Synchronous transformations of mineral and organic constituents of sedimentary rocks in geological structure with an initial extension and subsequent …

Lithology and Mineral Resources, Vol. 38, No. 3, 2003, pp. 209–222. Translated from Litologiya i Poleznye Iskopaemye, No. 3, 2003, pp. 251–266.
Original Russian Text Copyright © 2003 by Petrova, Le Thi Nginh, Stukalova, Sokolova, Nguyen Xuan Huyen, Phang Dong Pha.

Synchronous Transformations of Mineral and Organic
Constituents of Sedimentary Rocks in Geological Structure
with an Initial Extension and Subsequent
Compression Tectonic Regime
V. V. Petrova1, Le Thi Nginh2, I. E. Stukalova1, A. L. Sokolova1,
Nguyen Xuan Huyen2, and Phang Dong Pha2
1

Geological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, Moscow, 119017 Russia
e-mail:
2 Institute of Geology, National Center of Science and Technologies of Viet Nam, Nghihia Do Tu Liem Vien Dia Chat,
Hanoi, Viet Nam
Received October 21, 2002

Abstract—Sedimentary rocks of the section in the Red River fold zone of northern Viet Nam are considered.
It is shown that secondary mineral parageneses formed in two stages. The first stage (35–17 Ma ago) corresponded to the period of structure extension and sediment subsidence to a depth of about 6 km. This period and
subsequent ~10 Ma were marked by the formation of a usual dia- and catagenetic zoning of metasedimentary
rocks. The second stage (5–7 Ma ago) corresponded to processes of compression that were responsible for the
deformation of rocks into gentle folds and 1.5 to 2.2 times contraction of the section thickness in different
places. The sequential–mineralogical zoning was disturbed at this stage. Smectites and mixed-layer minerals
were replaced by chlorites and hydromicas. Organic material also responded to compression simultaneously
with inorganic components. The bituminous component was released from humic matter and rocks became
enriched in hydrocarbons.

Most intense processes of secondary mineral formation are observed under geotectonic settings with maximal gradients of pressure, temperature, and solution
chemistry. Oriented pressures, which result in rock
deformation, jointing (usually in extension zones), and
folding (compression zones) are most important in

areas with active tectonic regime. These processes are
accompanied by the formation of new mineral phases,
in addition to crushing, grinding, and recrystallization
of primary minerals. Yapaskurt was among the first
researchers who emphasized the need to study secondary alterations in strongly deformed rocks and compare
them with regional background transformations. He
wrote: “…two mechanisms of lithogenetic transformations are observed in rock-forming basins under miogeosynclinal tectonic conditions. The first mechanism
intensifies structural and mineral transformations in
rocks due to their subsidence and increase in lithostatic
pressure and temperature. The second mechanism is
responsible for locally superimposed dynamothermal
alterations at tectonic activation and deformation
stages. Both these processes are spatially and, probably,
genetically interrelated, representing elements of a single discrete-continuously developing fluid–rock system” (Yapaskurt, 1992, pp. 178–179).
Earlier, Marakushev (1986) proposed a slightly different concept, according to which the first group of

processes controls lithogenesis1 and the second one
governs metamorphism. He separated the activity of
these processes in time and believed that they correspond to different stages of geosynclinal belt formation. Lithogenesis corresponds to the geosynclinal
stage of sediment accumulation during their subsidence, whereas metamorphism corresponds to subsequent stages of deformation of geosynclinal sediments
and formation of orogenic fold belts accompanied by
the rise of geoisotherms and ascent of juvenile metamorphosing fluids.
Marakushev (1986) showed that authigenic mineral
formation during lithogenesis occurs in a relatively
closed system that is characterized by an approximately
uniform pressure on rocks and relevant interstitial solution. Dehydration of primary minerals under such conditions is hampered and incomplete, which results in
the coexistence of hydrous and anhydrous phases and
the formation of hydromicas. In contrast, metamorphism occurs in an open mineral-forming system with
filtering solutions characterized by high mineralization
and partial pressure. Such conditions are more favor1 Marakushev

(1986, p. 103) considered lithogenesis as “…deposition and subsequent transformation of sediments into sedimentary rocks during their simultaneous subsidence and increase in
temperature (in accordance with geothermal gradient) and pressure.”

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210

PETROVA et al.

able for the dehydration of primary minerals at lower
temperatures. As a result, stable anhydrous mineral
phases are formed during metamorphism at a higher
rate and shallower depths relative to catagenesis.
Secondary mineral parageneses produced by lithogenesis and metamorphism under low temperatures and
pressures and altered rocks can show such a strong similarity that “they differ only by the attitude… and can
frequently be discriminated only by the comprehensive
geological mapping of particular sequences” (Marakushev, 1986, p. 107).
Luk’yanova (1995) carried out extensive investigations of catagenetic processes in unstable tectonic settings and concluded that “…the intensity of catagenesis
in sedimentary formations of orogenic belts is more
dependent on the type of tectonic structures composed
of these sequences rather than on the their age and subsidence depth” and that “…the intensity of catagenesis
in sedimentary sequences increases in all stratigraphic
units regardless of their subsidence depth in areas with
intense tectonic movements and high heat flow. In geological structures with an intense tectonic activity, vertical catagenetic zoning is compressed (the thickness of
separate zones decreases), whereas catagenetic alteration of coeval rocks increases as compared with that in
structures with less intense tectonic movements. Zones
of early catagenesis in the zoning frequently disappear”
(Luk’yanova, 1995, p. 155).

ROLE OF STRESS IN THE FORMATION
AND EXISTENCE OF SECONDARY MINERALS
When and at what stage of geological structure
development does the primary sedimentary rock alteration intensify? Are the structure opening, intense heat
flow, and highly mineralized hot solutions essential for
such intensification? It is virtually impossible to answer
these questions based on the study of ancient (or relatively ancient) altered rock sequences that experienced
a long-term and intricate geological evolution. We
attempted to answer them using a strongly altered (secondary chlorite–hydromica assemblage) Neogene sedimentary sequence with a sufficiently clear geological
history as example.
The fold zone of the Red River valley in northern
Viet Nam served as an investigation object. This zone
is approximately 1000 km long and stretches from
Tibet to the Bac Bo Bay. It represents an important
geological boundary that separates Indochina and
South China. Some researchers believe that the Red
River suture zone originated as early as in the Precambrian (Cheng, 1987; Chenging, 1986) or Paleozoic
(Helmcke, 1985; Wang and Chu, 1988). However, the
majority of researchers believe that this event occurred
in the Mesozoic (Hutchison, 1989; Tran Van Tri,
1977). Reactivation and opening of the structure commenced in the Eocene as a result of differently oriented
stresses induced by the NE- or NNE-oriented Indian

