The last interglacial (MIS 5e) cycle at Little Bahama Bank: A history of climate and sea-level changes

. Shallow-water sediments of the Bahama region containing the last interglacial (MIS 5e) are ideal to investigate the region’s sensitivity to past climatic and sea level changes. Here we present new faunal, isotopic and XRF-sediment core data 10 from the northern slope of the Little Bahama Bank. The results suggest that the bank top remained flooded across the last interglacial “plateau”, ~129-117 ka, arguing for a relative sea level above -6 m for this time period. In addition, climatic variability, which today is closely coupled with movements of the intertropical convergence zone (ITCZ), is interpreted based on stable isotopes and foraminiferal assemblage records. During early MIS 5e, the mean annual ITCZ position moved northward in line with increased solar forcing and a recovered Atlantic Meridional Overturning Circulation (AMOC). The 15 early MIS 5e warmth peak was intersected, however, by a millennial-scale cooling event, consistent with a southward shift in the mean annual ITCZ position. This tropical shift is ascribed to the transitional climatic regime of early MIS 5e, characterized by persistent high-latitude freshening and, thereby, unstable AMOC mode. Our records from the Bahama region demonstrate that not only was there a tight relation between local sedimentation regimes and last interglacial sea level history, via the atmospheric forcing we could further infer an intra-interglacial connectivity between the polar and subtropical latitudes that 20 left its imprint also on the ocean circulation. and the AMOC forcing: 1. Termination 2: Strongly reduced d 18 O gradients between mixed-layer and thermocline-dwelling foraminifera suggest decreased water column stratification. High proportions of G. truncatulinoides could be attributed to a deep vertical mixing 345 as a result of sea surface cooling/salinification and intensified trade winds strength at times of ITCZ being depressed far to the south.


Introduction
The last interglacial (MIS 5e) has attracted a lot of attention as a possible analog for future climatic development as well as a critical target for validation of climatic models. This globally warmer-than-preindustrial interval is associated with significantly reduced ice sheets and a sea level rise up to 6-9 meters above the present levels (Dutton et al., 2015;Hoffman et collected directly from the split core sediment surface, that had been flattened and covered with a 4 µm-thick ULTRALENE SPEXCerti Prep film to prevent contamination of the measurement unit and desiccation of the sediment (Richter et al., 2006;100 Tjallingii et al., 2007). The core section between 150 and 465 cm was scanned at 3 mm step size, whereas the coarser-grained interval between 465 and 600 cm was analyzed at 10 mm resolution.
To account for potential biases related to physical properties of the sediment core, XRF intensities of Sr were normalized to Ca (Fig. 2), the raw total counts of Fe and Sr were normalized to the total counts of the 30kv-run; counts of Ca and Cl were normalized to the total counts of 10kv-run, excluding Rh intensity, because this element intensities are biased by the signal 105 generation (Bahr et al., 2014).
All data will be made available in the online database PANGAEA (www.pangaea.de).

Age model
By using our foraminiferal assemblage data, we were able to refine the previously published age model of core MD99-2202 (Lantzsch et al., 2007). To correctly frame MIS 5e, stratigraphic subdivision of the unconsolidated aragonite-rich sediment 110 package between 190 and 464 is essential (Fig. 3). In agreement with Lantzsch et al. (2007) we interpret this core section to comprise MIS 5, which is supported by key biostratigraphic markers used to identify the well-established faunal zones of late Quaternary (Ericson and Wollin, 1968). Thus, the last occurrences of G. menardii and G. menardii flexuosa at the end of the aragonite-rich sediment package are in agreement with the estimated late MIS 5 age (ca. 80-90 ka; Boli and Saunders, 1985;Slowey et al., 2002;Bahr et al., 2011;Chabaud, 2016). The coherent variability observed between aragonite content and 115 relative abundances of warm surface-dwelling foraminifera of Globigerinoides genus (G. ruber, white and pink varieties, G. conglobatus and G. sacculifer) between ~200-300 cm, points to simultaneous climate and sea level-related changes and likely reflects the warm/cold substages of MIS 5. The detected substages were then correlated with the global isotope benthic stack LS16 (Lisiecki and Stern, 2016) using AnalySeries 2.0.8 (Paillard et al., 1996). Further, boundaries between MIS 6/5e and 5e/5d as well as the penultimate glaciation (MIS 6) peak, defined from d 18 O record of G. ruber (white), were aligned to the 120 global benthic stack (Lisiecki and Stern, 2016).
