THESIS _~dcu\\.:' ) p, ,\', , _1 9 7 - wJi.., 12 ~pO-l'o.1.L M.c""r '-1' ~ Cr~Jt\t(.'I'}ttS t\),& £OCe.n12. hc\.ck C,xk..;J 8€olojj $:n.dh W~s+laj\~HAPTER SIX
6.0 COAL GEOLOGY
6.1 COAL SEAM DISTRIBUTION AND GEOMETRY
6.1.1 Seams Described By Previous Authors
In 1880 an 8ft seam was reported from the Paringa River (in Wellman 1955). Wellman also collected detrital \ coal and described the probable. seam locality as 3 miles upstream from the Paringa River mouth on the east side of the paringa River. Cotton (1985) located. a seam of a simi lar rank and thickness (Fig. 6.1) (ply samples with C.R.A. numbers: 33/268; 33/269; 33/270: 33/271 and 33/272) at N.Z.M.S.260 G36/236214 which lies within the Butler Forma tion. The samples have been analysed chemically and petro graphicallY in this study (see Appendix 6.4).
Douglass (1890) discovered five outcrops of coal in the headwaters of Ship Creek. Due to the difficulties of access, no further attempts have been made to relocate the seams. The access track shown on the map (Douglas 1890) from Wells Creek to the junction of Bullock and Fox Creeks still exists although the bench cut is overgrown and fallen away in places, however, the tracks up Wells. Creek and across to Dobsons Creek have reverted to bush and could not be relocated. Field relationships indicate the seams found by Douglass constitute part of the Law Coal Measure.
Evans (1937) discovered a seam in a tributary of Bul lock Creek (on the left hand side), to the north-west of both Fox Creek and the Bullock Creek Gorge. The seam, which has been relocated by this author (N.Z.M.S.260 F36/028103) is poorly exposed and highly sheared, outcropping in a structurally complex area. The seam and associated sheared and highly weathered sediments is faulted at an apparently low angle over a sheared, hard, green, fine grained sand stone (Greenland Group?) and is also faulted laterally to the south-west against a grey, calcareous siltstone (Tit i- -198-
Figure 6.1 Stratigraphic column showing the 3m coal seam exposed in a ".tributary. of the Paringa River, South Westland. Grid Reference N.Z.M.S. 1 191389 (after Cotton 1985).
Thickness Sample No. Lithology (m) (C.R.A.) Mst/Zst/Sst· carbo thinly bdd. >10 33/268 Clean br ight shiny coal. 0.5-0.6 0.8 33/269 Dirty dul1 coal, bright fragments, slightly , sheared.
33/270 Clean dull coal. Some bright layers.
33/271 Pale grey car b., sandy silt to dirty coal. fSst dk. gy. carb.· BreCcia, weathered gy. gn.
>50 Breccia, clast supported sandstone follated sandstone and minor quartz clasts from 5mm to 20cm diameter.
Sample 33/272 is a whole seam channel sample. -199- tira Formation). The seam is overlain by soil supporting a thick growth of vegetation.
Bolitho (1937) recorded a horizontal 3 ftseam at river level which cropped-out somewhere on the south side of the Paringa River between N.Z.M.S.260 G36/220230 and G36/220220. Both Wellman (1955) and the presentinvestiga tion failed to relocate the seam which may now be covered by river gravels, or may have been removed by the river which is presently undercutting the river bank in the vicinity.
6.1.2 otumotu Formation
No .coal seams have been located in the otumoto Forma- tion (as redefined in sections ~.O and 4.~). In the type section on otumotu Beach two thin coal bands crop out (C.R.A. sample nos. 39/207 and 39/208) lcm and 10cm .thick respectively, interbedded with sandstones, siltstones and mUdstones of the Topsy Member. The bands are continuous for the length of the exposure (2m - 3m). A few other coal bands, up to 5cm thick and interbedded with laminated mud stones, crop-out locally.
6.1.3 Butler Formation
Coal seams within the Butler Formation have been located in four areas: (1) Hydroslide Creek, a tributary of Lake Paringa; (2) the Mathers Creek - Gates Creek divide: (3) Lignite Creek, a tributary of the Paringa River; (4) Butler Creek on Mt. Arthur. Each area will be discussed in turn.
In Hydroslide Creek (N.Z.M.S.260 G36/198170) one , 50cm seam crops out laterally for 3m and has brown, wedge- shaped, mUdstone splits (accounting for 5-10cm thickness). This seam overlies 75cm of dark grey and black carbonaceous mud with 1cm bands of coal, and underlies 1m of grey mud stone (Fig. ,6.2). A white clay is interlaminated with the mUdstone which splits the seam. The seam has been channel sampled in 4x10cm plies from top to bottom (C.R.A. sample
THE liBRARY m;.IIVF~SITY OF CANTERBURY -200-
MEASURED SECTION DETAIL SHEET .. - Figure 6.2 LOCALITY: HYDROSLIDE CREEK: off Lake Paringa . I Stratigraphic column of the coal bearing sequence in HydrosUde Creek, showing the SCALE I: position of the coal seam sampled. The sequence repeats itself up the creek with approximately 15m of interbedded conglomerate and sandstone being followed by 5m to 10m of fine grained lithologies DESCRIPTION ~ and coal bands. I I 24
tQl~ pebb-9ranule.
Sst with thin c'arb •. 1:'111. Occ. q:: Qranules lam.
7 Mst ca~b. sharp upper contact. • fto random vitrinite , 1·04 ( 1,0/332--. c Coal. Black shiny. 1·32 Coal dirty 1'39 39JZ09.(::m 1·29 40/335/0R ..... Mst ca~b. with thin coal laye~s. 5 ..... ',:::. ::"::':;1.:' == mm laminatud fine sandstone I.~~~ 1·42 1.0/330 I t
Mst c~rb.with carb.lam. 1.0/331 3 c 1·38
£<1"CI( ca~b. lliyer. sharp "pp.,,. and lower cont"d;s. ·.·.'.7 2 .' .. m Sst; cm.bdd pinches and ~ .. ells to form l ..ns.,s.
I1st; ci.\rb. 1"111. 1 'c 0 •• 0'/ Sh.up cont .. c: t. • (7' •• , .<: . Q 0, CQI i pebb-Q~anul e:, b.J:!.. M.. t~i" (41)'i0 :;:Sst. ,<:>. a ' 0 •• Clasts (bOlO; 9~n 11 th i c clasts 4':';' () '. ""'0-,, ~ l1\ar"oon 11 .. lS1. - - - gy Sst clasts 2~;' qz cla3t~ ~O% -201 nos. 40/332, 40/333 40/334 and 40/335 respectively). Two thin coal bands were also sampled, one of 4cm (sample 40/330), from 2m below the seam and a 6cm band from 2.8m beneath the seam (sample 40/331) (Fig. 6.2).,
On the Mathers creek/Gates Creek divide, south-east of Gates Creek, near a· natural clearing in the bush (N.Z.M.S.260 G36/195195), a seam of unknown thickness (min imum thickness 2m) is poorly exposed (coal channel sample 36/281 and pollen sample G36/f31). The se'am dips 69° to the north-west and lies upon an unknown thickness of carbona ceous fine sandstone (Cotton 1985).
In the unnamed creek to the south of Lignite Creek (G36/236214), both t~ibutaries of the Paringa River, a 3m seam is exposed. This has been sampled as 4 plies (samples 33/268; 33/269; 33/270; 33/271) and the whole seam has, been channel sampled (33/272) (Fig. 6.1).
In Butler Creek, on the west side of Mt. Arthur (N.Z.M.S.260 G36/325255), a 50cm seam of sheared coal overlies 7m of black carbonaceous mudstone interlaminated with bands of sheared coal, the overlying lithology is not exposed. The seam has not been sampled. Coal bands occur throughout the sequence.
6.1.4 Tauperikaka Formation
Two highly lenticular coal seams within Moeraki Mem ber sediments, 30cm and 40cm thick, occur approximately 1km up Bishops Folly (creek) from S.H.6, and are both poorly exposed. The upper 30cm seam has been sampled (N.Z.M.S.260 G36/032112: C.R.A. sample no: 40/329). Additional small lenses of black shiny coal measuring 20cm across and 10cm high crop-out within interbedded mUdstone and cobble to pebble conglomerate. The additional lenses are probably logs.
Carbonaceous muds interbanded with coal occur within Moeraki Member sediments crops out on S.H.6 on the south- -202
west side of Breccia Creek, and a small lens of coal resemb- ling a coalified log crops out in Wells Creek within Moeraki Member sediments. No other seams have been located within the Tauperikaka Formation (as defined in Sections 2.0 and 4.3) •
6.1.5 Law Coal Measures
six main seams (Fig. 6.3) and several minor coal partings and bands crops out in Coal Creek (Map 5). The lower seam (Map 5; 297200226650) crops out on both sides of the creek and dips 20° to the north. On the left hand side 1m of brown carbonaceous mUdstone grades up into 55cm of coal (Figs. 6.4 and 6.5) (samples: upper half 39/201; -lower half 39/202). A hard, medium grained, carbonaceous sandstone overlies the seam with a sharp and undulose con tact. On the, right hand side of Coal Creek a structureless, black, sandy silt grades up into black carbonaceous mUdstone which is overlain with a gradational contact by 50cm of coal. A hard well rounded cobble conglomerate overlies the seam on an undulatory surface (Fig. 6.3).
The seam is repeated approximately 20m further up Coal Creek, in the scree slope on the left hand side (a change in elevation between exposures of 8m - 10m), due to faulting. Carbonaceous mudstone (30cm thick) grades up into 50cm of coal and the top contact of the seam is sharp and undulose with a highly weathered sandstone. The lateral extent of all exposures is limited to a few metres.
Five other seams occur further up Coal Creek (Map 5 and Fig. 6.3). A 3m -3.5m thick seam (Map 5; 297350225500, samples: upper half 39/203i lower half 39/204), dips 28° to the north-west and is exposed in a slip, on the left hand side, 20m -30m above the creek bed. The seam lies on a structureless, hard, carbonaceous, ,silty mUdstone with an abrupt contact and the seam is overlain, with an undulose contact, by a highly weathered yellow green, moderately sorted, medium sandstone. Mudstone bands of 1cm thickness split the seam. The seam crops out laterally for 4m and then FIGURE 6.3 L.H.S. Slip Exposure SEAM EXPOSURES IN COAL CREEK A tributary of Bullock (Cole) Creek, South Westland.
L.H.S. Slip face 20-30m 5.6m above creek bed...... ,'-~
L.H.S. R.H.S. 203 R.H.S.· of creek ofcreek Seam exposed below waterfall
201 205 i6 202 f5 204 206 f4 m
" '\i'.. ,,,-'''' Map 5 297200E 226650N 297350E 225450N r 297350E 225500N I\) o (,) I f numbers are all prefixed with F37 (e.g. F37/F6) and are palynological samples. Other numbers are all prefixed with 39 (e.g. F39/20 I) and are samples taken for chemical, geochemical and petrographical analyses.
297350E 225450N.
approx. 70m along stream course·
! 205m along stream course
D. Adams U. of C. 1986. -204-
Figure 6.4 Coal Creek, left hand side (Map 5: 297200226650), Law Coal Measures, (Kaiatan). Typical outcrop from which seams are sampled. (Photo - M AJiprantis)
Figure 6.5 Close up of figure 6.4. 55cm coal seam overlain with a sharp and undulose contact, by a medium sandstone. -205- is buried by scree on both sides.
The four upper seams crop out on either side of Coal creek. One, on the right hand side is at creek level (Map
0 5i 297350225450), is 1m thick, dips at 13 to th~ north-west and is exposed underneath a waterfall (samples: upper half. 39/204, lower half 39/205) (Map 5 and Fig. 6.3). The seam extends up dip for 9m and is terminated by a fault and down dip the seam pinches out. The seam overlies a structure less, grey, highly carbonaceous, silty mUdstone at a sharp undulating contact. The seam becomes cleaner upward and is overlain in the south-east by a structureless, grey, hard, moderately sorted, coarse to medium sandstone and in the north-west by a structureless, hard mUdstone. The contact in both cases is sharp and straight. The contact between the two overlying lithologies is not exposed.
The three seams to the left hand side of Coal Creek are exposed in a slip, one at creek level and two, which are 5.6m apart, approximately 100m above the creek (Map 5; 297400225450). The middle seam 0.5m .thick (Figs. 6.3 and 6.6) and overlain by laminated carbonaceous mUdstone at an abrupt contact. The seam overlies carbonaceous mudstone but the contact is not exposed. The uppermost seam is approximately 30cm thick, and is underlain by· light grey mUdstone with a gradational contact and overlain by a pebbly quartzose sandstone at an abrupt contact (Fig. 6.7). Nei ther of these two upper seams have been analysed for coal composition. The lowermost seam consists of 4m of coal and mUdstone bands. The seam is underlain by 3m of quartzose sandstone at an abrupt contact and overlain by quartzose sandstone at an abrupt contact. The seam is approximately 70m downstream from that exposed on the right hand side at Map 5; 297350225450 (Fig. 6.3). - 206-
Figure 6.6 Coal Creel<" ,above creek in a slip on the right hand side (Map 5: 297400225450). The middle of three seams exposed in the slip. The 0.5m thick seam lies within laminated carbonaceous mudstone. (Photo - M Aliprantis) -207-
Figure 6.7 Coal Creek, above creek in a slip on the right hand side (Map 5: 297400225450). Upper of three seams. The 30cm thick seam is under lain by a grey mudstone and over lain by a pebbly sandstone. (Photo - M Aliprantis) -208-
6.2 CHEMICAL ANALYSIS
6.2.1 Introduction
Proximate analyses were performed by C.R.A. on chan nel samples from whole seams, ply composites and coal bands. Calorific values and sulphur content were also determined (Appendix 6). Ash, volatile matter, fixed carbon, sulphur and calorific value are all corrected to a dry basis and volatile matter and fixed carbon are then bor~ected for min eral matter and sulphur using.a formula developed by Suggate (1959) and modified by Newman N.A. (1985).
suggate (1959) developed a formula to correct vola tile matter for the contributions of mineral matter and phur as follows:
VMdmmSf = 100 (VM db - 0.1 A db - S db) 100 - 1.1 A db S db
where 'dmmSf' dry, mineral matter and sulphur free and 'db' is on a dry basis (corrected for moisture). The formula assumes that all of the SUlphur is evolved with the volatile matter. However, Newman N.A. (1985) has estab lished that approximately one half of the sulphur content of Westland bituminous coals remains in the char. As the samples from South Westland all contain significant propor tions of pyrite the modified formula used to correct to the half sulphur basis is as follows:
VMdmm 0.5Sf 100 (VM db - 0.1 A db - 0.5 S db) 100 - 1.1 A db - S db
The suggate correction also assumes that the mineral matter/ash ratio is 1.1. In coals of high ash, the ratio may over or under correct volatile matter % depending on the coal mineralogy.
Ash percentages for all the coals in the South West land sequence are high, usually above 10% (db), with an -209- average of 31% (db) for all seams and bands sampled. Seams in the Law Coal Measures range between 10% and 42% ash (db). The seams in the Butler Formation have a far wider range from 8.7 to 60.7 (Appendix. 6).
A description and discussion of ash constituents is given in section 6.4.