subcontinent motion toward Tibet (Eurasian Plate), on
the one hand, and the SE-oriented Indochina Peninsula
movement, on the other hand (Fig. 1). According to
Gatinskii (1986), the newly formed linear structures
have all typical features of continental rifts.
According to Tran Ngoc Nam (1999), Phung Van
Phach and Bui Cong Que (1999), and other researchers,

the intensity of tectonic processes during the opening of
the Red River fault zone depended on the Indian Plateau–Eurasian continent distance and the convergence
rate of these blocks. At the first stage (16–35 Ma ago)
when the Indian Plateau was still located relatively far
from the Eurasian continent, maximum pressure on the
Indochina Peninsula was exerted in the NW–SE direction. The displacement along faults was sinistral. This
stage was marked by structure widening with the successive centripetal subsidence of basement blocks
along a system of steep faults (Fig. 2).
At the second stage (5–7 Ma ago), the Indian Plateau exerted a higher pressure on China and pushed it in
the western direction. Consequently, stress on the
Indochina Peninsula changed direction from the NW–
SE to NE–SW one, and the displacement along faults
became dextral (Fig. 3). In the middle and late
Miocene, the above process resulted in the successive
compression, rise, and folding of sediments in the fault
zone and the formation of several narrow fold belts
along the Red River fault zone (Fig. 4). The compression was maximal (1.5 to 2.2 times higher than in other
areas) in the northwestern part of the Red River continental basin (between towns of Lao Cai and Viet Ti).
According to data in (Tapponier, 1995), the sinistral
displacement in the Red River zone terminated 17 Ma
ago and the regional movement inversion occurred
about 5 Ma ago.
Phung Van Phach and Bui Cong Que (1999) noted
that the study region was also tectonically active in the
Pliocene–Quaternary when some areas continued to
rise, and sinistral and dextral faults reactivated. Tectonic movements during this period were, however,
related to peculiarities in the internal structure of the
Indochina–South China zone rather than the global displacement of plates.
As is seen in Fig. 2, the transverse cross section of
the Red River fault zone represents a relatively narrow

trough-shaped structure bounded in flanks by large
faults. The depth of its most subsided part is about
5 km, although some researchers estimate it at 7 km.
Boreholes drilled in its deepest part penetrated Upper
Mesozoic rocks, but the trough is mostly filled with
Cenozoic sediments subdivided into several units
(Fig. 5). Their brief description follows below.
Eocene–Oligocene. Phy Tien Formation ( –P 2, 3 pt).
Its lower part is composed of black argillites alternating
with breccia-type conglomerates, sandstones, and
brown-red siltstones. Its upper part consists of conglomerates, breccia-type conglomerates, gravelstones
with lentils of silty argillite, unsorted rocks, and argil-

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211

South China

Tibet

In

Ex
ten
do

ch

India

in

a

si o
nz
on
e

Pe

n.

500 km

South China

N

Lao Cai

Re
dR
iv e

200 km

Viet Nam
rf
au
lt z
on

Laos

e
Hanoi

Fig. 1. Linear extension structure representing the geological boundary between South China and Indochina (Tran Ngoc Nam, 1999).

Borehole
4

Kim Song

km
0

Mz

1

Borehole Borehole
209 14

P1

P2

N3

2

N2
N1
P2

3

P1

Kifn Anh

4
5

Mz

Fig. 2. Basement of the Hanoi Trough subsided along a system of steep normal faults. Paleotectonic reconstruction based on
(Le Viet Trieu, 1996).

lites. The rock color varies from red and red-brown to
less common black and reddish black. Clasts in conglomerates consist of metamorphic rocks, quartzites,
siltstones, and rhyolites. The matrix consists of detritus
of clayey, sericitic, and sandy–silty rocks. Slickensides
are abundant in the section. The thickness is 220–400 m.
LITHOLOGY AND MINERAL RESOURCES

Vol. 38

Oligocene. Dinh Cao Formation ( –P 3 dc). Black to
brown argillites alternating with lenses of breccia-type
conglomerates, gravelstones, dark gray sandstones, and
siltstones. Argillites are highly foliated and locally
strongly fractured. The rocks are strongly deformed as
in the previous formation. The thickness is 140 m.
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C

H

I

N

108° 00′

107° 00′

106° 00′

105° 00′

104° 00′

103° 00′

PETROVA et al.
102° 00′

212

A
23°00′

N
9

1

Lao Cai
N
2

Lo

8

N

Ri
ve

22°00′

rf
au
lt

Yen Bai

zo
ne

Re

O

3

5

4

S

20°00′

Minh Binh

1
EAST CHINA SEA

2
3
4

21°00′

Hon Gai

ne
zo

A

zo
roane al
d 1 ong
8a
Hanoi

lt
au
rf
ve
Ri

ne
ay
zo
Ch ault
rf
ive

dR
10
N

L

Fa
ult

N
1

12

BAC BO BAY

19°00′

Fig. 3. Cenozoic tectonic structure of northern Viet Nam (Phung Van Phach and Bui Cong Que, 1999). (1) Miocene sediments;
(2) Late Miocene (NE–SW oriented) tectonic compression; (3) Early Pliocene (NW–SE oriented) tectonic compression;
(4) Pliocene–Quaternary (N–S oriented) tectonic compression.

Oligocene–Miocene. Thuy Anh Formation

–P 3 −N1ta). Coarse-grained sandstones (with conglomerates and breccia-type gravelstones in the lower part)
alternating with siltstones and thick-bedded clays. The
rock color varies from light gray to whitish gray, dark
gray, and brown-gray. Coarse-grained rocks are characterized by obscure cross-bedding. In the Dong Kuang
Trough, the formation encloses limy conglomerates.
Fine-grained rocks are parallel- and thick-bedded. The
rocks have a graywacke composition and contain clasts
of limestones, quartzites, siliceous rocks, shales, and
basic and acid volcanics cemented by carbonate, clay,
and siderite. The thickness varies from 200 to >1000 m.
1

Lower Miocene. Phong Chau Formation ( N 1 fÒ).
In the central area of the trough, the lower part of the
section is composed of members of thick-bedded wellsorted sandstones with horizontal, wavy-horizontal,
and differently oriented cross-bedding. Its upper part
consists of wavy-banded members composed of platy
sandstones, siltstones, and dark to black argillites. The
rocks have mainly gray, dark gray, or gray (sometimes
brown-gray) with black lenticular interbeds color and
contain glauconite, siderite, and pyrite. It is assumed

that the sediments accumulated in small lagoons and
bays during sea transgression.
2

