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Reconstruction of Paleolithodynamic Formation Conditions of Cambrian-Ordovician Sandstones in the Northwestern Russian Platform

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Analysis of the paleohydrodynamic characteristics of sedimentary environments allowed us to reconstruct formation conditions of the Cambrian-Ordovician sandstone sequence (COS) in the Leningrad district. Reconstruction of the paleolithodynamic parameters showed that the real timing of the sequence (sedimentation duration) is considerably less than the related stratigraphic scale interval. Such a situation is also encountered in other sedimentary formations. Determination of the real sedimentation rate can affect the assessment of mineral resources in sedimentary basin.
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ISSN 00244902, Lithology and Mineral Resources, 2011, Vol. 46, No. 1, pp. 60–70. © Pleiades Publishing, Inc., 2011.
Original Russian Text © G. Berthault, A.V. Lalomov, M.A. Tugarova, 2011, published in Litologiya i Poleznye Iskopaemye, 2011, No. 1, pp. 67–79.
60
Lithodynamic processes represent one of the most
important factors in the formation of terrigenous sed
imentary sequences. Therefore, the study of pale
olithodynamics allows us to elucidate formation con
ditions of clastic rocks. Of special interest is the assess
ment of quantitative parameters of paleolithodynamic
processes. Such a possibility is provided by recent
studies in the field of hydraulic engineering, hydrody
namics, and geological engineering, which reveal rela
tionships between hydrodynamic characteristics of
depositional environments, parameters of the sedi
ment drift (hereafter, just drift), and textural–struc
tural characteristics of rocks. The established regular
ities (with regard to corrections for the solution of a
reverse problem) are used in the reconstruction of
parameters of lithodynamic processes in paleobasins.
The study was carried out in several stages to solve
the problem:
(1) Reconstruction of hydrodynamic parameters of
depositional environments based on the grain size
composition and rock textures. Relationships between
drift rate (scouring velocity and initial precipitation
rate of sediments of the given size) and grain size char
acteristics of sediments were established based on
experimental and natural observations (Hjulstrom,
1935; Grishin, 1982). In paleolithodynamic recon
structions, one should take into account that the min
imal drift rate is recorded during settling of the trans
ported clastic material on the bottom layer. There is no
1
2
3
4
1
4
3
question that the drift rate was greater during the stable
transportation of material (especially in the erosion
phase) than that during the formation of a routine sed
imentary layer. Since it is impossible to establish the
excess value with sufficient reliability in most cases,
the drift rate obtained during calculations is minimal.
(2) Based on the calculated values of the paleodrift
rate in the facies zone under study the dependence of
sediment load on hydrodynamic characteristics of the
environment, and the grain size composition of sedi
ments, one can assess the drift capacity.
1
Here, we
should take into account that such dependences are
commonly empirical, each having its own field of
application. For instance, the Chezy equation yields
the most reliable results for deep drifts with a relatively
fine material if the ratio between drift depth and parti
cle diameter tends to infinity (Julien, 1995); the Bag
nold equation (Bagnold, 1956) is applicable to a com
pletely turbulent environment at a great power of
drifts; and so on. The validity of choosing a method for
the reconstruction of lithodynamic parameters of a
specific zone in the basin under consideration deter
mines the accuracy of the results obtained.
1
The
drift capacity
means the maximum amount of the material
that can move in a unit of time in the alongshore drift of sedi
ments. The
drift power
characterizes the real sediment transport
rate. The drift
capacity
and
power
coincide for saturated drifts if
the drift is provided with loose material (
Morskaya…
, 1980).
5
6
1
Reconstruction of Paleolithodynamic Formation Conditions
of Cambrian–Ordovician Sandstones in the Northwestern
Russian Platform
G. Berthault
a
, A. V. Lalomov
b
, and M. A. Tugarova
c
a
28 boulevard Thiers, 78250 Meulan, France
email: berthault.guy@orange.fr
b
Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences,
Staromonetnyi per. 35, Moscow, 119017 Russia
email: lalomov@mail.ru
c
St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 198904 Russia
email: tugarova@mail.ru
Received September 16, 2009
Abstract
—Analysis of the paleohydrodynamic characteristics of sedimentation environments allowed us to
reconstruct formation conditions of the Cambrian–Ordovician sandstone sequence (COS) in the Leningrad
district. Reconstruction of the paleolithodynamic parameters showed that the real timing of the sequence
(sedimentation duration) is considerably less than the related stratigraphic scale interval. Such a situation is
also encountered in other sedimentary formations. Determination of the real sedimentation rate can affect
the assessment of mineral resources in a sedimentation basin.
DOI: 10.1134/S0024490211010056
4
4
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 6 2011
RECONSTRUCTION OF PALEOLITHODYNAMIC FORMATION CONDITIONS
4
61
Karelian Isthmus
Lake Ladoga
Gulf of Finland
St. Petersburg
Lamoshka R.
Izhora R.
Gatchina
Kingisepp
Luga R.
Tosna R.
Volkhov R.
Syas R.
12
Fig. 1.
Sketch map of the study region.
(1) Baltic–Ladoga Glint; (2) location of reference sections.
(3) Based on geometric parameters of the forma
tion under study (length in two perpendicular direc
tions and average thickness), estimates of the drift
capacity within the paleofacies zone, the partial ero
sion section of this rock complex, and the stability of
paleodrift direction, we can assess the real sedimenta
tion timing for this formation using the model of “res
ervoir sedimentation” (Julien, 1995).
INVESTIGATION OBJECT
The lithodynamic reconstruction was carried out
for the sandy part of the Cambrian–Ordovician
sequence located in the Leningrad district. First geo
logical data on the section were obtained as early as the
19th century. Stratigraphic, paleontological, and
lithological results of later investigations (Rukhin,
1939; Ul’st, 1959, and others), as well as information
published recently (
Geologiya…
, 1991; Popov et al.,
1989; Dronov and Fedorov, 1995, and others) allowed
a substantial lithostratigraphic subdivision of the sec
tion, but this statement mainly concerns with the
Ordovician clay–carbonate part. The sandy part of the
Cambrian–Ordovician sequence remains a compli
cated object for stratigraphers and is poorly subdivided
into individual layers that could be traced from one
exposure to another.
Field works on the study of Cambrian and Ordovi
cian rocks in the Leningrad district were carried out in
sections considered as reference ones for the region.
Most attention was concentrated on exposures in the
Tosna and Sablinka river valleys, where the terrigenous
sandy sequence between Lower Cambrian “blue
clays” and Lower Ordovician black shales of the Pak
erorot Horizon is completely exposed. A series of
1
exposures in the Izhora, Volkhov, and Syas river valleys
were also studied (Fig. 1).
In terms of tectonics, the sequence under study is
located at the northwestern periphery of the Moscow
Syneclise that was formed in the terminal Proterozoic.
This area was predominated by epeirogenic move
ments that governed its regressive–transgressive
nature (Geisler, 1956). In the early Paleozoic, a shal
lowwater sea basin with a high hydrodynamic activity
existed within the northwestern Russian Platform. The
northern boundary of the basin was governed by the
position of the Baltic Shield, which served as a source
of clastic material for the sedimentation area. Weath
ering crusts have not been established in the Baltic
Shield proper, but mineralogical maturity of the clastic
material transported to the sedimentation basin (the
content of unstable minerals in the heavy fraction of
COS does not exceed 10–15%) indicates a deep
chemical weathering of rocks in the provenance (Gur
vich, 1978).
The sequence is divided into the following three
formations from the bottom to top (Fig. 2).
The Middle Cambrian Sablinka Formation (
Є
2
sb
).
Classic exposures of the formation are located in the
Tosna River valley near the Settlement of Ul’yanovka.
The Sablinka Formation is composed of light gray,
pinkish, yellowish (ferruginized in places), well
graded, finegrained, poorly cemented quartzy sand
stones with plastic brownish gray clay interlayers 0.5–
1 cm thick.