The volatile matter (dmmO.5Sf) for the South Westland samples is documented in Appendix 6. Seams within the But ler Formation have volatile matter values (dmmO.5Sf) between 25.7 and 18.2. A seam in the Tauperikaka Formation (Moeraki Member) has a value of 34.7 and seams-in the Law Coal Mea sures have values ranging between 39.4 and 43.8. As the samples from South Westland are all sampled from outcrop and have undergone varying degrees of weathering, changes in volatile matter yield between pI of individual seams can not be related to type differences. The applicability of volatile matter values for estimating rank is discussed in Section 6.2.4.
suggateis (1959) formula for correction of calorific value for mineral matter and sulphur is
B.t.u. dmm8f = 100 (B.t.u. - 408) (100 - 1.10 A - S)
The formula has been used for the South Westland samples. However, when the formula is applied to coal from the Law Coal Measures values of 17,405 B.t.u./lb (sample 39/206) and from 16.612 B.t.u./1b to 16,465 B.t.u./1b (samples 39/203, 39/204 and 39/205) are obtained. New Zea- land coals are not known to have calorific values higher than 16,000 B.t.u./1b (the highest value shown on suggates N.Z. coalband is approximately 15,900 B.t.u. Suggate 1959). The anomaly may result from the Suggate correction formula for mineral matter, which in coals with a high ash requires a more complex correction for individual ash con stituents. -210-
6.2.2 Sulphur
Sulphur values within the South Westland samples have been reduced, and trends in values between seams hidden, by the effects of weathering which is evident in cOql particu late blocks where pyrite is undergoing replacement by iron oxide. organic sulphur content will also have been reduced by weathering. Weathering is also indicated by desiccation cracks in vitrinite macerals.
Sulphur values for searns in the Law Coal Measures are high (between 4% and 6.1%). The coal contains abundant pyrite which occurs among mineral matter and within macer als. Pyrite is undergoing replacement by haematite and hae matite veins cut across vitrinite macerals.
sulphur values in coals from the Butler Formation are lower than for Law Coal Measure samples and vary between 1.3% and 0.3%. The seams contain abundant pyrite, which occurs amongst mineral matter and within vitrinites and fusinites, and is being replaced by haematite, and haematite veining is also apparent.
Sulphur values from bands of coal within the otumotu Formation and for a small lens of coal within the Tauperi kaka Formation are all less than 1%.
The high sulphur values in coal from the Law Coal Measures may result partly from brackish influence during peat accumUlation. However the Law Coal Measures are over lain by a thick sequence of marine sediments (Tititira For mation) and conglomerate and sandstones within the Law Coal Measures may have facilitated permeation of sea water lead ing to secondary enrichment. - 21 1
6.2.3 Coal Rank
Introduction Assessment of rank is important because the degree of coalification causes chemical and structural changes in the coal. Chemical alterations vary during the individual stages of coalification making certain rank indicators more appropriate than others through particular rank stages (stach 1975, Table 6.1). Rank indicators are influenced by the type of coal which is entirely determined before burial of the coal. Weathering has also had an important influence on rank indicators from the coals sampled in South Westland. All coals were channel sampled from poorly exposed outcrops, usually beside creek channels or from slips. The effect of weathering on the coal increases the moisture content, decreases Specific Energy, decreases coking properties and alters volatile matter by first depressing, and then' with further weathering, slightly elevating the volatile matter (Suggate 1959).
Coal from the Otumotu and Tauperikaka Formations appears to be high volatile bituminous, coal from the Butler Formation may be high volatile, medium volatile bituminous and low volatile bituminous. Each rank determining para metre is discussed under separate headings.
(i) Calorific Value
On the basis of calorific values, coal bands in the Topsy Member of the Otumotu Formation on otumotu Beach are High Volatile Bituminous A coals.
Coals in the Butler Formation all have calorific val ues above 15,200 BtU/lb and above 15,500 Btu/lb calorific value ceases to become useful as a rank indicator (stach 1975). A seam in Hydroslide Creek from the Butler Formation shows a variation of 15,292 Btu/1b and 15,949 Btu/lb between two adjacent plies. The variation in calorific value between the individual plies of the seam do not reveal con clusive patterns relating to changes in coal type. Effects -212-
Rank Ref!, I Vol. M'I Carbon I Bed Cal. Value Applicabilily of Oirrerenl Rmotl d. a. f. d. a. I. Moisture Blullb Rank Parameters German USA % Vitrite (kcallkg) MJI kq r-0.1 r- 60 Torf Peat
~.c: I- 64 lignite ~ -;;;'" .,. /lOO 0 > r- 56 I-ca. 35 5 1-' 140001 .",., ~ 16·75 J:J "'" ~U Matt· e C I- 52 Sub- I- 0,4 ::::I -- 9900 Bit. - ca. 11 t- ca. 25 B r 48 f- (5500) '" 23,03 I Glanz- - - 0.5 I co - 0.6 r- 44 . 12600 t- 8-10 ~ I' - ca. 17 ca, r 170001 Flamm- I---~!fl i'i I B <::I t-- 0.1 29·31 '" .~ 1-·40 ,,;. I I--- => ii3 r- 0.6 ~ Gasflamm- a I C5 36 w ;> r:- ~ A '-' I - I- 1,0 I - 32 Gas- .&::. I r-- J. '---'- '" Medium I-I.l f- If,!,I1f) 20 r- ca. 87 .x r . IUBf,O! VolaliJe 36·05 OJ I '" ~ 1 Bituminous r- I.~ I- 24 i'i felt· .- m ,,;. 1 '" ~ low I- 20 I - r 1.6 '" I~ Volatile E
Table 6.1 The different stages of coalification according' to the German (D.I.N.) and North American (A.S.T.M.) classifications and different physical and chemical parameters used as rank indicators over the various coalification stages. (Stach et al. 1975) -213- of type on calorific value variability between isorank serial samples may have been distorted because of the consequences of weathering and unweathered samples need to be obtained to achieve conclusive results.
A coal lens in the Moeraki Member of the. Tauperikaka . Formation in Bishops Folly to the south of the mapped area is high volatile bituminous A. Seam composites in the Law Coal Measures all show anomalously high calorific values up to 17.405 Btu/1b (40.54 MJ/kg). As other rank determining parametres (e.g. reflectance) indicate the coal is high volatile bituminous the anomalous results are ascribed to inherent errors in calculating the calorific value (see discussion in Section 6.2.1).
Suggate (1959) defined a N.Z. coal band using several parametres including axes volatile. matter and calorific value. The South Westland samples (Appendix 6) all have greater than 7% ash (db), which is the cut-off point that Suggate (1959) uses for samples on the volatile matter calo rific value bivariat plot. Therefor~ the South Westland samples are not eligible for comparison to Suggate1s N.Z. coal band because the majority South Westland samples have high ash percentages (discussion on ash 6.2.1).
(ii) Volatile Matter
Volatile matter can be a useful indicator of rank in coals of medium volatile and low volatile bituminous rank because volatile matter falls rapidly with the increasing aromatization of the coal structure. However, volatile matter yield is also strongly influenced by coal type (New man and Newman 1982, Newman 1985). The effect of weathering on the samples will have reduced the volatile matter yields by an unknown amount.
On the basis of volatile matter, coal bands from the Topsy Member on otumotu Beach are high volatile bituminous A. -214-
Seams in the Butler Formation show a decrease in volatile matter from the west at Lake Paringa to the east around the Paringa River. If this trend reliably indicates rank variation coal seams in the west may be low volatile bituminous, while a coal seam on the east side of·· the Par inga River may be medium volatile bituminous. .Onthe same basis a lens of coal in the Moeraki Member of . the Tauperi kaka Formation in Bishops Folly, is high volatile bituminous A. The data is unreliable because of the changes in the volatile matter value caused by weathering in outcrop samples and unweathered samples need to be collected before reliable conclusions concerning trends in rank changes can be drawn.
(iii) Vitrinite Reflectance
The vitrinite reflectance (Ro random%) of twelve South Westland samples from the otumotu, Butler, Tauperikaka For mations and the Law Coal Measures have been measured by M. Johnston of the University of Canterbury at Auckland Univer sity and at the Geological Survey in .Wellington (Appendix 6). The reflectance measurement results from the two centres are comparable in that no consistant differances, between the two sets of results have been noticed.
The mean vitrinite reflectance of sample 39/209 from the Otumotu Formation on Otumotu Beach suggests a rank of High Volatile bituminous B (Fig. 6.8) (rank scale Table 6.2). Coal from the Butler Formation shows varying mean vitrinite reflectance measurements (Fig. 6.8) which suggest a medium volatile bituminous rank for the seams in Hydros lide Creek and for the seam on the east side of the Paringa River (33/269). A seam on Gates Hill (36/281) has a reflec tance which indicates a high volatile bituminous rank (Fig. 6.8). The coal lens from the Tauperikaka Formation in Bish ops Folly has a mean vitrinite reflectance indicative of high volatile bituminous B coal (Fig. 6.8). A ply sample (39/205) from a seam in the Law Coal Measures also indicates a high volatile bituminous B rank (Fig. 6.8). -215-
30
20
.1- 10 39/207 o
0-75 %
20
10 40/329 t
0-77 %
30
20 I-
10 39/205 I 0-6 I lO 0-72 %
Figure 6.8 Reflectograms of selected South Westland coal samples showing mean random reflectance (Ro) of teloco1llnite (vitrinite maceral) against the percentage number of counts (vertlcal axis). 0 = Otumotu Formation; t = Tauperlkaka Formation; 1 = Law Coal Measures; Sjimples. on the following two pages are all taken from the Butler FormatlOn. 216- 20
10 40/332
1-04 % 20
10 , 40/333
1'32·% 20
10 401334
,,39 % 20
10 40/335
1-29 %
10 40i330
Figure 6.8 continued. - 2 17-
20
10 40/331
Cl6
30
20
36/281
40 0'81 %
30
20-
10 33/269
1·19 % Figure 6.8 continued. -218-
A series of ply samples taken from a seam in Hydros lide Creek and from two coal bands immediately below the seam (40/332 -40/335 and 40/330 and 40/331) (Fig. 6.2) show a substantial variation in Ro mean and Ro 'standard devia tion. The vertical separation between samples is. considered too small to reflect any changes in rank. Between adjacent . plies a range of c.0.3% in Ro mean is exhibited and within the whole seam and the underlying coal bands the range is c. 0.4%. Newman J. (1984, 1985 a & b) has detected differences of up to 0.25% between top and bottom composites of individ ual seam intersections at Webb/Baynes Block, Buller Coal Field. Newman J. (1986) shows that type induced differances in Ro% between isorank high volatile and low volatile type coals appear to increase as rank increases in the high vola tile bituminous range (Fig. 6.9). Although weathering could have affected reflectance, the changes in reflectance between plies correlates well with changes in coal type (see Section 6.3.4) which indicates the effects of weathering on the Ro% random of telocollinite is minor and/or has affected each ply by comparable amounts. Variation in Ro% in South Westland serial samples therefore ascribed to varying coal type and provides evidence that differences in Ro% between isorank samples increases as rank increases to medium volatile bituminous (Fig. 6.10). 1·,0
SOURCES: R.neelo",.. from "' ...men 1196501 ..c.pl IOc .. 10' ---- me,t RcpoahOG Soctor $.OfJ'Ipl.a which ~ doetwmlrlltd 1·10 Cool
1-00
0-90 -...... t , Jf. ~ ., J(.. ~ Ia: w Jf. A -....::..... 0-80 ...... /GGniTclised (ond cpptOxim.ole) boronk ..u 0:: 6 II.~. line for Piko Rillar co.ol .2 2~ :!>o 3:1 40 45 :>0 5:1 Figure 6.9 Volotile rnotT18r '1. Reflectance/volatile matter plot for coals sampled during recent West Coa'st exploration programmes. Tie-lines link isorank serial samples. (J Newman 1986.) 1-6 liIlaw Coal Measures 1-5 ... Tauperikaka Formation """ II Butler Formation % o OlumolLl Formation 0 '·4 '" 40/331 ... 1-3 '-' !!= '-' 1-2 II 33/269 ....~... 1-1 I "~ 40/332 N 1-0 N ...= o ;; 0-9 26/281 0-8 II 0 + 0-1' x 391205 0-6 1 0 20 36 42 46 Volatile maUer (dmmfSn % Figure 6.10 Plot of vitrinite reflectance against volatile matter for South Westland coals. Tie lines link isorank serial samples, the vertical separation of which is considered to be too small to cause significant differences in rank. -221- 6.3 MACERAL ANALYSES. 6.3.1 Introduction Maceral compositions for 18 samples -from the Creta ceous and Eocene sequences have been determined (Appen dix. 6). The samples represent serial ply samples, whole seam channel samples, and coal bands and lenses from the formations that do not contain coal seams. The maceral characteristics of South westland coals are briefly dis cussed followed by separate descriptions of the maceral characteristics in coals from each of the coal bearing for mations. 6.3.2 Gen~ral Characteristics The South Westland samples are plotted on a triangu lar plot with axes of vitrinite, inertinite and exinite (Fig. 6.11). Due to the high rank of the majority of the samples from the Butler Formation, in which exinite has the same mean reflectance as vitrinite, exinites are difficult to recognise and the result is a spread of points down the inertinite axis. A triangular plot with axes of telocolli nite, desmocollinite and inertinite (Fig. 6.12) is therefore used to remove the major effects caused by a change in rank and to highlight the differences in overall type between coals from the various formations in the South Westland sequence. Where fusinite is easily distinguishable into pyrofu sinite and degradofusinite the distinction is made, other wise all the fusinite is counted as "undifferentiated fusi fl nite • Pyrofusinite is readily identified in most Butler Formation coals because of a strong yellowish colour and a usually distinctive cellular structure. Degradofusinite is pure white. Differentiation between the two types of fusi nite is important because of the differences in genesis and the important implications when deciphering swamp history. An abundance of pyrofusinite is usually ascribed to moor fires (after Stach et.al. 1975). II tri 100 E I Y )( LAW COAL MEASURES o ·TAUPER1KAKA FORMATION • BUTLER FORMATION , N N N 70 t v \ Inertinite Figure 6. J J group composition of on a mineral basis. -223- Inertinite )( LAW COAL Mt:ASURES o TAU PERI KAKA FORMATION EI 8U TLER FORMA nON FIgure 6.12 Maceral group composition of coal from South Westland using teiocollinlte, desmocollinite and inertinite to show the differences in coal type between the Formations with a minimal rank effect (for example: the mean maximum reflectance of exinite in most Butler Formation coals is equivalent to the mean maximum reflectance of vitrinite which produces a spread of points down the inertinite/ vitrinite axis in figure 6.11). -224- The major characteristics of the coal from the South Westland formations are each discussed in turn. (i) Butler Formation Seams and bands within the Butler Formation are char acterised by high inertinite percentages ranging up to 27.5% and usually between 10% and 20%. Fusinite and semifusinite are the major components and the fusinite usually consists half of degradofusinite and half pyrofusinite. Inertodetri nite is usually a minor component but may constitute up to 35% of the inertinite (sample 40/333). A bivariat plot with axes of inertinite and ash (db) reveals a good correlation for samples from the Butler Formation (Fig. 6.13) and shows an-increasing inertinite content with decreasing ash. Vitrinite macerals constitute between 72% and 99% of total macerals. However, in the majority of seams, the reflectance of exinite is equal to the reflectance of vitri nite, due to the coal rank, and desrnocollinite percentages are therefore elevated because the exinite macerals are not visible and contribute to the desmocollinite percentage. The percentage of telocollinite varies considerably from ply to ply and falls between 21% and 72%. The desmocollinite count shows and inverse relationship and falls between 21% and 51%. In sample 36/281, taken from a seam of lower rank than the other Butler Formation coal samples, in which the reflectance of exinite is lower than the reflectance of vitrinite, exinite contributed 5% of the maceral count and consisted of sporinite, cutinite and resinite, liptodetri nite and exsudatinite. The presence of the exinite is sig nificant as exinite can range from 3%-25% in Upper Rewanui seams at Greymouth (pers. comm. J. Newman) which implies other seams in the Butler Formation may have substantial amounts of exinite. The dominant texture in coal from the Butler· Forma tion is an interlayering of woody tissue with clay or with with axes of inertinite % and ash (d. b.) for coal samples Butler and the Measures. Butler Formation with the exception of those marked with an asterisk, show an inverse correlation for inertinite/ash. ' ,," 40/333 IC Law Cool Meosures 25 •.• Bufler Formali an - 20 40/334 .33/269 • 401332 •33/268 I 15 .401330 N N VI .331281 ~0 ...... Q) . .331270 -r:: 10 .-...... - '"""Q) - C ; .40/329 ~ - 5 )( 39/202 .40/335 )( 391205 39/204 )( x ",39/206 ... 