Fig. 1. Selected ODP drilling sites that have at least 10 cm/kyr sedimentation rates during the Brunhes chron (0–780,000 yr. BP) and contain at least some moderate to high-resolution paleomagnetic evidence for PSV, relative paleointensity, or paleomagnetic excursions.

Fig. 2. PSV records from replicate Holes at ODP Site 1061 from the Blake/Bahama Outer Ridge, northwest Atlantic Ocean. Numbers indicate selected PSV features that are correlatable between holes and with paleomagnetic results from ODP Site1063 (Bermuda Rise), more than1000 km away (Fig. 3). LE indicates the location of the Laschamp excursion in these records. All records are shipboard measurements of archive core halves after 20 mT a.f. demagnetization (Lund et al., 2001b).

Fig. 3. PSV records from replicate Holes at ODP Site 1063 from the Bermuda Rise, northwest Atlantic Ocean. Numbers indicate selected PSV features that are correlatable between holes and with paleomagnetic results from ODP Site1061 (Blake/Bahama Outer Ridge), more than1000 km away (Fig. 2). LE indicates the location of the Laschamp Excursion in these records. All records are shipboard measurements of archive core halves after 20 mT a.f. demagnetization (Lund et al., 2001b).

Fig. 4. Correlation of PSV records from ODP Sites 1233 (top) and 1234 (bottom), collected about 500 km apart from the southwest margin of Chile in the southeast Pacific Ocean. Selected correlatable PSV features are numbered for clarity. The grey intervals locate two excursions, 3α and 3β, that occur at both sites (Lund et al., 2006). These two excursions are equivalent in age (Lamy et al., 2004) to the Mono Lake and Laschamp Excursions, respectively. All records are shipboard measurements of archive core halves after 20 mT a.f. demagnetization. The Site 1233 record of Excursion 3β is shown at an expanded scale in Fig. 9.

Fig. 5. ODP Site 1062 inclination, declination, and relative paleointensity records for the Brunhes chron. Thirteen magnetic field excursions, labeled 3β-13α, can be identified by anomalously low inclinations and southerly pointing declinations. These are all associated with intervals of low relative paleointensity. All records are shipboard measurements of archive core halves after 20 mT a.f. demagnetization. The relative paleointensity estimate is based on the ratio of NRM (after 20 mT a.f. demagnetization) divided by magnetic susceptibility. The age model was determined by Grützner et al. (2002) using the carbonate stratigraphy at Site 1062 and the oxygen isotope stratigraphy of Bassinot et al. (1994).

Fig. 6. Brunhes paleointensity record from ODP Sites 983/984 (Channell, 1999 and Channell et al., 2004). Age models are independent and based on oxygen isotope data. Note the strong correspondence in the relative paleointensity estimates from two sites about 100 km apart. These records represent our most high-resolution evidence for overall Brunhes chron paleointensity variability. The ages of known Brunhes chron excursions (Table 1) are indicated by arrows. Note that all excursions occur in distinctive intervals of low paleointensity.

Fig. 7. Brunhes chron relative paleointensity record from southern hemisphere ODP Site 1089 (Stoner et al., 2003) compared with the record from ODP Site 983 (Channell, 1999) in the North Atlantic Ocean (Fig. 6). Age for Site 983 relative paleointensity in this figure is derived through optimal correlation of benthic oxygen isotopes and paleointensity to those at Site 1089 (after Fig. 17, Stoner et al., 2003).

Fig. 8. Detailed paleomagnetic record of Excursions 7α and 7β from ODP Site 1061. The data come from u-channels after 20 mT a.f. demagnetization. Relative paleointensity is estimated by dividing NRM after 20 mT a.f. demagetization by u-channel magnetic susceptibility. Repeating patterns of inclination lows (indicated by black rectangles) and easterly declinations (indicated by arrows) suggest the evolution of a complex pattern of field variability (vector waveform) that is related to excursions 7α and 7β but not limited to the excursions themselves.

Fig. 9. Detailed paleomagnetic record of Excursion 3β (Laschamp Excursion) from ODP Site 1233. The data are overlapping sections from three different holes at Site 1233. Each record is the shipboard measurement of archive core halves after 20 mT a.f. demagnetizaiton. The relative paleointensity is estimated by dividing the NRM after 20 mT a.f. demagnetization by magnetic susceptibility. Chronology is estimated from 25 AMS radiocarbon dates (Lamy et al., 2004) as summarized by Lund et al. (2006). The excursion occurs at 67 mcd at Site 1233 indicting the remarkably high sediment accumulation rate at this site (163 cm/kyr).

Summary of paleomagnetic evidence for existence/age of Brunhes chron excursions^a