Fig. 1: Location Map of the Mahuika Crater
Fig. 1: Location map of the proposed Mahuika Crater and the landmasses surrounding
the Tasman Sea. Bryant 2001 documented mega-tsunami features in Jervis Bay, near
Sydney, Australia. Stewart Island was the site of an eight-person expedition to look for
mega-tsunami evidence. The numbered dots in the ocean are DSDP cores 275, 276, 277.
Fig. 2: Location Map of the Mahuika Crater in Reference to
Nearby Landmasses and Bathymetry
Fig 2: Location Map of the proposed Mahuika Crater in reference to New Zealand’s
South Island, Stewart Island and Snare’s Island. The crater is to scale, and lies about 200
m below sea level, on the continental shelf. Mason Bay, on Stewart Island, was the
specific study area for the field trip to look for mega-tsunami resulting from the proposed
Fig. 3: The Tektite Field of the Proposed Mahuika Impact
Fig. 3: Map of the tektite field for the proposed Mahuika impact. Dredge locations
marked with small purple circles (D131, F80, D149, D160, F82, D73, D72) were
reported to contain tektites. Tektites were not found in the remaining dredge locations,
labeled in white. The Mahuika Crater itself is the 20 km large red circle. The dredge
hauls, taken from the New Zealand science cruises of the Endeavour and Taranui, lie
between 100 to 1000 m below sea level. Snare’s Island and Auckland Island are labeled
Fig. 4: Map of Tektite Strewn Fields and Source Craters
Fig. 4: Location and extension of the four tektite strewn fields on Earth. The solid
circles mark the location of the known source craters (Chesapeake Bay, Ries, and
Bosumtwi) and the suspected crater location for the Australasian strewn field. From
youngest to oldest: Australasian Strewn Field (750 ka), Ivory Coast Strewn Field (1 Ma),
Central European Strewn Field (15 Ma), and North American Strewn Field (35 Ma)
(After Montanari and Koeberl, 2000).
Roughly added to this map are the proposed Mahuika crater and tektite field, believed to
have formed from an impact 500 years ago. The Mahuika tektite field does not intersect
the Australasian strewn field in geographic extent or in the stratigraphic column.
Fig. 5: Aerial Photograph of Mason Bay Dunes, Stewart Island
Fig.5: Aerial photograph of dunes on Mason Bay, Stewart Island. The width of the
picture is 8 km; up is due north. The dark area to the left is the bay while the white areas
are beaches and sand lobes. The dunes were first hypothesized to be the tracks of mega-
tsunami; ground-truth studies showed them to be typical Aeolian sands.
Fig.6: Microtektite Surface Sculpture
Fig 6: Microtektite Surface Sculpture, from Glass, 1974. Scanning electron microscope
(SEM) photographs illustrate various shapes and surface textures observed on
microtektites. A. Translucent, finely-pitted yellow-green Australasian microtektite (core
RC9-137). B. Smooth teardrop from Australasian strewn field (core V19-153). C.
Irregular smooth Australasian microtektite (core V19-153). D. Australasian bottle-green
microtektite (BGMT) with irregular spheroidal shape and rough grooved surface typical
of BGMT. All tektites are between 50-100 µm.
Fig. 7: SEM Photographs of Proposed Mahuika Tektites
Fig. 7: SEM Photographs of proposed Mahuika tektite morphology and texture. A. Pale
green nodule (D160). B. Pale green nodule with “stemmed hemisphere” morphology
(D160). C. High magnification of the microtexture of the D160 tektites, revealing platy
surfaces. D. Interior of a glauconite pellet, Wittering Formation,Isle of Wright, England,
after M.Roe, Macaulay Inst (16).
Fig. 8: EDX Analyses of proposed Mahuika Tektites
Fig. 8: EDX analyses of two proposed Mahuika tektites. A. From a spheroidal-shaped
tektite. B. From a “stemmed hemisphere” tektite. Note the similarities in elemental
peaks. Au was added to the sample during SEM preparation to aid in its conductivity.
Figure 9: EDX Analyses of Granite from Snare’s Island and a
Proposed Mahuika Tektite
Fig. 9: EDX analyses of a granite sample from Snare’s Island (A), compared with that of
a proposed Mahuika tektite (B). The compositions do not match, as might be expected if
the granite can be used to represent the continental shelf on which the Mahuika Crater
Fig. 10: Optical Properties of the Proposed Mahuika Tektites
Fig. 10: Mahuika tektites when viewed under plane (A and C) and crossed polarized (B
and D) light of an optical microscope. The tektites are somewhat opaque in both pictures
of each grain. However, under crossed nicols they faintly transmit orange light,
especially at the edges, where the spheroidal grains are thin enough to view their optical
properties. White flecks in B and D show extinction properties when the stage is rotated,
suggesting that these nodules are microcrystalline, not glass. From D160 <150 µm
Fig. 11: “Stemmed Hemisphere” Grains Attached Together
Fig. 11: Several ‘stemmed hemisphere” grains attached together. These grains, with
similar morphology and optical properties of proposed Mahuika tektites, suggest that an
organic mold encased them.
Fig. 12: Foraminiferal Casts of Authigenic Substances
Fig. 12: Authigenic substances
inside foraminiferal casts. Round
objects inside the forams have the
same composition as the proposed
Mahuika tektites. A-D are of the
genus globigerina while E is a
Fig. 13: Terniary Diagram of Mahuika Tektites and Foram Balls
Mg +Al+Fe Mahuika Tektites
Strong Tektite Candidate
Snare's Island Rock
Ca+N a+K Si
Fig. 14: A terniary diagram showing how nine balls found within forams have the same
composition as the 35 proposed Mahuika tektites. Only nine foram nodules were
analyzed out of over 30 that were identified. Also shown are the theoretical positions of
the clay minerals glauconite, kaolinite, and illite. Rock from Snare’s Island was also
plotted, based on the idea that the granitic continental shelf could be tektite source rock.
A strong tektite candidate was found in D160; its position is also plotted.
Fig, 14: A Strong Candidate for a Mahuika Tektite
Fig. 14: A strong candidate for a Mahuika Tektite, found in dredge location D160. The
smooth surface, craters and deep grooves matches previously published tektites (Fig. 6
and Glass, 1974).
Fig 15: A Strong Candidate for Impact Derived Silicon Carbide
Fig.15: EDX analysis of a blue grain in dredge haul F80.
Au present is from sample preparation. Peaks suggest that it is SiC, an impact generated
mineral. SiC is also used as an industrial abrasive; its presence could be a contaminant.
Fig. 16: Strong Candidates for Shocked Minerals
Fig 16: Plane polarized view (A) and crossed polarized view (B) of a quartz grain (upper
right) and a zircon grain (left) that are strong candidates for shock features. The zircon
grain has one clear direction of shock, while the quartz grain has multiple.
From D153 >150µm fraction, near the edge of the proposed crater.