40/331 391201 lC 39/203 0 t I ! • 0 10 20 30 40 50 60 I db % -226- desmocollinite containing inertinite. The telocollinite may exhibit varying reflectance and is seen to grade into semi fusinite. Large pieces of pyrofusinite in which cells are filled with clay, pyrite, collinite, or resinite, are incor porated within desmocollinite which has compacted and flowed around the larger pieces of pyrofusinite. Size estimates of macerals are restricted to studies on 'particulate' mounts. Telocollinite occurs both as a structurally continuous mac eral and as a broken maceral (not considered small enough to count as vitrodetrinite - see Stach 1975). Structural deformation has distorted the laminated and layered texture into micro recumbent folds and numerous micro faults offset vitrinite macerals.· Weathering has cracked telocollinite, and replacement minerals (e.g. haematite) cross cut macerals in vein form. (ii) Tauperikaka Formation The coal lens in the Moeraki Member exhibits a high telocollinite (56%) to low desmocollinite (21.0%) ratio, a high exinite count with abundant spores and well preserved cutinite and mesocutinite. Exinites are easily recognised by their low reflectance compared to vitrinite. A moderate amount of inertinite is also present which consists mainly of fusinite and semifusinite. Telocollinite is both broken and unbroken. The mac erals are laminated without evidence of cross cutting root structures. (iii) Law Coal Measures The coal in the Law Coal Measures has telocollinite percentages between 20% and 35% and desmocollinite percent ages between 67% and 54%. Exinite ranges between 0.6% and 5.8% and has probably been slightly underestimated, because the spores are bleached and have a similar reflectance to vitrinite. Biochemical alteration of spores, under condi- -227- tions where the pH of the swamp water is raised, ultimately raises the reflectance of the spores (Diessel pers. comm.). Inertinite percentages are usually low (5% or less) . The inertinite consists mostly of inertodetrinite and scler otinite. Large amounts of metaexudatinite are present (between 0.2% and 2.2%). Exsudatinite first becomes appar ent in coals at the sub-bituminous/bituminous - coal bound ary. It develops from lipid constituents of liptinites and huminites and its genesis is related to that of fluid petro leum (Stach eta al. 1975). "Metaexsudatinitell is used, to distinguish from exsudatinite, because metaexsudatinite has a higher reflectivity than vitrinite in coals with ranks equivalent to, or higher than the coking-coal stage (ca. 20% VeM.), where the sub-maceral first becomes apparent (Fig. 6.14). The metaexsudatinite elevates the inertinite count as the metaexsudatinite has a similar reflectance to inerti nite in coal from the Law Coal Measures. A bivariate plot with axes of inertinite and ash (db) fails to reveal a con vincing trend in the Law Coal Measure samples (Fig. 6.13). The texture of the coal in the Law Coal Measures is distinctive, compared with all other South Westland samples, because the coal forming peat has been degraded by intense bacterial action. The distinction between telocollinite and desmocollinite is difficult because boundaries of telocolli nite are not generaly outlined by cutinite and the desmocol linite is hard to distinguish because there is little exinite and very little inertinite. Much of the telocoll nite is broken up and at least some of the breaking is due to structural deformation as microfaulting is common and there has been flowage of macerals since deposition. The large component of metaexsudatinite has also broken up telo collinite macerals. -228- Figure 6.14 Metaexsudatinite (me) In telocollinite (t). -229- 6.3.3. Tissue Preservation and Tissue Gelification (i) Introduction The relative amounts of 'structural' material versus 'non-structural' material within seams is classified using a Tissue Preservation Index (TPI), modified from Oiessel (1984) where structural material is here defined as material which contains cellular structures, and non structural mate rial includes vitrinitic ground mass and vitrinite and iner tinite detritus which on account of their small size, no longer show cell structures. . The Tissue Preservation Index (T.P.I.) is calculated as follows telocollinite % + telinite % + fusinite % + semifusinite % desmocollinite % + vitrodetrinite % + inertodetrinite A low T.P.I, which indicates poor tissue preservat ion, results from any combination of; (1) a low proportion of plants with woody tissue compared with soft tissue plants within the swamp; (2) rapid rates of decomposition due to a relatively high pH of swamp water: (3) rapid rates of decom position due to oxygenation of peat. A relatively high T.P.I. suggests accumulation of peat in a forest moor (Oies sel 1984). The T.P.I. of the coal bands and seam composite samples are shown in (Appendix 6). A T.P.I.greater than 1 is considered high, a T.P.I. less than 1 is considered low (Oiessel 1984). The Tissue Gelification Index (T.G.I.) (after Diessel 1984) measures the amount of structural material in the peat ·that has undergone conditions of high oxidation as opposed to structural material in the peat which has undergone rela tively little oxygenation. T.G.I. = telinite + telocollinite fusinite + semifusinite ',."': 230- The higher the T.GoI. value, the less oxygenation the peat has undergone which indicates relatively wetter condi tions as opposed to relatively dry or fluctuating conditions which are assigned to anything less than 2.0 .in the case of Australian coals (Diessel 1984) 0 The T.G.I. values for the South Westland samples are shown in Appendix 6 and range from values of infinity to 1.3. (ii) Discussion The ToP.I. of coals within the Butler Formation is both high.and low and varies between seams and within seams. All of the seams represent at least one period when the swamp represented a forest moor. Pollen spores and plant fragments from the Butler Formation are representative of Nothofagus and other species typical of a podocorp forest. Coal with a low T.P.I. (lowest value 0053 - sample 40/334) may indicate areas of open water with water plants, example reeds, that lack woody tissue. Alternatively the coal may represent peat with woody tissue that has undergone oxygenation associated with bacterial and fungal decomposi tion in raised areas of the swamp. Both of these mecha nisms, in different parts of the swamp, are probably respon sible for the proportion of low T.P.I. values for Butler Formation coals. A raised pH in swamp water, to explain decomposition of woody material, is considered unlikely because; (a) a proportion of every Butler Formation doal seam displays an abundance of woody tissue and. the lack of general decomposition associated with prolific bacterial decomposition, that is typical of swamps with a raised pH, is not evident, and; (b) mechanisms of elevating the pH of swamp water such as a marine influence, or an elevated pH in stream water, are both considered unlikely due to (i) the complete lack of marine indicators within the Formation, and more importantly, the. non marine plant associations repre sented by pollen and macrofossils and (ii) because there is no evidence of limestones within the South Westland basin during the deposition of the Butler Formation. The abun dance of reed plant fossil fragments (Section 5.2 Plant Macrofossils from Mt. Arthur) and high fusinite and pyrofu sinite percentages (Appendix 6) support the conclusions -231- that both raised areas of swamp, supporting woody vegetation and undergoing oxygenation, and swamp characterised by areas of open water dominated by reeds, coexisted. Seams and plies with high T.P.I. usually have a high T.G.I. indicating a relatively wet swamp.- Seams with low T.P.I. have a corresponding low T.G.I. which suggests that the T.P.I. has been reduced by bacterial and fungal decompo sition associated with oxygenation. One ~xception is ply sample 40/330 which has a relatively low T'.P.I. and a rela tively high T.G.I. which may represent a wet swamp with both soft and woody plants occurring together, or suggests rather wet conditions lacking oxygen in an open ,water reed swamp in which woody material was not represented, but was supplied from a peripheral area. The moderately high inertinite con tent (15%) may therefore result from transport from a raised area adjacent to the open water reed swamp. Substantial differences in T.P.I. and T.G.I. values between seams and within seams in the Butler Formation sug gest a range of sequential or co-existing moor types char acterised by areas covered with stands of trees, and areas with more open water characterised by reeds and sedges. Raised areas of the swamp were probably subject to lower and fluctuating water levels which lead to oxygenation of the peat surface and increased decomposition through bacterial action. The coal lens in the Moeraki Member of the Tauperi kaka Formation has a relatively high T.P.I. (2.64) and high T.G.I. (10.57) and is typical of a relatively wet forest moor. Coal within the Law Coal Measures has a very consis tent set of T.P.I. (0.32-0.67) and high T.G.I. (11.3 - infi nity) values. The T.P.I. is relatively low and the T.G.I. indicates a very wet environment. Either the swamp was treeless and consisted mainly of reeds, or the woody tissue has been destroyed by bacterial action caused by an eleva tion in the pH of the swamp water. The bleaching of spores -232- suggests an elevated pH. The elevated pH infers either that the swamp was influenced by a marine environment, or that the presence of limestone was elevating the pH of stream water flowing into the swamp. Lithostratigraphic data is inconclusive, the influence of a marine environment. can only be inferred in the upper part of the Law Coal Measures. The Abbey Limestone had been deposited and marls were· being deposited within the marine part of the South Westland basin during Law Coal Measure swamp deposition, however there is no evidence that limestone was exposed. The presence of a marine environment during the Eocene, combined with the evi dence of an elevated pH in· the Law Coal. Measure swamps implies the swamps were influenced by the marine environ ment. There ~re no vertical trends in coal type within the Law Coal Measures, all of the swamps produced the same end product. 6.3.4. Coal Type Six coal types exist, each exhibiting different sets of maceral proportions, chemical analyses, maceral textures, T.P.I.'s and T.G.I.'s. Type I coals are confined to and include all of the coal from the Law Coal Measures. The Butler Formation Coals comprise Types II, III, IV, V and VI which are all related in that they occur together and interdigitate within the same inferred environmental setting of raised swamps covered with woody stands of vege tation and lower lying areas covered with ponds and lakes, dominated by reed vegetation. The coal from the Tauperikaka Formation also constitutes Type VI. Type I. Type I coals are characterised by a low telocollinite to high desmocollinite ratio, negligible inertinite (T.P.I. 0.67 to 0.32) and less than 5.8% exinite (Table 6.2 and Fig. 6.15). A distinctive feature is the loss of contrast between telocollinite and desmocollinite which is due to the desmocollinite containing very little inertinite and exinite TabJe 6 •.2 TYPE CHARACTERISITCS Type T.P.I. T .G.I. Exinite Inertinite . Ash(db) . S(db) I 0.67-0.32 infinity - 11.3 5.8-0.6 4.8-1 42.2-10.6 6.00-4.03 II 0.89-0.53 1.75- .38 >20 32.3-12.0 . 1.32-1.22 0.98-0.77 2.76-1.64 5.0 45.6-42.7 0.51-0.36 IV 1.28 2.9 18.4 27.1 0.32 I V 1.2 4.2 5.1 2.7 60.7 N I.J,J I.J,J VI 3.03-1.63 infinity-l 0.57 5.8-1.2 60.1-55.3 0.27-0.19 I General Comments I loss of contrast between vitrinite macerals. Bleached spores. II pyrofusinite and inertodetrinite content. Wide range of vitrinite reflectence. III abundant pyrofusinite and interlaminated vitrinite macerals and clay_ IV Inertinite consists mostly of· fusinite and semifusinite. V Finely inter laminated telocoUinite arid clay. Inertinite consists of fusinite, semifusinite and inertodetrlnite. Negligable inertinite. - value contributed to metaexsudatinite. -234- Figure 6.15 Typical Type I coal, which consists of a high proportion of desmocollinite. Also shown are telocollinite (t), vitrodetrinite (v), resinite (r) and sclerotini te (s). Note the loss of contrast between telocollini te and desmocollinite. Figure 6.16 Desmocollinite in Type I coal. A lack of inertinite and exinite IS responsible for difficulties in distinguishing between telocollinite and desmocollinite. Sclerotinite (s) and resinite (r). -235- (Fig. 6.16) and because telocollinite is not outlined by cutinite Framboidal pyrite may have been present originally but this is difficult to sUbstantiate due to recrystallisa tion. The coal is characterised by high pyrite contents and abundant mineral matter which is ,dominantly composed of quartz with minor clay (Fig. 6.17). The T.G.I. (Table 6.2) indicates a rather wet environment but the T.P.I. (Table 6.2) is low, indicating destruction of wood tissue or a reed swamp. A lack of rooting structures, seat earths or cross cutting plant structures su~gests the coal may be hypautoch thonous. Bleaching of spores, homogenisatiori of macerals and possibility of destruction of wooq,ytissue in a rela tively wet environment indicative of a raised pH in the swamp water. A raised pH may result from a marine iriflu ence, or' the presence of limestone within the. depositional basin which raises the pH of stream water entering the swamp. The T.G.I. and high mineral matter is consistent with a high water table in a swamp which was relatively unprotected from floods. Type II Type II coals are characterised by a low telocolli nite to a high desmocollinite ration (20% 30% to 40% -50%), very high inertinite (Table 6.2) and ~ range of ash values (db) from 32.3% to 12.0%. High percentages of pyrofusinite and inertodetrinite constitute the inertinite content (Fig 6.18). The T.G.I. (Table 6.2) indicates relatively dry conditions and the T.P.I. (Table 6.2) indicates destruction of woody tissue which is supported by the wide range of vitrinite reflec tance and raised mean reflectance values indicating oxygena tion of the peat. Pyrite is low and sulphur values are mod erately low (Table 6.2). The type can be interpreted in two ways, either as the raised part of a forest moor characterised by a fluctu- -236- Figure 6.17 Mineral matter band in Type I coal. The band consists mostly of quartz grains. Also shown are framboidal pyrite (f) and a peat clast (p). Figure 6.18 Fusinite (white) and desmocoHinite (grey). Also shows inertodetrinite (j) and vitrodetrinite (v). -237- ating water table, periods of drying out and forest fires, or, the type may represent a relatively low part of the swamp characterised by open water and reeds which is receiving abundant oxygenated detritus and. charred woody tissue from adjacent raised parts of the swa~p which are dominated by woody vegetation. The ash values (Table 6.2) support both interpretations indicating that some parts of the swamp producing Type II coal are raised forest moors and other parts of the swamp are low lying open water and reed environments .. Type III Type III coals are characterised by moderate telocol linite to high d~smocollinite (T.P.I. 0.98-0.77), moderately high inertinite, a high T.G.I., a wide range of reflectance in vitrinite macerals, an abundance of pyrofusinite anq high ash (db) values (Table 6.2 and Fig. 6.19). The mineral matter is dominated by clay interlaminated with vitrinite macerals ( . 