The Sablinka Formation is divided into two subfor
mations that are similar in the lithological composi
tion but different in textures: horizontal parallelbed
ded structures with ripple marks and fine crisscross
lamination predominate in the lower subformation;
3
3
62
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 1 2011
BERTHAULT et al.
unidirectional crossbedded structures are character
istic of the upper subformation. The detailed textural
analysis of the COS sequence is given in the next sec
tion.
The formation extends over the whole Leningrad
district east of the Luga River and occurs with erosion
on the Lower Cambrian “blue clays.” The erosion
boundary is relatively even and downcuttings are wide
with gentle slopes. The paleorelief amplitude is several
meters. Thickness of the Sablinka Formation
increases eastward from 2–3 to 10–13 m.
The
Ladoga Formation
(
Є
3
ld
)occurs with erosion
on the Sablinka sandstones. It is represented by yel
lowish gray, medium to finegrained, well graded,
quartzy and quartz–feldspar, and poorly cemented
sandstones with
Lingula
shells along with lenses and
isometric spots enriched in ferric oxides.
The lower boundary of the formation is clearly ero
sional. Downcuttings of the Ladoga Formation floor
(up to 5–10 m wide and 1 m deep) are observed within
individual exposures. Downcuttings of the erosional
paleorelief include basal pebblebeds of brownish gray
clay balls encountered in the underlying Sablinka For
mation. In the lower part, sand becomes medium
grained; crossbedded structures and ripple marks are
encountered. Massive or flatbedded finegrained
sandstones (with clay interlayers up to 0.5–1 cm thick)
are found higher in the section.
Rocks of the Ladoga Formation are thin: up to 1–
1.2 m in the western part of the Leningrad district and
up to 3 m in its eastern part.
The
Tosna Formation
(
Є
1
ts) is established through
out the whole Leningrad district. It occurs with ero
sion on sandstones of the Ladoga Formation and lies
with conformity under the Kopor Formation repre
sented by black mudstones of the same age. The Tosna
Formation is composed of coarse to medium
grained, mainly quartzy, and poorly cemented sand
stones with valves of inarticulate brachiopods and
detrital material. The trough and cross bedding is
characteristic of the rocks. Thickness of the formation
varies from 2 to 5 m.
W – SW
Lamoshka Izhora Tosno Volkhov Lava Syas
E – NE
1 m
50 km
O
1
kp
C
1
si
C
2
sb
1
C
2
sb
2
C
3
ld
O
1
ts
C
3
ld
O
1
ts
O
1
kp
123456789
Fig. 2.
Section of Cambrian–Ordovician sandstones in the Leningrad district.
(1) Pebble; (2) coarse to mediumgrained sand; (3) finegrained sand; (4) clay; (5) shale; (6) shell detritus; (7) unidirectional
crossbedded series; (8) crisscross bedding; (9) ripple marks. (Sb
1
) Sablinka Formation, lower subformation; (Sb
2
) Sablinka For
mation, upper subformation; (Ld) Ladoga Formation; (Ts) Tosna Formation.
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 6 2011
RECONSTRUCTION OF PALEOLITHODYNAMIC FORMATION CONDITIONS
4
63
STRUCTURAL ANALYSIS OF ROCKS
FROM THE CAMBRIAN–ORDOVICIAN
SANDY SEQUENCE AND FACIES–DYNAMIC
CONDITIONS OF THEIR FORMATION
Cambrian and Ordovician sandy rocks of the Len
ingrad district exhibit sedimentation textures that are
interesting and important for understanding the
sequence formation—first of all, different types of
bedding and ripple marks, as well as inter and intras
tratal erosional surfaces. When studying textures, most
attention was concentrated on the shape and spatial
position of joints and laminas inside lamina series (if
possible, in two perpendicular crosssections), as well
as series extension and thickness. Azimuth and dip
angles of laminas were also measured. Based on mea
surements of the cross bedding, rose diagrams were
compiled for each of the distinguished age units:
recurrence percentage for crossbedded series was
plotted on diagrams. Terminology and classification of
bedded structures and ripple marks are given after V.N.
Shvanov (1987).
The
Sablinka Formation, lower subformation
(
Є
2
sb
1
).
Flatbedded structures distinguished at its base give
way to crossbedding higher in the section. In general,
flat, parallel, and multidirectional cross bedding is
characteristic of the subformation. The upper part of
the subformation shows surfaces with ripple marks
with the ripples 3.5–4.5 cm high and the spacing
between them 20 cm wide (Fig. 3).
According to numerous measurements in rocks
exposed in valleys of the Tosna and Lava rivers, dip
azimuths of the crossbedded laminas exhibit two
opposite directions: westnorthwestward and east
southeastward (Fig. 4a).
The data obtained allow us to establish the genetic
type of textures. Linearity and, as a rule, parallelism of
joint series, shape of laminas, bedding pattern in per
pendicular sections, and narrow rays of rose diagrams
directly indicate the generation of these textures due to
the migration of rectilinear transverse sand ridges
under the influence of bottom currents. Moreover,
inclined joints suggest the migration of ridges during a
pulsating input of the material (Kutyrev, 1968),
whereas symmetrical ripple marks formed in the wave
agitation zone indicate the shallowwater nature of the
basin (Frolov, 1992).
Flatbedded structures in the lower part of the sub
formation suggest that this part of the section was
accumulated under relatively deepwater conditions
below the wave agitation zone (without bottom cur
rents) during the settling of sediments from suspension
delivered from the adjacent shallower regions of the
shelf. Sedimentation conditions changed during dep
osition of the upper part: crossbedded series with
opposite dip directions of oblique lamina and ripple
marks indicate that the textures formed in shallow
water, hydrodynamically active marine conditions in
the wave agitation zone with periodic bottom (most
5
probably, tidal) currents. Each tide or ebb cycle
formed its own ridge system, which partially or com
pletely destroyed earlier ridges and buried them as
crossbedded series. Although relationship between
the flow direction and the inclination of crossbedded
series is ambiguous (Kutyrev, 1968), the rose diagram
of cross bedding can approximately reflect the clastic
material transport in the paleobasin. For the studied
sequence characterized by two opposite directions of
material transport, the resultant component is
directed eastward and indicates an alternating (inter
tidal?) regime during the alongshore eastward drift of
sediments
2
.
The
Sablinka Formation, upper subformation
(
Є
2
sb
2
).
The upper part of the Sablinka Formation shows
asymmetrical ripple marks with the following parame
ters: 30–50 cm long, 3–6 cm high, ripple indexes
varying from 6–7 to 10, and gentle/steep slope ratio
ranges within 1–3.
Relatively thick and chiefly extended unidirec
tional (predominantly to the east) crossbedded series
impart a specific appearance to the member (Fig. 5).
Thickness of the series is 25–35 cm and length is no
less than 10 m. Joints are straight and subhorizontal.
Deformed and overturned crossbedded structures
of the synsedimentary syngenetic nature appear in
sandstones in the western part of the Leningrad district
(Fig. 6). This fact most likely indicates the destruction
of sand ridges during increase of the flow rate above the
critical value possible for their existence (Reineck and
Singh, 1978). The general eastern direction of cross
bedded series inclination is retained within the entire
domain of the Sablinka Subformation.
2
The
alongshore drift of sediments
means a resultant unidirec
tional alongshore transport of sediments over a long time inter
val. The drift of sediments may proceed both under the influence
of wave energy and diverse currents (for instance, windborne or
tidal) (
Morskaya…
1980).
3
Fig. 3.
Ripple marks in sediments of the Sablinka Forma
tion.
64
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 1 2011
BERTHAULT et al.
The nature of textures suggests that the sequence
was formed in a stable hydrodynamic regime under the
influence of mainly unidirectional longterm drift,
with intensity decreasing from west to east. The east
ward drift direction substantially dominated (Fig. 4b).
