Terrestrial Palaeoecology and Global Change

146 Valentin A. Krassilov. Terrestrial Palaeoecology
Fig. 64. Crustal structures of New Zealand and adjacent
Pacific rises (plateaux) interpreted as crustal
blocks borderd by imbricate foreland/foredeep/islandarc
belts over the major fault zones. Blocks: (Ca)
Campbell, (Ch) Chatham, (Lh) Lord Howe, (No)
Norfolk, (Tk) Three Kings. Ophiolitic thrust belts:
(AP) Alpine, (HR) Hikurangi, (KM) Kermadek, (TA)
Taupo, (VM) Vening Meinesz.
(1) Ophiolites, (2) Flysch trough, (3) Volcanic arc, (4)
Granitoid belt (Foreland), (5) Faults, (6) Contours of
oceanic structures.
Turning to the eastern margin, we find a similar, although differently interpreted, collage
of “terrains”, some equivalent to cratonic blocks of the western margin, the other
appearing as giant overthrusts. A once popular idea of their transequatorial drift from
various locations in the Southern Hemisphere is presently under a revision (Colpron &
Price, 1995; Keppie et al., 2001; Morozov et al., 2001; Stamatakos et al., 2001). New
palaeolatitude estimates indicate a Cretaceous location in the Northern Hemisphere midlatitudes
(about 53°N for Wrangellia: Stamatakos et al., 2001). The available factual
evidence for long-distance transport is far from convincing (see Colpron & Price, 1995
for a critical review). The discrepant magnetic signatures might have been due to tectonic
rotation rather than long-distance rafting. However, a counterclockwise rotation
might have actually displaced continental fragments north of their original location in the
circum-Pacific shear zone.
The western and eastern arms of circum-Pacific belt are linked by the tectonic structures
of Chukotka, Koryak Highlands, Alaska and the Bering Shelf (Fig. 65). The Triassic
– Jurassic geosyncline deposits of northern Alaska are traceable over the – dextrally
displaced – Chukotsk Peninsula from Laurentiy Bay to Kolyuchinskaya Guba (Inlet),
while the Late Jurassic to Neocomian Koyukuk andesite belt (Globerman et al., 1983)
might extend to the coeval Kuryan belt of southern Anyuy (Migachev et al., 1984).
A volcanic belt of the same age has developed along the southern margin of Talkitna
block. It is overthrust by the Maastrichtian to Eocene Valdis/Orca ophiolitic nappes (Tysdal
& Case, 1983) and intruded by the Aleutian-Alaskan batholites. The thrust belts appear
continuous form the Kenai – Koryak arc over the Bering Shelf to the Olyutorsk Range
of northern Kamchatka, where the coeval nappes constitute the Campanian/Maastrichtian
to mid-Eocene sequence of the Olyutorsk, Ukelayat and Koryak complexes (inter-