6.20). The type is interpreted as an open water reed dom inated swamp which received abundant oxygenated and charred material from adjacent raised areas of swamp. The adjacent raised areas of swamp where covered with stands of woody vegetation under which the peat surface suffered bacterial and fungal action,' and destruction by forest fires, as a result of repeated periods of drying out due to fluctuating a water table. Type IV Type IV coals are characterised by a high telocolli nite to moderate desmocollinite ratio (40%- 45% to 30%), high inertinite, consisting of pyrofusinite degradofusinite and semifusinite and inertodetrinite (Fig 6.21), a moderate amount of mineral matter (Fig. 6.22), low pyrite and high T.G.I. and T.P.I. values (Table 6.2). -238- Figure 6.19 Telocollinite (t) and desmocollinite in Type 1II coals. Semifusinite (sf) and abundant inertodetrinite are also apparent. Black flecks are clay not exinite. Figure 6.20 A typical texture in Type III coals of clay inter laminated with vitrinite (mostly telocollinite) macerals. -239- Figure 6.21 An abundance of inertinite mixed with vitrodetrinite and desmocollinite. A wide range of reflectance between inertodetrinite (i) and vitrodetrinite (v) is apparent. Pyrofusinite (p) IS a common inertinite constituent. The photo micrograph is not typical of Type IV coal. Figure 6.22 Telocollini te (t) and desmocollinite with abundant clay (black) and inertinite (white). Abundant pieces of vitrodetrinite (v) are encompassed within the desmocollini teo -240- The type is interpreted as a wet forest swamp with periods of drying out and flooding. Type V Type V coals are characterised by a high telocolli nite to moderate desmocollinite ratio (40% 30%), high inertinite, consisting of fusinite, semifusinite, and iner todetrinite, high exinite, high pyrite and very high mineral matter (Fig 6.23 and Table 6.2). The T.P.I. and the T.G.I. are both high (Fig 6.24 and Table 6.2). The type is characterised by finely laminated clay and vitrinite macerals. The dominant texture, high mineral matter, T.P.I. and T.G.I. values suggests a high water table, indicating a pond or lake setting where floods are introducing allochthonous material. Type VI Type VI coals are characterised by very high telo collinite to low desmocollinite proportions, low or negli qible inertinite (T.P.I. 3.03 to 1.63), very high T.G.I. and T.P.I. values and very high mineral matter (Fig 6.25). The type is consistent with a forest moor with a rel atively high stable water table responsible for poor oxyge nation of the peat. The type may also represent a low lying area adjacent to a relatively wet forest moor which is accumulating woody material from the forest moor environ ment. The latter interpretation better explains the high ash content. Influence of Coal Type on Coal Reflectance In the sample series 40/335 to 40/332 from a seam in the Butler Formation in Hydroslide Creek the lowest ply 40/335 rests on mUdstone and contains the highest ash value (55.3%db). Under the reflectance microscope, a large amount - 241 - Figure 6.23 Typical Type V coal, showing teJocolJini.te (t), abundant sporinite (s) and inertodetrinite (i). A range in reflectance between vitrinite and inertodetrinite is apparent. Microfaulting off-sets the te loco !lin i te. Figure 6.24 Typical Type V coals. A grain of structured vitrinite shows collinite (c) and tel1inite (t). -242- Figure 6.25 Photomicrograph showing a Type VI coal. Type VI coals mainly consist of telocollinite (t) and a low proportion of desmocollinite (d). White lines outlining telocollinite may represent exinite which , because of the coal rank, now has a reflectance s rightly higher than vitrinite. -243- of quartz and clay is evident, and the sample contains a relatively small proportion of inertinite. These features indicate a high water table and within the swamp, and the peat is inferred to have been relatively poorly oxygenated. The sample has a relatively low reflectance. (Ro random% 1.29) compared to 40/334 and 40/333. Compared with 40/335, ply samples 40/334 and 40/333 have less ash and four to five times the amount of inerti nite. The inertinite consists of equal proportions of degradofusinite, pyrofusinite and semifusinite indicating frequent oxygenation of the swamp due to drying of the peat surface, and forest fires. The peat, therefore, is inferred to have accumulated in a relatively well drained swamp with a fluctuating water table. Relatively high Ro% values for 40/334 and 40/333 (Ro% 1. 39 and 1. 32 respectively), compared with values of ply samples above and below, are a reponse to the change in the coal type. The upper ply (40/332) shows an increase in the ash content and a small decrease in the amount of inertinite compared to the underlying plies. The upper ply is then overlain by a thick structureless mUdstone (Fig. 6.2) which indicates the accumulation of peat ceased due to a rising water table. The cessation of peat accumulation may have been related to a single event such as a forest fire, which produced the large amount of pyrofusinite in sample 40/332. The large standard deviation in Ro% for 'sample 40/332 (Fig 6.8) may be a result of autochthonous material. The rising water table is responsible for relatively poor oxyge nation of the swamp which would accumulated relatively poorly oxygenated peat, but which might also recieve addi tional material of relatively well oxygenated peat from adjacent raised areas of the swamp, which were relatively well oxygenated (Fig. 6.26). The relatively low Ro% for sample 40/332 (Ro% 1.04) compared to samples 40/332 and 40/333 is a result of th~ coal type which reflects rela tively poor oxygenation of the peat compared to samples 40/333 and 40/334. 244- Figure 6.26 Diagram showing a peat swamp with adjacent raised areas and lower areas in which the lower, less well oxygenated part of the swamp receives material from the raised, relatively well oxygenated part of the swamp. The raised areas support woody vegetation due to the relatively low water table, whereas the lower parts of swamp support reeds which fringe areas of open water. The peat swamp is interpreted as a typical· Butler Formation coal forming swamp. -245- ~ontributions of Coal Geology to Reconstructing ~nvironments of Deposition (i) otumotu Formation Factors crucial in the formation of peat swamps are a) the evolutionary development of the flora, b) the cli mate, c) the geographical and tectonic characteristics of the region. Geographical and tectonic prerequisites are 1) a slow continuous rise in ground water table that is propor tional to peat accumulation, 2) a protective barrier against river, floods and marine inundations, 3) a restricted supply of detritus to the hinterland by streams which otherwise may interrupt peat formation (Stach et.al.1975). The lack of coal in the otumotu Formation is probably due to the tectonic setting and may also reflect the cli mate. Peat did not accumulate because spasmodic floods con stituted the main supply of water, and.caused water levels to fluctuate rapidly. Following periods of flooding ponds and lakes dried up and long dry periods with little or no surface water were established. There is no evidence of a marine transgression which might have maintained a continu ous rise of ground water and as deposition of Topsy Member sediments drew to a close, the tectonic setting appears to have been relatively stable (no evidence of subsidence or uplift untill the Piripauan)~ A rather dry climate is inferred from the lithofacies sequence of the Tauweritiki Member, which resembles the deposits of alluvial fans presently developing in semi-arid climates (see section 5.U), and from the pollen assemblage (Raine pers. comm.). (ii) Butler Formation The forests of the Piripauan may indicate a change to a wetter climate. water tables rose as a response to subsi dence, which eventually lead to the marine transgression in the Haumurian. -246- The progression of coal types in the Hydroslide Creek seam (ply samples, 40/332 i 40/333 i 40/334; 40/335) is typical of the autocyclic development of peat deposition in the But ler Formation swamps, which produces an upward succession of mud, reed peat, forest peat and then mud. Tbe increased desiccation of the swamp upward within the seam indicates the peat forming area is became progressively drier as the swamp vegetation became better established, which may have been due to protection from flooding from a fluvial environ ment. One or a combination of, a forest {ire 'which destroys surface vegetation and prevents the swamp surface keeping pace with subsidence-rising water tables, a return to flood ing from a nearby fluvial source or an increased rate of subsidence, may then have been responsible for drowning of the swamp which resulted in deposition of a thick a thick, overlying mUdstone sequence. Fluctuating water levels, that lead to drying out and desiccation of the peat surface, are evidence of ooding of swamp areas which were in proximity to streams. Flooding is also responsible for thehypauto chonous nature of the coal. Deposition of stream sediment appears to be concentrated in parts o~f the swamp which are inferred to be low lying with relatively high water tables. The inverse correlation between inertinite and ash (Fig. 6.13) indicates that raised areas of the swamp, that are subject to forest fires and peat surface desiccation, are not receiving as much mineral matter'as lower lying areas of the swamp, which are less well oxidised and not subject to forest fires. However where large amounts of detrital inertinite (inertodetrinite) are supplied to a rel atively low lying part of the swamp (Fig 6.26), the resul tant coal will contain both abundant mineral matter and inertini te. A sample containing both high mineral matter' and high inertiriite results in an anomalous plot outside the inverse correlation between ash and inertinite (e.g. sample 40/333) . An inferred low lying inactive tract characterised by laterally interdigitating forested swamps, reed swamps and lakes adjacent to and protected from a fluvial environment, -247 has produced rather thick seams (up to 3m), which were prob ably laterally extensive and extended for approximately equal distances in all directions (structural complications have seriously disrupted seam continuity). The seams are not overlain by stream channel conglomerates but usually by suspension material from semi permanent ponds and lakes which indicates the fluvial environment was relatively con fined and inactive tracts were established over long periods of time, which produces the potential for extensive and thick peat deposits. Mineral matter valtieswill increase and seams will pinch out towards paleo-stream channels because of periodic flooding from stream channels carrying material into adjacent swamps. Seams have not been correlated as complex faulting patterns, associated with folding and poor outcrop, makes the task of correlation impossible. (iii) Tauperikaka Formation Both this author and cotton (1985) have concluded that the Tauperikaka Formation lacks coal seams, although evidence that relatively wet forest moors did accumulate peat is found in remnant lenses of coal in the Moeraki Mem ber in Bishops Folly. The absence of true seams is attrib uted to relatively rapid, unrestricted sweeping .of fluvial flood plains by channel systems and frequent flooding from channel systems (Section 5.3.1) which did not allow thick quantities of peat to accumulate, and more importantly caused the removal of any substantial accumulations of peat. The high energy marine environment of the Paringa Member seems an unlikely setting for the accumulation and preservation of peat as this generally requires protection from both marine water and strong tidal currents. Coal seams interbedded with marine tidal sequences have been recently described (Breyer et. ala 1986) however the sequence lacked tidal channel bedforms. Sediments reflect a very low energy marine environment and the margi- -248 nal marine hinterland must also have been characterised by low energy processes to protect the marginal marine swamps from fluvial activity and to allow peat to accumulate. strong tidal currents in embayments along the. coast and a hinterland characterised by high energy processes are inferred to be responsible for the lack of coal sea~s in the paringa Member (see section 5.3.2) (iv) Law Coal Measures There are two possible influences on coal swamp development in the Law Coal Measures. One influence, which may control coal seam characteristics in the lower part of the Law Coal Measures, is a fluvial environment in which migration of stream channels controls the duration of pea~ accumulation, which decides the peat thickness. The raised pH in the swamp water is probably due to the influence of a marine environment in which the sea water is responsible for backing up brackish water in depressions between active alluvial fans. return the fluvial regime to the swamp area, is responsible scouring the upper peat sur- and covering the peat with conglomerate or sand (Fig. 6.27). A similar interpretation presented for the sediments on the Cretaceous iary boundary in the Kaitan gata Coalfield, southeast Otago, where the fluvial environ ment type sediments do not reveal a marine influence but palynology and maceral analyses support a marine influence in the swamps (Brown 1986, Raymond 1985). The alternation of seams with sandstones in the upper part of the Law Coal Measures either reflects the cyclical nature of the abandonment and return period of the fluvial regime or cyclical marine transgressive-regressive events. Deposition of the peat in the swamp may be terminated by minor marine transgressive events, responsible for covering the swamp with the texturally mature, quartzose sandstones in the upper part of the succession, before a final trans gression ended the deposition of the Law Coal Measures (Fig 6.27) . Figure 6.27 One possible paleoenvironmental reconstruction of a swamp during the deposition of the upper part of the Law Coal Measures, showing a fresh to brackish water, estuarine - lagoon complex protected by a barrier system. Interbedded conglomerate, silty mudstone and coal seams underlying the estuarine - lagoon complex represent the lower part of the Law Coal Measures. All of the seams analysed from both the lower and upper parts of the sequence indicate swamp water with a raised pH. B A F I '".j:l' '" o 0·5 km B = barrier beach complex mudstone R = reed swamp F = flood plain sandstone M = mud flats ~ conqlomerate S = sluggish, meandering streams coal A = edge of abandoned alluvial fan ! _ _ I silty mudstone -250- j.4 ASH CONSTITUENTS 6.4.1 Introduction The major aim in determining the ash constituents of coal samples in this study is to isolate differences between seams in the cretaceous formations and seams in the Eocene Law Coal Measures. Major element analyses for high temperature ash of 10 samples from the Butler Formation and Law Coal Measures are presented in Table 6.3. The method of preparing and analys ing samples is detailed in Section 3.2. Information from X.R.D. analyses of low temperature ash is also drawn upon (Section 3.2) and the X.R.D. charts are presented in Appen- 8. Relevant ash constituents are discussed as follows. Plots of weight percentage of both Si02 and Al203 again~t total ash are shown in Figure 6.28. The 03 bivariate plot clearly illustrates a difference in the amount of Al203 present between Butler Formation coals and Law Coal Measure Coals. Petrographic analysis has indicated that coal from the Butler Formation contains a relatively large amount of clay which is often interlaminated with vitrinite macerals (section 6.3.4), and analyses by X.R.D. have confirmed the presence of abundant kaolinite and illite (Appendix 8, diffractograms 6 - 9). The relatively high Al20 3 for these ashes can be attributed to the clay compo nent which will also account for a proportion of the Si02 . In comparison, high temperature ash from coal of the Law Coal Measures contains relatively little A1203' reflecting the large amount of quartz in the coal which was evident in X.R.D. analysis of the mineral matter (Appendix 8, diffrac tograms 10,11 and 12). Table 6.3 Major element analyses for high temperature ash of coal from the Butler Formation & Law Coal Measures. 39/207 39/202 33/270 39/206 39/203 39/201 39/209 39/205 33/268 MgO % 1.17 1.29 1.64 1.36 0.61 1.14 1.1 2.074 1.173 Na20 % 0.68 2.15 0.12 0.41 0.84 1.47 0.231 1.473 0.231 Si20 % 59.90 61.54 55.13 67.07 59.75 66.85 64.593 62.194 53.384 Al203 % 17.50 5.17 32.75 . 14.98 4.11 6.57 30.547 5.394 33.868 S03 % 0.64 12.08 0.16 2.08 2.89 11.23 0.481 O. J22 0.224 P205 % 0.13 0.15 0.57 0.23 0.21 0.13 0.063 0.053 0.955 I N VI Fe203 % 5.74 6.13 5.79 4.95 28.78 5.13 5.446 17.105 4.162 MnO % 0.03 0.06 0.03 0.01 0.13 0.07 0.014 0.036 0.026 Ti02 % 10.11 1.27 0.95 1.28 0.77 .. 1.04 1.196 1.187 1. 131 CaO % 0.61 8.17 0.38 2.03 2.06 8.03 0.630 5.865 1.198 K20 % 3.53 0.40 4.34 3.07 0.43 0.45 4.400 0.550 2.734 LOI % 0.00 0.00 0.00 0.00 0.00 0.00 0.000 0.000 Total % 100.05 98.41 101.86 97.47 100.57 102.28 108.727 96.051 99.088 -252- o 10 2030 40 ASH db % Figure 6.28 Bivariate plots of wt % 5i02 in Ash against Ash (db) % and wt % A1203 in Ash against total Ash (db) % • ..c ~ 2·5 Figure 6.29 Bivariate plot of wt % Na20 in Ash .:: 2-0- against . I o total Ash (db) % SJ1·5 z o~ 1-0 ...... o ~ 0-5 '. i-02 -04. -06 -08 -10 100%A Ash (db) % -253- A bivariate plot of the weight percentage of Na20 in ash against (total ash)-1 is shown in Figure 6.29. Even with the limited data base for Eocene Coals a good regression shows that Na20 declines as carbonaceou$ matter declines and that at 100% ash there is "0" Na2ocontent (pers. corom. N.A. Newman). Therefore the sodium is totally organically associated and the amount of sodium within different seams from the Law Coal Measures remains constant. The Butler Formation coals have very low Na20 content which provides a good way of distinguishing Cretaceous from Eocene coals. The Fe203 in ash from the Law Coal Measu~es samples (Fig. 6.30) may be predominantly derived from the pyrite, which is confirmed by X.R.D. analyses (Appendix 8, diffrac tograms 11 and 12). Hematite, identified by petrography in samples from both coal bearing formations,will also con tribute to the Fe203. Iron oxides in the coals are assumed to result from weathering of pyrite, or possibly iron carbo nates. Although the distinction between formations is poor, on the basis of Fe203 in ash, the very iron-rich ashes in the Law Coal Measure samples correspond to the presence of pyrite. (iv) CaO A plot of the weight percentage of CaO against total ash shows a good separation between samples from the Butler Formation and samples from the Law Coal Measures (Fig. 6,31) A large amount of calcium carbonate, both as grains (Fig. 6.32) and as disseminated blebs amongst desmocollinite, is evident under the microscope. The high proportion of CaO may be epigenetic and a probable source is the limestone and calcareous sediments overlying the Law Coal Measures. The Law Coal Measures -254- 28·8 ::x: VI« 8 Xx X+ ~17~ X 7 N ~ 2 2 X X 1 - 1 • • , o - i ° •• i 10 20 30 40 10 30 50 Ash% db ASH db % Figure 6.30 Figure 6.31 Bivariate plot of wt % Fe203 In Ash Bivariate plot of wt % CaO in against total Ash (db) %. Ash against total Ash (db) %. Figure 6.32 Disruption of epigenetic carbonate (c) due to structural deformation (pers. comm. N.A. Newm.3n). -255- consist of conglomerate and sandstones, and the majority of the seams are also overlain by either sandstone or conglomerate, which would have assisted with permeability prior to sedimentation of the overlying sediments stage of diagenesis. The CaO content has probably been reduced by substantial weathering. 