The
Ladoga Formation
(
Є
3
ld)
occurs with hiatus
on the Sablinka sandstones with basal pebble beds
(clay balls) at the base. They are overlain by the cross
bedded sandstones with a series of small thickness
(15–20 cm) and length (1–1.5 m). The cross bedding
is flat, crisscross, and multidirectional. Laminas are
emphasized by linguloid shells. Symmetrical ripple
marks (probably waverelated) are developed at the
top of crossbedded sandstones.
It is apparent that the basal layer of the Ladoga For
mation was deposited under conditions of the suprac
ritical erosional rate of the flow. Then, the sediments
of the Ladoga Formation were mainly deposited in less
active hydrodynamic conditions (probably related to
deepening of the basin) under the influence of differ
ently oriented waves and tidal currents. Azimuths of
crossbedded lamina dip indicate the alternating sub
latitudianal migration of sand material during the result
ant alongshore eastward drift of sediments (Fig. 4c).
The
Tosna Formation
(
O
1
ts
). The trough and criss
crossbedded horizon (1–1.2 m thick), which occurs
either on the basal crossbedded sandstones (about 20
cm thick) or without them above the contact with the
Ladoga Formation, represents the main textural
0
180
(a) 0
180
(b)
0
180
(c) 0
180
(d)
Fig. 4.
Rose diagrams of crossbedding directions in the Cambrian–Ordovician sandstone sequence in the Leningrad district: (a)
Sablinka Formation, lower subformation; (b) Sablinka Formation, upper subformation; (c) Ladoga Formation; (d) Tosna For
mation.
Fig. 5.
Unidirectional crossbedded series in sandstones of
the Sablinka Formation.
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 6 2011
RECONSTRUCTION OF PALEOLITHODYNAMIC FORMATION CONDITIONS
4
65
parameter determining the appearance of the Tosna
Formation. This bedding type was attributed in litera
ture to the migration of crescent sand ridges along the
bottom, which are formed under the influence of a
strong but mainly turbulent flow (Kutyrev, 1968;
Shvanov, 1987). The height of paleoridges is likely
comparable with the thickness of crossbedded series
and varies from 8–9 to 20 cm.
From the bottom to top, bedded structures vary
from crossbedded to troughbedded; the trough bed
ding passes into the cross, flat, parallel or alternate
bedding with an upsection thinning of crossbedded
series up to the appearance of small obscure cross
bedded structures.
The rose diagram of lamina dip in sandstones of the
Tosna Formation demonstrates two cross directions of
the sediment transport: the main sublatitudinal dip
(Fig. 4d) with the prevailing eastward direction and
the additional submeridional dip with the prevailing
southsouthwestward direction.
We can assume that sands of the Tosna Formation
were formed under the influence of an intense turbu
lent flow grading with time into the temperate laminar
one. The alternate sediment migration proceeded
under conditions of the basic eastward transport of the
material.
Hence, the studied Cambrian–Ordovician terrige
nous sequence shows a regular increase in the hydro
dynamic activity during sedimentation within the
Sablinka Formation from its bottom to top and a suc
cessive decrease in the activity during deposition of the
Ladoga and Tosna formations. In general, the inten
sity of hydrodynamic processes decreased eastward in
the area, probably, due to an increase in the paleobasin
depth.
Table 1 demonstrates average values of grain size
characteristics of the studied sediments for the distin
guished Middle Cambrian–Lower Ordovician forma
tions in the Leningrad district. Analysis of grain size
parameters of sediments along the strike suggests that
they are mainly marked by decrease in size and
increase in the degree of grading (
σ
) and structural
maturity (excess) from west to east.
The sequences in the section are generally charac
terized by the cyclic nature of variation in grain size
characteristics during small fluctuations of these
parameters, with amplitude increasing to the top of
the section.
CALCULATION OF DRIFT PARAMETERS
Many formulas have been proposed for the calcula
tion of drift parameters over the last fifty years. How
ever, no universal method has been elaborated so far,
and each of the available equations has its own sphere
of application. Standing out amidst several calculation
models are some basic ones, which pretend to be com
plex and universal, and their simplified versions that
are less refined and oriented to the solution of partic
ular problems with a simpler mathematical apparatus.
In the proposed methods, the drift capacity is cal
culated based on grain size characteristics of sedi
ments and parameters of depositional environments.
Parameters of the environment for paleohydrody
namic reconstructions can be established with some
Fig. 6.
Deformed crossbedded sedimentation structures
in rocks of the Sablinka Formation.
Table 1. Grain size parameters of the main stratigraphic units
Sablinka Formation (
Є
2sb) Ladoga Formation (
Є
3ld) Tosna Formation (O1ts)
west center east
west center east
west center east
Ma, mm
0.28 0.18 0.16 0.13 0.23 0.12 0.30 0.26 0.21
σ, mm
0.56 0.61 0.62 0.41 0.59 0.48 0.57 0.53 0.64
As 2.22 1.5 1.76 1.12 1.9 1.35 2.25 1.9 1.58
Ex 10.9 9.6 12.8 4.4 5.4 6.2 17.5 15.3 21.5
Hr (entropy)
0.65 0.59 0.54 0.72 0.61 0.64 0.61 0.64 0.56
Note: Data on grain sizing of clay interlayers were not taken into account.
(Ma) Arithmetic mean for grain size, (@[sigma]) standard deviation, (As) asymmetry of distribution, (Ex) excess, (Hr) relative entropy
of distribution.
66
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 1 2011
BERTHAULT et al.
constraints determined by the solution of a reverse
problem: calculation based on grain size characteris
tics of sediments under study reflects hydrodynamic
characteristics of the flow at the sedimentation stage,
flow intensity at the sediment transport stage being
probably higher.
The Einstein method (Einstein, 1950) is one of the
basic methods in geoengineering lithodynamic calcu
lations. The method is applicable for calculation of the
total discharge of sediment load (tractional and sus
pended). Its application is constrained by the predom
inance of bed load transported by traction and salta
tion over the suspended load, as well as a considerable
width of water channel relative to its depth, where the
hydraulic radius of the channel (
R
h
) equal to the cross
section area/“wet perimeter” length (width plus dou
ble depth) ratio is nearly equal to the channel depth.
These peculiarities of the Einstein method suggest that
the error of its application is minimal for bottom cur
rents in a shallow sea basin composed of sandy mate
rial.
The specific total sediment discharge per flow
width unit
q
t
can be calculated according to the Ein
stein method as the total discharge of bed load
q
b
and
suspended
q
s
load that can be expressed by the equa
tion:
(1)
where
h
is the flow depth;
С
is the suspended load con
centration;
v
x
is the horizontal component of the
velocity in the flow direction
(
x
);
z
is the vertical coor
dinate.
Omitting complicated mathematical transforma
tions presented in the monograph
Erosion
and Sedi
mentation
(Julien, 1995), we obtain the equation:
q
t
=
q
b
[1 +
I
1
ln(30
h
/
d
s
) +
I
2
], (2)
where
d
s
is the medium size of suspended load, and
two integrals
I
1
and
I
2
have a numerical solution or can
be calculated using nomograms elaborated by Ein
stein.
The function suggested by Einstein for the calcula
tion of drift capacity takes into account the relation
ship between different grain size classes of sediment in
flows of different intensities. On this basis, the equa
tion (1) can be presented as:
q
t
=
Σ
i
t
q
ti
,(3)
where
i
t
is the content of igrain size class in sediment;
q
ti
is the specific discharge of igrain size class.
Gathering of necessary information about bottom
sediments of a paleobasin is the first step in the method
application. We distinguished four spatially stable sed
imentary complexes: the lower and upper subforma
tions of the Sablinka Formation, as well as the Ladoga
and Tosna formations. The results of the grain size anal
ysis for 19 size classes within the range from >2 mm to
1
qtqbCvxz,d
0
h
+=
<0.01 mm (in total, about 450 samples) were averaged
and grouped for the further treatment in three grain
size classes, each representing no less than 19% of the
total material volume (0.45–0.22, 0.22–0.11, 0.11–
0.055 mm). We also calculated other necessary param
eters (average size of particles in the class; settling
velocity for particles of this size; and percentiles
d
16
,
d
35
,
d
50
,
d
65
,
d
84
) (Table 2).
