amounts of dasyclads and oncoids, wave and current-agitated settings by accumu- and small amounts of benthic foraminiferans lation of resident dasyclads and foraminifera along and molluscs. They formed in quiet, slightly with peloids and intraclasts derived from deeper lagoon settings (down to depths of 3 m, reworked muds or micritization of grains. Water and rarely as much as 8 m; Fig. 8) below the depths probably ranged from 0 to 2 m (Fig. 8) and zone of frequent wave reworking. Given the overlapped those of the oolitic facies, but waters isolated platform setting, this low-energy envir- were not sufficiently supersaturated to form ooids. onment may have resulted from the sheltering Grainstones may have developed in areas of mobile effect of reefs, islands and tidal flats along the substrates whereas packstones may have devel- eastern, windward margin of the platform (Velic´ oped beneath stable bottoms, perhaps beneath et al., 2002). Without this sheltering effect, subtidal mats or vegetation (cf. Bathurst, 1973). bottom sediments at such shallow lagoonal depths probably would have been winnowed Radial-ooid grainstone (hypersaline shallow during storms, as in the present-day Bahama subtidal/intertidal shoals and ponds) grapestone lithotopes, and the fines transported off-platform or into sheltered peritidal settings These facies (described in Table 1) are thin to in the lee of islands (Illing, 1954; Imbrie & thick, horizontally bedded grainstones (less com- Purdy, 1962). Lack of open-marine foraminifer- monly packstones) that lack high-energy sedi- ans, echinoderms and , indicates mentary structures. They include light grey units that the platform-interior was relatively re- dominated by fine-grained ooids and darker, stricted compared with the open ocean, and brown to grey units composed of poorly sorted, possibly had near-normal to slightly elevated sand-sized to granule-sized whole, fragmented salinities for these facies. The abundant micro- and recoated ooids (‘vadoids’ of Tisˇljar, 1985). bial oncoids suggest that waters were relatively Oolitic units (Fig. 5D) also contain some grape- supersaturated with respect to calcium carbo- stone-like aggregates (mainly of ooids) as well as nate, compared with the present-day conditions lesser amounts of peloids, gastropods and algae. (Riding, 1992). Intense bioturbation homo- The ooids appear to be primary radial calcite

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Table 1. Tithonian platform interior facies.

Hypersaline shallow subtidal/intertidal Moderately Facies Tidal flat Restricted lagoon shoals and ponds Shoal-water shallow lagoon ‘Deeper’ lagoon Lithology Fenestral lime Unfossiliferous Ooid grainstone- Intraclast-peloid Skeletal-peloid Lime mudstone mudstone-wackestone; lime mudstones packstone packstone wackestone-packstone to oncoid-dasyclad Microbial laminite; and grainstone, wackestone-floatstone Planar laminite locally skeletal Color Light brown Light brown Dark brown to gray Light brown Light brown Light brown (coarser oolites); light gray (finer oolites)

Ó Sedimentary Wavy lamination, Thin-bedded, Thin to thick bedded; Thin to Thin to medium Thick-bedded, 06ItrainlAscaino Sedimentologists, of Association International 2006 structures common homogenous scarce erosional thick bedded bedded commonly heavily LLH-; micrite; contacts with bioturbated polygonal rare burrow underlying fenestral dessication cracks; fenestrae carbonates fenestral lamination; millimetre laminae of lime mudstone and peloid-skeletal packstone Fabric Poorly sorted, mud- Dominantly Poor- to well-sorted, Range from well- Poorly sorted, Poorly sorted muds with to granule-size mud-size fine-sand to granule-size sorted to mud matrix with sand- to granule-size poorly sorted, sand- to rare grains fine sand granule-size grains to granule-size Grain types Micritized peloids, Rare peloids Ooids (commonly broken Intraclasts, peloids, Oncoids, peloids, Oncoids, hydrozoans,

intraclasts and rehealed), peloids, scarce scarce ooids and rare micrite intraclasts greenhouse Jurassic Late grapestone-like aggregates oncoids and ooids intraclasts

Sedimentology Biota Calcareous algae, small Fossils absent Calcareous algae, Calcareous algae and Common calcareous Common calcareous benthic foraminifera, to sparse; gastropods benthic foraminifera algae and benthic algae and benthic and calcified rarely may have and molluscs foraminifera, bivalves, foraminifera, less cyanobacteria gastropods common gastropods common ostracods, (Cayeuxia?) and ostracods in a few beds molluscs, gastropods, bivalves, encrusters, ,

54 hydrozoans(?) 317–337 , Environment Tidal zone 0–2 m 0–2 m 0–3 m 0–4 m 0–6 m; max. 8 m water depth 323 324 A. Husinec and J. F. Read

(1986) suggested that slightly younger Purbeckian ooids were originally high-Mg calcite. The finer- grained oolitic units are shallow marine ooid shoal facies. Where there was more restriction, as in hypersaline ponds and restricted lagoons, the ooids grew to relatively large sizes (cf. Loreau & Purser, 1973). Periodic exposure caused grain breakage and regrowth of ooid cortices with submergence (Tisˇljar, 1985). Many of these oolitic units are transgressive and located at bases of parasequences, whereas thin oolitic units in the upper parts of parasequences are regressive (Husinec & Read, 2006; Fig. 5F).

