Publication Date:
2023-12-14
Description:
Understanding planktic foraminiferal depth habitat along with consistent taxonomic concepts is key to accurate reconstruction of paleoceanographic records. The Oligocene‐Pliocene long‐ranging and widely distributed species Dentoglobigerina venezuelana lived in the mixed layer (shallower) during the early Oligocene, whereas the same species calcified at thermocline or subthermocline depths (deeper) during the late Oligocene and Miocene. The exact timing of the species' depth habitat change and its possible relationships with Oligocene climate dynamics remain unknown. Here we reveal isotopic records of D. venezuelana along with the Paragloborotalia siakensis group (a mixed‐layer dweller) by using sediments at Integrated Ocean Drilling Program Site U1334 in the eastern equatorial Pacific throughout the Oligocene. A two‐step depth habitat change of D. venezuelana is apparent: (1) from upper to lower mixed layer (~27.4 Ma) and (2) from lower mixed layer to thermocline depth (~26.3 Ma). In addition, the planktic foraminiferal faunal assemblage experienced a marked change from dominantly thermocline (deeper) species to abundant mixed‐layer (shallower) species, suggesting that depth habitat shifts of D. venezuelana were clearly related to thermocline deepening in the eastern equatorial Pacific. Comparison of the first isotopic shift (~27.4 Ma) at multiple sites (U1334, U1333, and 1218) revealed a southward depth habitat change of D. venezuelana within ~200 kyr, implying overall thermocline deepening with reduced steepness in the eastern equatorial Pacific. We consider that global warming conditions during the late Oligocene likely caused thermocline deepening with upwelling decrease in the eastern equatorial Pacific, guiding D. venezuelana to adapt to greater depths in the water column.
Keywords:
320-U1334A; Accumulation rate, planktic foraminifera by number; AGE; calculated from Pälike et al., 2010; Cassigerinella chipolensis; Catapsydrax dissimilis; Catapsydrax martini; Catapsydrax unicavus; Chiloguembelina cubensis; Density, dry bulk; Dentoglobigerina altispira globosa; Dentoglobigerina baroemoenensis; Dentoglobigerina galavisi; Dentoglobigerina globularis; Dentoglobigerina pseudovenezuelana; Dentoglobigerina sellii; Dentoglobigerina spp.; Dentoglobigerina tripartita; Dentoglobigerina venezuelana; Depth, composite revised, adjusted; Depth, composite revised, corrected; DEPTH, sediment/rock; DRILL; Drilling/drill rig; Dry mass; DSDP/ODP/IODP sample designation; equatorial Pacific; Exp320; Foraminifera; Foraminifera, benthic; Foraminifera, planktic; Globigerina anguliofficinalis; Globigerina angulisuturalis; Globigerina brazieri; Globigerina ciperoensis; Globigerina praebulloides; Globigerinella obesa; Globigerinella praesiphonifera; Globigerinita glutinata; Globigerinita uvula; Globigerinoides spp.; Globoquadrina euapertura; Globoquadrina praedehiscens; Globorotaloides eovariabilis; Globorotaloides hexagona; Globorotaloides permicrus; Globorotaloides testarugosa; Globoturborotalita ouachitaensis; Globoturborotalita woodi connecta; Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP; Joides Resolution; Number; Oligocene; Pacific Equatorial Age Transect I; Paragloborotalia kugleri; Paragloborotalia nana; Paragloborotalia opima; Paragloborotalia pseudocontinuosa; Paragloborotalia pseudokugleri; Paragloborotalia siakensis; planktic foraminifera; Protentella spp.; Pseudohastigerina naguewichiensis; Ratio; Sample code/label; Sedimentation rate; Subbotina angiporoides; Subbotina corpulenta; Subbotina eocaena; Subbotina gortanii; Subbotina linaperta; Subbotina spp.; Subbotina utilisindex; Tenuitella clemenciae; Tenuitella gemma; Tenuitella munda; Tenuitella neoclemenciae; Tenuitella praestainforthi; Tenuitella spp.; Tenuitellinata angustiumbilicata; Turborotalia ampliapertura; Turborotalia increbescans; Turborotalita quinqueloba
Type:
Dataset
Format:
text/tab-separated-values, 2160 data points
Permalink