The hydraulic size in Table 2 was calculated by the
formula:
w
= (4(
G
– 1)
gd
s
/3
C
D
)
0.5
,(4)
where
G
is the specific weight of particles;
g
is the free
fall acceleration;
d
s
is the diameter of sediment parti
cles,
C
D
is the drag coefficient related to the Reynolds
number for ballshaped particles
(Re
p
)
C
D
= 24/Re
p
(Julien, 1995).
The calculation is made for each distinguished grain
size class, and the obtained results are summed up.
A detailed description of the Einstein method for
practical calculations is given in (Julien, 1995).
Results of an analogous calculation made for the COS
of the Leningrad district allowed us to determine the
specific capacity of drift for each of four studied
sequences (Table 3).
CALCULATION OF SEDIMENTATION
DURATION IN THE SEQUENCE
UNDER STUDY
Parameter of the specific capacity of drift is insuffi
cient for calculating the sedimentation duration for
the sequence under study, since this parameter in the
pure state is applicable only in the case of unidirec
tional and temporally stable drift. In actual practice,
parameters of drifts are changeable with time and
space. The structural analysis of sediments presented
above suggests periodic changes in the drift direction
and variations in its intensity that are manifested as
inter and intraformation erosion boundaries
(increase in drift intensity) and clay interlayers
(decrease in drift intensity) that should be taken into
account in calculations.
Orientation of the crossbedding indicates a peri
odic change in the drift direction in all of the studied
sequences, with the ESE direction generally being the
predominant one. With such a drift regime, the input
of material to a unit cell of the active layer and incre
ment of the section thickness are determined by the
difference in opposite vectors of material transport rel
ative to the general hydrodynamic energy in the unit
cell (the sum of all vectors).
For assessing the total drift efficiency based on the
rose diagram of crossbedding directions, we have pro
posed the coefficient of asymmetry (
К
аs
) calculated by
the formula:
К
аs
=
|
V
+i
V
–i
|
/
Σ
V
i
,(5)
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 6 2011
RECONSTRUCTION OF PALEOLITHODYNAMIC FORMATION CONDITIONS
4
67
where
V
i
is the unit vector of the dip of crossbedded
series,
Σ|
V
+i
V
–i
|
is the sum of absolute values of vec
tor differences for opposite directions, and
Σ
V
i
is the
sum of values of all rose diagram vectors. For symmet
rical distribution,
К
аs
= 0; for unidirectional distribu
tion,
К
аs
= 1. The calculated coefficients of asymmetry
for the studied sequences are presented in Table 3.
The detailed analysis of erosional surfaces shows
that erosional boundaries within the studied Cam
brian–Ordovician sequence can be divided into two
types. Erosional interlayer surfaces inside formations
are discontinuous and nonpersistent along the strike.
Such textures are determined by the turbulent nature
and local pulsation of drift velocities (Berthault,
2002).They exert no substantial influence on the total
thickness of the sequence.
Taking into account peculiarities of erosion con
tacts between formations, one can infer that sheet ero
sion essentially dominated over riverbed (deepsea)
erosion. Under these conditions, baselevel of the ero
sion of sequences under study is not always reliably
established. Therefore, in order to get a more correct
value of the primary volume, we take into account the
maximal revealed thickness of the sequence (
H
max
)
assuming that the primary thickness of sediments and,
correspondingly, the formation volume could be
greater.
Using the calculated value specific capacity of drift
(
q
t
), coefficient of asymmetry for the drift (
К
аs
), length
of the sequence in the direction drift direction (
L
)
(about 200 km in the segment accessible for study),
and the maximal established thickness of the sequence
(
H
max
), the sedimentation duration for the COS
sequence in the Leningrad district (
t
s
) can be calcu
lated by the formula:
t
s
= (
H
max
L
)/(
q
t
K
ас
). (6)
The calculation results are presented in Table 3.
Table 2. Grain size characteristics of Cambrian–Ordovician sandstones
Grain size, mm Grain size composition in time units, % Hydraulic size (fall ve
locity in water, w), mm/s
Fractions average (d3)
Sb
1
Sb
2
Ld Ts
>0.45 0.64 2.52 3.87 7.12
0.45–0.22 0.34 21.97 40.21 24.08 36.88 42
0.22–0.11 0.17 49.02 28.48 31.87 44.21 19
0.11–0.055 0.08 22.47 24.34 32.97 9.44 5
<0.055 5.90 4.44 7.21 2.35
Percentile
d
16
0.082 0.088 0.070 0.106
d
35
0.112 0.112 0.095 0.150
d
50
0.134 0.170 0.117 0.190
d
65
0.168 0.217 0.162 0.220
d
84
0.220 0.250 0.250 0.280
Note: (Sb1) Sablinka Formation, lower subformation; (Sb2) Sablinka Formation, upper subformation; (Ld) Ladoga Formation;
(Ts) Tosna Formation. Percentiles d16, d35, etc. denote the particle size (mm), relative to which 16, 35, etc. % of particles
have smaller sizes.
Table 3. Parameters of the formation of Cambrian–Ordovi
cian sandstones in the Leningrad district based on the Einstein
method (1950) and Julien model of “reservoir filling” (1995)
Studied
sequence
q
1
,
m2/day
К
аs
L
,
km
H
max
,
mts, yr
Sb
1
4.7 0.34 200 8 2755
Sb
2
8.5 0.63 200 4 409
Ld 5.1 0.49 200 3 656
Ts 3 . 7 0. 4 7 2 0 0 4 15 6 5
Total
: 26 5384
Note: (q1) Specific capacity of drift (sediment discharge) per
drift width unit (calculation based on the Einstein
method); (Kas) asymmetry coefficient for rose diagram
of cross bedding; (L) reliably established length of the
studied sequence within the study region; (Hmax) max
imal thickness of the sequence; (ts) sedimentation time
based on formula (3); (Sb1) Sablinka Formation, lower
subformation; (Sb2) Sablinka Formation, upper sub
formation; (Ld) Ladoga Formation; (Ts) Tosna For
mation.
68
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 1 2011
BERTHAULT et al.
The relative error of parameters involved in the cal
culation can be rather high. In some cases, the relative
error of primary parameters is extremely hard to esti
mate. Therefore, we can state with confidence only the
order
of the value under calculation.
Values of the specific capacity of drift obtained for
different COS units confirm the inference based on
the suggesting a cyclic regressive–transgressive struc
ture of the sequence. Such a similarity of the results
obtained by independent methods indicates the real
assessment of sedimentation parameters for the pale
obasin.
RELATIONSHIP BETWEEN
SEDIMENTOLOGICAL
AND STRATIGRAPHIC DATA
Thus, we observe a situation when the sedimenta
tion duration substantially differs from the duration of
stratigraphic time interval (hereafter, stratigraphic
duration) correlated to the sequence under study,
which varies from 20 to 30 Ma according to different
assessments.
To determine the time of hiatuses (sediment
rewashing), we use the following formula
(Romanovskii, 1977):
V
=
kH
/(
T
T
*)
p
, (7)
where
V
is the sedimentation rate,
k
is the coefficient
including the thinning of primarily formed layers (cor
rection for compaction),
H
is the maximal thickness of
rocks within the distinguished stratigraphic unit,
T
is
the unit duration (Ma), and
T
*
* is the total time of
hiatuses, and
p
is the measure considering the intensity
of interlayer washouts during the sequence formation.