6.4.2 Conclusion In conclusion, the coals from the two coal bearing· formations in South Westland can be distinguished using Na20 content, and are also distinguished using a combination of CaO and Al203 contents in conjunction with X.R.D. analysis of mineral matter, and coal type. Differences between coals of the Butler Formation and the Law Coal Measures with respect to, quartz and clay contents are consistent with the inferred swamp environments. Kaolinite formation is not favoured under conditions of a raised pH, which are inferred for the swamps in the Law Coal Measures. Butler Formation swamps had low lying areas with high water tables, where suspension load introduced from nearby fluvial systems could settle out. In comparison, the Law Coal Measure swamps, which contain less clay and more quartz, may have been subject to continual movement of water through the swamp, indicated by the hypautochthonous nature of the coal. The lack of quartz grains in the Butler Formation swamp may be due to leaching by humic acids (Renton 1982). -256- 6.5 ECONOMIC GEOLOGY 6.5.1 Coal Seams The coal seams in South Westland have been deformed by faulting to a degree that even small private mines are unlikely to be considered. The least disrupted seams are part of the Law Coal Measures which crop out in Coal Creek with dips between 10° and 30°. However these seams appear to terminate against faults within tens of'metres. Several seams less than 1m thick, and.two seams, one of 4m and one of 3m thickness, crop out in Coal Creek. The coal contains abundant mineral matter, a large proportion of which occurs as pyrite and quartz rich dirt bands, but the coal contains very little clay. An access track from S.H.6, which lies within 4km of the coal seams j would present few problems. Access via a bullock track from ,the coast to the upper reaches of Coal Creek was available in the 1950's (Wellman 1955). However, high transport costs as a result of the distance of the coalfield from markets and port facilities, and the absence of a rail facility, severely constrain any venture from com peting on a viable basis with mining in the Greymouth / westport area. Any mining venture in South Westland could only be considered for local consumption, due to the limited scale of a possible mine. 6.5.2 Petroleum Source Rocks Both the otumotu (Motuan to Arowhanan) and Tauperikaka Formations (Haumurian) may have potential as a petroleum source, as these rocks contain organic matter. However, the Butler Formation (Piripauan) and the Law Coal Measures (Kaiatan), which are both sequences containing thick coal seams, are the most likely source rocks in the South Westland sequence. -257 The coal appears to have passed through the petroleum formation stage (sub-bituminous A, ~ 0.55% Rm oil; where Rm is the mean reflectance of vitrinite) and the expulsion stage (high volatile bituminous coal 0.7% Rm oil; stach et al 1975). The reflectance values for some of the Butler Formation coal (Appendix 6) suggest rank eXCeeds high volatile bituminous and therefore, where source and reservoir rocks are closely associated by depth, smaller oil deposits in which petroleum is lighter and more paraffin rich, or gas deposits, could be expected. However/ Newman and Newman (1982) showed that the variation in vitrinite type can complicate the use of vitrinite reflectance for assessment of"thermal maturity. None of the work in this study is sufficiently extensive to reliably indicate a lateral rank gradient. However, if the structural complications have had an influence on coal rank by substantially thickening the sequence/ there may be a decrease in rank as structural complexities decrease away from the Alpine Fault. Any such trends will have important implications for the genesis of oil and gas deposits offshore. An oil seep at Madagascar Beach (south of the study area) occurs in steeply dipping sediments which have prob ably allowed oil from an unknown depth down-dip to migrate to the surface (Healy 1938, in Nathan eta ale 1986). 6.5.3 Petroleum Reservoir Rocks Potential reservoir rocks are difficult to determine as little is known about the porosity or permeability of limestones and other sediments in the sequence offshore. The cretaceous sequence onshore has been compacted and cemented to the extent where porosity has been greatly diminished .. Dolomite cement has filled pore spaces in the otumotu Formation sediments, which are very indurated and poorly sorted and are unlikely to contain reservoir rocks. The Tauperikaka and Butler Formations are also very indu rated/ and the rock fragment component in the Butler and -258- Tauperikaka Formations has deformed between quartz grains and filled pore spaces. Well indurated quartz sandstones in the upper sequence of the Law Coal Measures are well cemented with silica cement, and both porosity and permeability in the coal measures onshore must be considered minimal. The likelihood of structural traps on-shore are minimal as the rocks have been severely deformed and numerous faults are potential migration paths· for oil and gas to escape to the surface (Section 7.0). However, it is uncertain whether the basal thrust in the d:uplex system is exposed and there is.the possibility of·a relatively less deformed sequence containing structural traps underlying the thrust complex (see Section 7.0). The amount of structural deformation decreases offshore, where there is a greater potential for structural traps. The sequence may be repeated vertically in a stack of thrust sheets bounded by flat lying ind thrust faults, and there is a good·· potential for areas where cap rocks are thrust over reservoir rocks. Recumbent folds in the vicinity of leading edges on thrust planes may also form structural traps. -259- CHAPTER SEVEN 7.0 STRUCTURE Existing Interpretation The Alpine Fault lies immediately to the southeast of the mapped area (Map 1) and its presence has tended to dic tate the structural interpretations of the South Westland and Westland areas. A consequence of this' is that where the geology on the West Coast suggests that large offsets have taken place to bring into juxtaposition rocks with a differ ent geological history, or rocks which have clearly been deposited at a large distance apart in the original paleog eography, the setting suggests that an hypothesis of strike slip faulting, on steeply dipping faults, should be explored initially, when attempting to interpret structure and tec tonic evolution. Previous work in South Westland by Cotton (1956), Wellman (1955), Nathan (1977) and Cotton (1985) either show or imply all the major faults as steeply dipping and this explicitly or implicitly implies a history of strike-slip faulting and/or normal or high angle reverse faulting. Cotton (1956) proposed a "monoclinal tectonic development" with "transverse deformation associated with movement on the Alpine fault", and the interpretation has been adopted by subsequent workers. Introduction The restricted nature of the outcrop inland from the coast, and complete lack of outcrop on bush clad ridges between creeks, inhibits the correlation of small scale structural features. Only the major faults that separate formations or formation members, or faults that are corre latable between creeks and across valleys are shown, in order to explain the basic outcrop pattern. The time to present much of the smaller scale data, e.g. faulting which is restricted to individual outcrops, has not been available during this thesis. -260 The poor creek exposures usually do not reveal the strike or the dip of fault planes. Therefore, where the line of a fault plane between creeks can only be inferred, guesses as to the effects of the topography' on the fault outcrop pattern are not made, as the resultinginterpreta tion may mislead future workers. Therefore, outcrops repre senting faults are joined by a straight dashed line, which only indicates the strike direction of faults which have shallow dips. The true position of the fault outcrop cannot be ascertained without artificial exposure or subsurface data as there is not enough outcrop data of the required quality to draw structural contours on the fault planes. 7.1 FAULTS . From the Paringa River to Bald Hill in the south west, the Mistake Fault separates uplifted Greenland Group, to the south of the fault, from cretaceous and Tertiary sediments (Map 1). The uplifted Greenland Group, to the south of the Mistake Fault is capped remnants of mid and upper cretaceous sediments. The Mistake Fault crops out in the headwaters of Coal Creek where Greenland Group sediments are thrust over Tertiary limestone along a horizontal fault plane (Fig. 7.1). The Mistake Fault has not been located to the north until Venture Creek where the fault plane is exposed as a 4m pug zone between calcareous siltstone and limestone (Tititira Formation) and Greenland Group lithologies. A change in lithology, between two outcrops, from Tertiary to Paleozoic sediments marks the presence of the fault in Tokakoriri Creek but the fault itself does not crop out. In the headwaters of Pearson and Mathers Creeks the creek beds run to the north-east from gorges in Greenland Group rocks onto sheared Cretaceous and Tertiary sediments, although the fault plane itself is not exposed. There is no expression of a possible continuation of the Mistake Fault on the east side of the Paringa River where the com plete Cretaceous sequence is preserved with sedimentary contacts, the base of which is assumed to lie with an angu- -261- Figure 7.1 A diagram taken from a field skefctl showing the Mistake Fault revealed in a slip face in the headwaters of Coal Creek (right hand side). A thick, black, gouge zone is flat lying for 100m across the slip face. Sheared Greenland Group lithologies (Paleozoic) overlie the thrust plane and crop out to the top of the slip (approximately 125m of Greenland Group exposed). Underlying the thrust plane is a structureless very hard, white limestone (5m to 15m thick) which over lies approximately 20m of highly sheared, massive, calcareous mudstone of the TititiraFormation (Tertiary) which crops out to the base of the slip. A further lj.Om from the slip up Coal Creek, sheared Greenland Group lithologies crop out in a slip face on the left hand side. -262- lar unconformity on Greenland Group rocks. For the discussion of the remaining faults the area represented in Map 1 is divided, for simplicity, into four regions: a} Ships Creek to Tokakoriri Creek; b} . Tokakoriri Creek to Abbey Rocks; c} Abbey Rocks to the Paringa River; d} Paringa River to Mt Arthur, and each area will be dis cussed in turn. a). Ship's Creek to TokakoririCreek Bullock Creek Fault Zone: The next major fault to the north of the Mistake Fault crops out in Bullock Creek (N.Z.M.S.260 F36/027103) and separates calcareous siltstone sediments from Greenland Group (Map 1). The fault zone consists of a series of rejoining fault splays where each fault splay encloses either Greenland ~roup or almost vertically dipping Titi tira Formation lithologies. The position of a fault splay is usually marked by a change from Greenland Group to Titi tira Formation lithologies, or visa versa, between two outcrops which often show sheering but 'rarely reveal the actual fault planes themselves (Fig. 7.2). The tip line 'Of a thrust surface crops out in a tributary of Wells Creek (N.Z.M.S.260 F37/023097) where a 10cm pug zone separates underlying sheared red brown sand stone of the Greenland Group and overlying light brown limestone. The thrust plane is undulatory and dips in a series of rounded steps with a maximum dip of 40° and a minimum of 18° to the southwest and west. Grave Creek Fault Zone: To the north of the fault zone exposed in Bullock Creek, a major fault, previously called the Arnott Fault (Young 1968), crops out in Bullock Creek (N.Z.M.S.260 F36/026105) and Grave Creek (F36/054135), and is evident -263- Figure 7.2 Junction of Bullock (Cole) Creek and Fox Creek (Map 1: F36/029102). Tititira Formation (Southland to Taranaki). Shearing associated with a fault splay. Outcrop is 6m to 7m across. (Photo - M Aliprantis) Figure 7.3 Breccia Creek, cutting on State Highway 6 (Map 1: F36/042125). An anastamosing fault system in steeply dipping Tauperikaka Formation, Moeraki Member (early to mid Haumurian) beds (weathered orange yello'.v). To right of fault, relatively undisturbed Paringa Member beds ( early to mid Haumurian) (grey green) dip to the north-west at 35°. Road side crash barrier for scale. -264- in Bishops Folly and Breccia Creek, and separates Greenland Group lithologies from the Tauperikaka Formation sediments (Map 1). The fault· encompasses rejoining splays which enclose Butler Formation and Tauperikaka Formation litholo gies. To the south of the mapped area, the fault is inter preted to rejoin the "Bullock Creek fault zonel! as Green land Group sediments do not crop out in Wells Creek. To the north the fault probably crosses the coast on otumotu Beach as the Greenland Group is not exposed between Ter tiary and Cretaceous sediments, further to the north in the Mathers Creek and Gates Creek area. The strip of Greenlarid Group between Wells Creek and Tokakoriri Creek (Map 1) is interpreted as being enclosed by a rejoining splay and may represent an eroded horse. Breccia Creek Fault: A major fault to the north of the fault outcropping in Bullock and Grave Creeks is best exposed in Breccia Creek (N.Z.M.S.260 F36/043125) and is also exposed in Bishop's Folly to the south west (F36/027113) and along the coast from Murphy Beach (F36/067153) to the northwest. The fault exposure in Breccia Creek is steeply dipping near the present land surface and is accompanied by an anastamosing fault system enclosing numerous horses, in a zone about 20m wide. The fault system separates ver tically dipping sheared and highly deformed lithologies of the Moeraki Member (Tauperikaka Formation) from gently dipping sediments of the Paringa Member (Tauperikaka Forma tion). The anastamosing system of faults occurs totally within the Moeraki Member sediments and the boundary fault between the two members is marked by a pug zone of a few centimetres thickness, by the discordance in the dip of the beds on either side of the fault and by a pronounced change in weathering colour (from yellow and orange in the Moeraki Member sediments to grey green in the Paringa Member sedi ments (Fig. 7.3). The fault probably crosses S.H.6 near the Bullock (Cole) Creek bridge to the south-west but is not exposed, and to the north-east the fault crosses the -265- coastline out to sea (Map 1). Numerous other smaller faults confined to single outcrops are exposed within the area. A well exposed fault within sediments of the Tauperikaka Formation exposed in a S.H.6 cutting, north-west of the Breccia. Creek Valley shows a thrust fault which dips steeply towards the present land surface but which levels out and runs sub-horizontally at depth beneath the surface (Fig. 7.4). b). Tokakoriri Creek To Abbey Rocks The structure of the area between Tokakoriri Creek and Abbey Rocks is presently under investigation (Alipran tis, MSc thesis in prep.). The interpretation' here is that Abbey Formation being thrust over the Tokako riri Formation on a fault splay which branches the Mistake Fault and which appears to steepen in dip toward the coastline (Map 1). The coastline is crossed by numer ous minor faults both steeply dipping and low angle, with accompanying shear zones. c). Abbey Rocks To The paringa River A fault to the north of the Mistake Fault, extending from the coast south west of Piakatu Point, east to the Paringa River (Map 1), inferred from the change in lith ology between two outcrops in a tributary of Gates Creek (N.Z.M.S.260 G36/193217). The change in lithology is from Tokakoriri Formation sediments, which dip to the north (on the south side of the fault contact), to Tauperikaka Formation sediment, dipping to the north (on the north side of the fault contact). The same fault zone may also be exposed near the mouth of Mathers Creek where a highly calcareous grey silty mUdstone containing clasts of basalt is highly sheared and is faulted against a glauconitic medium to fine quartz sandstone with quartz and lithic pebbles. The large block in which the exposure is revealed -266- Figure 7.4- North-west of Breccia Creek, road cutting on State Highway 6 (map 1: F36/039124-) Tauperikaka Formation (Haumurian). A minor anastamosing asymptotically shaped thrust showing a sharp increase in dip on approaching the synorgenic erosion surface. The outcrop consists of sheared sandstone and silty mudstone. Thin curved pug zones within areas of intense shearing mark the areas of major dislocation (see diagram below). \ --- - -267- may not be in situ but due to its size the block can not have slumped far. The Tokakoriri Formation on the south side of the fault is enclosed in a rejoining splay, (to form what is probably an eroded horse), between the Abbey Formation and the Tauperikaka Formation (Map 1). The plane of the fault splay is not expressed in outcrop but the fault splay's position is constrained by the change in lithology from the Abbey Formation sediments to the Tokakoriri Formation sedi ments between two outcrops. The fault is not exposed and does not appear to cross to the east side .of the Paringa River and, more importantly, the strip of Tertiary Forma tions (including the Abbey and Tokakoriri Formations) which are exposed for a considerable distance to the south-west of the paringa River (Map 1) too, are not exposed on the east side of the Paringa River. The fault bounded wedge of the Tauperikaka Formation sediments (N.Z.M.S.260 G36/180220 G36/210130) that crops out between the Abbey and Tokakoriri Formations to the south and the Abbey Formation to the north (Map 1) consis tently shows dips to the north and is cut by numerous east west trending faults which resemble a imbricate fault pat tern. The fault boundary on the north side of the wedge of Tauperikaka Formation sediments, that separates the Abbey limestone from the Tauperikaka Formation, crosses the mouth of the Paringa River (G36/255246) to the north-east where the outcrop pattern is similar. An allochthonous block of Awarua limestone is incorporated as a slice within the fault to the west where the fault crosses the coast to the south-west of Piakatu Point (Map 1). The Abbey limestone is partly separated from the Tititira Formation, which forms the coastal cliffs between Tititira Head and Piakatu Point, by the Tititira Fault (Nathan 1977) the trace of which is obvious on aerial pho tographs. -268- g). The Paringa River To Mt. Arthur Except for a major fault (that crosses the mouth of the paringa River) which separates the cretaceous Forma tions from the Tertiary Formations near the coast, no other major faults have been recognised (Map 1), although a large number of minor faults which strike north-west, and which are difficult to correlate between any two exposures, crop out within the area covered by cretaceous Formations. Mt. Arthur is separated from the Paringa area by a large swamp (Ohinemaka and Micmac Creeks area) and is difficult to relate to the geology of the Paringa Hill range but the outcrop pattern at Mt. Arthur is similar. The sequence appears conformable in both areas; .an almost complete sequence is preserved and contacts between formations are sedimentary as opposed to fault controlled. This sequence preserved to the east of the Paringa River seems to bea coherent entity with the remnants of the Cretaceous Formations which lie on the Greenland Group everywhere to the south of the Mistake Fault throughout the area mapped, strongly related by the conformable nature of the stratigraphy and the lack of fault controlled formation boundaries. 