Geology Reference
In-Depth Information
D. annullatissima and P. paucifoliata have not
been found within the study interval (N. Preto and
O. Piros, pers. comm. 2006; Piros and Preto, 2008).
In terms of correlation to the Latemar, D. annul-
latissima occurs only in the lowermost part of
the Latemar succession (Gaetani et al ., 1981) and
P. paucifoliata is even older. However, D. annulata
was found within the study interval and is
consistent with the biostratigraphy of Ogilvie
Gordon (1927) for the upper peritidal member of
the Mendola Formation. The lowermost portion
of the peritidal member is reported to contain
ammonoids of the avisianum subzone indicat-
ing a late Anisian age, which is consistent with a
175-m-thick succession of cycles in the Latemar
that includes the upper portion of the Lower
Tepee Facies, the entirety of the lower cyclic
facies, and the lower half of the Middle Tepee
Facies (see Manfrin et al ., 2005, p. 480, Fig. 3).
The upper portion of the peritidal member of the
Mendola Formation may correlate to portions of
the Latemar stratigraphy above this interval,
including the upper portion of the Middle Tepee
Facies and/or the upper cyclic facies. In sum,
while biostratigraphy does not tie the Mendola
succession to a specifi c interval within the
Latemar, it does indicate that there is a biostrati-
graphic overlap of the Mendola and Latemar
cyclic successions.
section within the Latemar extended cyclic
stratigraphy. Importantly, this sets up a common
time origin for the two sections and an opportu-
nity to investigate specifi c cyclic patterns shared
by the two sections.
The assessment of stratal frequencies (i.e. bun-
dling frequencies) common to the two sections
is extremely challenging due to the short length
of the Mendola measured section (36 cycles).
Multiple graphical and statistical signal analysis
techniques are needed to focus on different
aspects of the Mendola section's stratal patterns
and its corresponding Latemar counterpart.
To present a full range of views, Fischer plots,
harmonic analysis, spectral coherency and
cross-phase analysis were used as follows.
Running cross-correlation analysis
To study the similarity of stacking between cyclic
sections, a running cross-correlation procedure
may be applied. This technique was developed by
Anderson & Kirkland w(1966) to correlate intra-
basinal sequences of varves in the Permian Castile
Formation. Subsequently, the technique was for-
malized in Dean & Anderson (1974). Running
cross-correlation was later used by Holland et al .
(2000) as an independent means to correlate
regional stratal patterns and to corroborate
biostratigraphic correlations.
Preto et al . (2004) applied this 'semi-automated'
technique to the Latemar Platform, successfully
correlating their Cimon del Latemar cycle thick-
ness series to the Cima Forcellone cycle thick-
ness series. The results are replicated here in
Fig. 7a and give a perfect match for the 'marker
horizon M' that Egenhoff et al . (1999) observed
in their fi eld measurements of both localities
(Fig. 7c).
STATISTICAL CORRELATION OF THE
MENDOLA AND LATEMAR SECTIONS
Statistical time-series analysis of the Latemar
and Mendola cycles sheds light on the strati-
graphic patterns in the sections and their inter-
relationships. Running cross-correlation analysis
pinpoints the most likely position of the Mendola
Fig. 7. Running cross-correlation analysis of cycle thickness series within the Latemar Platform, and between Mendola
Pass and the Latemar Platform. The 95% confi dence limits were estimated by interpolating the '95% Confi dence Belt'
of Taylor (1990, Table 8.6, p. 139) to sample sizes (i.e. degrees of freedom) of 180 (for intra-Latemar correlation) and
36 (for Mendola-Latemar correlation). (a) Pearson correlation coeffi cients obtained by progressively shifting the Cimon
del Latemar cycle thickness series of Preto et al . (2001, 2004) relative to the cycle thickness series at Cima Forcellone
of Goldhammer et al . (1987), with 57 additional cycle measurements within the Tepee Facies from Dunn (1991) (see
Appendix 1 for details). A singular peak correlation occurs between the Cimon del Latemar series and Cima Forcellone
Cycles 356 to 504. (b) Pearson correlation coeffi cients obtained by progressively shifting the Mendola Pass cycle thick-
ness series (this study) against the Cima Forcellone cycle thickness series. Peak correlation occurs at a unique interval of
36 cycles in the Cima Forcellone series, Cycles 351 to 386, which corresponds to the lowermost 30 cycles of the Cimon del
Latemar series. In both (a) and (b) the 95% confi dence limits widen at the top of the section as the shifting shorter series
(Cimon del Latemar or Mendola) rolls off the upper end of the longer (Cima Forcellone) series, resulting in ever-decreasing
degrees of freedom in the calculated coeffi cients. (c) Detail highlighting the relative positions of the correlated intervals
with respect to Cima Forcellone.
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