Then, the hiatus time can be calculated by the for
mula:
T
* =
T
kH
/(
Vp
). (8)
Substituting in formula (8) the values
T
= 25 Ma,
V
= 26
×
10
–4
m/yr, and k = 1.2 (the average compac
tion value for sands is taken to be 20%), we reckon p = 1
(intralayer washouts are of the local nature) and thick
ness is 26 m. Thence, the time corresponding to hia
tuses for COS sedimentation makes up:
T
* = 25
×
10
6
yr –
1.2
×
26
m/26
×
10
–4
m/yr =
24.988
×
10
6
yr.
Thus, the calculated real time of formation (sedi
mentation duration) corresponds to about 0.05% of
the stratigraphic age of this sequence. It should be
noted that the sedimentation duration based on the
Einstein method is of the conservative nature. If we
proceed from sedimentation characteristics of sedi
ments, the duration obtained for their formation
appears to be extremely low in the geological scale.
Based on the analysis of intertidal cycles, Kulyamin
and Smirnov (1973) showed that the “pure” sedimen
tation time for similar COS in the Baltic region is esti
mated at approximately 170 paleodays (133 for the
Middle–Upper Cambrian Sablinka sandstones and 40
for the Lower Ordovician Pakerort sandstones). The
above authors write: “The values obtained are shock
ing” (Kulyamin and Smirnov, 1973, p. 699). They
attribute such results to an infinitesimal preservation
of sediments in analogous sections with respect to the
stratigraphic time range.
Based on the sedimentation analysis of the COS
from the Leningrad district, “pure” sedimentation
time for Lower Paleozoic sands can be estimated at
100–200 yr. The paradox is that geological time of the
Sablinka sequence formation amounts to 10–20 Ma
(Tugarova et al., 2001, p. 89). The authors explain this
paradox by the rewashing of sediments in shallow
water marine conditions with active lithodynamics,
where processes of accumulation and seafloor erosion
occur side by side and replace one another depending
on parameters of storms and currents.
Such a situation is not unique. S.V. Mayen wrote:
“Due to a wide development of concealed hiatuses…,
only a negligible (0.01–0.001%) share of total sedi
mentation time is commonly documented” (Mayen,
1989, p. 24).
Since relationship between erosion and transport
parameters of the drift is exponential, the main vol
ume of geological work (erosion–transfer–deposi
tion) under intense hydrodynamic conditions is
accomplished during activation and is far in excess of
geological work performed under stable conditions.
For instance, all erosional work and the most part of
accumulation in alluvial channels take place during
flood and at its recession (Chalov, 2008). The coastline
deformation during a year is mainly governed by two or
three most intense storms (
Rukovodstvo…
, 1975).
Major hydrodynamic events in paleobasins related
(presumably) to megatsunami caused by tectonic pro
cesses can play a crucial role in the deposition of the
lower (marine) molasse, which terminates the com
plete sedimentological evolution of deep ocean
trenches (Lalomov, 2007). On continental slopes with
intense dynamic processes, such as landslides or large
scale turbid flows, thick sedimentary sequences can be
deposited instantly from the geological standpoint.
All these objects are characterized by a sharp
inconsistency between the stratigraphic duration pre
scribed to this sediment complex and the real time of
sedimentation. Along with elements formed under
intense (sometimes catastrophic) sedimentation con
ditions, which make up the main part of the section,
the rock complexes include (to be more exact, must
include) evidence of longterm hiatuses or erosion of
the most part of deposited sediments. The evidence is
not always present in the explicit form, and this state
ment is valid not only for terrigenous rocks. As
S.I. Romanovskii writes, “…even a monotonous lime
stone sequence includes concealed breaks (diastems),
which account for much of the time responsible for the
section formation. However, since there is no possibil
ity to get even rough estimates of the hiatus duration,
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 6 2011
RECONSTRUCTION OF PALEOLITHODYNAMIC FORMATION CONDITIONS
4
69
geologists have to ignore this issue. …In oceans, a con
siderable part of time falls on hiatuses…. Erosion can
not be considered here as the main cause of section
incompleteness, although other causes cannot also be
pointed out exactly. Marine geologists have found a
fortunate avoidance of this complicated problem and
designated the hiatus as the period of nondeposition of
sediments. Thus, the geological record … fixes short
activation intervals separated by essentially longer inter
vals of inactivity” (Romanovskii, 1988, pp. 22, 23).
The relationship between such notions as “sedi
mentation rate,” “sediment deposition rate,” and
“section increment rate” is the subject of wide specu
lation in the geological literature at present
(Romanovskii, 1988;
Lithogeodinamika…
, 1998;
Baikov and Sedletskii, 2001; and others), and this is
related not only to pure scientific interest. For many
mineral resources of the sedimentary genesis, the opti
mal relationship between sedimentation rate and sec
tion increment rate is the governing factor for their
formation. For instance, titanium–zircon placers rep
resent a product of the enrichment of mineralogically
mature sandy sediments under conditions of stable
lithodynamic processes of moderate intensity (Patyk
Kara et al., 2004). It is relatively fast (by geological
standards) sedimentation of the COS that probably is
responsible for the following fact: commercial Ti–Zr
placers have not been revealed in the region so far
despite the concurrence of many favorable factors
(availability of the source of heavy ore minerals in
igneous and metamorphic rocks of the Baltic Shield,
presence of intermediate collectors of Ti–Zr minerals
in the Late Precambrian and Early Cambrian sedi
mentary complexes, and mineralogical maturity of the
COS in the northwestern Russian Platform).
The sedimentation rate has a direct influence on
the formation of mineral resources at the stage of sed
imentation. This shows up in the process of placer for
mation and, most probably, chemogenic sediments of
the sedimentation series. Therefore, the knowledge of
the real sedimentation rate is important not only for
lithology and sedimentology, but also for the study of
processes responsible for the formation of sedimentary
mineral resources.
CONCLUSIONS
Thus, the application of lithodynamic geoengi
neering calculations for assessing the sedimentation
duration of the sandy portion in the COS in the Len
ingrad district showed that these sandstones were
formed instantaneously from the geological stand
point, and the sedimentation duration of the sequence
does not exceed 0.05% of its stratigraphic age interval.
This work has confirmed ideas of former researchers
about a rather fast formation of the sequence and pre
sents the quantitative assessment of sedimentation.
Conditions, under which the sedimentation time
essentially differs from the stratigraphic one, are char
1
1
acteristic not only for the shallowwater platform ter
rigenous formations (e.g., the COS of the northwest
ern Russian Platform), but also a series of other sedi
mentary formations. Therefore, the traditional
method of calculating the sedimentation rate by sub
division of the sequence thickness into the duration of
the comparable stratigraphic scale interval can yield a
fortiori understated value.
Since the sedimentation rate has a direct influence
on the formation of sedimentary mineral resources of
the sedimentogenic series (placers and partially
chemogenic ores), the real sedimentation rate should
be taken into account in the study of sedimentary ore
genesis.
ACKNOWLEDGMENTS
We are grateful to M.V. Platonov (Faculty of Geol
ogy, St. Petersburg State University) for the assistance
in field works.
This work was supported by the Guy Berthault
Foundation (France) and the Russian Foundation for
Basic Research (project no. 090500268a).
REFERENCES
Bagnold, R.A., Flow of Cohesionless Grains in Fluid,
Phi
los. Trans. R. Soc. London
, 1956, no. 954, pp. 235–297.
Baikov, A.A. and Sedletskii, V.I., Superhigh Rates of Terrig
enous Sedimentation on the Continental Block in the
Phanerozoic, in
Problemy litologii, geokhimii i osadochnogo
rudogeneza
(Problems of Lithology, Geochemistry, and
Sedimentary Ore Genesis), Moscow: Nauka, 2001, pp. 93–
108.
Berthault, G., Analysis of the Main Principles of Stratigra
phy Based on Experimental Data,
Litol. Polezn. Iskop.
,
2002, no. 5, pp. 509–515 [
Lithol. Miner. Resour.
(Engl.
Transl.), 2002, no. 5, pp. 485–497].