Given that sedimentation rates at the glacial/interglacial transition could have changed drastically due to increased production of Sr-rich aragonite material above the initially flooded carbonate platform top (Roth and Reijmer, 2004;Chabaud et al., 2016), Clim. Past Discuss., https://doi.org/10.5194/cp-2018-38 Manuscript under review for journal Clim. Past Discussion started: 11 April 2018 c Author(s) 2018. CC BY 4.0 License.
we applied an additional age marker to better frame the onset of the MIS 5e "plateau" and to allow for a better core-to-core comparison. Thus, we tied the increased relative abundances of warm surface-dwelling foraminifera of Globigerinoides genus, 125 which coincides with the rapid decrease in foraminiferal d 18 O record at 456 cm, with the onset of MIS 5e "plateau" at ~129 ka (Masson-Delmotte et al., 2013). This age is in good agreement with many marine and speleothem records, dating a rapid poststadial warming and monsoon intensification to 129-128.7 ka (Galaasen et al., 2014;Govin et al., 2015;Jiménez-Amat and Zahn, 2015) coincident with the sharp methane increase in the EPICA Dome C ice core (Loulergue et al., 2008;Govin et al., 2012). Although we do not apply a specific age marker to frame the decline of the MIS 5e "plateau", the resulting decrease in 130 the percentage of warm surface-dwelling foraminifera of Globigerinoides genus as well as the initial increase in the planktic d 18 O values dates back to ~117 ka (Fig. 4), which broadly coincides with the cooling over Greenland (NGRIP community members, 2004). A similar subtropical-polar climatic coupling was proposed in earlier studies from the western N. Atlantic STG (e.g., Vautravers et al., 2004;Schmidt et al., 2006a;Bahr et al., 2013;Deaney et al., 2017).

XRF data in the lithological context
In Fig. 2 XRF-derived elemental data are plotted against lithological and physical sediment properties. Beyond the intervals with low Ca counts corresponding to high Cl intensities (at 300-325 cm and 395-440 cm), Ca intensities do not vary significantly, which is in line with a stable carbonate content of about 94% Wt (Lantzsch et al., 2007). Our Sr record closely follows the aragonite curve and the grain size data, demonstrating that the interglacial minerology is dominated by aragonite. 140 Beyond the intervals containing reduced Ca intensities, a good coherence between Sr/Ca and aragonite content is observed.
The rapid increase in Sr/Ca and aragonite is found at the end of the penultimate deglaciation (Termination 2, T2), coeval with the elevated absolute abundances of G. menardii per sample (Fig. 4). The gradual step-like Sr/Ca and aragonite decrease characterizes both the glacial inception and the later MIS 5 phase. Intensities of Fe abruptly decrease at the beginning of the last interglacial, but gradually increase during the glacial inception ( Fig. 5D). At ~120 ka (355 cm), a minor but clear increase 145 in Sr intensities goes along with the change in aragonite and grain-size (Figs. 2 and 4), arguing that this feature is not a signal artefact but represents a significant sedimentological shift. Between ~112 and 114.5 ka, the actual XRF measurements were affected by a low sediment level in the core tube. Clim. Past Discuss., https://doi.org/10.5194/cp-2018-38 Manuscript under review for journal Clim. Past Discussion started: 11 April 2018 c Author(s) 2018. CC BY 4.0 License.

Climate-related proxies
During the major deglacial transition, ~135-129 ka, low isotopic gradients between G. ruber (white), G. truncatulinoides (dex) 150 and G. inflata are consistent with high relative abundances of G. truncatulinoides (dex) and G. inflata (Fig. 5). Across MIS 5e species of Globigerinoides genus dominate the total assemblage, however, significant changes in the proportions of three main 6 Discussion 160

Platform sedimentology and sea level change
In shallow-water records from the Bahamas, downcore variations in Sr/Ca intensity ratio can be applied as a good proxy for relative sea level (RSL) change (Chabaud et al., 2016). However, given that the measured intensities of Ca account for more than 70% of all elements signal intensities, Sr/Ca values are strongly dependent on the quality of the Ca signal. While our Sr record likely represents a non-affected signal because of good coherence with the aragonite curve, some of the Ca intensity 165 values are reduced due increased seawater content, as evidenced by simultaneously measured elevated Cl intensities (Fig. 2).