Middle Miocene. Phu Cu Formation ( N 1 pc). It
includes three subformations. The lower subformation
is composed of fine- to medium-grained well-sorted
sandstones alternating with siltstone beds characterized

by horizontal-parallel small-scale lamination. The
upper part of the subformation largely consists of massive coal-bearing argillites (80%) alternating with horizontally bedded light to dark gray sandstones. Plant
impressions are abundant. The thickness is 100–800 m.
The middle subformation is composed of light gray
medium-grained sandstones alternating with thin-laminated siltstones containing glauconite in the lower part
and alternating massive coal-bearing siltstones and
argillites with rare sandstone interbeds in the upper
part. The thickness varies from 180 to >300 m.
The upper subformation consists of gray to light
gray, medium-grained, thin-bedded, slightly cemented
sandstones and siltstones with abundant remains of
marine fossils, plant impressions, and glauconite
grains. The middle part of the subformation encloses
siltstones, argillites, and rare coal seams and lenses.

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SYNCHRONOUS TRANSFORMATIONS
105° 00′

105° 30′
a

Ch

104° 30′
22° 00′

ay

c

ve
rf
au

5m
30

zo
ne

rf

au

Tuyen Quang

ne
zo

lt

180/30

zo

ne

Co Phuc
Tran Yen
Ç
Yen Bai

22° 40′

0

Ri

ve

lt

lt
au
rF
ve
Ri

Lo

NW

Hinge 240/20

Ri

d
Re

Hoang Trang

213

0/3

5

Thac Ba Dam

d

Doan Hung

Ä

0

4

SW

8m

22

5/

60

0/

24

35

Vhu Tho
Cam Khe

21° 20′

1

N2

N1

Proterozoic

coal

/80

N1–2

/70

Yen Bai

/75

N1

NE

225

N1

230

0
m

N1

N2–Q

Ç

0

240

2 km

Yen Bai ridge

ic
zo

1

leo

0

Pa

300
200
100

e
5 10 m

b

ëÇ
Ä

N2–Q

N1

Fig. 4. System of narrow fault zones along the Red River near the town of Yen Bai and folding direction in Neogene sedimentary
rocks in particular areas (Phung Van Phach, Bui Cong Que, 1999). (a) Strike of fault zones along the Red, Lo, and Chay river valleys:
(1) outcrops of Neogene sedimentary rocks; (b) A–B profile in Fig. 4a; (c) NW–SE oriented compression of Miocene–Pliocene ( N1–2)
sedimentary rocks in the Tran Yen area; (d) NW–SE oriented compression of Miocene–Pliocene (N1–2) sedimentary rocks in the Co
Phuc area; (e) inclined attitude of Miocene (N1) sedimentary rocks and coal seams in the Hoang Trang area overlain by horizontal
layers of Pliocene–Quaternary (N2−Q) sediments.

The rocks with wavy bedding alternate with massive
varieties.
Massive siltstones and argillites are strongly
cemented and alternate with gray to light gray mediumgrained sandstones and thin-laminated siltstones with
impressions of brackish-water macrofossils. The rocks
enclose abundant coal seams, particularly in the Kien
Xuong and Tien Hung areas, as well as abundant siderite, pyrite, and glauconite. The thickness is 2000 m.
Three sea transgressions accompanied by sedimentation in boggy settings are assumed.
Upper Miocene–Pliocene. Tien Hung Formation
1
3
( N 1 – N 2 th). It is subdivided into two subformations.
The lower subformation is composed of coarse- to
medium-grained sandstone with lenses of gravelstones,
argillites, and gray to dark gray siltstones enclosing
abundant coal seams. Sandstones contain abundant leaf
impressions. Preponderant are coarse-grained rock
varieties. The section located near the sea yields marine
fossils.
The upper subformation consists of coarse-grained

sandstone with gravel, fine-grained sandstone, siltstone, and clay interbeds and coal lenses. The rocks are
less compact and slightly cemented. The light gray and
massive clays enclose plant remains. The upper part of
LITHOLOGY AND MINERAL RESOURCES

Vol. 38

the subformation consists of gray to dark gray, wellsorted, fine-grained sandstone alternating with parallelbedded siltstones and argillites.
It is assumed that the lower subformation formed in
marine settings at the initial stage of transgression,
whereas the upper one formed in a boggy delta.
2–3

Pliocene. Vinh Bao Formation ( N 2 vb). It is
composed of greenish yellow thin-laminated siltstones
with interbeds of well-sorted sandstones consisting of
well-rounded grains. The rocks enclose foraminifers
and other marine fossils. The thickness is 100–300 m.
The sediments presumably accumulated in marine
settings during extensive transgression covering the
entire trough.
The considered factual material suggests that the
Red River fault zone experienced two different periods
of development.
The first period was marked by the formation of
extension structures, which originated in the latest
Mesozoic and evolved up to the Pliocene. The evolution
was accompanied by the subsequent centripetal subsidence of basement blocks along the system of steep
faults. Eocene–Oligocene sediments occur in the deepest (about 5 km) part of the newly formed troughshaped valley, whereas Miocene–Pliocene sediments
No. 3

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214

PETROVA et al.

VH

Index

Series

System

Group

Q

Hanoi Trough

TH

Along the Red
River valley

Vhuh Tho

Yen Bai

Qui Mong

Sh4

Bach Luu

Van Yen
Sh3

PC

Trai Hut

Sh2

?

