TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

3.2 The Emperor Seamount Chain
The Hawaiian Ridge and the Emperor Seamount Chain define a nearly con-
tinuous 6000 km long age progressive track of hot spot magmatism ranging in age
from ∼ 85 Ma at Meiji Seamount ([79]) to active volcanism on the Island of Hawaii
(Fig. 3.1). The northwest trending Hawaiian ridge meets the northerly trending
Emperor Seamount Chain south of Koko Seamount (48-49 Ma) [43] (Fig. 3.1).
Early plate reconstructions (e.g., [95]) and recent paleomagnetic studies (e.g.,
[34]) have indicated that the Hawaiian hot spot was close to a mid-ocean spread-
ing center during the formation of Meiji and Detroit Seamounts. Of the oldest
two seamounts, Detroit Seamount is the best sampled and has thus been a focus
of studies aimed at understanding the nature of the Late Cretaceous interaction
of the Hawaiian hot-spot with a MOR e.g., [72, 79].
3.3 Detroit Seamount
3.3.1 Samples
Detroit Seamount covers an area of ∼ 10,000 km 2 and likely represents the
remains of multiple coalesced shield volcanoes [43, 72]. Detroit Seamount was
sampled at multiple drillsites during Legs 145 and 197 of the Ocean Drilling Pro-
gram (ODP). Huang et al. [72] provided a thorough review and interpretation of
whole-rock isotopic and geochemical variations in basalts recovered from Detroit
Seamount. I focused on samples recovered from Sites 1203 and 884 (see Fig. 3.1).
Site 884 is on the northeastern flank of DSM where 87 m of igneous basement was
cored [118] (Fig. 3.1). Basalt samples cored at Site 884 represent 13 flow units
that consist of tholeiitic massive flows in the upper portion of the cored section
and highly plagioclase phyric pillow lavas in lower portion of the cored section
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