Because enhanced seawater content in the sediment appears to reduce only Ca intensities, leaving measures of elements with higher atomic numbers (e.g., Fe, Sr) less affected (Tjallingii et al., 2007;Hennekam and de Lange, 2012), normalization of Sr counts to Ca results in very high Sr/Ca intensity ratios across the Cl-rich intervals. The general consistency of the measured Sr intensities argues against an early marine diagenesis that would strongly reduce and homogenize the Sr/Ca intensity ratio, 170 altering isotopic signatures and often causing a change in sediment color (Chabaud, 2016) that is not observed in our sediment core. Consequently, the spikes in Sr/Ca within the last interglacial could be related to a change in physical properties of the sediment, such as elevated sediment porosity linked to increased sand size fraction, that would facilitate enhanced pore-water Clim. Past Discuss., https://doi.org/10.5194/cp-2018-38 Manuscript under review for journal Clim. Past Discussion started: 11 April 2018 c Author(s) 2018. CC BY 4.0 License. content in these intervals Tucker and Bathurst, 2009;Chabaud, 2016). Indeed, the late MIS 5e Sr/Ca spike falls within the interval of strongly decreased sediment density and increased porosity (Labeyrie and Reijmer, 2005). 175 However, on the basis of these data alone it is not possible to assess whether the observed sedimentological and geochemical shifts represent a syn-or postdepositional change. Yet, comparing all the records it seems conceivable that the pronounced Sr/Ca and Cl spikes may contain clues about interglacial sedimentary regime changes on the upper slope of the LBB at these times.
Beyond these problematic intervals described above, XRF-derived Sr/Ca values agree well with the aragonite curve and, thus, 180 can be interpreted in terms of RSL variability (Fig. 4). Around 129 ka, Sr/Ca as well as aragonite content rapidly reach maximum values, indicating the onset of the LBB flooding interval. Absolute abundance of G. menardii per sample supports the inferred onset of the flooding interval ( Fig. 4D), since amounts of planktic foraminifera in the sample can be used to assess the relative accumulation of platform-derived vs. pelagic sediment particles (Slowey et al., 2002). After G. menardii repopulated the tropical waters at the end of the penultimate glaciation (Bahr et al., 2011;Chabaud, 2016), its increased 185 absolute abundances are found between ~131-129 ka. That feature could be attributed to a reduced input of fine-grained aragonite at times of partly flooded platform. Consequently, as the platform top became completely submerged, established aragonite shedding gained over pelagic input, thereby reducing the number of G. menardii per given sample.
Despite some possible isostatic subsidence (1-2 m per hundred thousand years), the LBB is generally regarded as tectonically stable (Carew and Mylroie, 1995;Hearty and Neumann, 2001). Considering that the modern water depth of the platform is 190 between 6-10 m, a RSL above -6 m of its present position is required to completely flood the platform top and allow for a drastic increase in aragonite production (Carew and Mylroie, 1997;Chabaud et al., 2016). In that context, the onset of the major flooding interval with RSL above -6 m could be assumed from c.129 ka on (Fig. 4). Since the last interglacial sea level highstand is estimated to have been 6-9 meters above the modern (Dutton et al., 2015), an additional sea level rise of 12-16 m must have been reached some time later within MIS 5e. A late peak is indeed in agreement with a continuing deglaciation 195 observed in the northern hemisphere (e.g., Bauch et al., 2012;Deaney et al., 2017); a sea-level contribution from the Antarctic Ice Sheets have also been suggested (Hearty and Neumann, 2001;O´Leary et al., 2013). Our data do not allow to make assumptions about the exact timing of the last interglacial sea level peak, which is controversially placed by different studies into either early (Grant et al., 2012;Lisiecki and Stern, 2016), mid or late MIS 5e (Hearty and Neumann, 2001;Hearty et al., 2007;Kopp et al., 2009;O´Leary et al., 2013;Spratt and Lisiecki, 2016). And yet, our proxy 200 records suggest that the aragonite production on top of the platform was abundant until late MIS 5e (unequivocally delimited by foraminiferal d 18 O and faunal data), arguing for a longer-lasting flooding interval of the LBB across MIS 5e (~12 ka with the RSL above -6 m), when compared to previous sea level reconstructions (Fig. 4H). The drop in RSL below -6 m only during the terminal phase of MIS 5e (~117 ka on our timescale) is corroborated by a coincident changeover in the aragonite content and the increase in absolute abundance of G. menardii, further supporting the hypothesis that aragonite shedding was 205 suppressed at that time, causing relative enrichment in foraminiferal abundances (per sample).