Botvinkina, L.N.,
Metodicheskoe rukovodstvo po izucheniyu
sloistosti
(Manual for the Study of Bedding), Moscow:
Nauka, 1965.
Chalov, R.S.,
Ruslovedenie: teoriya, geografiya, praktika
(Study of Channels: Theory, Geography, and Practice),
Moscow: LKI, 2008.
Dr o n o v, A. V. a n d Fe do r o v, P.V. , C ar b o n i fe r o u s Or d o v i c i an
in the Vicinity of St. Petersburg: Stratigraphy of Yellow and
Frozen Sediments, Vestn. St. Petersb. Univ., Ser. Geol.
Geogr., 1995, issue 2, no. 14, pp. 9–16.
Einstein, H.A., The Bed Load Function for Sediment
Transport in Open Channel Flow,
Technical Bulletin No
1026
, Washington, DC: U.S. Dept. Agric., Soil Cons. Serv.,
1950, pp. 1–78.
Frolov, V.T.,
Litologiya
(Lithology), Moscow: Mosk. Gos.
Univ., 1992.
Geisler, A.N., New Data on the Lower Paleozoic Stratigra
phy and Tectonics in the Northwestern Russian Platform,
in
Materialy po geologii evropeiskoi territorii SSSR
(Materi
als on the Geology of the European Part of the USSR),
Moscow: Gosgeoltekhizdat, 1956, pp. 174–184.
70
LITHOLOGY AND MINERAL RESOURCES Vol. 46 No. 1 2011
BERTHAULT et al.
Geologiya i geomorfologiya Baltiiskogo morya. Svodnaya
ob"yasnitel’naya zapiska k geologicheskim kartam M
1:500000
(Geology and Geomorphology of the Baltic Sea:
Summary Explanatory Note to Geological Maps of Scale 1:
500000) Grigyalis, A.A., Ed., Leningrad: Nedra, 1991.
Grishin, N.N.,
Mekhanika pridonnykh nanosov
(Mechanics
of NearBottom Debris), Moscow: Nauka, 1982.
Gurvich, S.I.,
Zakonomernosti razmeshcheniya redko
metal’nykh i olovonosnykh rossypei
(Regularities in the Dis
tribution of Rare Metal Stanniferous Placers), Moscow:
Nedra, 1978.
Hjulstrom, F., The Morphological Activity of Rivers as
Illustrated by River Fyris,
Bull. Geol. Inst. Uppsala
, 1935,
no. 25, pp. 89–122.
Julien, P.,
Erosion and Sedimentation
, Cambridge: Cam
bridge University Press, 1995.
Kulyamin, L.L. and Smirnov, L.S., Intertidal Cycles of Sed
imentation in Cambrian–Ordovician Sands of the Baltic
Region,
Dokl. Akad. Nauk SSSR, Ser. Geol.
, 1973, vol. 212,
no. 13, pp. 696–699.
Kutyrev, E.I.,
Usloviya obrazovaniya i interpretatsiya kosoi
sloichatosti
(Formation Conditions and Interpretation of
Oblique Bedding), Leningrad: Nedra, 1968.
Lalomov, A.V., Reconstruction of Paleohydrodynamic For
mation Conditions of Upper Jurassic Conglomerates in the
Crimean Peninsula,
Litol. Polezn. Iskop.
, 2007, no. 3, pp.
298–311 [
Lithol. Miner. Resour.
(Engl. Transl.), 2007, no. 3,
pp. 275–285].
Litogeodinamika i minerageniya osadochnykh basseinov
(Lithogeodynamics and Minerageny of Sedimentary
Basins), St. Petersburg: VSEGEI, 1998, p. 480.
Mayen, S.V.,
Vvedenie v teoriyu stratigrafii
(Introduction to
the Theory of Stratigraphy), Moscow: Nauka, 1989.
Morskaya geomorfologiya. Terminologicheskii spravochnik
(Marine Geomorphology: Terminological Handbook),
Moscow: Mysl’, 1980, p. 280.
PatykKara, N.G., Gorelikova, N.V., and Bardeeva, E.G.,
History of the Formation of Titanium–Zirconium Sands in
the Central Deposit in the European Part of Russia,
Litol.
Polezn. Iskop.
, 2004, no. 6, pp. 451–465 [
Lithol. Miner.
Resour.
(Engl. Transl.), 2004, no. 6, pp. 441–453].
Popov, L.E., Khazanovich, K.K., Borovko, N.G., et al.,
Opornye razrezy i stratigrafiya kembroordovikskoi fosfori
tonosnoi obolovoi tolshchi na severozapade Russkoi plat
formy
(Reference Sections and Stratigraphy of the Cam
brian–Ordovician PhosphoriteBearing Obolovo Sequence
in the Northwestern Russian Platform), Leningrad: Nauka,
1989.
Reineck, H.E. and Singh, I.B.,
Depositional Sedimentary
Environments
, Berlin: Blackwell Sci. Publ., 1978. Trans
lated under the title
Obstanovki terrigennogo osadkonako
pleniya
, Moscow: Nedra, 1981.
Romanovskii, S.I.,
Fizicheskaya sedimentologiya
(Physical
Sedimentology), Leningrad: Nedra, 1988.
Rukhin, L.B., Cambrian–Silurian Sandy Sequence of the
Leningrad District,
Uchen. Zap. LGU, Ser. Geol.Pochv.
Nauk,
1939, issue 4, no. 11. pp. 89–101.
Rukovodstvo po metodam issledovaniya i rascheta peremesh
cheniya nanosov i dinamike beregov pri inzhenernykh izys
kaniyakh
(Manual for the Study and Calculation of Dislo
cations of Debris and Dynamics of Coasts during Engineer
ing Surveys), Moscow: Gidrometeoizdat, 1975, p. 239.
Shvanov, V.N.,
Petrografiya peschanykh porod (komponent
nyi sostav, sistematika i opisanie mineral’nykh vidov)
(Petrography of Sandy Rocks: Composition, Systematics,
and Description of Mineral Species), Leningrad: Nedra,
1987.
Tugarova, M.A., Platonov, M.V., and Sergeeva, E.I., Litho
dynamic Characteristics of Terrigenous Sedimentation of
the Cambrian–Lower Ordovician Sequence in the Lenin
grad District, in
Istoricheskaya geologiya i evolyutsionnaya
geografiya
(Historical Geology and Evolutionary Geogra
phy), St. Petersburg: NOU Amadeus, 2001, pp. 81–91.
Ulst, R.J.,
Lower Paleozoic and Silurian Sediments of the
Baltic Region and Content of Dispersed Organic Matter
Therein
, Riga: AN Latv. SSR, 1959.
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RESUMO-Quintilhões e inumeráveis pedras rachadas encontradas em todo planeta terra, com pouco desgaste de tempo, ou com pouco tempo de sedimentação acima das mesmas, revelam um imenso acidente recente na terra, bem como aspectos catastrofistas que implicam em aceleradores de elétrons capazes de perturbar o núcleo arrancando nêutrons e prótons, e consequentemente ter criado proporção de elementos químicos que passaram a ser instáveis, e inclusive rochas com aparência de bilhões de anos, em segundos. O conjunto de evidências evolutivas, genéticas, paleontológicas, geológicas, astronômicas, dos estudos em física de plasma e colisão de íons pesados, demonstram claramente que temos uma outra cronologia e história do universo, da terra e das espécies. Neste trabalho apresentamos evidências de que impactos de asteroides possam ter participado deste evento recente, na forma de chuva de asteroides, pois possuem poder de gerar aceleração de partículas perturbadoras do núcleo atômico para não somente acelerar decaimento radioativo "envelhecendo rochas" como também criar elementos instáveis a partir de estáveis, explicando pequenas proporções deles na terra e milhares de meteoros que nos rodeiam. Esta quebra de paradigma datacional , tão esperada na academia que passa tanta vergonha e descrédito ao ver fósseis contendo tecidos orgânicos serem datados em milhões de anos, nos abre espaço para conjugar acontecimentos consequentes ocorridos imediatamente um depois do outro (temporalidade), que estavam separados por uma espécie de absolutismo datacional na geologia e paleontologia convencional atual, que restringiam o saber científico livre, e impediam sobretudo de harmonizar arqueologias (274 fontes incluindo bíblica) , aspectos genéticos (entropia e meia vida curta do DNA), evolutivos-paleontológicos (falta de mudança morfológica fóssil e repetição de formas de vida em 71% nas amostragens fósseis o que expressa sepultamento em larga escala de todas as espécies da terra em um tempo único e não separado) .