7.2 FOLDING Three structural areas are defined by folding pat terns and they are: (1) The coastal strip between Abbey Rocks and Ship Creek as far south as the Bullock Creek Faulti (2) the area inland, between the Bullock and Mistake Faults , the surface of which is covered mainly by the Tititira Formation which is exposed in Coal, Bullock (Cole), and Tokakoriri Creeks; (3) and the area covered by Cretaceous sediments to the east of the Paringa River. -269- 1}. The coastal strip between Abbey Rocks and Ship Creek as far south as the Bullock Creek fault zone The otumotu, Butler, and Tauperikaka Formation sedi ments between otumotu Point and Ship Creek that crop out within the coastal strip, are folded in a series of cascade recumbent folds. For example an overturned limb that dips at 43°, to the south, .is exposed in S.H.6 cuttings to the east of Grave Creek. In the creek, which is below the level of S.H.6, the beds are the right way up and dip towards the coast. The overturned limb of an inferred large recumbent fold is well exposed along Monro Beach where beds in the Tauperikaka Formation dip between near vertical and 60°. The upper limb crops. out on the hillside behind the coastal exposure (Map 3, and cross sections), however the strike and dip is not obtainable due to the poor exposure. The folding pattern is probably simil~r to the structural style of folding in the Abbey Formation to the south-west of Abbey Rocks (G36/191132) where there is vertical stacking of recumbent folds (Figs. 7.5 and 7.6). Small scale folding on limbs of large recumbent folds is also apparent. In Breccia Creek, the sequence has been repeated three times within 12m, laterally, by a double set of open recumbent folds (Fig. 7.7). Small scale folding is evident in most creeks but fold axes are rarely seen. As the well-exposed example in Breccia Creek illus trates, the.upper limbs of the recumbent folds are several times longer than the lower limbs, hence outcrop pattern will be naturally biased towards the upper limb. younging directions are often difficult to ascertain in creek out crop, therefore, many overturned limbs may not have been recognised. Small e folding is also associated with faulting . where bedding has buckled in response to fault movements (Fig.7.S). -270- Figures 7.5 &. 7.6 West of Abbey Rocks (Map 1: G36/131191) Abbey Formation (Mangaorapan - Runangan). Large scale recumbant folds in limestone. - 271 - ;(12 o 2m t.-.i Figure 7.7 Breccia Creek (Map I: F36/041127) Tauperikaka Formation (Haumurian). Recumbant folding in which upper limbs are several times longer than the lower limbs. Figure 7.8 Monro Beach (Map I: F 36/092168) Tauperikaka Formation (Haumurian). Small scale kink antiform associated with a fault. -272- 2). The area inland, between the Bullock Creek fault zone and the Mistake Fault The inland strip which includes the otumotu Forma tion, Arnott Basalt, Law Coal Measures and Tititira Forma tion sediments exposed north of the Mistake Fault in Coal, Bullock, Breccia, Grave and Tokakoriri Creeks shows a dif ferent style of deformation from both the coastal strip of rocks and the area east of the paringa River. The sedi ments are encompassed within a large monoc1ina1 structure that dips north-west and north (Map 1.). The structure dips steeply between 60 0 and 80°, towards the zone of faulting at the junction of Bullock (Cole) and Fox Creeks, which forms the north-west boundary of the structural area. Small scale folds with gently plunging axes, parallel to the axis of the monocline, cause undulations in the upper limb of the monoclinal structure. Folding in the steeply dipping part of the structure may be more complicated than in shown in the cross sections (in map pocket) as younging directions are difficult to determine in the Tititira For mation sediments exposed in Bullock Creek. 3). The area covered by Cretaceous sediments to the east of the Paringa River The style of structural deformation to the east of the Paringa River is very different from the deformation along the coast, south of Abbey Rocks. A nearly complete sequence is preserved from basement up to the Rasse1as Member of the Tauperikaka Formation in a large syncline plunging to the north-west. The limbs of the syncline are folded by open folds (synclines and anticlines) that plunge to the north-west, north and north-east with limbs that generally dip between 10 0 and 30 0. Locally intense defor mation characterised by tight folding and recumbent folds with shattering of the rock, is associated with faulting. -273 7.3 INTERPRETATION Discussion Cotton (1985) made the observation that IImany creeks have stratigraphic sequences which bear little relation to their neighbours, but at the same time "have consistent ll strike directions , and that "numerous faults seem the only logical answer". The conventional method of presenting cross sections through faulted areas where there is little control on fault orientations is to show the faults dipping within a few degrees of the vertical in orq.er to avoid making hypothetical statements about the nature of the faults. However, vertical faults do make a positive statement about the faulting style and imply either normal or strike-slip faulting, (after Bradshaw 1986). An example of a "conven tional" cross section through the sequence from Bald Hill to the coast is shown in Fig. 7.9. Normal faulting would explain the juxtaposition of the Tititira Formation against the Greenland Group in Bul lock across the Bullock Creek fault zone, if the Greenland Group had been uplifted and overlying Cretaceous and Tertiary sequences removed. Normal faulting also explains the uplift of the Greenland Group and t~e removal of Cretaceous and Tertiary sediments south of Mistake Fault. Strike-slip faulting might account for the close proximity of the depositional sites of the Law Coal Mea sures and the Abbey Limestone which were both deposited in the Kaiatan. However, a model based on normal and strike-slip faulting has some major short-comings and each is discussed in turn. 1. The bulk of the outcrop data available on large scale faulting features indicates low angle faulting. This suggests a reason for the highly sinuous nature of the faults between outcrops, in those areas of better control -274- I- ..J ::> .\" ;\ A' _2 2000 ~ :.:: ..J W 0 u.. ""l>: 1000 w v> a.. 0 ::c v> CD 0 0 o O·Sm ~'--~------~------~I o 1 km D TAUPERIKAKA FORMAT]ON D TJTITIRA FORI1ATlOH OTUMOTU FORMATION D LAW COAL HEASURES Figure 7.9 D A cross section from Bald Hill to ' the mouth of Bullock Creek on the coast. A = N.Z.M.S. F 36/025123 D GREENLAND GROUP 10 1ARNOTT BASALT AI = N.Z.M.S. F37/033095 A" = N.Z.M.S. F37/048077 The cross section is shown in a conventional style where faults are interpreted as steeply dipping normal faults. Where shallow dips are apparent at the surface (e.g. Mistake Fault) the faults turn and dip steeply beneath the surface. -275- with a greater density of outcrop data. Those smaller scale faults that decrease in dip asymptotically downwards from the synorogenic erosion surface, near Breccia Creek (Fig. 7.4), are also typical of an imbricate type of sys tem. An imbricate system of faults is also apparent in the Gates Creek area. 2. The succession in Tokakoriri Creek, characte rised by angular unconformities witn large pieces of the sequence not represented, is a typical basin margin succes sion. Anomalously, the succession is in close proximity to a thick, complete sequence of Cetaceous and Tertiary Forma tions, including the thickest sequence of the Abbey lime stones, exposed along the coast. The Tokakoriri Formation and the Abbey Limestone are not represented in the Tokako riri Creek succession. Normal faulting is not an" adequate mechanism to juxtapose such contrasting successions~ one from the basin margin and one from the central part of the basin, although large strike-slip displacements could. 3. Assuming that the presence of the Abbey lime stone continues to the south of the Abbey Rocks vicinity, the close proximity of the Law Coal Measures to the Abbey Limestone, both of which were deposited at the same time, is more likely to be the product of faulting rather than a rapid facies change, and again normal faulting is not an adequate mechanism for the juxta-position of the two forma tions unless a large strike-slip component is responsible (see "4"). 4. If strike-slip faulting is used to juxtapose unrelated parts of the sequence, the lateral extent of the faults and the amount of offset that the faults must accom modate, implies that the outcrop pattern, which is structu rally similar for at least 25km south of the Paringa River, should continue along strike to the north of the Paringa River and not stop on the south-west side as it appears to. The outcrop pattern on the north-east side of the Paringa River is very different from the outcrop pattern on the south-west side (see Map 1). The fault bounded strip of -276- Tertiary Formations to the west of the river is not appar ent on the east side, and yet as previously described there seems to bea continuity of the cretaceous sequence across the paringa River southeast of the Mistake Fault, preclud ing truncation of the northeast striking structures by a major fault down the Paringa River valley. An alternative is to explain the outcrop pattern, faulting and folding patterns, using a model based on a thrust system. Three cross sections are presented (see cross sections in the map pocket) and each is discussed in turn. Gates Creek Cross section In the Gates Creek cross section (uppermost section) the Mistake Fault is interpreted as a sole thrust fault in what a duplex thrust system that has subsequently been buckled, with further compression into an antiformal stack (Fig. 7.10). The Mistake Fault is shown dipping to the south because the only well exposed outcrop of the fault plane in Coal Creek on Bald Hill shows the fault to be at a very low angle and in some places horizontal, and indicates that the Greenland Group has been thrust over Tertiary sediments. Further evidence in the Gates Creek area, shows the Greenland Group to the south of the Mistake Fault to have upthrown and stripped of the bulk of the Cretaceous Tertiary sequence, and the downthrown side of the fault, to the north, has, predictably, preserved the greater thick ness of sediments. The splay that branches out from the Mistake Thrust Fault at depth which does not crop out, and is thrusting the Tertiary sequence (Abbey Formation) over Arnott Basalt, crops out on the coast to the south-west of Gates Creek and in that area is thrusting the Abbey Formation over the Tokakoriri Formation and Arnott Basalt (interpreted from data collected by M. Aliprantis, MSc thesis in prep.). -277- LEADING . IMBRICATE FAN IMBRICATE, FANS { TRAILING IMDRICATE FAN THRUST SYSTEMS HINTERLAND DIPPING DUPLEX DUPLEXE.S - ANTIFORMAL STACK FORELAND DIPPING OUPLEX Figure 7.10 The classification of different thrust systems (Boyer et al. 1982). A FORELAND HINTERLAND B Cleavoge .;\. " : " -- ...... ~ ":::"J-,'<" ...... ;...... :,:: ...... :::.,~:~.. ~~.5' ~~ ...... foreland 'dipping - - - - , ...... """"~~-i~':::-::...... -.;;:--.::".:,. ,,...... ,,.::--;;;:,::;,~ -C""'M-L ...... ,,~,~, subsidiory roulls ,"-" " ... " Incipienl horse " " with rolling hinge Figure 7.11 Formation of forward dipping duplexes. Horses are numbered from oldest "Ill to "5" which is not yet fully developed. The bedding within horses may be predominantly the right way up (A) or upside down (B). Although structures often face down, they are always forward facing (after Boyer et al. 1982). -278- steeply dipping faults in the Greenland Group below the Mistake Fault are interpretive and represent the prod ucts of block faulting in the basement during sedimentation of the cretaceous sequence, and prior to thrusting. The antiformal stack thrust system explains three features of the outcrop pattern on the west and east sides of the Paringa River, each of which will be discussed in turn. 1. From the south to the north within Gates . Creek, the fault bound packages of sediments all appear to young and dip in the same direction but their stratigraphic posi ti.on is reversed so that the Abbey Formation underlies the Tokakoriri Formation and the Tokakoriri Formation underlies the Tauperikaka Formation. The development of 'horses in which the sediments are forward facing, but the horses, are in a reverse stratigraphic order a typical development a forward dipping duplex (Fig. 7.11). 2. As the fault bounded strip of Tertiary sediments does not appear to crop out on the east side of the Paringa River, it is logical to assume that the Tertiary sediments are exposed through an eyelid window in a thrust, and that the axis of the folded thrust surface plunges beneath the stratigraphy that crops out on the east side of the Paringa River (Campbell, J. pers. comm.). Windows may form by simple differential erosion into undisturbed planar faults, but they usually form through culminations (Boyer & Elliot 1982; Diegel 1986). 3. Assuming that the stratigraphy to the east of the Paringa River is underlain by a s'ole thrust, the north west trending fault system in the outcrop is probably an emergent imbricate fan system exposed around the anti formal closure which explains the large amount of structural thickening in the Cretaceous Formations between Paringa Hill and Lagoon Creek. For example, Cotton (1985) esti mated .the Tauperikaka Coal Measures (of Nathan 1977) in the Paringa River area as up to 1500m thick, however, the Tau- -279- perikaka Formation (new), which includes all of the sedi ments of the Whakapohai Sandstone (Nathan 1977), is only approximately 100m thick in the type section and probably no more than 200m thick elsewhere, once structural thicken ing has been taken into account. Tokakoriri Creek to Monro Beach Cross section In the cross section the Mistake Fault is shown as a sole thrust in an imbricate system. If the imbricate fam ily of subsidiary contraction faults, which are shown curv ing from the sole thrust, also curve to a roof thrust, the thrust system will be a duplex. Although a roof thrust is not shown in the cross section from Tokakoriri Creek, the style of deformation suggests the presence of a roof thrust extending from an area offshore, over the section shown and dipping to the south of the section. The Greenland Group and Cretaceous Formations lie within a thrust sheet (The Mistake Thrust Sheet) which has been thrust over the under lying sequence. Compression has also buckled the duplex into an anti formal stack. The thrust system explains three major features of outcrop pattern: 1. The most important factor is the explanation of the close proximity of a basin margin sequence, which crops out in Tokakoriri Creek with the thick sequence of Abbey limestones. Using the thrust system, the limestone, together with the Tauperikaka Formation, (which is also not represented in the Tokakoriri Creek sequence), are thrust from the south-east with the Mistake Thrust Sheet over the Tokakoriri Creek sequence. Greenland Group, otumotu Forma tion and Butler Formation sediments are also thrust over the Tokakoriri Creek sequence with the thrust sheet. with the effects of crustal shortening removed, the Abbey lime stone probably lay a considerable distance to the south east of the Tokakoriri Creek sequence. -280- 2. The model provides an explanation for the out crop pattern which shows from the south-east to the north west fault-bounded Paleozoic, Tertiary, Paleozoic and Cre taceous juxtaposed blocks between which there is little marked change in the elevation of the synorogenic erosion surface. A change in positive relief between the blocks might be expected if normal faulting was preferentially uplifting the Greenland Group faulted blocks. 