As mentioned above, the inferred LBB flooding time period differs from the actual minimal ice volume interval, but it appears to correspond roughly with the well-known last interglacial "plateau" of low benthic d 18 O values between ~129 and 116-118 ka (Adkins et al., 1997;Cortijo et al., 1999;Masson-Delmotte et al., 2013). Given that the intra-interglacial sea level change is plausible, this observation underscores the importance of critical consideration of deep-sea d 18 O records, accumulating both 210 ice volume and ocean temperature/salinity signals.

Termination 2
Prior to the MIS 5e "plateau", the elevated occurrences of transitional to subpolar species G. inflata indicate generally coldwater conditions off the LBB (Fig. 5). Isotopic gradients between d 18 O values in surface-and thermocline-dwelling foraminifera during T2 are strongly reduced, arguing for decreased water column stratification. At times of suppressed 215 overturning during T2 , the inferred decreased stratification could have resulted from sea surface cooling/salinification and/or subsurface warming (e.g., Zhang, 2007). Nevertheless, direct surface/subsurface temperature estimations across T2 and early MIS 5e so far reveal warm/cold conditions for the subtropical western N. Atlantic (Bahr et al., 2013). It is known, however, that species-specific temperature signals should be considered with caution, as they could be complicated due to adaptation strategies of foraminifera, such as seasonal shifts in the peak foraminiferal tests flux and/or 220 habitat changes (Schmidt et al., 2006a, b;Bahr et al., 2013;Jonkers and Kučera, 2015). Alternatively, reduced water column stratification could have led to a situation when calcification of the thermocline-dwelling foraminifera could have commenced in shallower and, therefore, relatively warmer waters, causing a lower isotopic gradient between shallow-and deep-dwelling foraminifera (Mulitza et al., 1997).
High abundances of G. truncatulinoides (Fig. 5E) further support the hypothesis involving reduced stratification and deep 225 vertical mixing, given that today this species requires reduced upper water column stratification to be able to complete its reproduction cycle with changing habitats, from c. 400-600 m to near-surface depths (Lohmann and Schweizer, 1990;Hilbrecht, 1996;Mulitza et al., 1997). For instance, in the modern tropical Caribbean, reproduction of G. truncatulinoides is inhibited by strong thermocline in well-stratified waters (Schmuker and Schiebel, 2000). This is in contrast to the subtropical N. Atlantic where winter sea surface cooling (T<23°C) and deep mixing occur alongside with increase of G. truncatulinoides 230 up to 15% (Levitus et al., 2013;Siccha and Kučera, 2017). It could, therefore, be proposed that the overall abundance of G. truncatulinoides in our subtropical settings was at least partly controlled by oceanic conditions occurring nearer to the sea surface (Mulitza et al., 1997;Jonkers and Kučera, 2016).
Sea surface water properties as well as vertical convective mixing in the Bahama region are closely related to the strength of the atmospheric circulation as defined by the position of the ITCZ (e.g., Slowey and Curry, 1995;Wolff et al., 1999). Today, 235 intensified trade winds coupled with cold meteorological fronts enhance upper water column mixing in the region through evaporative cooling during boreal winter, when the ITCZ is at the southernmost position (e.g., Wilson and Roberts, 1995).
