Abrupt changes (Heinrich events) in late Quaternary North Atlantic marine environments: a history and review of data and concepts

Abstract

In the last several years evidence has mounted that a series of abrupt changes in sediment delivery and palaeoceanography effected the North Atlantic; they are recorded in a variety of proxy records but most dramatically in changes of grain‐size and mineralogy associated with postulated iceberg rafting events, specifically Heinrich (H) events. This review paper examines the evidence for such evidence prior to the development of the ‘Heinrich event’ concept (1988–1992), and then examines the explosion of data and correlations that stemmed from the acceptance and use of this paradigm. Specific attention is focused on ideas pertaining to the cause(s) of glaciological mechanisms, sediment delivery, and sediment source, and major gaps in our understanding of the underlying glaciological, glacial geological, and glacial marine processes are stressed. Abrupt changes across boundaries associated with H‐2 in the Labrador Sea are illustrated from core HU87033‐009LCF. The case is made that correlations between records need to be more rigorous, especially within the range of radiocarbon dating, but it appears that abrupt changes in the delivery of iceberg rafted debris, which characterize these intervals, are multisourced. It is unclear how global ‘climate’ can simultaneously influence the abrupt behaviour of ice margins in different parts of the world—for marine‐based margins, changes in relative sea‐level are one possibility. A qualitative model is presented for triggering H events, which includes global changes in mass balance, changes in relative sea‐level at ice margins due to glacial isostasy, and changes in the basal thermal regime of tidewater ice‐streams. © 1998 John Wiley & Sons, Ltd.

Ice streams in the Laurentide Ice Sheet: a new mapping inventory

“…These have been interpreted to record major collapses of the ice sheet (in which ice streaming appears prominent) with inferred effects on the global climate system (Andrews, 1998;Bond et al, 1992;Heinrich, 1988;Rashid & Piper, 2007;Rashid, Saint-Ange, Barber, Smith, & Devalia, 2012). The growth in the identification of ice streams has been mirrored by attempts to test and refine numerical models of their activity in the LIS (Kaplan, Pfeffer, Sassolas, & Miller, 1999;Marshall & Clarke, 1997;Marshall, Clarke, Dyke, & Fisher, 1996;Pfeffer et al, 1997;Stokes & Tarasov, 2010;Tarasov & Peltier, 2004;Winguth, Mickelson, Colgan, & Laabs, 2004).…”

Simulating Heinrich event 1 with interactive icebergs

“…Paleoceanographic records provide ample evidence that ''great armadas of icebergs'' (Heinrich 1988) were a prominent feature of the last glacial climate (reviews : Hemming 2004;Andrews 1998). Six episodical discharges of icebergs into the North Atlantic Ocean, so-called Heinrich events (e.g.…”

“…Broecker et al 1993), have been registered as distinct layers of ice rafted detritus (IRD) in marine sediment cores from the North Atlantic. Sedimentological and mineralogical evidence (see references in Andrews 1998;Hemming 2004) shows that most IRD originated from the Laurentide Ice Sheet, although other ice sheets (i.e., Eurasian, Icelandic, Greenland) also contributed (e.g. Grousset et al 2001).…”

Millennial‐scale depositional cycles related to British Ice Sheet variability and North Atlantic paleocirculation since 45 kyr B.P., Barra Fan, U.K. margin

“…In order to explain the existence of Heinrich-like events sourced from other ice sheets it has been suggested that a major collapse of the LIS could propagate to other glacial margins by inducing a rapid sea level rise of several meters [MacAyeal, 1993;Andrews, 1998]. However, the synchroneity of IRD deposition during Heinrich …”