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Resumo : O paradoxo da estase morfológica na literatura paleontológica, SPM ( stasis paradox morphological ) representa uma grande incógnita que segundo Ernest Mayr, é o maior problema da teoria histórica da Evolução. A SPM é uma anomalia porque esperaríamos encontrar muita diversidade morfológica e taxonômica nas amostras fósseis e nunca repetição de mesmas formas. Se não bastasse este problema , descobrimos outro maior : Fósseis vivos que não mudaram morfologicamente durante centenas de milhões de anos (ficaram em estase) , ao serem submetidos a mudanças ambientais, apresentam mudanças morfológicas hoje e ainda com tendência a não voltar a forma anterior. Ou seja, mesmo se centenas de artigos científicos tentem de várias maneiras justificar a anomalia da PMS e tentar salvar a teoria da evolução histórica, calculamos ser impossível justificarem como fósseis vivos permaneceram sem mudanças em suas várias amostras fósseis e mudarem hoje. Segundo meta-análise de 58 trabalhos de Simpson , existe 71% de repetição de formas nos fósseis, e questionamos este fato com o contraste de podermos assistir em tempo real, mudanças morfológicas geradas facilmente por pressões ambientais. Podemos até fabricar em tempo real mudanças também no nível de sub especiações, gerando inumeráveis variações morfológicas e taxonômicas que são testemunhadas apenas na biodiversidade de hoje, mas não nos trilhões de fósseis e bilhões de amostras . Estimamos haver trilhões de fósseis no mundo, e as bilhões de amostras já coletadas são consideradas como sendo amostras de 570 milhões de anos e até 3,5 bilhão de anos se considerarmos bactérias e fósseis anteriores a explosão cambriana e Ediacara, contando uma historia evolutiva da vida que sai das formas de vida mais simples e acidentalmente vai formando seres mais complexos, porém além de encontrarmos complexidades maiores que as atuais em amostras fósseis antigas, podemos perceber uma tendência maior de simplificação, perda de tamanho, perda de inteligencia, perda de características na historia dos seres vivos e não de ganho, como considerado quando se observa alguma sobrevivência adaptativa. Será que o fato de haver 71% de repetição de formas nos fósseis, indica um catastrofismo global que foi capaz de sepultar as diversas populações de ancestrais tipo básicos defendidos pelo movimento dos biólogos da baraminologia (que defendem os antigos tipos básicos originais da cladística muito citados e “refutados” por Darwin)? Será que o fato da extinção total das famílias e esquemas corporais das primeiras camadas sedimentares contendo fósseis do Ediacara e Cambriano, representam apenas o fato delas estarem mais ao fundo e por receberam maior aporte sedimentar geradas por uma catástrofe global se extinguiram totalmente? Mais estudos são necessários para defender esta mudança de paradigma, porém apresentamos alguns pontos aqui que nos fazem refletir esta possibilidade.
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Resumo : O paradoxo da estase morfológica na literatura paleontológica, SPM ( stasis paradox morphological ) representa uma grande incógnita que segundo Ernest Mayr, é o maior problema da teoria histórica da Evolução. A SPM é uma anomalia porque esperaríamos encontrar muita diversidade morfológica e taxonômica nas amostras fósseis e nunca repetição de mesmas formas. Se não bastasse este problema , descobrimos outro maior : Fósseis vivos que não mudaram morfologicamente durante centenas de milhões de anos (ficaram em estase) , ao serem submetidos a mudanças ambientais, apresentam mudanças morfológicas hoje e ainda com tendência a não voltar a forma anterior. Ou seja, mesmo se centenas de artigos científicos tentem de várias maneiras justificar a anomalia da PMS e tentar salvar a teoria da evolução histórica, calculamos ser impossível justificarem como fósseis vivos permaneceram sem mudanças em suas várias amostras fósseis e mudarem hoje. Segundo meta-análise de 58 trabalhos de Simpson , existe 71% de repetição de formas nos fósseis, e questionamos este fato com o contraste de podermos assistir em tempo real, mudanças morfológicas geradas facilmente por pressões ambientais. Podemos até fabricar em tempo real mudanças também no nível de sub especiações, gerando inumeráveis variações morfológicas e taxonômicas que são testemunhadas apenas na biodiversidade de hoje, mas não nos trilhões de fósseis e bilhões de amostras . Estimamos haver trilhões de fósseis no mundo, e as bilhões de amostras já coletadas são consideradas como sendo amostras de 570 milhões de anos e até 3,5 bilhão de anos se considerarmos bactérias e fósseis anteriores a explosão cambriana e Ediacara, contando uma historia evolutiva da vida que sai das formas de vida mais simples e acidentalmente vai formando seres mais complexos, porém além de encontrarmos complexidades maiores que as atuais em amostras fósseis antigas, podemos perceber uma tendência maior de simplificação, perda de tamanho, perda de inteligencia, perda de características na historia dos seres vivos e não de ganho, como considerado quando se observa alguma sobrevivência adaptativa. Será que o fato de haver 71% de repetição de formas nos fósseis, indica um catastrofismo global que foi capaz de sepultar as diversas populações de ancestrais tipo básicos defendidos pelo movimento dos biólogos da baraminologia (que defendem os antigos tipos básicos originais da cladística muito citados e “refutados” por Darwin)? Será que o fato da extinção total das famílias e esquemas corporais das primeiras camadas sedimentares contendo fósseis do Ediacara e Cambriano, representam apenas o fato delas estarem mais ao fundo e por receberam maior aporte sedimentar geradas por uma catástrofe global se extinguiram totalmente? Mais estudos são necessários para defender esta mudança de paradigma, porém apresentamos alguns pontos aqui que nos fazem refletir esta possibilidade.
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Chromium is a strategic metal, but more than a half of Russia’s needs are met by imports, so new deposits of chromites, including unconventional placer deposits, are of industrial and scientific interest. Previous studies and current works of the authors of the article have established the chromite placer metal content of Permian-Jurassic deposits of the Volga-Ural basin, which has industrial and potential significance: within the Lukoyanovsky placer area (Nizhny Novgorod region), the industrial chromite content of Jurassic coastal-marine titanium-zirconium placers has been established; in the south-west of Bashkiria, chromite-bearing sands (Sabantuy occurrence) with increased contents, but not yet clear industrial potential. The study of the typomorphism of chromites indicate their close relationship with the chrome spinel of ophiolite associations. The assumed overthrust structure of chromite-bearing hyperbasites of the Urals suggests a wide distribution of chromite-bearing sands within the Upper Permian-Jurassic Volga-Ural paleobasin, in which the increased content of chromites was controlled by hydro- and lithodynamic conditions favorable for placer formation. Questions of the genesis of chromite placer occurrences in the Ural part of the East European Platform, their distribution and primary sources need further study.
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Conglomerates and sandstones related to Upper Jurassic division of Mesozoic rocks make up the Main Range of the Crimean Mountains. Grain size and structural features testify to active hydrodynamic regime of depositional environments. Conglomerates contain a small quantity of exotic granite-granodiorite pebbles and boulders probably transported from the Ukrainian Crystalline Shield situated 400 km north of the Crimean Peninsula. Paleohydrodynamic parameters and transportation mechanisms of debris were modeled with the help of different methods used in geoengineering computations. The results obtained demonstrated satisfactory convergence of the data. The calculations showed that the rocks under investigation were formed during a short (from geological standpoint) but very intense episode of sedimentation related to active tectonic processes that were responsible for the activation of hydrodynamic and sedimentation processes in the paleobasin.