Previous studies from the western subtropical N. Atlantic have shown that time periods with reduced AMOC strength are consistent with southward displacements of the ITCZ and its associated rainfall belt, causing sea surface salinification (Schmidt et al., 2006a;Carlson et al., 2008;Bahr et al., 2013). Acknowledging the fact that our study region lies too far north to be 240 influenced by changes in the winter position of the ITCZ (Ziegler et al., 2008) -this would be of primary importance for modern-like winter-spring reproduction timing of G. truncatulinoides (Jonkers and Kučera, 2015) -we suggest that a southward displacement of the mean annual position of the ITCZ during T2 (Wang et al., 2004) could have promoted favorable conditions for G. truncatulinoides through generally strong sea surface cooling/salinification amplified by intensified atmospheric circulation. 245 In the Bahamas, siliclastic input by other processes than wind transport is very limited, therefore, increased Fe content in the sediments could be attributed to enhanced trade winds strength which is coupled with a southern shift of the ITCZ (Roth and  Reijmer, 2004). Accordingly, the elevated XRF-derived Fe counts in our record during T2 (Fig. 5D) may support intensification of trade winds and increased transport of Saharan dust at times of enhanced aridity over N. Africa, i.e., during colder periods (Helmke et al., 2008;Tjallingii et al., 2008). Finally, increased velocities of the wind-driven Antilles Current 250 in the southwestern limb of the STG during glacial interval and T2 are thought to enhance winnowing of fine-grained material on the northern slopes of LBB, which, together with the limited supply of aragonite needles, promoted enhanced sediment consolidation (Chabaud et al., 2016).

Early MIS 5e
Various environmental properties (temperature, salinity, nutrients) can account for the proportional change in different 255 Globigerinoides species (Fig. 6). G. sacculifer -it makes up less than 5% of the planktic foraminiferal assemblage around the LBB today (Siccha and Kučera, 2017) -is abundant in the Caribbean Sea and tropical Atlantic and commonly used as a tracer of tropical waters and geographical shifts of the ITCZ (Poore et al., 2003;Vautravers et al., 2007). Also, G. ruber (pink) shows rather coherent abundance maxima in the tropics (between 20°N and 20°S), while no such affinity is observed for G. ruber (white) and G. conglobatus (Siccha and Kučera, 2017;Schiebel and Hemleben, 2017). Therefore, fluctuations in relative 260 abundances of G. sacculifer and G. ruber (pink) are referred here as to represent a warm tropical end-member (Fig. 1B).
As shown in Fig. 7B, relative abundances of the tropical species (here and further in the text G. ruber (pink) and G. sacculifer calculated together) increased before the onset of the last interglacial "plateau" at ~129 ka. This transition was possibly coupled with the intensification of the Gulf Stream at MIS 6/5e boundary (Bahr et al., 2011). In addition, a gradual rise in accumulation of redox-sensitive element molybdenum (Mo) in sediment data from Cariaco Basin is observed across the penultimate 265 deglaciation (Fig. 7D). At that latter location, high Mo content is found in sediments deposited under anoxic conditions, occurring only during warm interstadial periods associated with a northerly shifted ITCZ (Gibson and Peterson, 2014). Accordingly, a gradual northward migration of the mean annual position of the ITCZ at the onset of MIS 5e could be implied.
In line with increasing low latitude summer insolation (Fig. 7C), this ITCZ displacement would also promote a northward expansion of tropical pool waters (Ziegler et al., 2008). Because core MD99-2202 is located at the northern edge of the ITCZ 270 influence, the rapid shift in foraminiferal proportions at ~130 ka could, in fact, represent the onset of warm pool waters influence, which resulted from a gradual northward-directed ITCZ movement. Similarly, the pronounced increase in the  (Figs. 6-7), may then reflect a continuing northward expansion of the tropical pool waters. Abrupt sea surface warming at the onset of the interglacial "plateau" is likewise found in some proxy records from the western subtropical N. Atlantic ( Fig. 7E; Cortijo et al., 1999;275 Deaney et al., 2017). Within some age uncertainties such a switch to warmer conditions could, however, correspond to the rapid rise in accumulation of Mo in sediments from the Cariaco Basin (Fig. 7D). by U-Th to be centered around 127 ka, is also evident in an isotopic record from the southwestern slope of the LBB (Slowey et al., 1996;, suggesting at least a regional expression of the event. Simultaneously, the XRF record from the Cariaco sediments reveals a stadial-like Mo-depleted (ITCZ southward) interval (Fig. 7D). The close similarity between the tropical-species record from the Bahamas and the XRF data from Cariaco Basin supports the hypothesis that the 285 annual displacements of the ITCZ are also documented in our faunal counts. Moreover, because the aforementioned abrupt climatic shift at ~127 ka cannot be reconciled with the insolation changes, additional forcings at play during early MIS 5e should be considered.