Lime mudstone (restricted lagoon) These facies (described in Table 1) are light brown, thin-bedded homogenous lime mudstone with very rare peloids, gastropods and ostracods. They formed in nearshore very shallow (mainly <1 m), low-energy restricted settings seaward of tidal flats. Waters may have been hypersaline as suggested by the very restricted biotas.

Fenestral carbonates and microbial laminites (tidal flat) These facies (described in Table 1) are light brown, and include planar (mechanical) lami- nites, wavy or crinkly microbial laminites and Fig. 4. Idealized succession of facies within a Titho- fenestral laminites. They contain peloids, smaller nian parasequence. Oolitic units at the base of para- intraclasts, benthic foraminifera, calcareous algae sequences are generally absent from the Lower and calcified cyanobacterial tufts (Cayeuxia?), Tithonian. In the Upper Tithonian, the basal oolitic and less common ostracods. The microbial lam- units are mainly transgressive (upward narrowing inites are common in the Lower Tithonian plat- triangle). Although facies are shown as a shallowing upward succession (upward widening triangle), they form-interior and formed in intertidal settings have overlapping depth ranges implying facies mosa- with well-developed microbial mat covers and ics. Symbols are explained in Fig. 7. low to moderate sediment influx; this formed alternating mat and sub-centimetre sediment-rich ooids that formed from seawater with low Mg/Ca layers with only a few fenestrae (cf. Logan et al., ratios compatible with Late Jurassic seawater 1974). The laminoid fenestral carbonates (Fig. 5G (Stanley & Hardie, 1998), although Strasser and H) are common in the oolitic Upper Titho-

Fig. 5. Thin-section photographs of typical facies. Scale bar is 2 mm. (A) Oncoid floatstone with foraminifera Par- urgonina caelinensis. (B) Skeletal wackestone-packstone with numerous fragments of dasyclad Clypeina jurassica. (C) Skeletal-intraclast-peloid grainstone with numerous fragments of dasyclad Campbelliella (curved sparry grains with micritic rinds). (D) Poorly sorted ooid grainstone composed of whole and fragmented-and-recoated radial ooids, some with cerebroid outlines (arrows). (E) Transgressive indurated contact between fenestral, tidal flat carbonate with dispersed ooids and grapestone-like aggregates of ooids and peloids (bottom), and the overlying ooid packstone (top). (F) Contact between meniscus micrite-cemented ooid grainstone (bottom) and the overlying skeletal (Camp- belliella) wackestone-packstone (top). Aragonitic grains have been leached; lack of leaching of ooids indicates pri- mary radial calcite mineralogy. (G) Fenestral composed of intraclasts, peloids and lumps of calcified filamentous cyanobacteria(?), some with radiating habit. Some larger fenestrae are lined with micritic cement and fine turbid bladed calcite. (H) Fenestral peloid-ooid grainstone composed of very poorly sorted peloids and com- posite grains, many of which are micritized and superficially coated. Oolitic coats are composed of thin concentric envelopes of yellowish radial calcite (arrows).

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AB

C D

E F

G H

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Fig. 6. Stratigraphic columns of the Tithonian sections showing facies stacking, parasequences, and parasequence sets. Location of sections shown in Fig. 1B. Heavy black vertical bars mark portions of sections enlarged in Fig. 7. (A) Lower Tithonian section MSV; section lies in the more interior location than section LSL. (B) Lower Tithonian section LSL. (C) Upper Tithonian section LSL. nian, and formed in well-drained organic-poor, PARASEQUENCES AND STACKING intertidal to supratidal flats with a thin mat cover, PATTERNS high sediment influx and incipient cementation (Logan et al., 1974). Teepees generally are absent. We use the following definitions in the sense of Hypersalinity is suggested by lack of burrowing in Van Wagoner et al. (1988). A parasequence is a these facies and lack of charophytes, which are shallowing-upward, conformable succession of freshwater algae (cf. Hardie & Ginsburg, 1974). genetically related strata bounded by marine

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lithologically defined lower and upper Tithonian units and the Early and Late Tithonian age defined by the fossils. An idealized shallowing- upward facies succession is shown in Fig. 4, although the full complement of facies is seldom observed within a single parasequence. The lack of a high-resolution on the plat- form (and indeed most platforms) makes assign- ing fifth-order and sixth-order cycle nomenclature (e.g. Anderson, 2004a,b) potentially risky because of the possibility of sub-Milankovitch cycles being confused with precessional cycles, the problem of autocycles, and the problem of differ- entiating, with surety, between precessional, obliquity and short-term eccentricity cycles (Zu¨ hlke et al., 2003). Thus we have opted to use the descriptive terms ‘parasequence’ and ‘parase- quence sets’, which do not have a time connotation.

