Distribution of contourite drifts on convergent margins: Examples from the Hikurangi subduction margin of New Zealand

Contourite drift systems form a significant component of the marine clastic sedimentary record. Although contourites form in all tectonic settings, few studies have described their development along convergent margins; such characterization is needed to underpin oceanographic and palaeoenvironmental studies in active settings. This study is the first to document contourite drift development along the Hikurangi subduction margin of New Zealand. Integration of bathymetric, seismic and well data enables five classes of drift to be recognized around the subduction wedge, occurring in three principal associations: (i) an upper slope drift association of giant elongate mounded (ca 150 km long, 50 km wide and up to 1100 m thick) and plastered drifts (ca 300 km long, 8 km wide and <600 m thick), which occurs upon and inboard of a major intrabasinal thrust‐cored high, whose long axis parallels the coast; shallow bottom currents disperse sub‐parallel to this axis; (ii) a spatiotemporally discontinuous association of confined and mounded hybrid drifts (ca 500 m long, <2 km wide and up to 500 m thick) that occurs along the mid‐to‐outer slope domain of the wedge, recording the interaction of along‐slope and downslope currents within trench‐slope basins; and (iii) a trench fill assemblage that implies the passage of abyssal bottom currents across a 40 km reach of the trench‐axial Hikurangi Channel‐levée, with associated modification of the channel form and of overbank sediment waves. The fundamental presence of contourites along this margin appears to depend on the orientation and strength of oceanographic bottom currents. However, drift type and evolution vary depending on the slope gradient and the presence of irregular seafloor topography created by tectonic structures. The documented drifts are generally smaller, less continuous, and develop more intermittently than similar styles of drifts documented on passive margins; this mode of occurrence may be characteristic of contourite development on convergent margins

Excess type 2 diabetes in African-American women and men aged 40-74 and socioeconomic status: evidence from the Third National Health and Nutrition Examination Survey

OBJECTIVE—To examine whether socioeconomic status (SES) explains differences in the prevalence of type 2 diabetes between African-American and non-Hispanic white women and men.
DESIGN—Cross sectional study of diabetes prevalence, SES, and other risk factors ascertained by physical examination and interview.
SETTING—Interviews were conducted in subjects' homes; physical examinations were conducted in mobile examination centres.
PARTICIPANTS—961 African-American women, 1641 non-Hispanic white women, 839 African-American men and 1537 non-Hispanic white men, aged 40 to 74 years, examined in the Third National Health and Nutrition Examination Survey (NHANES III), a representative sample of the non-institutionalised civilian population of the United States, 1988-1994.
MAIN RESULTS—Among women, African-American race/ethnicity was associated with an age adjusted odds ratio of 1.76 (95% confidence intervals 1.21, 2.57), which was reduced to 1.42 (95% confidence intervals 0.95, 2.13) when poverty income ratio was controlled. Controlling for education or occupational status had minimal effects on this association. When other risk factors were controlled, race/ethnicity was not significantly associated with type 2 diabetes prevalence. Among men, the age adjusted odds ratio associated with African-American race/ethnicity was 1.43 (95% confidence intervals 1.03, 1.99). Controlling for SES variables only modestly affected the odds ratio for African/American race/ethnicity among men, while adjusting for other risk factors increased the racial/ethnic differences.
CONCLUSIONS—Economic disadvantage may explain much of the excess prevalence of type 2 diabetes among African-American women, but not among men.


Keywords: diabetes mellitus; ethnic groups; socioeconomic factor