Although the full resumption of the AMOC from a shallow or weak mode during T2 occurred only by ~124 ka, several studies show that the AMOC abruptly recovered at the beginning of MIS 5e, apparently due to a deepened winter convection in the 290 Labrador Sea (Adkins et al., 1997;Galaasen et al., 2014;Deaney et al., 2017). In accordance with previous studies from the tropical N. Atlantic suggesting a coupling between ITCZ position and ocean overturning (Rühlemann et al., 1999;Schmidt et al., 2006a;Carlson et al., 2008), it could be argued that the northward ITCZ shift coeval with the rise in tropical foraminifera proportions at our site at ~129-128 ka was consistent with the deepening of NADW and resumption of the AMOC (Fig. 7E).
In turn, the millennial-scale climatic reversal between 127 and 126 ka could have been related to the known reductions of deep 295 water ventilation during early MIS 5e (Galaasen et al, 2014;Deaney et al., 2017). A corresponding cooling and freshening event -referred elsewhere as to a Younger Dryas type event -is captured in some high-and mid-latitude N. Atlantic records Clim. Past Discuss., https://doi.org/10.5194/cp-2018-38 Manuscript under review for journal Clim. Past Discussion started: 11 April 2018 c Author(s) 2018. CC BY 4.0 License. Irvali et al., 2012;Schwab et al., 2013;Govin et al., 2014;Jiménez-Amat and Zahn, 2015;Zhuravleva et al., 2017a). Coherently with the Younger Dryas type cooling and the reduction/shallowing in the NADW, an increase in Antarctic Bottom Water formation is revealed in the Southern Ocean core data, arguing for existence of an "interglacial" 300 bipolar seesaw (Hayes et al., 2014). The out-of-phase climatic relationship between high northern and high southern latitudes, typical for the last glacial termination (Barker et al., 2009), could be attributed to a strong sensitivity of the transitional climatic regime of early MIS 5e due to persistent high-latitude freshening (continuing deglaciation) and suppressed overturning in the Nordic Seas. This is important because it helps to explain such a late occurrence of the Younger Dryas type event during T2, when compared to the actual Younger Dryas in the last deglaciation. 305

Late MIS 5e
Relative abundances of tropical foraminifera in our core suggest an early SST maximum (between 128 and 124 ka) in the lowlatitude N. Atlantic, which agrees in time with the recent compilation of global MIS 5e SST (Hoffmann et al., 2017). As the insolation forcing decreased during late MIS 5e and the ITCZ gradually moved southward (Fig. 7C-D), the white variety of G. ruber started to dominate the assemblage (Fig. 6), arguing for generally colder sea surface conditions. The inferred broad 310 salinity tolerance of this species, also to neritic conditions (Bé and Tolderlund, 1971;Schmuker and Schiebel, 2002), was used in some studies to link high proportions of G. ruber (pink and white varieties) with low surface salinities (Vautravers et al., 2007;Kandiano et al., 2012). The plots of the global distribution pattern of G. ruber (white) and G. ruber (pink), however, suggest that when relative abundances of these two species are approaching maximum values (40% and 10%, respectively), the sea surface salinities would be higher for specimens of the white variety of G. ruber (Hilbrecht, 1996). Therefore, the 315 strongly dominating white vs. pink G. ruber variety observed in our records during late MIS 5e could be linked not only to decreasing SST, but also to increasing sea surface salinity.
In their study from the western STG, Bahr et al. (2013) also reconstruct sea surface salinification during late MIS 5e in response to enhanced wind stress at times of deteriorating high-latitude climate and increasing meridional gradients. Accordingly, our isotopic and faunal data (note the abrupt decrease in G. sacculifer proportion at 120 ka; Fig. 6B) suggest a pronounced climatic 320 shift that could be attributed to a so-called "neoglaciation", consistent with the sea surface cooling in the western Nordic Seas and the Labrador Sea (Van Nieuwenhove et al., 2013;Irvali et al., 2016) as well as with a renewed growth of terrestrial ice Clim. Past Discuss., https://doi.org/10.5194/cp-2018-38 Manuscript under review for journal Clim. Past Discussion started: 11 April 2018 c Author(s) 2018. CC BY 4.0 License. (Fronval and Jansen, 1997;Zhuravleva et al., 2017b).