Sh1

Fch
TA
DC
PT

Doan Hung

Sl3

Luc Yen

Sl2

Bao Yen

Lo River

Sl1

Cenozoic

QuaterTertiary (Paleogene-Neogene)
nary
EoceneOligoceneMiocene
Pliocene
Oligocene
Miocene
1
1
2
3
1
N2
Q
P3 – N1
N1
N1
N1 – N2
P2–3

Along the valley
Chay River

1

5

13

9

2

6

10

3

7

11

4

8

12

a

b

14
b

15

a b c

16

a

Fig. 5. Correlation of Cenozoic sections in the Red River valley. Based on (Le Thi Nghinh et al., 1991). (1) Olistostrome-type boulder breccia; (2) sandstone, siltstone, and argillite with subordinate boulder breccia; (3) argillite and siltstone with subordinate boulder breccia; (4) boulder conglomerate; (5) conglomerate with different-sized pebbles; (6) gravelstone; (7) sandstone; (8) siltstone;
(9) argillite; (10) marl; (11) alternating sandstone, siltstone, and clay; (12) alternating siltstone and clay; (13) sediments with coal
seams and lenses; (14) large unconformities: (‡) with weathering crust, b) with erosional surface; (15) unconformities: (a) small,
(b) vague contact; (16) organic remains: (a) freshwater fauna, (b) marine fauna, (c) flora.

are distributed along flanks of this structure. The sediments accumulated in shallow-marine, coastal-marine,
and coastal-boggy settings during several stages corresponding to insignificant transgressions. The age of
sediments is determined on the basis of abundant plant
impressions and shallow-water marine fossils.
The second period (terminal Miocene–Pliocene)
was characterized by a change in the direction of pressure on the newly formed extension structure, which
resulted in the successive compression, rise, and folding of accumulated sediments and the formation of several narrow fault zones. As a result, the former extension structure turned into the compression structure
accompanied by a significant shortening of the section.
According to data in (Tran Nghi et al., 2000), the resulting section seems to be approximately two times
shorter as compared with the initial one.
Consequently, secondary minerals could be formed

owing to both diagenetic and catagenetic alteration of
sediments during their subsidence (extension period)
and changes in mineral formation parameters in the
course of compression-related rise and folding of sediments (compression period). The section near the town
of Yen Bai was selected for the thorough study of secondary mineralization (Fig. 6). The main part of the
section was sampled (samples V-1–V-5, V-11, and

V-12) along the profile extending from the Yen Bai
bridge to the northeast (Fig. 6b). The remaining part of
the section was examined in the area located southwest
of the bridge. Samples V-14 and V-15 were taken near
the Lo River (Bach Luu section). The section thickness
exceeds 1650 m (Fig. 6a). Its lower part is composed of
cobblestones (Member Ia), and only its upper part is
exposed. It is overlain by conglomerates and gravelstones with coal lenses (lower part of Member Ib). Pebbles in conglomerates consist of quartzites, siliceous
rocks, basic and acid volcanics, limestones, and shales.
Conglomerate beds alternate with thick-bedded sandstones, siltstones, and less common argillites. The
rocks have a gray color with whitish, brownish, or dark
tints. The thickness is about 300 m. The sequence
formed during the Oligocene–Miocene transition
period.
The quantity of sandstone, siltstone, and argillite
interbeds increases upward and banded patterns of the
sequence become gradually thinner. Sandstones
become fine- to medium-grained and the amount of siltstone and argillite interbeds increases. The middle part
of the section encloses abundant coal seams. Several
rhythms are distinguished in the section each beginning
with coarser material and terminating with the finergrained one (upper part of Member Ib and members II

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SYNCHRONOUS TRANSFORMATIONS

215

Other
minerals

Illite-smectite
Smectite
Kaolinite

Chlorite-smectite
Chloritevermiculite

Coal rank

10Ra max, %

Diffractogram fragments related to reflection
from plane [001] of layer silicates.
(Regions, Å: 9–10–Micaceous minerals,
~14–chlorites)

Alluvial sediments

80–100

hvAb-mvb

80–114

hvAb-lvb

9.98
14.0

10.0

V-3
V-11/1
V-11/2
Sandstone Argillite
near coal
9.98

Ib
m

10.0

10.0

9.98

V-13/2
V-13/1
V-13/3
V-5
Sandstone Argillite
Siltstone
9.98 14.2
Gray
Sample V-4
(sandstone)
9.98
Sample V-3
(coarse-grained sandstone)
10.0

300

V-2

V-11/3
Siltstone

14.1

9.98

Crush zone in
sandstones

14.2

V-4a, b

14.0

hvBb

14.0

71–77

10.0

V-12/3
V-12/2
Argillite

10.0

V-5

V-12/1

V-15/2 V-15/3
V-15/4
Argillite
Sandstone
9.99

V-8

14.2

hvBb-lvb

14.1

14.1

10.0

V-9

14.2

V-10/1-13*

z?

Clayey siltstone

10.0

10.0

V-13

71–115

?

V-14/6

V-11/1-4

d, m
c

Tobacco-colored argillite
with siltstone interbeds,
coal seams, and calcite
veinlets
Gray argillite with rare
siltstone interbeds

V-14/4
V-14/5
Sandstone

9.98

Intensely crushed
dark gray argillite with
calcite veinlets

14.0

9.98

14.1

V-14/3

14.2

d, c

V-15/1-4
V-12/1-3

10.0

m

Alternating laminated
detrital argillite, siltstone,
and sandstone

Sandstone with
conglomerate interbeds
and coal seams
Alternating conglomerates and coarsegrained sandstones

hvAb

14.1

Alternating argillite,
sandstone, and coal

83–90
78–90

10.0
14.2

c
? m

V-14/1-6

14.1

c, g

9.98

10.0

Coarse-grained sandstone
with conglomerate clasts
Gray argillite with
coal seams

14.1

Quartz
Feldspar
Mica

Chlorite

reflectance
10Ra min-

Sample no.

Organic matter

Mixed
layer

Description

14.1

100

Miocene

50 50

50

II

50

100

100

III

Mineral composition

Lithology

Member
50 Thickness, m
20

IV

100

Pliocene

Q

50

Age

(a)

V-8
Argillite:

V-9

Gray
tobacco-colored platy

61. Sample V-1a (sandstone); 63. Organic matter

120

Sandstone and argillite
Abundance and size of
pebbles in conglomerates
sharply decreases.
Sandy cement

300

Sandy conglomerate
(locally with
cobblestone),
sandstone interbeds
(0.5–1.0 m),
and thin coal lenses

z, m

V-1e

9.98

V-1d

Sample V-1e
(argillite)

74–85

V-1b

Sample V-1Ò
(sandstone)

9.98
Sample V-1b
(sandstone at the contact with coal lens)

75–82

Ia

hvAb

hvBbhvAb

V-1a

9.98

14.1

z

14.1

V-1c
9.98

>1000

EoceneOligocene

Oligocene-Miocene

10

Sample V-2
(clayey siltstone)

Sample V-1a
(sandstone)

Cobblestone

Fig. 6. (a) Composite Neogene section in the northwestern part of the Red River Depression (the detailed characteristics of this
section interval is shown in Fig. 6b). Sign “+” in the column “Mineral composition” designates the presence of a particular mineral
in the sample. Letter designations: (g) gypsum, (d) dolomite, (c) calcite, (m) metahalloysite, (z) zeolite.
(b) The bed-by-bed characteristics of section near the Co Phuc Settlement (see Fig. 4d).

and III). The sediments have early to late Miocene age.
The thickness is more than 1000 m.
The section is crowned by greenish yellow thin-laminated siltstones with layers of well-sorted sandstones

composed of well-rounded grains. This member (IV) is
LITHOLOGY AND MINERAL RESOURCES

Vol. 38

arbitrarily assigned to the Pliocene. The thickness varies from 50 to 350 m.
All rocks in the section are deformed into folds with
the strike varying from 180° to 300° and dip angle ranging from 30° to 80°. The rocks of members II–IV are
No. 3

2003


216

PETROVA et al.

