412
to and partly overlapping six Cordilleran terranes.
Paleocurrent and provenance studies provide partial
constraints on the reconstruction of terrane amalgamation and post�suture displacement on a series
of terrane-bounding faults. Kleinspehn {1 985) described four main hy potheses of relative terrane
motion.
11.4.8 Cratonic Basins
The origin of sedimentary basins and uplifts within
stable areas such as the Canadian Shield and adjacent stable platform is controversial (M iall 1990,
Sect. 9.3.6.1). Most hypotheses involve the reactivation of ancient lineanients or zones of weak ness to
provide loci of subsidence and uplift, although the
mechanisms for generating vertical movements
within stable cratons are not dear. Many cratonic
tectonic elements may be related to plate-margin
processes) and intraplate stress is increasingly being
invoked to explain the initiation or reactivation of
major intracratonic structures at distances far removed from the main locus of extension or compression (e.g., Cloetingh et a! . 1985; Sanford et a!. 1985;
Miall 1986; Heller et a!. 1993 ; Sect. I 1.3.5). Emb ry
(1 990a, 1991) suggested that during the Mesozoic
intraplate stress led to tilting on a continental scale
and provided the cratonic sediment sources and
paleoslope for the delivery oflarge volumes of terrigenous detritus to Sverdrup Basin, on the northern
margin of the North American craton. Mia!! (1986)
suggested that intraplate stress transmitted from
Caledonian compression at the suture between
North America and Europe generated thrust faultbounded uplift of the Boothia Uplift, in the Canadian
Arctic Platform, from which was shed the alluvial fan
and fluvial wedge of the Devonian Peel Sound formation (Mial l and Gibling 1978). Dott et a!. (1986)
demonstrated that fluvial and eolian processes
formed widespread but thin clastic sheets in the
Wisconsin area, flanking the southern margin of the
Canadian Shield, during two periods of transgression following low stands of sea level, in the Late
Camb rian and again in the Middle Ordovician. Isopachs of the Tertiary Eyre Formation of the Great
Artesian Basin, Australia, indicate rejuvenation of
Paleozoic structures; basins became deeper and
upwarps were uplifted (Wopfner et a!. 1974)
Descriptions of the regional geology of large platform areas such as interior Australia (V eevers 1984;
Morgan 1993 ) and cratonic Canada (Stott and
Aitken 1993 ) iu dicate the long-term persistence of
Tectonic Control of Fluvial Sedimentation
ancient basins and upwarps, with the widespread
distribution of thin nonmarine sheets at times when
much thicker clastic wedges are being deposited in
marginal basins. Veevers (1984, p. 161) stated:
"The Cainozoic record of central Australia is a continuation back to 60 Ma of the present pattern oflocal sags, such
as Lake Amadeus, within highlands flanked by broad
plains. Today, little sediment is shed by the highlands, and
the wholly carbonate province on the south, in the Great
Australian Bight, is traceable in the Eucla Basin back to the
Eocene. What little sediment escapes central Australia to�
day, via the coherent stream system on the east and south�
east - the Finke River and others to the south are the only
streams that maintain flow out of the region -i s concen�
trated in the sump of Lake Eyre and the dunefields of the
Simpson Desert, and this pattern (but not facies) of depo�
sition persists to the beginning of the Cainozoic in the
fotm of the Eyre Formation (Wopfner et al. 1974). The
aeolian sand dimes of the Great Sandy Desert of the Can�
ning Basin and of the area to the north between 18° and 22°
S, in which only a few tens of meters of sediment have
accumulated, are the only other sediment derived from
central Australia."
Sloss (1 979) has argued for the existence of vertical crustal movements within the craton - true
epeirogeny- but mechanisms to explain it have been
lacking until recently. Gurnis (1 990, 1992 ) proposed
that mantle convection beneath the crust results in
continental-scale differential heat distrib ution and
consequent heating and cooling of different parts of
the overlying earth's surface, resulting in broad regional uplifts and downwarps because of the effects
on crustal densities. These processes maintain what
is called dynamic topography. The effects of crustal
heating cause uplift. This occurs along the flanks of
new continental rift systems (e.g., parts of presentday East Africa) and ab ove mantle plumes. Subsidence takes place over cooling areas of the earth's
crust, such as areas of aging oceanic crust distant
from spreading centers, and over regions of mantle
downwelling. The stratigraphic effects of this process have yet to be evaluated in detail.
11.5 Basic Paleogeographic Models
for Nonmarine Basins
On a basin scale, the architecture of the alluvial fill
can be classified into a series of distinctive styles,
governed by the tectonic control of basin shape and
paleoslope (Miall !98!b ). A basin-fill classification is
given in Table 11.4, in which depositional systems
are simplified into nine basic types: 1. lacustrine, 2.
alluvial fan/fan delta, 3. low-sinuosity fluvial, 4.
to and partly overlapping six Cordilleran terranes.