3. The large scale recumbent folding in the Creta ceous sediments on the coast is a very different style of structural deformation compared with the open gently plung ing folds of the Cretaceous and Tertiary sediments 500m away in the Tokakoriri Creek succession. Clearly the sedi ments that comprise the Mistake Thrust Sheet have been thrust a relatively long distance and the buckling and folding of sediments in the thrust sheet is probably mainly a response to compression as a higher horse is folded over a lower horse above a glide horizon. The stratigraphy underlying the Mistake Thrust Fault does not reflect the amount of compression evident in the sequence in the Mis take Thrust Sheet. Bald Hill To Bishop's Folly Cross section In the Bald Hill to Bishop's Folly section the take Fault is shown as a sole thrust fault. The Mistake thrust sheet comprised of horses of Greenland Group, Tauperikaka Formation, and Tititira Formation sediments. The thrust sheet has been thrust from the south over the Greenland Group, Law Coal Measures and Tititira Formation. A sequence of Cretaceous rocks might also lie between the Greenland Group and the Law Coal Measures in the sequence underlying the thrust sheet. The system is a duplex system in which shortening has also bunched up the horses and buckled the basal thrust to form an antiformal stack. The monocline structure in the sequence underlying the sole thrust might also be due - 281 - to the shortening. The thrust sheet model explains three features of the outcrop pattern: 1. The thrust sheet is the most likely interpreta tion of the limited outcrop data on the Mistake Fault plane. The model also provides a reasonable mechanism for the interfaulting of the steeply dipping beds, of the Titi tira Formation with the Greenland Group and the structural thickening, by faulting, of the Tauperikaka Formation towards the coast. 2. The thrust model provides a method of increasing the original distance between the depositional sites of· the Abbey Formation and the Law Coal Measures, by compensating the immense amount of crustal shortening. 3. The thrust model provides an explanation for. the difference in the style of folding between the sequence below the-Mistake Thrust and the sequence within the Mis take thrust sheet. The three cross sections described are shown together in (Fig. 7.12). The differing widths of exposure of the sequence underlying the Mistake Thrust Sheet from south to north can be accounted for by changes in the degree of plunge of the antiformal axis of the folded Mis take Thrust Fault. Overall the axis of the Mistake Thrust Fault plunges to the north and eventually passes beneath the synorogenic erosion surface on the west of the Paringa River. The plunge of the Mistake Thrust Fault beneath the surface has concealed the sequence underlying the Mistake thrust Fault, and so that only the sediments of the Mistake Fault thrust sheet are exposed on the east side of the Paringa. The outcrop picture is complicated by the presence of an additional thrust fault (labelled UA") and overlying thrust sheet that crops out to the south and south-west of Abbey Rocks. It lies beneath the Mistake Thrust Fault (labelled "B") and is thrusting Tertiary sediments over -282- BLOCK DIAGRAM OF THE MISTAKE F AULT AND MISTAKE THRUST SHEET. INCLUDING UNDERLYING AND OVERLYING THRUST SHEETS Figure 7.12 Diagram shows the relationship of BLOCK 1 the three cross-sections (in map pocket) and the continuity of the Mistake Fault and Mistake Thrust Sheet from Bald Hill to the Paringa River. The general plunge on the axis of the folded Mistake Fault is also apparent. BLOCK 2 WHAKAPOHAI RIVER BLOCK 3 - Direction of thrusting The Mistake Thrust Sh.eet --- Aerial .extrapolation of the Mistake Faull plane Thrust sheet u~derlying the Mistake Fault . D.RM.ADAMS U.of C. 19B6. -283- Arnott Basalt and the Tokakoriri Formation. The window through the Mistake Thrust Fault between Abbey Rocks and the Paringa River therefore reveals a lower thrust sheet, rather than revealing the sequence which. underlies the Mistake Thrust Fault from Waterfall Creek to Bald Hill. The roof thrust fault on the Mistake Thrust Sheet, labelled "C", also forms the sole thrust of a thrust sheet overlying the Mistake Thrust Sheet. Some fUrther implications of the thrust system are: a) since the Mistake Thrust diverges from and is in close proximity to the Alpine Fault at the Paringa River and the thrust surface of· the Mistake Thrust dips towards the Alpine Fault it is reasonable to assume that the Mistake Thrust is a splay off the Alpine Fault; b) the amount of structural deformation in the Pal eozoic, cretaceous and Tertiary sequence, which is a func tion of the compressive tectonic regime, probably decreases offshore away from the Alpine Fault. Therefore, a' rela tively undeformed sequence with horizontal reflectors, representing the leading thrust planes, are expected in seismic charts of offshore areas. Recent geophysical information (Esso Exploration and ProductionN.Z. Ltd. 1968; McNaughton & Gibson 1970) indicates that a very thick almost flat lying sequence occurs offshore (Nathan 1977). The charts have not been analysed for reflections repre senting thrust planes. c). The fault controlled valleys within the Green land Group, south of the Mistake Fault outcrop at Bald Hill, run parallel to the Alpine Fault (Map 1) and may be controlled by an imbricate system of splays off the Mistake Fault. d). cotton (1956) and Nathan (1977) interpreted the antiformal stack as a giant monoclinal fold trending paral lel to the coast from Milford Sound to 'Buttress Point, which also extended northwards for over 100km (interpreted from geophysical evidence - McNaughton et. al. 1970; in Nathan 1977). This implies the thrust system (antiformal stack) may extend for a considerable distance to the south and north of the mapped area. -284.- south Westlands Tectonic situation The Alpine Fault, which passes within 5km of the mapped area in the vicinity of the Paringa River S.H.6 bridge, runs at the foot of the Southern Alps down the length of the South Island, and indicates an offset of up to 450km between the Dun Mountain ultramafic belt in Nelson and corresponding rocks in otago. Recent work by Sibson et ale (1979)' on rock struc ture within the fault zone, and work by Woodward (1979) on gravity anomalies indicates that it is an oblique reverse fault dipping at a relatively low angle to the east. Dips along the length of the fault are likely to be highly vari able. The exposures between Franz Josef and Haast indicate a dip at least as low as 40° (Fig 7.13) which is sup ported by the work of Sibson et al. (1979). Wellman (1955) expressed concern at the apparent anomaly represented by the straight trace of the fault when considering the numer ous low dips observed on the fault plane in the South West land region and suggested that the low dips were due to , ~ superficial gravitational collaspe along a fundfmentally steeply dipping fault zone. Recent work indicates that the direction of motion on the fault has changed from strike slip in mid Tertiary times to oblique slip with a sUbstan tial compressional component of 20mm/y today, and up to 70km of shortening may have occurred perpendicular to the fault in the last 10 million years (Walcott 1979). The mechanics and partitioning of this strain component is a matter of debate. The shortening may have been accommodated in a com bination of any of 4 areas: 1) on the Alpine Faulti2) on faults east of the Alpine Fault; 3) as aseismic strain in rocks east of the Alpine Fault; 4) on faults within the rocks west of the Alpine Fault. Suggate (1968) estimated displacement on post gla cial terraces at Paringa and Berryman (1979) estimated post glacial movement at Okuru and on secondary faults of the -285- Figure 7.13 Havelock Creek (N.Z.M.S. 1: S78/565549). Alpine Fault exposure showing fault gouge (blue) within Haast Schist (Triassic Jurassic) which is thrust over post glacial gravels (post :- 14,000 years B.P.) (Photo - S Nathan). 286- Alpine Fault and on the eastern side of the Southern Alps. Berryman concludes that movement on both the Alpine Fault and the secondary faults and faults on the eastern flank of the Southern Alps only accounts for 50% - 60% of the tec tonic uplift. Walcott (1979) estimates that no more than one third of the plate motion has been accommodated by the Alpine Fault and that the remainder of the slip could not be accommodated on the relatively smaller faults east of the Alpine Fault, and concluded that the substantial part of the plate motion was accommodated in aseismic permanent strain within the rocks east of the fault. Several recent papers describe areas with oblique slip components where the shortening component· and the transcurrent component have been partioned into separate structural domains. Pettinga (1980) describes an accreting margin above the subducting Pacific ate on the east coast of the North Island where oblique shortening has caused thrusting in the rocks near the coast and strike-slip is evident in the axial ranges between the coastal section and the Taupo Volcanic Zone in the central North Island. The reverse situation would apply to South Westland where the transcurrent component is accommodated east of the Alpine Fault and on the Fault itself and the shortening component has been accommodated to a minor extent by oblique thrust ing of the fault but mostly by thrusting and shortening in the Greenland Group, cretaceous and Tertiary sequence to the ~est of the Fault. Woodcock and ROber~~on (1982) describe a Mesozoic Cenozoic continental margin in the south-west of Turkey' where an imbricate thrust belt has developed alongside a strike-slip belt due to the original mechanical inhomoge neity of the margin (Fig. 7.14). Foreland thrusting asso- - ciated with the Alpine Fault has been described further north in south Nelson where the Alpine Fault swings due north and runs parallel with the Glenroy Valley and the Haast schists on the east side of the fault are being BEY OAGLARI KUMLUCA ZONE GOOENE ZONE '. ,, ,, I , N ,, 00 ~ SUt.ML ~~ !,o ~~~ verticol stole' horlz. scale 'c. ~. ,st.wI1IIO'IIl ""rW-'" loll ...... )4 -''';:' Figure 7.14' ·f\n imbricate thrust belt developed alongside a strike sUp belt in an oblique slip tectonic in south-west The two belts have developed due to the mechanical of the (Woodcock et al. 1982) -288- thrust over the Western Province (Rose 1985). The rocks to the west of the Alpine Fault are clearly accommodating much of the shortening. Campbell & Cutten (1985), working to the west of the Alpine Fault in the region of the Glenroy Valley, have described a complex thrust zone where a large allochthon has been detached and emplaced on a spoon shaped, heavily sheared thrust affected by post emplacement folding. The complex underlying the thrust has also been involved in imbricate thrusting of fault bounded basement rocks (Fig. 7.15). The geographical situation of the South Westland sequence west of a major tectonic boundary (Alpine Fault) and with a strike-slip regime with a large component of shortening to be accommodated, is therefore, highly condu cive to the development of a system in which strike-slip mainly concentrated within ·the Alpine Fault zone and .the shortening component disseminated aCross a broad zone east and west the Fault. Much of the compression that Wal cott (1979) attempted to accommodate as aseismic strain the rocks the east of the fault, or shortening that Adams (1978) suggested was accommodated by uplift and ero sion in the Southern Alps more likely to have been accommodated in a South Western thrust zone, as well as on faults in otago (e.g. the Dunstan Fault). The thrust sys tem proposed for the South Westland sequence accommodates a large proportion of the shortening that may have occurred in the last 10 million years. Thrusting in the South Westland sequence can only be dated as post Miocene which is after the time of deposition of the Tititira Formation, but thrusting probably coincides with the change to a SUbstantial compressional regime and a thrust component on the Alpine Fault. -289- a) SECTIONS THROUGH THE MATAKITAKI ALLOCHTHON NW SE tntlr•• .... ,- ..... , - -- - - III " 10 10 0 -5 r -10 -10 Figure 7.15 Sections through the structure west of the Alpine Fault in the vicinity of the Glenroy and Matakitaki Rivers, showing six thrust sheets within ... the imbricate thrust system. WSW a: u ENE a} Two sections through the upper three sheets within the folded ... e I~ I~ ~ imbricate thrust system. \ 10 ,6. IQ b} . Cross-section to the south of sections "a." Shows the lower three sheets structur:ally below sheets in figure "art (Campbell & Cutten 1985, unpublished diagrams). -10 PRE TERTIARY UNITS Sparoo Fm o Haasl schist o McNe. granodiorite Moilai Group Glenroy Metamorphic Froo Flo I Fm ( I • limestone) 1P£l Comple" Horse Terrace Fm Lee River Group :8 lI'oabbro dodunile Monol., Fm km o 2 G Oouble Creek Fm b) THE ALPINE FAULT ESE - WNW CROSS SECTION IN THE UPPER GLENROY Brllli. ShtQf' POUt,n SympCHhtflc youn .. 1no ~I-yaunoinll •co Sh.ar en S2 I : ." :> i% LII c co ESE <> U 20 I~ 15 -- --; 10 -10 . -20 Biolihl Zona Chlorite -lO Zona RAPPAHANNOCK GROUP PRE TERTIARY UNITS 1 o DEVILS KNOB 1 ,",' MI SChi'IOSiIY} o FYFE METAMORPHIC COMPLEX DSPARGO III ~ Schi,tosity Cl ALFRED FORMATION - OF.ROG FLAT MT ARTHUR GROUP lIlT CANN GRANITE -290 CONCLUSION In conclusion, a thrust model is presented that describes the type of structural regime. that probably exists in South Westland, a model that requires refining through further, and more d~tailed, structural mapping. The thrust system is a less surprising model compared to the more conventional normal and strike slip faulting.m.od els with respect to: the available outcrop evidence, the paleogeography of the Cretaceous Tertiary succession, the outcrop pattern (particularly to the east and west of the paringa River) and the present geographical situation of South Westland with respect to today's tectonic regime. The direction of motion on the Alpine Fault has changed from strike-slip in mid Tertiary times to oblique slip with a SUbstantial compressional component in post Miocene time. A sUbstantial amount of shortening, in the range of 40km and possibly more, has occurred perpendicular to the fault. The transcurrent component is probably accommodated east of the Alpine Fault and on the Fault itself and the shortening component has been accommodated to a minor extent by oblique thrusting on the Fault but mostly by thrusting and shortening in the Paleozoic, Creta ceous and Tertiary rocks to the west of the Alpine Fault. The shortening component is also accommodated in thrust and reverse faulting and folding well to the east of the Fault. The Mistake Fault, a splay off the Alpine Fault, is a sole thrust fault in duplex thrust system which has subsequently been buckled, with further compression into an anti formal stack. The outcrop pattern is complicated by the presence of an additional thrust fault and overlying thrust sheet that crops out to the south and south-west of Abbey Rocks which lying beneath the Mistake Thrust Fault, and which is thrusting Tertiary sediments over Arnott Basalt and the Tokakoriri Formation. The possibility of the existance of further thrust sheets above and/or below the Mistake Thrust Sheet is likely and requires further investigation. -291- A model in which both the Cretaceous and Tertiary rocks are being thrust westward has major implications for the paleogeography of both Cretaceous and Tertiary rocks, because the Cretaceous and Tertiary sedimentary basins must have lain to the east of a basement high. Three major structural implications of the thrust model are:. 1). Analogies with similar foreland structures elsewhere suggest that the apparently simple almost flat lying sequence revealed in the seismic stratigraphy off~ shore could contain blind thrusts and inversions or repeti tions of the Cretaceous-Tertiary stratigraphy. 