Sample no.

10.0
14.0

c, d

14.0

9.98

14.0
9.95

14.1

c, d

V-10/7

10.0

c

V-10/8

10.0

V-10/9

c, d

V-10/10

14.0

c

9.98

V-10/11

coal

rank
other
minerals

14.0
14.0

10.0

c, d

V-10/5
9.95

lvb

14.0

V-10/3

c

14.1
9.98

14.0

c, d

50

Vc, d 10/2

V-10/1

Siltstone

9.98

80–114

10

Sandstone

35

Detrita
argillite

25

Sandstone

50

V-10/4

Siltstone

c, d

6

Detrital
argillite

35

Detrital
siltston

35

Detrital
argillite
with coal

9.98

14.0

Description

quartz
feldspar
mica
chlorite

c, d

Fe

Diffractogram
fragment

V-10/6

50

Laminated
argillite
with Fe

Sandstone

Fe

80–100

Fe

70

hvAb-mvb

20

Argillite with ferruginous
interbeds

105

50

reflectance

10Ra, %

Argillite Alternating sandstone and thin argillite

35

25

organic
matter

Detrital
argillite

Lithology

Mineral composition

Laminated
argillite

Thickness, m

(b)

Fig. 6. (Contd.)

strongly lithified and overlain by horizontal undeformed (or slightly deformed) Quaternary sediments.
In terms of lithology, sandy–clayey rocks are similar
to each other through the entire section and largely
composed of arkose varieties. They consist of quartz
with subordinate feldspars (both sodic and potassic

varieties) and biotite. Sandstones enclose rare clasts of
quartzites and acid volcanics.
The peculiar feature of the rocks is their intense secondary (superimposed) alteration that is most prominent in members II–IV (Fig. 6a). The cement in the
lower coarse-grained member is altered to a lesser
extent. The clayey component of the cement in sandstones and siltstones, as well as the entire argillite, are
replaced by chlorite–mica aggregates (Figs. 7a–7d).
During the argillite replacement, about two thirds of
primary smectite is transformed into mica and approximately one third is altered into Mg-chlorite. These proportions (with some variations) are mainly typical of
the middle and upper parts of the section (Figs. 6a, 6b;
fragments of X-ray diagrams). Similar proportions are
also preserved in the replaced cement of sandstones and
siltstones (Figs. 7a–7d). Such stable proportions of
mica and chlorite components in the replaced rocks of
different grain sizes are particularly well seen in small
fragments of the section. Figure 6b demonstrates the
bed-by-bed closeup transverse view of the Co Phuc section shown in Fig. 4d. It is evident that regardless of the
rock type (argillite, siltstone, or sandstone), the proportion of mica and chlorite components in the secondary
aggregates remains unchanged. Micas are mostly represented by well-crystallized dioctahedral varieties. Their
structures virtually lack expanding interlayers. Micas
with a low content of expanding interlayers (no more

than 5%) are rare.
It should be noted that alteration of sedimentary
rocks, including argillites, results in disappearance of
their clayey (smectite) constituent. Of all examined
rocks, only sandstone from Sample V-4a shows an
insignificant quantity of smectite in the cement. Mixedlayer minerals (chlorite–smectite, chlorite–vermiculite,
and illite–smectite) occur in insignificant quantities
only in some samples. No confinement of these minerals to certain parts of the section is noted.
The structure of the primary cement in rocks
changes as well: it looks like the cement is “squeezed
out.” Quartz and feldspar grains and sandwiched biotite
flakes are closely spaced. Their cement forms thin films
that can be observed in the microscope only under large
magnification. The distribution of newly formed mica
shows a distinct layering. Signs of solid-phase recrystallization are discernible in all primary minerals. Consequently, blastogenic textures are developed in all sedimentary rock types.
The primary biotite is partly or completely replaced
by Fe-chlorite. Mixed-layer silicates are also commonly developed after biotite. Feldspars are partly
replaced by kaolinite, which is sometimes observed in
the cement as well (Fig. 7a, Sample V-11-4). Quartz
grains are mostly unaltered. However, they are
deformed and frequently split into uniformly elongated
blocks in areas of maximum compression. Sometimes,
recrystallization (blastogenesis) of quartz and biotite
grains is observed (Fig. 7a, Sample V-11-4). At inter-

LITHOLOGY AND MINERAL RESOURCES

Vol. 38

No. 3

2003


1.541

SYNCHRONOUS TRANSFORMATIONS

1.699

Q

1.980
2.127
2.23
2.28
2.465
2.56
2.85
2.95
3.24-3.18 Fs
3.50 Chl 3.34 Q
3.71 Chl
4.98 Mi

4.25 Q

0.15 mm

9.95 Mi

7.0 Chl
9.98 Mi
11.8 ?
14.0 Chl

Sample V-12/1

7.0 Chl
~11 ill + sm
14.0 Chl

1.540

(b)

3.34 Q

4.25 Q
4.70 Chl
4.97 Mi

0.3 mm

1.817

Sample V-15-2

1.994
2.127

2.28
2.456
2.56
2.85 Chl
2.98
2.19 Fs
3.52 ïỴ

7.14 Kaol
9.98 Mi

Mixed-layer ill.-sm

0.3mm

1.817
Q

0.15 mm

Sample V-14-1

2003

(d)

(f)