Lower Tithonian parasequences and parasequence sets The Lower Tithonian parasequences commonly are 0Æ7–4Æ5 m thick, but a few are up to 8 m thick and probably are compound parasequences. They are dominated by subtidal facies (Figs 6A and 7A), typically skeletal-oncoidal wackestone/ floatstone and mudstone, grading up into intra- clast-peloid packstone-grainstone. Some parase- quences (36%) are capped by restricted, unfossiliferous lime mudstone, a few of which contain fenestrae suggestive of spar-filled bur- rows. Intraclast-peloid packstone-grainstone and skeletal-peloid wackestone-packstone also are common as parasequence caps (31% and 24%, respectively), while <10% of parasequences are capped by oncoid floatstone (Fig. 8A). Further into the platform-interior (Mljet Island section; Figs 6B and 7B), the Early Tithonian parase- Fig. 6. Continued. quences are still dominated by muddy subtidal facies, but grainstones are less common, and flooding surfaces. A parasequence set is a succes- fenestral, planar and microbial laminites cap sion of genetically related parasequences which most parasequences (55%; Fig. 8B). Oncoid float- form a distinctive stacking pattern that may be stone and restricted lime mudstone cap some bounded by major flooding surfaces, sequence parasequences (18% and 13%, respectively), boundaries, or boundaries of systems tracts. A whereas intraclast-peloid packstone and skel- systems tract of a depositional sequence may etal-peloid wackestone-packstone cap few contain one or more parasequence sets. The (<10%) parasequences. Tithonian succession consists of a lower unit of The Lower Tithonian parasequences are ar- dominantly subtidal parasequences, and an ranged in sets commonly 10 m thick, but ranging upper unit dominated by peritidal and oolite- from 8 to 15 m and composed of three to six bearing parasequences (Fig. 6). Moreover, the parasequences (Fig. 6A and B). Parasequences upper part is characterized by the presence of within each set tend to be characterized by pro- the dasyclad alga Campbelliella. However, there gressively shallower lithofacies upward within the need not necessarily be coincidence between set (cf. Anderson, 2004a,b). That is, parasequences

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Fig. 7. Enlarged portions of the stratigraphic columns of Fig. 6. (A) Subtidal parasequences typical of the Lower Tithonian at section LSL (Fig. 1B). (B) Peritidal cycles typical of the upper part of the Lower Tithonian section MSV (Fig. 1B) in more interior location relative to section LSL. (C) Typical Upper Tithonian parasequences with thick basal ooid grainstone units and laminate caps in section LSL (Fig. 1B).

Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 54, 317–337 Late Jurassic greenhouse 329 in the lower part of a set consist dominantly of oncoid-skeletal wackestone-mudstone and skel- etal-intraclastic subtidal facies, whereas the uppermostparasequence(s) are capped by restric- ted lime mudstones some of which are fenestral; caps in the more interior part of the platform are microbial and planar laminites. Some of these facies-defined parasequence sets are evident on the Fischer plots as small rises and falls, but many are not.

Upper Tithonian parasequences and parasequence sets Fig. 9. Histograms showing: (A) frequency of facies The Upper Tithonian parasequences are 1–3 m forming caps to parasequences, (B) number of ooid thick and are rarely more than 4 m thick. The grainstone-packstone occurrences that are transgressive basal portion of the section is dominated by vs. regressive. parasequences consisting of intraclast-peloid packstone-grainstone capped by fenestral-lamin- stones and skeletal-peloid wackestone-packstone, ated carbonates. The bulk of the Upper Tithonian are less common as parasequence caps (Fig. 9A). is oolitic (Figs 6C and 7C). These parasequences The Upper Tithonian parasequence sets are (Fig. 4) consist of basal transgressive oolites variably developed and are commonly 8–12 m (Husinec & Read, 2006), overlain by skeletal thick, ranging from 5 to 20 m. They consist of three mudstone-wackestone (rare), intraclast-peloid to six parasequences per set (Figs 6C and 7C). Thin packstone-grainstone (common), regressive oolite units of the deeper subtidal facies occur in the (rare), unfossiliferous mudstone, and most (57%) lower parts of some sets, as do thicker oolitic are capped by fenestral grainy and muddy car- carbonates. Peritidal fenestral carbonates cap para- bonate (Figs 8C and 9A,B). Restricted lime mud- sequences in upper parts of some sets; in others, fenestral carbonates occur throughout the set. Some parasequence sets coincide with small rises and falls on the Fischer plots, but many do not.

INTERPRETATION

Climate The Adriatic Platform during the Late Jurassic occupied a low-latitude tropical region (below 22°N; e.g. Stampfli & Mosar, 1999; Neugebauer et al., 2001), within the area of high evaporation as inferred from coeval evaporite deposits else- where and uniformitarian principles (Ziegler Fig. 8. Bar graphs showing range of stratigraphic dis- et al., 2003), and associated with the Pangean tances of facies below base of laminite cap or top of restricted lime mudstone, used as a datum to estimate megamonsoon (Parrish et al., 1982; Hal- minimum water depths of facies. In all the plots, the lam, 1984). The low-latitude regions during the facies are arranged from shallowest to deepest, but they Late Jurassic were either desert or seasonally have markedly overlapping depth ranges. (A) Plot of summer or winter wet, and lacked a tropical ever- depth ranges of facies in subtidal parasequences in wet biome (Rees et al., 2004). A seasonal wet/dry Lower Tithonian using top of restricted mudstones as climate for the Adriatic Platform is supported by datum, section LSL. (B) Plot of depth ranges of facies in lack of arid climate indicators such as widespread peritidal parasequences in Lower Tithonian plotted below laminate caps, section MSV. (C) Plot of depth platform-interior evaporites and lack of humid ranges of facies at section LSL in peritidal, oolitic indicators such as coal and extensive bauxites. parasequences, using base of laminate caps as datum; Evaporites in the platform succession are limited transgressive oolites not included. to rare probable gypsum pseudomorphs in some

Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 54, 317–337 330 A. Husinec and J. F. Read of the subtidal facies, which could have formed modes. The long-term trends of atmospheric CO2 from saline groundwaters during shallow restric- models (e.g. Geocarb III of Berner & Kothavala, ted platform phases. Limited burrowing in the 2001) are relatively robust but they become more tidal flat facies is compatible with hypersaline uncertain at the finer scale (few tens of millions of tidal waters. ), presenting conflicts with climate proxy The global seawater Sr-isotope curve is marked data (cf. Royer et al., 2004). These discrepancies by a pronounced minimum in the - between pCO2 and palaeotemperatures (Veizer followed by a transition to 87Sr- et al., 2000) may be due to a low-resolution enriched values through the Late Jurassic and palaeoclimate record masking the high-amplitude into the Early Cretaceous (Jones et al., 1994; climate fluctuations (Weissert & Erba, 2004). Gro¨cke et al., 2003). This is consistent with Model results of a warmer Kimmeridgian-Titho- increasing weathering rates throughout the Late nian world with an elevated greenhouse effect of Jurassic and Early Cretaceous (Weissert & Mohr, Moore et al. (1991), show that the greatest warm- 1996). An increased continental erosion and ing occurs over the higher-latitude oceans and runoff is further suggested by depleted Nd- least over the equatorial and subtropical regions. isotope values of Tethyan sediments, with the It also indicates that the trade winds bring heavy most depleted values towards the end of the rainfall to eastern Gondwana and the Tethys Sea Jurassic and in the Early and mid-Cretaceous margin, and a strong monsoon system over (Stille & Chaudhuri, 1993). This eutrophication Southeast Asia. caused widespread carbonate platform growth Sea surface temperatures probably increased crises and repeated carbonate platform drowning from the Middle into the Late Jurassic marking a (Hallock & Schlager, 1986; Masse, 1989; Weissert warm phase in the overall cool mode of the Middle & Erba, 2004) under increasingly zonal climate Jurassic to Early Cretaceous (Frakes et al., 1992). conditions. The impact of accelerated weathering This Late Jurassic warm, relatively dry climate, and nutrition poisoning was far less dramatic for probably promoted the development of hyper- the Late Jurassic carbonate platforms, which may salinity on the Adriatic Platform, and restriction be a consequence of a monsoon-controlled rain- of the platform-interior. This hypersalinity pro- fall pattern with rainfall belts shifted to mid- moted widespread ooid formation over wide areas latitudes (Weissert & Mohr, 1996). of the platform-interior during shallow-water Weissert (1989) has shown how the Late phases (Husinec & Read, 2006), but was not Jurassic C-isotope curve shifts from relatively sufficiently arid to generate evaporite units. The positive d13C-values near +3Æ0& in the Kimme- intense dolomitization further inboard makes it ridgian-Early Tithonian to values near +1Æ30& in difficult to determine how far into the platform the the Late Tithonian-Berriasian. Recently, Gro¨cke oolitic facies extends (Husinec & Read, 2006). et al. (2003) reported a positive shift from the Early to Middle Tithonian to the Tithonian- Accommodation rates and parasequence Berriasian boundary. The excessive burial of durations organic carbon at times of high Tithonian carbon- ate accumulation rates (and times of high sea- Accommodation rates for the Tithonian were ca ) level) was initiated by a greenhouse climate 12–15 cm kyr 1 based on a duration of the inter- associated with a monsoonal rainfall pattern val of 5Æ3–6Æ5 Myr (Gradstein et al., 1994, 2004) controlled by the disintegration of Pangea during and a thickness of up to 750 m. These are the Late Jurassic (Sheridan, 1983; Ziegler, 1988; far higher than the accommodation rates ) Parrish, 1993). Weissert & Mohr (1996) argued (1Æ4–3Æ3 cm kyr 1) of the slightly younger, English that the Middle and Late Tithonian drop in and Spanish Purbeck (Berriasian) sections des- C-isotope values is possibly related to a reorgani- cribed by Anderson (2004a,b). The Adriatic Plat- zation of the global climate system. form underwent the highest subsidence rates in The Tethyan pelagic bulk O-isotope curve the Tithonian compared with any time before or (Weissert & Erba, 2004) and palynological data after, even during the Late Cretaceous collisional from Northern Europe (Abbink et al., 2001) point event (Fig. 3). This rapid subsidence followed to cool Oxfordian and Early Kimmeridgian cli- Kimmeridgian platform differentiation and local mates, followed by a long-term warming trend drowning within deeper water intraplatform lasting from the Kimmeridgian into the earliest troughs. These high subsidence rates favoured Cretaceous. The models and proxy records pre- the platform record capturing most of the high- sent conflicting evidence for warmer and cooler frequency sea-level oscillations. Approximately