Paleocurrent and provenance studies provide partial
constraints on the reconstruction of terrane amalgamation and post�suture displacement on a series
of terrane-bounding faults. Kleinspehn {1 985) described four main hy potheses of relative terrane
motion.
11.4.8 Cratonic Basins
The origin of sedimentary basins and uplifts within
stable areas such as the Canadian Shield and adjacent stable platform is controversial (M iall 1990,
Sect. 9.3.6.1). Most hypotheses involve the reactivation of ancient lineanients or zones of weak ness to
provide loci of subsidence and uplift, although the
mechanisms for generating vertical movements
within stable cratons are not dear. Many cratonic
tectonic elements may be related to plate-margin
processes) and intraplate stress is increasingly being
invoked to explain the initiation or reactivation of
major intracratonic structures at distances far removed from the main locus of extension or compression (e.g., Cloetingh et a! . 1985; Sanford et a!. 1985;
Miall 1986; Heller et a!. 1993 ; Sect. I 1.3.5). Emb ry
(1 990a, 1991) suggested that during the Mesozoic
intraplate stress led to tilting on a continental scale
and provided the cratonic sediment sources and
paleoslope for the delivery oflarge volumes of terrigenous detritus to Sverdrup Basin, on the northern
margin of the North American craton. Mia!! (1986)
suggested that intraplate stress transmitted from
Caledonian compression at the suture between
North America and Europe generated thrust faultbounded uplift of the Boothia Uplift, in the Canadian
Arctic Platform, from which was shed the alluvial fan
and fluvial wedge of the Devonian Peel Sound formation (Mial l and Gibling 1978). Dott et a!. (1986)
demonstrated that fluvial and eolian processes
formed widespread but thin clastic sheets in the
Wisconsin area, flanking the southern margin of the
Canadian Shield, during two periods of transgression following low stands of sea level, in the Late
Camb rian and again in the Middle Ordovician. Isopachs of the Tertiary Eyre Formation of the Great
Artesian Basin, Australia, indicate rejuvenation of
Paleozoic structures; basins became deeper and
upwarps were uplifted (Wopfner et a!. 1974)
Descriptions of the regional geology of large platform areas such as interior Australia (V eevers 1984;
Morgan 1993 ) and cratonic Canada (Stott and
Aitken 1993 ) iu dicate the long-term persistence of
Tectonic Control of Fluvial Sedimentation
ancient basins and upwarps, with the widespread
distribution of thin nonmarine sheets at times when
much thicker clastic wedges are being deposited in
marginal basins. Veevers (1984, p. 161) stated:
"The Cainozoic record of central Australia is a continuation back to 60 Ma of the present pattern oflocal sags, such
as Lake Amadeus, within highlands flanked by broad
plains. Today, little sediment is shed by the highlands, and
the wholly carbonate province on the south, in the Great
Australian Bight, is traceable in the Eucla Basin back to the
Eocene. What little sediment escapes central Australia to�
day, via the coherent stream system on the east and south�
east - the Finke River and others to the south are the only
streams that maintain flow out of the region -i s concen�
trated in the sump of Lake Eyre and the dunefields of the
Simpson Desert, and this pattern (but not facies) of depo�
sition persists to the beginning of the Cainozoic in the
fotm of the Eyre Formation (Wopfner et al. 1974). The
aeolian sand dimes of the Great Sandy Desert of the Can�
ning Basin and of the area to the north between 18° and 22°
S, in which only a few tens of meters of sediment have
accumulated, are the only other sediment derived from
central Australia."
Sloss (1 979) has argued for the existence of vertical crustal movements within the craton - true
epeirogeny- but mechanisms to explain it have been
lacking until recently. Gurnis (1 990, 1992 ) proposed
that mantle convection beneath the crust results in
continental-scale differential heat distrib ution and
consequent heating and cooling of different parts of
the overlying earth's surface, resulting in broad regional uplifts and downwarps because of the effects
on crustal densities. These processes maintain what
is called dynamic topography. The effects of crustal
heating cause uplift. This occurs along the flanks of
new continental rift systems (e.g., parts of presentday East Africa) and ab ove mantle plumes. Subsidence takes place over cooling areas of the earth's
crust, such as areas of aging oceanic crust distant
from spreading centers, and over regions of mantle
downwelling. The stratigraphic effects of this process have yet to be evaluated in detail.
11.5 Basic Paleogeographic Models
for Nonmarine Basins
On a basin scale, the architecture of the alluvial fill
can be classified into a series of distinctive styles,
governed by the tectonic control of basin shape and
paleoslope (Miall !98!b ). A basin-fill classification is
given in Table 11.4, in which depositional systems
are simplified into nine basic types: 1. lacustrine, 2.
alluvial fan/fan delta, 3. low-sinuosity fluvial, 4.