Notably, a small but coherent increase in the aragonite content and Sr counts is evident at 120 ka and coincides with the change towards finer-grained sediments, altogether arguing for a change in sedimentary regime before the end of the major flooding 325 interval at ~117 ka (Figs. 2 and 4). Further interpretations of the aragonite changes based on the available data appear rather speculative, given that the aragonite precipitation on the platform top at times of sea level highstand is controlled by level of aragonite supersaturation, which, in turn, depends on a number of climate-related parameters, such as CO 2 amounts, temperature, salinity, water depth above the bank top as well as residence time of the water mass above the platform (Morse and Mackenzie, 1990;Morse and He, 1993;Roth and Reijmer, 2004;. Nevertheless, the coherent shift in the carbonate 330 minerology revealed after 120 ka may support major oceanographic and atmospheric changes during the late phase of MIS 5e possibly coupled with a significant sea level change.

Conclusions
New isotopic, faunal and XRF evidence combined with published sedimentological data from a sediment core obtained from the slope of the LBB were studied for changes in water masses, sedimentary regimes, and RSL change across the last 335 interglacial. By using new data, we were able to better constrain the last interglacial cycle in the investigated core section (cf. Lantzsch et al., 2007). Elemental analyses, aragonite content and foraminiferal abundance records suggest that the LBB became rapidly flooded at ~129 ka. The carbonate platform remained submerged until late MIS 5e, ca. 117 ka, implying a prolonged interval with a RSL above -6 m. Although our data do not allow us to reconstruct the exact timing of the last interglacial sea level peak, our sedimentological proxies point to changing sedimentary regimes on the slope of the LBB, 340 possibly as a result of intra-interglacial sea level and/or climatic fluctuations.
The overall climatic evolution of the last interglacial cycle in the Bahama region was closely coupled with ITCZ movements, which, in turn, were the result of insolation and the AMOC forcing: 1. Termination 2: Strongly reduced d 18 O gradients between mixed-layer and thermocline-dwelling foraminifera suggest decreased water column stratification. High proportions of G. truncatulinoides could be attributed to a deep vertical mixing 345 as a result of sea surface cooling/salinification and intensified trade winds strength at times of ITCZ being depressed far to the south. Clim. Past Discuss., https://doi.org/10.5194/cp-2018-38 Manuscript under review for journal Clim. Past Discussion started: 11 April 2018 c Author(s) 2018. CC BY 4.0 License.
2. Early MIS 5e: Computed together, relative abundances of tropical foraminifera G. sacculifer and G. ruber (pink) agree well with the published ITCZ-related Cariaco record (Gibson and Peterson, 2014), suggesting climatic coupling between the regions. Based on these data, a northward displacement of the mean annual ITCZ position, in line with strong insolation 350 forcing, could be inferred for early MIS 5e. However, an abrupt climatic shift intersected the early MIS 5e warmth. This so-called Younger Dryas type cooling event likely involved AMOC-related forcing that influenced (sub)tropical climate.
The relatively late occurrence of Younger Dryas type cooling event, when compared to the actual Younger Dryas in the last deglaciation, is attributed to the transitional climatic regime of early MIS 5e, characterized by persistent high-latitude freshening and unstable deep-water overturning in the N. Atlantic. 355 3. Late MIS 5e: Overall sea surface cooling and possibly salinification is reconstructed for the Bahama region, in accordance with insolation decrease and a gradual southward displacement of the mean annual ITCZ. A coherent change is observed in faunal, isotopic and sedimentological proxies, arguing for coupled oceanic and northern hemisphere cryospheric reorganizations before the end of the major flooding period.   (Lantzsch et al., 2007) with (A) global benthic isotope stack LS16 (Lisiecki and Stern, 2016). (C) Aragonite content (Lantzsch et al., 2007) and (E) relative abundances of G. menardii and G.
menardii flexuosa are shown to support the stratigraphic subdivision of MIS 5.