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320 parasequences developed on the platform Relative sea-level changes during the Tithonian which, given its duration (5Æ3–6Æ5 Myr; Gradstein et al., 1994, 2004), sug- The Fischer plots (Fischer, 1964; Read & Gold- gests that the parasequences have average dura- hammer, 1988) for the Tithonian interval, LSL tions of 16–20 kyr. Given the uncertainty on the section (Fig. 10) show a long-term relative sea- boundary ages of stages, this is close to the level rise and fall. Estimates of the duration are probable duration of precession in the Jurassic based on the estimated 16–20 kyr age range of the which is only slightly less than 19 and 23 kyr parasequences making up the third-order se- (Berger et al., 1989). This supports a relatively quences, and could be erroneous if the estimated complete record of precessional beats for the parasequence duration is wrong. On this long- platform, perhaps coupled with additional para- term rise and fall, the following third-order sequences being formed because of autocyclic sea-level cycles are superimposed: (1) a 1 Myr processes (Wilkinson et al., 1997) or sub-Milan- third-order relative sea-level cycle starting at the kovitch sea-level changes (cf. Zu¨ hlke et al., 2003). base of Tithonian composed of rise and fall up to

Fig. 10. Fischer plots of cumulative departure from mean cycle thick- ness versus stratigraphic position, of sections LSL (and MSV, inset) plot- ted beneath stratigraphic column of section LSL. Parasequences and parasequence sets shown on strati- graphic column by upward widen- ing triangles. Third-order, relative sea-level cycles shown by numbers on Fischer plots. Note that the inclined lines at the bases of the triangles on the Fischer plots using stratigraphic position (rather than cycle duration) no longer represent subsidence, as they did in Fischer plots originally. Subtidal para- sequences dominate sections on the long-term rise, while peritidal and oolitic peritidal cycles dominate the long-term fall. Facies legend is the same as in Fig. 6.

Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 54, 317–337 332 A. Husinec and J. F. Read parasequence 46, followed by (2) a shorter-term Fischer plots. This suggests that short-term eccen- (<0Æ8 Myr) rise and fall up to parasequence 77. tricity (100 kyr) sea-level changes (or eccentricity This is followed by (3) a ca 3 Myr relative modulation of precessional sea-level changes; sea-level cycle comprised of a rapid rise up to Anderson, 2004a) were relatively small (a few parasequence 105, a covered interval, then a metres). Longer-term Fischer plot bundles at the relatively stable relative sea-level to parasequence scale of 40–60 m are very poorly developed 178, and then a long-term fall to parasequence suggesting that the 400 kyr signal (long-term 243. This is followed by (4) a ca 1Æ5 Myr relative eccentricity, perhaps modulating precessionally sea-level cycle comprising a relatively low rise driven sea levels) was also very small. That the and a longer-term fall to the Tithonian-Berriasian short-term and long-term eccentricity signal is so boundary. In the basal Berriasian, this is mani- poorly represented in the stratigraphy is compat- fested by the development of an emergence ible with a greenhouse climate and a relatively horizon of clayey breccia. Thus the large-scale ice-free Earth at this time. Dominant eccentricity stacks of parasequences appear to be third-order forcing of sea levels appears to be typical of times sequences. However, these are subtle in the field, of significant ice buildup at the poles. At such not delimited by significant bounding discon- times, precessional sea-level changes modulated formities, or clear maximum flooding surfaces, by large eccentricity forcing, only infrequently and are indicated by the thickness trends of the flood the platform tops, thus few precessional parasequences. These trends relate to thicker- cycles are preserved on the peritidal platforms. than-average parasequences in the transgressive This is because the platform fills to the highstand systems tracts and thinner-than-average para- position of one or two large precessional cycles, sequences in the highstand tracts, which the preventing smaller precessional cycles from Fischer plots bring out. Such subtle third-order flooding the platform, thus resulting in missed sequence development is evident in the green- precessional beats (Goldhammer et al., 1990). house platform of the USA (Koerschner & Read, 1989; Montanez & Osleger, 1993). Formation of parasequences The Fischer accommodation plot is similar to the Arabian Plate Tithonian sea-level curve (Haq The average duration of the parasequences sug- & Al-Qahtani, 2005) which is characterized by a gests that they mainly formed by precessional sea- small relative sea-level cycle (our relative sea- level changes. In the way of additional support, level cycle 1, and perhaps 2) followed by a longer, Strasser (1994) and Strasser et al. (2004) sugges- larger, relative sea-level cycle (our cycle 3, and ted that parasequences (called elementary se- perhaps 4; Fig. 10). It is similar to the Haq et al. quences) in the Late Tithonian of the French (1987) global curve which shows four sea-level Jura were also the product of precessional forcing, cycles, but differs from it in that the Fischer plot as were those in the Lower Cretaceous Berriasian shows that cycle 3 is of longer term and higher of England (the sixth-order cycles of Anderson, amplitude than the others. When corrected for 2004a). The very shallow water facies on the sediment and water loading (Read & Goldham- Adriatic Platform and the scarcity of palaeosol mer, 1988), any long-term (5 Myr) sea-level formation at tops of parasequences suggest that change might have been <25 m, unless the the sea-level changes were of low amplitude. The Fischer plots have grossly underestimated ampli- subtidal parasequences typical of the Lower tudes. It might have been even less than this, if Tithonian section formed during the overall the long-term rise and fall on the Fischer plot long-term sea-level rise associated with third- were related to increased, then decreased Titho- order sea-level cycles 1 and 2 (Fig. 10). When nian subsidence. These low amplitudes of sea- coupled with the high platform subsidence rates level change are compatible with relatively little in the Tithonian, this generated much accommo- ) ice and greenhouse conditions. dation (roughly 15–17 cm kyr 1) on the platform. The approximate average duration of para- Long-term platform sedimentation rates had to be sequences (16–20 kyr) is strongly suggestive of a in excess of long-term accommodation to keep the precessional cyclicity driving high-frequency sea- platform in water depths of no more than a few level changes of relatively low magnitude. metres. At a minimum sedimentation rate of ) Although the facies stacking suggests bundling 20 cm kyr 1,a2Æ7 m cycle (the average subtidal of three to six parasequences into parasequence cycle thickness) could form in about 15 kyr. This sets 10–15 m thick, such bundling of para- would result in little time being lost between sequences into sets is poorly shown on the deposition of successive subtidal cycles, which is

Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 54, 317–337 Late Jurassic greenhouse 333 supported by the lack of tidal or supratidal facies states of the waters. Once the platform became the (except in the more interior part of the platform; site of predominantly very shallow-water depos- MSV section). The high rates of accommodation ition in the Upper Tithonian, the platform waters during the long-term rise would also suppress the became more restricted (evident in the biotas) and effects of precessional relative sea-level falls, thus highly supersaturated with respect to calcite. inhibiting the exposure of the subtidal facies (cf. This favoured precipitation of calcite ooids Koerschner & Read, 1989; Goldhammer et al., around skeletal and non-skeletal nuclei in more 1990). Hence the shallowest water facies in Lower platform-interior, shallow-water settings (Husi- Tithonian subtidal parasequences are the relat- nec & Read, 2006). ively sparse occurrences of barren lime mudstone (section LSL), and further platformward, tidal flat Modelling and significance of parasequence laminite caps in upper parts of parasequence sets sets in section MSV. On the falling limbs of the latter half of the For modelling, we opted to have the precessional Fischer plot for the Upper Tithonian, sea-level sea-level signal ride on the obliquity and eccen- fall reduced accommodation by at least 50 m over tricity signal. However, in a greenhouse setting it 2Æ5 Myr (excluding the duration of the short-term would be just as reasonable to have precessional third-order rises). This would have reduced total sea-levels modulated by eccentricity, rather than ) accommodation to between 9 and 12 cm kyr 1,a riding on the eccentricity signal. This does not 30% decrease in accommodation for the Upper make a great deal of difference to the develop- Tithonian section. The decreased accommodation ment of the platform top stratigraphy. However it during deposition of each cycle caused smaller would have a significant effect if we were relative sea-level rises, and enhanced relative sea- modelling deeper subtidal facies, which is not level falls compared with the transgressive Early the concern of this paper. Given the long-term ) Tithonian. This decreased accommodation, cou- accommodation rates of 12–15 cm kyr 1, the pled with the higher sedimentation rates of the weak bundling of parasequences at the 10–15 m shallower water settings, would cause more rapid scale and at the 40–60 m scale is likely to have shallowing to sea-level. Thus, an Upper Titho- been a response to small, short-term (100 kyr) and nian parasequence (average thickness of 2 m) long-term (400 kyr) eccentricity sea-level changes would shallow to sea-level in a minimum of (Fig. 11) or variation of precessionally driven sea 10 kyr at a minimum sedimentation rate of levels within the short-term and long-term eccen- ) 20 cm kyr 1 leaving at least 5–10 kyr in which a tricity bands. Short-term and long-term eccentri- cycle would have been at sea-level, with depos- city bundling also is evident in the Late Tithonian ition of intertidal microbial laminites culminating of the French Jura and the Early Berriasian of in supratidal surfaces. Hence, the Upper Titho- England (Strasser, 1994; Anderson, 2004a). The nian shows a dominance of tidal flat-capped poor development of those signals in the Titho- cycles, compared with the Lower Tithonian, in nian cyclic record supports the idea that there which the tidal flat-capped cycles are located in was little ice at the poles at this time, as the the more interior part of the platform. These were strength of the eccentricity signal in the Late only able to prograde out towards the margin Pleistocene record is considered to be a response during the long-term fall of the Upper Tithonian. to significant ice sheets (Raymo & Ruddiman, The abundance of oolitic peritidal cycles in the 1992; Hinnov & Park, 1999). This supports the Upper Tithonian, along with the evidence for idea that the Tithonian was a time of global exposure and vadose diagenesis (Tisˇljar, 1979, greenhouse conditions with little polar ice. 1985) must reflect this marked decrease in Development of high-frequency sea-level cycles accommodation. Oolitic units are absent from on such an ice-poor Earth has been ascribed to a the Lower Tithonian even though intermittent combination of locking up of water in high- shallow-water conditions were present in the latitude mountain glaciers, draining and filling more interior parts of the platform. It cannot be of rift basin lakes, variation in aquifer water just shallow-water depths that limited the develop- levels, and heating and cooling of the oceanic ment of ooids to the Upper Tithonian section. water column (Jacobs & Sahagian, 1993). Perhaps the increased, parasequence-scale flood- The modelling (Fig. 11) supports the idea of ing events in the Lower Tithonian resulted in small sea-level changes driven by precessional open-marine, near-normal salinity waters on the forcing with only small eccentricity signals or platform which inhibited high supersaturation eccentricity modulation of precession. With