No. 3

1.658

11.6

4.25 Sample V-11/4

7.06 Chl
9.95 Mi
14.0 Chl

0.15 mm

3.34 Q

3.19 Fs
3.57 Kaol
3.70 Fs
4.44
4.97 Mi

Sample
V-13-3

Vol. 38

3.03 Cat
3.18 Fs
3.67 Fs
3.85 Cat 3.34 Q
4.02 Fs

4.69 Chl
4.25 Q
4.95 Mi
5.5 Fs
6.32 Fs
7.0 Chl

2.95

4.25 Q

4.70 Chl
4.98 Mi

2.88

9.94 Mi
14.0 Chl

1.979
2.127
2.23
2.28
2.56 2.456

2.456
2.56
2.85 Chl 3.19 Fs
3.34 Q
3.24

3.53 Chl

1.817 Q
1.890
1.906 Cat
1.978 Q
2.09 ä‡Ú
2.127 Q
2.23 Qua
2.28 Q
2.456 Q
2.55

Q

1.817

0.10 mm
0.10 mm

1.700

1.980
2.127
2.24
2.28

1.700 Qua

(a)

1.817

0.10 mm
0.10 mm

(c)

1.671
Q

0.15 mm

(e)

LITHOLOGY AND MINERAL RESOURCES

1.540

0.15 mm

0.15 mm

217


218

PETROVA et al.

granular boundaries, quartz grains frequently display
convexo-concave contacts typical of conformal microtextures usually produced by the mechanical compression of rocks (Figs. 7e, 7f, Sample V-14-1). Altered
rocks usually lack free spaces. When present, they are
filled with chlorite or, in very rare cases, by chlorite
associated with embryonic epidote grains. Sometimes,
regardless of its constituents, the entire rock is replaced
by calcite. In addition, insignificant quantities of
metahalloysite, dolomite, gypsum, siderite, and, probably, zeolite are also found.
Thus, the following features can be considered typical of secondary mineral formation in rocks:
(1) absence of sequential–mineralogical zoning;
(2) development of secondary mica–chlorite assemblage; (3) absence of smectite and sporadic occurrence
of mixed-layer minerals; (4) presence of recrystallization (blastogenesis) textures in the majority of rock
types; (5) development of sinuous and convexo-concave (conformal) contacts between mineral grains;
(6) strong compaction of rocks; and (7) striate, uniformly oriented, and elongated distribution of constituent mineral grains.
The wide distribution of secondary mica and chlorite, presence of recrystallization textures, development
of conformal contacts between mineral grains, and
strong compaction of rocks, all these features indicate
intense alteration of primary sedimentary material.
Under conditions of normal geothermal gradient, such
alterations occur in the course of subsidence to depths
of 5–7 km or more and are usually considered an indicator of intense catagenesis. The lack of sequential–
mineralogical zoning and presence of oriented textures
in altered rocks suggest, however, that the process was
more complicated. The transformation of primary rocks
was probably caused not only by changes in parameters
of mineral formation during their subsidence, but by
other factors as well. These processes can be explained
by the geological history of the studied fold zone.
According to available data (Gatinskii, 1986), heat
flow in the Red River fault zone is as high as

~0.1 Wt/m2. Its geological structure does not provide
grounds to suggest significant changes in heat flow values during the period from the Eocene to Recent. The
calculated temperature for the depth of ~5 km approximates ~ 250°ë. Consequently, the temperature and
pressure, which were responsible for the formation of
mineral associations indicating intense catagenetic

alteration, were typical of deepest zones of the trough
during its extension. Thus, it can probably be assumed
that the overlying layers of the section were altered at
the extension stage of the structure following the classical subsidence scheme, i.e., from smectites to transitional mixed-layer phases and further to chlorites. The
subsequent compression of sediments resulted in dehydration of clays and mixed-layer structures and their
transformation into chlorites and micas that are more
stable in new environments. This was probably also
stimulated by a shift of the interstitial solution boiling
point under the additional pressure. Stability fields of
minerals, such as chlorite, mica, and epidote, could also
shift toward lower temperatures. Stable primary minerals were corroded or partly recrystallized at surface and
near-surface levels under the compressive stress. Consequently, heaving and compaction textures were
developed.
Thus, the formation of secondary mineral assemblages in this zone occurred in two stages. The first
stage corresponded to structure extension and produced
the usual diagenetic and catagenetic zoning of metasedimentary rocks. The second stage was characterized by
compression and resulted in the distortion of metasomatic zoning. Structures of typical surficial and nearsurficial hydrous minerals, which were stable at low
pressures, were replaced by anhydrous or low-hydrous
crystalline structures that were more stable under new
stress conditions. The difference between deep and
near-surficial secondary mineral assemblages was virtually leveled. Mixed-layer minerals and smectites
were only preserved in areas where the pressure was
minimal, e.g., where cobblestones and conglomerates
from lower horizons could resist the pressure. The

sandy or clayey cement in them is less altered, as compared with finer-grained sandstones, siltstones, and
argillites from higher horizons.
The behavior of organic matter buried in different
parts of the section is remarkable. According to (Le Thi
Nghinh et al., 1991), lower Miocene sediments of the
Hanoi Depression enclose only humic organic matter,
whereas middle–upper Miocene sediments contain
some sapropel, in addition to the dominant humic
organic matter. Results of the pyrolysis indicate that all
examined samples of organic matter buried in the studied section correspond to type III kerogene that forms
only from humic organic matter. It is logical, therefore,
to assume that the majority of organic matter was trans-

Fig. 7. Compositions and textures of inequigranular rocks from the Yen Bai section. Photomicrograph (without analyzer) and diffractograms corresponding to bulk composition of particular samples: (a) Sample V-11-4. Fine-grained sandstone from the upper
part of the section. Filmy cement. Kaolinite and mixed-layer illite–smectite are developed after feldspar and biotite, respectively;
(b) Sample V-12-1. Siltstone from the upper part of the section. Aleuropelitic texture. Chlorite and mica laths are poorly oriented.
Primary quartz and biotite grains show recrystallization signs. Smectite and mixed-layer minerals are replaced by mica; (c) Sample
V-13-3. Alternating argillite and siltstone from the middle part of the section. Aleuropelitic texture. Mica and chlorite laths and coaly
particles (black) are slightly oriented. Smectite and mixed-layer minerals are replaced by mica; (d) Sample V-15-2. Argillite from
the upper part of the section. Pelitic texture. Chlorite and mica laths are slightly oriented. Smectite and mixed-layer minerals are
replaced by mica; (e, f) Sample V-14-1. Fine- to medium-grained sandstone from the upper part of the section. Filmy cement. Convexo-concave contacts between quartz grains and deep fissures filled with cement are well seen.
LITHOLOGY AND MINERAL RESOURCES

