The sedimentary sequence at Site 1150 yields common to rare planktonic foraminifers, with the exception of the upper part of Subunit IA, where foraminifers are abundant (Table T1). This sequence includes 10 intervals barren of planktonic foraminifers (Fig. F2), especially in Subunit IIIC. The preservation of foraminiferal tests is generally poor to moderate, due to slight deformation and agglutination by secondary calcification.
We identified seven stratigraphically important taxa of planktonic foraminifers from 94 samples from Holes 1150A and 1150B (Table T1). The fauna of Site 1150 is characterized by abundant occurrences of Neogloboquadrina spp. throughout the sequence. A few specimens of the tropical to subtropical species such as Globigerina nepenthes and Globoquadrina dehiscens sporadically occur. According to stratigraphic distributions of fossil species (Fig. F2), eight biohorizons are recognized for Site 1150 in descending stratigraphic order as follows: the LO of Neogloboquadrina asanoi is recognized between Samples 186-1150A-14X-5, 42-44 cm, and 16X-1, 40-44 cm, around the boundary between Subunits IA and IB. The LO of Globorotalia puncticulata is detected between Samples 186-1150A-17X-2, 40-42 cm, and 18X-4, 38-42 cm, in the Subunit IB. The FO of Globorotalia inflata (modern form) is present between Samples 186-1150A-18X-4, 38-42 cm, and 25X-2, 40-44 cm, in Subunit IB. The FO of N. asanoi is identified between Samples 186-1150A-36X-6, 40-42 cm, and 39X-4, 40-42 cm, in Subunit IIA. The LO of Globorotalia ikebei is recognizable between Samples 186-1150A-44X-6, 40-44 cm, and 48X-6, 39-43 cm, in Subunit IIB. The FO of G. ikebei is found between Samples 186-1150A-64X-2, 39-42 cm, and 66X-6, 40-43 cm, just below the boundary of Subunits IIB and IIIA. The LO of G. nepenthes is recognized between Samples 186-1150B-7R-1, 40-44 cm, and 11R-1, 40-43 cm, near the boundary of Subunits IIIA and IIIB. The LO of G. dehiscens is detected between Samples 186-1150B-45R-2, 40-42 cm, and 46R-4, 39-41 cm, in Unit IV.
Planktonic foraminifers of Site 1151 are more abundant than those of Site 1150, generally common to abundant (Table T2), with the exception of 11 intervals of barren of planktonic foraminifers (Fig. F3). The preservation of foraminiferal fossils is generally moderate, due to slight deformation and agglutination by secondary calcification.
We detected 16 stratigraphically important taxa from 87 samples from Hole 1151A (Table T2). The planktonic foraminiferal faunas of this site are dominated by N. pachyderma (sensu lat.), Globigerina bulloides, and Globigerinita glutinata throughout the sequence. Tropical key species such as G. dehiscens, Globorotalia plesiotumida, and Sphaeroidinellopsis spp., sporadically occur (Fig. F3). Eight biohorizons are recognized for Site 1151 in descending stratigraphic order as follows: the LO of N. asanoi is recognized between Samples 186-1151A-6R-1, 42-45 cm, and 7R-3, 40-44 cm, just below the boundary between Subunits IA and IB. The LO of G. puncticulata is detected between Samples 186-1151A-7R-3, 40-44 cm, and 9R-1, 40-43 cm, in Subunit IB. The FO of G. inflata (modern form) is present between Samples 186-1151A-9R-3, 40-43 cm, and 10R-5, 40-44 cm, in Subunit IB. The FO of N. asanoi is identified between Samples 186-1151A-16R-1, 40-43 cm, and 16R-3, 40-43 cm, in Subunit IIA. The LO of G. ikebei is recognizable between Samples 186-1151A-16R-5, 40-44 cm, and 18R-1, 40-43 cm, in Subunit IIA. The FO of G. ikebei is found between Samples 186-1151A-35R-1, 55-57 cm, and 41R-1, 38-41 cm, in Subunit IIC. The LO of G. nepenthes is recognized between Samples 186-1151A-50R-1, 40-43 cm, and 54R-1, 39-43 cm, in Subunit IIIA. The LO of G. dehiscens is detected between Samples 186-1151A-89R-3, 40-43 cm, and 92R-5, 40-44 cm, in Unit IV.