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This text offers a thorough analysis of erosion, transport and sedimentation of soil and solid particles by surface waters. The author has aimed for simplicity of presentation, stressing physical understanding based on Newtonian mechanics. He explains fundamental concepts pertaining to the hydrodynamic forces exerted on solid particles, with a lucid treatment of potential flow, viscous flow, turbulent flow, and boundary layers. The text presents detailed methods and procedures commonly used in engineering practice. It also features a variety of exercises and problems for students and researchers, along with numerous examples and case studies for practicing engineers seeking solutions to real-world problems. Students, reseachers, and practitioners in civil, environmental, agricultural, mechanical and chemical engineering, hydrology, sedimentology, and natural resources will find valuable information in this text intended for the classroom and beyond.
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This book is aimed at graduates and those with a basic knowledge of fluid mechanics and partial differential equations. It consists of 12 chapters that examine the theory and application of selected methods. Each chapter summarises fundamental principles, gives the derivation of relevant equations, quotes examples and case histories, then sets a series of appropriate problems and exercises. Most of these problems can be solved with algebraic equations, others require the use of a computer. Chapters cover areas such as physical properites, dimensional analysis, flow mechanics, particle motion, bedforms, load and reservoir sedimentation. -S.E.Long
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From the reviews: "...This is an extremely useful reference text for the sedimentary geologist to own. It is well produced with clear illustrations and text, and gives excellent factual information on a large number of topics." (Palaeogeography, Palaeoclimatology, Palaeoecology) "...represents a significant contribution to the literature of geoscience. It should be in the library of anyone seriously intereted in sedimentology."(Marine Geology) "This book is still unsurpassed in providing a good, basic synthesis of modern sedimentary environments, especially the physical attributes of the deposits being formed and the processes responsible..." (Sedimentary Geology)
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Part I . The results of previous experiments (Bagnold 1954) on the stresses set up in a uniform gravity-free dispersion of solid grains when uniformly sheared in a fluid are applied to the nonuniform case of grain flow over a gravity bed, assuming the results are quantitatively applicable to any sufficiently thin shear layer. It is found that if the bed is composed entirely of potentially mobile grains a stress-equilibrium relation at the bed surface can be defined whereby the magnitude of a certain ‘bed load’ of grains in transit over unit bed area is given in terms of the applied tangential stress. The bed load is independent both of the existence of any additional suspended load and of the degree of dispersion of the grains. The state of internal fluid motion enters as a single experimental constant. From a consideration of the stability of this equilibrium relation it is possible to predict the conditions under which an initially plane bed surface should become rippled; and general quantitative agreement is found with experimental data both for wind-blown and water-driven grains. Primary and secondary bed rippling are distinguished. The magnitude of the ‘form-drag’ due to primary bed ripples can be calculated. That due to secondary ripples is definable as an experimental constant. The gravity-free experiments disclosed that the shear resistance of a grain dispersion may vary as the square or the first power of the rate of shear, analogously to that of a true fluid, according to the value of a number G analogous to a Reynolds number. The square law is followed when the effects of grain inertia dominate over those of fluid viscosity. Assuming that the phenomenon of ‘saltation’ as observed over a gravity bed is an inertia effect, the conditions for saltation are predictable. The results again agree quantitatively with observation. Part II . The resistance offered by the grains to their displacement along the flow is shown to be proportional to their normal immersed weight component. And their measurable mass transport rate is hereby proportional to the rate of useful work done in transporting them. On this basis separate expressions are found for the transport rates of the bed load and suspended load, in terms of the applied tangential stress and of a tangential and a normal relative velocity respectively. When conditions are restricted to those of the ‘stream case’ these velocities become constant for any given system, being functions of an appropriate constant mean drag coefficient. The bed-load transport-rate expression found gives magnitudes, and variations of magnitude with grain size, in agreement with the experimental data for wind-blown sand. Agreement is also found for water-driven grains in open channels from the threshold of movement up to a certain value of the applied stress. The experimental rates are then found to increase suddenly. This increase is attributed to the development of an additional suspended load. The abrupt development of a suspended load may be explained as due to a change in the nature of the fluid turbulence when the stationary boundary becomes occluded from the fluid flow by a concentrated layer of moving bed-load grains. The assumption that under these new moving-boundary conditions the available fluid energy derived from shearing over the bed is equally apportioned between bed-load and suspended-load transport work leads to values for the suspended-load transport rate which agree closely with the experimental data. A critical relation emerges between the gravity slope of the bed, the fall velocity and the mean transport velocity of the suspended grains at which their transport may become very large. Conditions are examined under which the steady transport may be possible of grains of heterogeneous size or density. Part III . When the fluid flow is non-inertial (laminar) and the grain flow is also non-inertial the semi-empirical relations found previously for the internal stresses are such that both viscosity and shear rate can be eliminated, and a differential equation obtained whose solution gives the grain concentration in terms only of distance from the bed and of the applied tangential stress. It appears that with constant applied stress (unlimited flow depth) the degree of grain dispersion greatly exceeds that to be expected in turbulent fluid flow. But when the applied stress diminishes linearly with distance from the bed boundary a possible solution gives constant grain concentration throughout the flow. This appears to explain certain experimental results, including the behaviour of ‘slurries’. The effect is examined of a fixed or partially fixed bed on the grain flow in a turbulent fluid. The effect may be pronounced in the case of suspended grains. Under certain clearly definable conditions a loose grain bed must cease to remain stationary. And if the fluid flow above is turbulent the whole grain bed should flow at constant maximum concentration, underneath the flow proper and separated from it by a moving-bed surface interface at which the concentration is discontinuous. This explains phenomena sometimes found under river torrents. The factors giving rise to and limiting the development of bed features (dunes) on a bigger scale than ripples are examined. Dune formation appears as an inherent tendency of the grain flow alone, which may or may not be inhibited by the conditions of the fluid flow.
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Based on the study of the Tsentral'noe deposit, specific features of the formation of mineral assemblages of complex titanium–zirconium placers are considered. The placers formed during the multiple redeposition of clastogenic minerals from source rocks and younger sedimentary rocks (intermediate collectors of titanium–zirconium minerals). The location of erosion and sedimentation zones significantly varied in the Phanerozoic in the adjacent region, resulting in the development of intricate relationships between different-aged terrigenous rocks (possible intermediate collectors) that provided the formation of new mineral assemblages of clastogenic ore minerals. In addition, erosional processes during the continental evolution of the study region could promote the exposure of more ancient rock complexes, the local washout of crystalline basement rocks, and the delivery of ore minerals from the latter rocks to the coastal zone of sedimentary basins. The aim of this communication is to attract the attention of researchers to the issue of the formation of mineral assemblages of complex placers of heavy minerals with similar hydraulic grain dimension and migration capacity for concentration in a rather narrow grain size range. Such mineral assemblages only slightly inherit the primary compositional features of provenances and primarily reflect changes in the sedimentation environment.
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Stratigraphy, the basis of geological dating, was founded in the 17th century on the three well-known principles assumed by Nicolas Stenon: superposition, continuity, and original horizontality. Successive observations and experiments show that Stenon's stratigraphic model was not in line with experimental data, because it had “overlooked” the major variable factor of sedimentology:the current and its chronological effects.
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Reprinted from Bulletin of the Geological Institute of Uppsala, v. 25. Errata slip inserted. Inaugural dissertation--Uppsala. Bibliography: p. [442]-452.
Litologiya (Lithology), Moscow: Mosk
  • V T Frolov
Frolov, V.T., Litologiya (Lithology), Moscow: Mosk. Gos. Univ., 1992