Vol. 38

No. 3

2003

SYNCHRONOUS TRANSFORMATIONS

219

B, %
Sample V-1-1
80

60

Wave length =
N=
Ra =
MSD =
Ra max =
Ra min =
∆Ra =

546.0
10
7.86962
0.22009
8.22125

8.00

8.20

Wave length =
N=

Ra =
MSD =
Ra max =
Ra min =
∆Ra =

Sample V-8a

7.545
0.67625

546.0
50
8.7292
0.95065
10.7737
6.3775
4.39625

40

20

100

7.45 7.60

7.80

Sample V-10-1

80

Wave length =
N=
Ra =
MSD =
Ramax =
Ra min =
∆Ra =

6.3

546.0
50
8.69485
1.62598
11.31

8.0

10.0 10.8
Wave length =
N=
Ra =
MSD =
Ra max =
Ra min =
∆Ra =

Sample V-15-1

6.7225
4.5875

546.0
50
8.5368
0.29714
9.00125
7.8075
1.19375

60

40

20

0

6.65

8.00

10.00

11.35

7.75

8.00

8.50

9.00
Ra, %

Fig. 8. Reflectance of organic matter from the Yen Bai section.

formed into variably metamorphosed coal during the
studied area extension and organic matter subsidence.
According to I.E. Stukalova who carried out optical
examination of organic matter samples from the section
exposed near the town of Yen Bai (Fig. 6), the humic
organic matter from interstices between conglomerate
pebbles in the lower part of the section (samples V-1-1,
V-1-2, and V-4, Figs. 6a, 8) is characterized by minimal
reflectance values in air (10R‡ = 71–85%), which correspond to high-volatile bituminous B and A coals
(hvBb and hvAb, respectively). The humic matter is
composed of large tabular vitrinite clasts with a distinct
cellular structure but without notable anisotropy. The
clasts show a distinct texture and contain an admixture
of sedimentary material sometimes filling cell hollows.
Thin films and separate particles of organic matter
enclosed in strongly deformed sandstones and siltstones from the middle part of the section (samples VLITHOLOGY AND MINERAL RESOURCES

Vol. 38

8a, V-10-1, and V-10-7) are characterized by a very
irregular reflectance. The 10R‡ values vary in separate

particles from 71 to 115%, which correspond to coals
ranging from hvAb to lvb (low-volatile bituminous
coal) ranks (Figs. 6a, 8). The genesis of organic matter
is unclear because no classical vitrinite features were
observed in examined grains. Organic matter is represented by different-sized fragments of irregular shapes.
Two groups of fragments are distinguished by their
reflectance. The smallest fragments are characterized
by the minimal reflectance.
Thick beds of organic matter from the upper part of
the section (Fig. 8, Sample V-15-1) consist of large particles of the humic variety frequently represented by
crushed and twisted fragments of tree branches. Thin
sections show the presence of vitrinite veinlets with
reflectance value 10R‡ = 87–90% corresponding to
high-volatile bituminous A coal (hvAb).
No. 3

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220

PETROVA et al.

Table 1. Results of the geochemical analysis of organic matter from the Yen Bai section
Sample no.

Position
in the section

V-1b

V-10-1
V-15-1

Lower
Middle
Upper

IRR, %

Corg , %

88.0
74.3
87.5

56.60
0.82
11.75

Pyrolysis results

BC, %
BC, % lumiextraction
nescence
0.2100
0.0485
0.0119

0.2400
0.0400

0.0003

S1, mg/t

S2 , mg/t

Tmax , °C

0.35
0.15
0.11

26.27
0.90
1.40

462.8
450.0
539.2

Note: (IRR) Insoluble rock residue; (BC) bitumen content in rocks determined by the chloroform–bitumen analysis (chloroform extraction).

Table 2. Group composition of bitumens from different parts of the Yen Bai section
Sample no.
V-1b
V-10-1
V-15-1

Position
in the section

Lower
Middle
Upper

Hydrocarbons, %

Resins, %

saturated

aromatic

benzol

alcohol–benzol

22.2
35.8
25.8

21.8
28.2
18.2

29.0
17.6
19.7

20.4
14.0

20.9

These data suggest that the section demonstrates a
reverse pattern of metamorphism: organic matter from
the lower (deep) zone is less metamorphosed, whereas
the organic matter from upper levels shows more
intense alteration. Moreover, the metamorphism of
organic matter is maximal in strongly dislocated sectors
of the central part. If we assume that all primary humic
matter was transformed into coals, their distribution
pattern is as follows: the lower part of the section contains high-volatile bituminous (B, A) coals, the middle
part encloses coals ranging from high-volatile A to lowvolatile ranks, and the upper part mainly includes highvolatile A ranks (Figs. 6a, 6b).
Geochemical studies made it possible to significantly elucidate the mode of organic matter transformation within the sedimentary section during the intricate
geological evolution. We analyzed three samples (V-1b,
V-10-1, and V-15-1) from the lower, middle, and upper
parts of the section, respectively (Table 1). The maximum Corg content (56.6%) is typical of the lower part,
whereas the minimal concentration (0.82%) is recorded
in the middle (strongly deformed) part. The sample
from the upper part of the section shows medium Corg
contents (11.75%). Based on results of pyrolysis, all
samples should be referred to type III (Van Crevelen
diagram) corresponding to transformation of humic
organic matter.
It appeared that organic matter in all three examined
samples contains both bituminous and coaly components. The maximal bitumen content (relative to the
total Corg concentration) is observed in the middle part,
where bitumen is dominated by saturated and aromatic
hydrocarbons. Bitumen from the lower part is characterized by a high content of resins, whereas the bitumen
from the upper part is represented by asphaltenes
(Table 2).

Asphaltenes, %
6.6
4.4
15.4

The pyrolysis revealed that the S2 value is always
higher than S1; i.e., the bitumen is a syngenetic product
in the entire section. It was extracted most easily from
the sample characterizing the middle part at the lowest
temperature of 450°C (Table 1).
The extracted bitumen components also differ in
molecular–mass distribution of n-alkanes (Fig. 9).
Low- and medium-molecular paraffin hydrocarbons
(n-C12 to n-C25 with maximum of n-C17) dominate in
samples V-1b (the lower part of the section) and V-15-1
(upper part). Medium- to high-molecular paraffin
hydrocarbons (n-C19 to n-C31 with two maximums of
n-C17 and n-C27) prevail in Sample V-10-1 from the
middle part of the section.
These data clearly indicate that the transformation
of humic organic matter was a uniform process through
the entire section (formation of bitumen and preservation of the coal component). The transformation of
organic matter into bitumen directly correlates with
stress intensity. The thickness of organic-rich beds is
also very important: the lower their thickness, the
deeper the transformation of organic matter. Owing to
the existence of compact pebbly material, organic matter from the lower part of the section could probably
retain the transformation degree attained during the
maximal subsidence of rocks (i.e., hvBb and hvAb

ranks). The subsequent compression during the folding
and ascent of sedimentary rocks could cause disruption
of internal bonding within the coal structure. This could
probably cause both mechanical destruction of carbonaceous particles and intricate transformation at the
molecular level. Coal metamorphism under stress
evolved according to an unusual scenario of generation
and transformation of bitumen from asphaltene via
intermediate phases to anthraxolite and shungite rather
than from brown coal via intermediate phases to anthra-