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Fig. 11. Computer model run for 400 kyr duration showing synthetic stratigraphy generated by small sea-level changes typical of a greenhouse world with Milankovitch climate forcing and little ice (inset shows periods and magnitudes of sea-level changes used in model run; the 19 kyr and the 100 kyr signals were asymmetric with a rapid ) rise and gradual fall). Maximum platform sedimentation rate was 30 cm kyr 1, peaking at 1 m water depth and ) ) decreasing with water depth. Driving subsidence ranged from 5 cm kyr 1 on the inner platform to 7Æ5 cm kyr 1 in the basin. The small 100 kyr signal generates the 10–15 m bundling. Having small 100 and 400 kyr sea-level changes is key to having relatively complete preservation of precessional cycles, because with larger sea-level changes, there are numerous missing beats. Having a larger 400 kyr signal results in numerous missed beats in the upper two bundles.

) driving subsidence of about 4–6 cm kyr 1, maxi- manifested by the weak (to absent) bundling of ) mum platform sedimentation rates of 30 cm kyr 1 parasequences into 100 and 400 kyr sets on the decreasing with depth, small precessional sea- Fischer plots. Such bundling, where present, level changes (5 m or so), along with a 100 kyr results from thicker parasequences occurring signal of 5 m, and a very small (2 m) 400 kyr low in a set, and thinner parasequences higher signal, stacking patterns similar to those observed in the set, which is evident in the model output in the Tithonian are produced. Peritidal para- (Fig. 11; cf. Goldhammer et al., 1990). This sequences are produced, with bundling of three results from the increased accommodation asso- to five parasequences into parasequence sets. ciated with the small eccentricity signal. Increasing the magnitude of the precessional Thus in summary, the shallow character of the signal tends to cause periodic flooding of the facies within parasequences, the presence of tidal platform to greater depths than observed in the flat caps on parasequences in the platform-interior data. Increasing the magnitude of the 100 kyr that progressively extend out towards the margin eccentricity signal tends to cause periodic flood- in the Upper Tithonian highstand, the apparent ing of the platform to significantly greater depths precessional durations, the need for suppressed than observed and, more importantly, causes eccentricity sea-level changes, the poor develop- increased number of missing precessional beats ment of eccentricity bundling on Fischer plots, and from the platform record (see Hardie & Shinn, the lack of significant emergence horizons (palaeo- 1986; Goldhammer et al., 1990). Increasing the sols), all point to the Tithonian as being a hot, magnitude of the 400 kyr sea-level changes cau- greenhouse, relatively ice-free world within the ses numerous missed beats in the upper para- overall Middle Jurassic–Early Cretaceous ‘cool’ sequence sets of a 400 kyr bundle which is not mode of Frakes et al. (1992). observed. The effect would be similar had we used a sea-level curve consisting of precessional sea levels modulated by short-term and long-term CONCLUSIONS eccentricity (cf. Anderson, 2004a,b). The low-amplitude precessional signal, and the The exposed Upper Jurassic (Tithonian), carbon- evidence for suppressed 100 and 400 kyr sea- ates of the Adriatic Platform, Croatia, have well- level changes, all are compatible with greenhouse developed parasequences dominated by very conditions. The small eccentricity signal also is shallow water facies. These include dasyclad-

Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 54, 317–337 Late Jurassic greenhouse 335 oncoid mudstone-wackestone-floatstone (shallow evolution of the southern North Sea. Global Planet. Change, lagoon water depths, typically <4 m depth), 30, 231–256. skeletal-peloid wackestone-packstone (very shal- Anderson, E.J. (2004a) Facies patterns that define orbitally forced third-, fourth-, and fifth-order sequences and sixth- low lagoon), intraclast-peloid packstone and order cycles and their relationship to ostracod fauni- grainstone (shoal), radial-ooid grainstone (hyper- cycles: the Purbeckian (Berriasian) of , England. In: saline shallow subtidal/intertidal shoals and Cyclostratigraphy – An Essay of Approaches and Case ponds), lime mudstone (restricted lagoon), fenes- Histories (Eds B. D’Argenio, A.G. Fischer, I.S. Premoli tral carbonates and microbial laminites (tidal flat). Silva, H. Weissert and V. Ferreri), SEPM Spec. Publ., 81, 245–260. Long-term accommodation was high, 12– Anderson, E.J. (2004b) The cyclic hierarchy of the ‘Purbeck- )1 15 cm kyr . Accommodation (Fischer) plots ian’ Sierra del Pozo Section, Lower Cretaceous (Berriasian), show four third-order relative sea-level cycles southern Spain. Sedimentology, 51, 455–477. superimposed on a 5–6 Myr long-term rise and Bathurst, R.G.C. (1973) Carbonate Sediments and their Dia- fall. These sea-level cycles have some similarities genesis. Elsevier, Amsterdam, 620 pp. Berger, A., Loutre, M.F. and Dehant, V. (1989) Influence of the with the published sea-level cycles of the Arabian changing lunar orbit on the astronomical frequencies of pre- Plate and the global curve. insolation patterns. Paleoceanography, 4, 555– The Tithonian parasequences are of roughly 564. 20 kyr average duration and were probably Berner, R.A. and Kothavala, Z. (2001) GEOCARB III: A revised formed by precessionally driven, small sea-level model of atmospheric CO2 over time. Am. J. Sci., 301, 182–204. changes. During the long-term, 2Æ5 Myr sea-level Bernier, P. (1984) Les formations carbonate´es du Kimmerd- rise, predominantly subtidal cycles were depos- giene et du Portlandiene dans le Jura me´ridional. Strati- ited, whereas peritidal cycles developed on the graphie, micropaleontologie, se´dimentologie. Doc. Lab. long-term (2Æ5 Myr) sea-level fall. Evidence of an Ge´ol. Fac. Sci. Lyon, 92, 803 pp. eccentricity signal in the parasequence bundling Bosellini, A. (2002) «re-write» the geodynamics of the eastern Mediterranean and the paleogeography of the is relatively weak and produced successively Apulia Platform. Earth-Sci. Rev., 59, 211–234. more restricted facies upward in parasequence Boss, S. and Rasmussen, K.A. (1995) Misuse of Fischer plots sets but little clear signal on the Fischer plots. as sea-level curves. Geology, 23, 221–224. Palaeosols are conspicuously absent from the Day, P.I. (1997) The Fischer diagram in the depth domain; Tithonian, suggesting that the relative sea-level atool for sequence stratigraphy. J. Sed. Res., 67, 982–984. De Castro, P. (1993) Observations on Campbelliella Radoicic, falls driven by precession were suppressed by the 1959 and Neoteutloporella Bassoullet et al., 1978 (green high accommodation rates. The parasequence algae, Dasycladales). In: Studies on Fossil Benthic Algae stacking patterns strongly suggest that the Titho- (Eds F. Barattolo, P. De Castro and M. Parente), Boll. Soc. nian was probably a time of global greenhouse Paleont. Spec. Vol., 1, 121–184. conditions during the Middle Jurassic to Early Fischer, A.G. (1964) The Lofer cyclothems of the Alpine Tri- assic. Geol. Surv. Kansas Bull., 169, 107–149. Cretaceous ‘cool’ mode. Frakes, L.A., Francis, J.E. and Syktus, J.I. (1992) Climate Modes of the Phanerozoic. The History of the Earth’s Cli- mate over the Past 600 Million Years. Cambridge University ACKNOWLEDGEMENTS Press, Cambridge, 274 pp. Goldhammer, R.K., Dunn, P.A. and Hardie, L. (1990) Depo- sitional cycles, composite sea-level changes, cycle stacking Support for this work was provided by Fulbright patterns, and the hierarchy of stratigraphic forcing: exam- grant no. 68428172 to A. Husinec and NSF grant ples from Alpine Triassic platform carbonates. GSA Bull., EAR-0341753 to J.F. Read. We thank L. Fucˇek, I. 102, 535–562. Vlahovic´, D. Palenik, T. Grgasovic´, D. Maticˇec, and Gradstein, F.M., Agterberg, F.P., Ogg, J.G., Hardenbol, J., Van N. Osˇtric´ for assistance in field work, which was Veen, P., Thierry, J. and Huang, Z. (1994) A Mesozoic time scale. J. Geophys. Res., 99, 24051–24074. supported by the Ministry of Science, Education Gradstein, F.M., Ogg, J.G. and Smith, A.G. (2004) A Geologic and Sport of Croatia. We also thank B. Sokacˇ for Time Scale 2004. Cambridge University Press, Cambridge, help in calcareous algae determination. 610 pp. Constructive reviews and suggestions by E.J. Gro¨cke, D.R., Price, G.D., Ruffell, A.H., Mutterlose, J. and Anderson and A. Strasser, and the editor Baraboshkin, E. (2003) Isotopic evidence for Late Jurassic- Early Cretaceous climate change. Palaeogeogr. Palaeo- I. Montan˜ ez are acknowledged with thanks. climatol. Palaeoecol., 202, 97–118. Hallam, A. (1984) Continental humid and arid zones during the Jurassic and Cretaceous. Palaeogeogr. Palaeoclimatol. REFERENCES Palaeoecol., 47, 195–233. Hallock, P. and Schlager, W. (1986) Nutrient excess and the demise of coral reefs and carbonate platforms. Palaios, 1, Abbink, O., Targarona, J., Brinkhuis, H. and Visscher, H. 389–398. (2001) Late Jurassic to earliest Cretaceous paleoclimatic

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