LITHOLOGY AND MINERAL RESOURCES

Vol. 38

No. 3

2003


SYNCHRONOUS TRANSFORMATIONS
250
200
150
100
50

V-1b-1

10 15 20 25 30 35 40 45 50 55 60 65 70
200

100
50
10 15 20 25 30 35 40 45 50 55 60 65 70
300

V-15-1

200
100
0

degree of compaction and maximal bitumen content. It
is enriched in light hydrocarbons with the widest spectrum of n-alkanes and acyclic isoprenides.
As shown above, these processes are accompanied
by transformation of the inorganic constituent along the
entire section corresponding to the deep catagenesis
stage.

V-10-1

150

10 15 20 25 30 35 40 45 50 55 60 65 70

Fig. 9. Chromatograms of the bitumen-saturated fraction.

cite. This process was accompanied by the transformation of humic matter, which was already metamorphosed to hvBb and/or hvAb coal, into bitumen. The
smaller the organic matter particles, the more complete
and prominent is this process in the studied rocks.

As early as in the late 1960s–early 1970s, the importance of natural coal dispersion under tectonic stress for
organic matter transformation was shown in (Sterenberg et al., 1968; Ettinger et al., 1974). These authors
demonstrated that dynamic impact on coals initiates the
disruption of weakest bonds in lateral chains and
between carbon layers. A prolonged mechanical impact
triggers the destruction of rigid carbon lattices. This is
accompanied by distortion of the ordered aromatic part
of macromolecules and increase in the quantity of disordered carbon in lateral chains (Ettinger et al., 1974).
Subsequent experimental works (Tsarev and Soroko,
1985) confirmed that static and dynamic loads stimulate the generation of hydrocarbon and other gaseous
components from organic matter, simultaneously
increasing the carbonization degree of kerogenes and
the content of hydrocarbon fraction in bitumens.
According to these researchers, mechanical stress
results in the destruction and fragmentation of complex
hydrocarbon molecules and the subsequent formation
of simpler, although more ordered, compounds that
compose the insoluble fraction of organic matter.
Precisely these processes were observed in the
examined organic matter. In zones of maximal compression, organic matter is characterized by the highest
LITHOLOGY AND MINERAL RESOURCES

Vol. 38

221

CONCLUSIONS
Thus, it is established that the exhumation of young
sedimentary rocks, their deformation into gentle folds,
and 1.5 to 2.2 times compaction are accompanied by

synchronous transformations of their organic and particularly, inorganic constituents. These transformations
are superimposed on dia- and catagenetic alterations of
earlier stages.
As a result of oriented stress impact, sedimentary
rocks acquire many specific features of rocks metamorphosed at the deep catagenesis stage: (1) development
of the secondary mica–chlorite assemblage, decomposition of smectite, and sporadic formation of mixedlayer minerals; (2) development of recrystallization
(blastogenesis) textures in most rock types; (3) development of sinuous and convexo-concave (conformal)
contacts between mineral grains; and (4) maximum
rock compaction. However, there are some differences
reflected, first of all, in the lack of sequential–mineralogical zoning. Under the stress, secondary layer silicates loss water. Some minerals, such as chlorite and
mica, are stable even under elevated pressures at all
depths. If the section contains compression-resistant
rock layers (e.g., conglomerate or cobblestone), their
cement can retain secondary minerals that formed at
dia- and catagenetic stages of rock transformation
before the stress. This can produce pseudozonal patterns in the section, but this zoning reflects differences
in elastic properties of host rocks and relevant irregular
distribution of pressure therein rather than progressive
changes in parameters of mineral formation with sediment subsidence. The elevated and uniformly oriented
pressure is also responsible for a peculiar striate and
extended distribution of secondary minerals in the rock.
In addition to chlorite and mica, kaolinite developed
after feldspars and calcite filling late fissures also indicate the stress impact upon rocks.
Humic organic matter, which occurs in the section
as separate beds, lenses, and inclusions, also responses
to the stress impact. The capacity of rock beds to resist
stress and alteration directly correlates with their thickness. Under the influence of additional oriented pressure, humic organic matter can be transformed into different grade coals and enriched in bitumen as well.
Data obtained in the course of this study indicate that
bitumen is generated from coals metamorphosed to
ranks hvBb and hvAb under the stress impact. Liquid

and gaseous hydrocarbons released from solid humic
matter under the stress load are concentrated in rocks.
No. 3

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PETROVA et al.

Thus, the rocks are transformed into low-grade oil-generating formations.
ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research, project no. 01-05-64595.
REFERENCES
Atlas of the Palaeogeography of China, Wang, H., Ed.,
Beijing: Cartographic Publishing House, 1985.
Cheng, Y., A Cognitive Basis and Discussion on the Nappe
Structure of Ailao Shan-Diancang Shan Geology, Yunnan,
1987, no. 6, pp. 291–297.
Chenging Fan, The Tectonic-Metamorphic Belt of Mt Ailao
in Yunnan Province, Yunnan, 1986, no. 5, pp. 281–291.
Ettinger, I.L., Cherkinskaya, K.T., Shterenberg, L.E., Elinson, M.M., and Kasatochkin, V.I., Mechanochemical Reactions during the Dispersion of Coals, Mekhanoemissiya i
mekhanokhimiya tverdykh tel (Mechanical Emission and
Mechanical Chemistry of Solids), Frunze: Ilim, 1974,
pp. 271–273.
Gatinskii, Yu.G., Lateral’nyi strukturno-formatsionnyi
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Nedra, 1986.

Helmcke, A.B., The Permo-Triassic “Paleotethys” in Mainland Southeast Asia and Adjacent Parts of China, Geol.
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Hutchison, C.S., Geological Evolution of South-East Asia,
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Le Thi Nghinh, Nguyen Xuan Huyen, Nguyen Trong Yem,
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LITHOLOGY AND MINERAL RESOURCES

Vol. 38

No. 3

2003