2). The thrust model suggests that cumulative strain rates are expressed well west of the Alpine Fault and therefore geodetic monitoring of strain for a ·few kilo metres on either side of the Fault may give misleading results. Imbricate systems usually young in the age and activity of faults both from top ~o bottom and from hinter land to foreland. Triangulation patterns established on the uppermost and oldest thrust sheet will not record either the thrusting occurring lower in the system or the propagation of the active tip line well to the west.Fur thermore both the strain geometry and rates are inhomoge neous between belts on either side of, and through the Alpine Fault zone. 3). Imbricate thrusting appears to project along the Alpine Fault to the north and sguth of the area mapped and is also apparent to the west of the Alpine Fault in the region of the Glenroy Valley, South Nelson (Campbell and cutten 1985). Predictably, if thrusting has occured in these two areas, it is likely similar thrust systems are developed along the entire length of the Alpine Fault which suggests that other areas of the West Coast geology may require to be reassesed. -292- CHAPTER EIGHT 8.0 GEOLOGICAL HISTORY The Cretaceous Period The presence of localised alluvial fan sedimentation in the mid Cretaceous indicates areas of SUbstantial relief and tectonic activity prior to and d~ring deposition of the Tauweritiki Member (Otumotu Formation). Alluvial fan wedge sediments merge with alluvial plain sediments and a system of fault controlled valleys and uplifted areas is implied. stratigraphically and sedimentologically, the Tauweritiki Member is similar to the Hawk's Crag Breccia of the Poro rari Group (Laird in/tress 1987), which occurs on both flanks of the Paparoa Range in Westland, and Laird suggests deposition in grabens or fault angled depressions. Tectonic activity died down during deposition of the Topsy Member and an inland semi-arid, tectonically stable, basin aggraded with fluviatile and lacustrine and then ephemeral flood and lacustrine deposits until sediment accumulation ceased in the Motuan. The Topsy Member is sim ilar to the Bullock Formation (Laird in Press) of the Poro rari Group in Westland which was deposited largely in a lacustrine environment. The Otumotu Formation was mainly derived from the Greenland Group, although the Tuhua Group provided a minor input. A simplified reconstruction of the Cretaceous Geology of New Zealand (Bradshaw et ale 1980) displaces the South Westland basin from the present day position to a position approximately 100km off shore from Fiordland's south-western coastline (Fig. 8.1). The Mid Cretaceous Puysegur-1 sequence (Fig. 8.2) in the south-western corner of Fiord land, which contains microfloral assemblage similar to those within the Topsy Member, may represent deposition from trac tion currents in a terrestrial-marginal marine environment and later in a sub-marine fan environment. The South West land basin was flanked by Gondwanaland to the west, and lay -293- 10 9 B 8 WOIt)opo In 60 . Caplits (. Oill Mr 5 M Po!eOlOIi: foreland 200 k m OpPfOl. I Figure 8.1 Simplified sketch of the carboniferous to Cretaceous geology of New Zealand shown as a series of terranes on the Gondwana margin. Left, possible original arrangement. Right, current configuration due to dextral faulting and strain related to the Indian Pacific plate boundary. The South Westland basin is marked with an asterisk (modified from Bradshaw et al. 1980). Green Isleis {"":,,~!':'..~ OLIGOCENE ., ','" ·.·0.·· .. " ...... Alternating marl and pelagic chalk. Chalky Island '., ...... •.• locally with thick interbeds of Formation coarse arkosic sandstone Conglomerate. sandstone. carbonaceous. siltstone. EOCENE Puysegur-2 and coal. with overlying redeposited sequence sequences including channellised breccia conglomerate west 01 Green Islets DISCONFORMITY :_--r'._'_':~. MID .. "~.''''':-:'. CRETACEOUS -=;..-r ~'.' Puysegur-1 "'::f;:.~.~ . • Alternating thick-bedded graded sequence ;::---:.. :-=-;-;;:.::.~" sandstone and carbonaceous siltstone ~.-.:;...~' ~'~:-=:~" 200 metres Conglomerate, cross bedded sandstone. carbonaceous siltstone. coal 100 to REGIONAL UNCONFORMITY Basement rocks Figure 8.2 /' Generalised stratigraphic column through the Balleny Group including the Puysegur-l sequence (Puysegur Point, south-west Fiordland) and Puysegur-2 sequence (Gates Harbour to Big River, south-west Fiordland). (Bishop 1986.)\ -294- inland from a coastline to the east. There is a hiatus in tectonic and sedimentary acti vity from the mid cretaceous (Arowhanan) until late creta ceous (Piripauan). During the Piripauan, coal forming swamps and lakes formed in depressions on the paleorelief of the Greenland Group basement and the otumotu Formation. Rivers flowed from a distant area of Greenland and Tuhua Group rocks undergoing uplift and erosion. Subsidence allowed water levels to keep pace with peat' deposition which resulted in thick (3m) seams of coal. Occasionally, rapid subsidence, forest fires or rising water tables were respon sible for an influx of sediment and caused drowning of peat swamps which established lakes. The land surface was cov ered by thick stands of forest (including Nothofagus) inter spersed with lakes and reed swamp environments and, the cli mate was probably more temperate or humid than in the mid cretaceous. The Butler Formation is derived from a Greenland Group and Tuhua Group source and indicates the granite is better exposed than in the mid Cretaceous. A disconformity at the top of the Butler Formation, marked by scouring and a change in sedimentation characteristics between the Butler Formation (Mp) and the Tauperikaka Formation (Mh), reflects a hiatus in sedimentation. During the early to mid Haumurian (Moeraki Member, Tauperikaka Member), coastal fluvial environment, with lat erally migrating low sinuosity streams, developed. A marine transgression from the south-east caused stream chan,nels to silt up, to keep pace with the rise in water table, and inactive tracts were subjected to repeated flooding. Back swamps are generally not represented due to their low pres ervation potential. The Moeraki Member sediments are derived mainly from local Greenland Group and Tuhua Group sources, and to a minor extent, from underlying cretaceous Formations. -295- During the early to mid Haumurian times a marine transgression from the south-east continued and a tide dom inated coastline, characterised by tidal inlets or embay ments, developed, which is reflected in the deposition of the Paringa Member. To the north-west, relatively sheltered tide and fluvial dominated estuarine environments developed at the landward end of the tidal inlets. The transgression continued from mid to late Haumurian times and established a large open marine bay in which both the. sediment grain size and the diversity and density of burrows decreased in an off shore direction (Rasselas Member sediments). The change in environment, within the Tauperikaka Formation from onshore to offshore may be responsible for changes in-the relative proportions of the constituents in the sediment composition. The rock fragment proportion is greatly depleted by coastal processes, the quartz proportion significantly increased and the relative proportion of the microcline increased to a minor extent. Alternatively, the compositional adjustments may result from changes in the source rock, from a Greenland Group and Tuhua Group source, to a hypothetical deeply weathered granitic landmass to the east or west of the present coastline (Nathan 1977). A hypothetical granitic landmass is unnecessary to explain the presence of quartz rich sandstones, which lac~ fine sand and silt size quartz grains and rock fragments, when a coastal environment, characterised by high energy tidal currents, is present. The Tuhua Group was probably better exposed than in the mid Cretaceous and provided abundant coarse quartz grains and microcline fragments. Throughout the Cretaceous sequence there is no evi dence to suggest sediments were derived from any other source other than: a) The Greenland Group; b) a granitic source, most likely the Tuhua Group and c) from underlying South Westland Formations, because there is no evidence of rock fragments derived from metamorphic rocks of a higher grade than the Greenland Group, or of grains derived from a plutonic source with a different composition from the Tuhua Group granites. The assumption that ,the.Paleozoic rocks of -296- the Fiordland complex have not at any time during the creta ceous been a source rock, has major implications. Firstly, the "central belt" of intensely deformed igneous and sedi mentary rocks that lay to the east of the South westland cretaceous basin was probably submerged, a fact supported by the marine rocks of the mid cretaceous Puysegur 1 Formation in south-western Fiordland. Secondly, up until the end of the Cretaceous, source rocks of sediments not in the immedi ate vicinity of depositional sites, probably lay to the west of the South Westland basin and are now encompassed within the Lord Howe Rise. Thirdly, mylonite fragments are derived from faults that were within the Greenland Group and Tuhua Group and not from the Alpine Fault or any fault within the Fiordland complex "central belt" rocks. The presence of mylonite fragments suggests a great zone of tectonic dislocation. With the onset of rifting of the New Zealand continent away from Gondwanaland at the end of the Cretaceous, major listric detachment faults may have developed with lithospheric extension (Bradshaw 1986). Ero sion of the fault zones may have provided mylonite frag ments, the crustal thinning would certainly have resulted in the marine transgression from the south-east. Evidence of a marine transgression in the late creta ceous is the earliest on the West Coast as a transgression is not recorded before Eocene time in north Westland and west Nelson (Suggate 1978),' although marginal marine condi tions are inferred in the Brunner Coal Measures at Greymouth (Fig. 8.3) in the Paleocene (J.Newman pers comm.). Extensional tectonics in late Haumurian time, causing thinning of the continental crust, was probably responsible for the eruption of the Arnott Basalt which was intruded into the otumotu, Butler and Tauperikaka Formations. GREYMOUTH WESTPORT QUATERNARY Eight Mile PLIOCENE AND O'Keefe s- 5-5- Formation UPPER MIOCENE Formation Stillwater Mudstone LOWER Welsh ~",.....,..-=-...-=t-lnongClhua MIOCENE f..'-i' ...... ,....,....O'+- Formation------....;..,.--:-~~~~l~~~otlko uo Limestone ...._-'--1->_----'" -'--It Cobden Tiropahi Limestone -I-I Limestone -1-, -, OLIGOCENE Waitakere Limestone -1-1-1- '-1-1-1 -=.,1-=1-1- Koiata Formation EOC E Island ''';'';~''';'':'''~~ Sandstone 07 Brunner Brunner cool measures Cool Measures -""'....,..~...... ;;;;;;o:-r=-r__-----=.;;:.::.:...:.:.::..:;;.;;;;-=-.=.:....:..-=--,._r:'~:r:;~.r;'1 ~~~~- Hawks UPPER Paparoa MID Crag Coal CRETACEOUS Breccia. Measures CRETACEOUS Ohika Hawks Crag Fo., filation r/".,..,..,-Breccia --.:..------:---vK'=a:::ra;;;m::e;;;a;-;G"'ro=nT;ite::::--1?;r/;"J/'XT'I MID PALEOZOIC Greenland Greenland Group . LOWER PALEOZOIC Group Charleston ? PRECAMBRIAN Metamorphic Group Figure 8.3 Generalised stratigraphic columns of the Greymouth-Westport sequences, North Westland. (Lewis and Laird, in press) -298- Tertiary Period The sediments of the Paleocene and early Eocene peri ods indicate general subsidence and a decreasing sediment supply until only fine mud and calcareous ooze w~s being deposited in middle Dannevirke time (lower Abbey Limestone) (Nathan 1977). During the Kaiatan sedimentation of a marl (upper Abbey Formation) continued in one part of the South Westland basin and was interrupted by periodic eruptions of the oti tia Basalt. Debris flows of basaltic breccias wheredepo sited on calcareous muds of the Abbey Formation (observed in exposures at the mouth of the Paringa River). To the west the marine part of the South Westland basin, erosion of source areas was responsible for the development of marginal marine alluvial fans (Law Coal Measures) between which coastal coal forming reed swamps developed producing seams of up to 4m thick. The source area was composed Green land and Tuhua Group rocks and lay at some distance form the depositional centre, (indicated by textural maturity of fluvial transported and deposited conglomerates). Minor fluctuations in sea level are probably respon sible for the sequence of interbedded coal seams and sand stones, towards the top of the Law Coal Measures t which were deposited during a marine transgression. To the south of the area, at Jacksons Bay and Martins Bay,the coal measures of late Eocene age lie directly on basement and are suc ceeded by limestone (Suggate 1978). Either just before, or during the Kaiatan a second source. area consisting of Green land Group, andesite and dacite may have provided angular boulder laden debris flows (within Buttress Conglomerate), presumably from an area adjacent to the depositional site. However the timing of the deposition of the Buttress Con glomerate remains uncertain and deposition could have occurred at any time before the Kaiatan. The tectonism and erosion that led to deposition of the Law Coal Measures may be related to the extensional tec- -299- tonics during the Eocene which occurred in the Greymouth and westport areas where marginal marine coal measures are over lain by marine formations (Fig. 8.3). Extensional tectonics during the late Eocene would explain both the' eruption of the otitia Basalt and the marine transgression. The Law Coal Measures have stratigraphic and sedimentary similari- , . ties to the Puysegur 2 sequence (Fig. 8.2) which is also overlain by a marine sequence comparable to the post Eocene sequence in South Westland. In the Bald Hill area, the Law Coal Measures are overlain by the Tititira Formation with an unconformity which represents approximately 20 million years (Nathan 1977). Post Miocene structural History The direction of motion on the Alpine Fault has changed from strike-slip in mid Tertiary times to oblique slip with a SUbstantial compressional component in post Miocene time. A SUbstantial amount of shortening, in the range of 40km and possibly more, has occurred perpendicular to the fault, on the west side of the fault. The transcur rent component is probably accommodated east of the Alpine Fault and on the Fault itself and the shortening component has been accommodated to a minor extent by oblique thrusting on the Fault but mostly by the development of duplex thrust systems in the Paleozoic, Cretaceous and Tertiary rocks to the west of the Alpine Fault and also in thrust and reverse faulting and folding well to the east of the Alpine Fault. structural evidence of the faulting and folding that occurred during the Cretaceous and Eocene has been distorted by the more recent post Miocene thrusting, which combined with the limited amount of exposure in south Westland, pre vents any further interpretation than has already been inferred from sedimentological studies. -300- Imbricate thrusting appears to project along the Alpine Fault to the north and south of the area mapped and is also apparent to the west of the Alpine Fault in the region of the Glenroy Valley, South Nelson (Campbell and Cutten 1985). Predictably, if thrusting has occured in these two areas, it is likely similar thrust systems have developed along the entire length of the Alpine Fault. -301- ACKNOWLEDGEMENTS Acknowledgement and special thanks are due to Dr. J.D. Bradshaw (University of canterbury) for his help in the field and for discussions and constructive criticism of naterial in this thesis which has benefited from his reviews. I wish to express my appreciation to Mr. S. Nathan (Geological Survey) for suggesting the project, providing logistic support during the mapping stages of the project and for providing access to, and funds for, ·coal chemical analyses and pollen analyses. The initial stimulus for the project came from a contract with the Forest Service and I acknowledge their financial support and the assistance pro vided by forestry personal. I acknowledge and express my thanks to Mr. N.A. New man and Dr. J. Newman (University of Canterbury) for the. many hours they spent teaching me coal geochemical and petrographic techniques, and for the discussions on, and review of, aspects of this manuscript. I also acknowledge and thank Mr. M.D. Johnston (University of Canterbury) assessing coal reflectance. I acknowledge and express. my thanks to Mrs. J.K. Campbell (University of Canterbury) for her thought provoking discussions on, and reviews of the structural geology, and Dr. S.D. Weaver (University of Can terbury) for reviewing the section on the Arnott Basalt. The manuscript has also especially benefitted from the con tribution of a plant fossil analysis by Mr. I. Daniel (Uni versity of canterbury) and by access to palynological data prepared by Dr. I. Raine (Geological Survey). Thanks are also due to Mark Aliprantis for accompany ing me into the more inaccessible parts of the field area during the course of mapping and also for his stimulating discussions in the bar of the Fox Glacier Hotel whilst wait ing for torrential rain to subside. I am grateful to other field assistants including Scott Petersen, John Kennedy, Mike Stewart, Richard Doyle, Udo Wezenberg and Lisa Brownie. Special thanks are also due to Lisa for her patience and tolerance whilst typing this manuscript. -302- The following Geology Department technical staff (University of Canterbury) are thanked for advice and assis tance: Albert Downing (photography), Kerry Swanson and Carol wiltshire (staining thin sections), Karen Holder (thin sec tion preparation) . I also want to express my thanks to those who have . permitted me to quote from, and use unpublished material and illustrations, which includes: Lewis and Laird in press, "Gravity flow deposits"; Laird in press, "Sheet S37 - Puna kiki"i Campbell and Cutten for structural cross sections through an area west of the Alpine Fault, South Nelson. without the support and encouragement of my family, this thesis would not have been possible. -303- REFERENCES Adams, C.J. 1975: Discovery of Precambrian Rocks in New Zealand: age relations of the Greenland Group and the Constant Gneiss, South Island.' Earth and Planetary Science Letters 28: 98 - 104. Adams, J. 1978: Late Cenozoic Erosion in New Zealand Ph.D thesis, Victoria University, Wellington. Aliprantis, M.D. in prep: Tertiary Geology of the Paringa Region, South Westland, with Special Attention to a Structurally Deformed Coastal Section. Msc thesis, University of canterbury, New Zealand. Allen, J.R.L. 1963: The ification of cross- stratified units, with notes on their origin. Sedimentology, 2: 93 - 114. Allen, J.R.L. 1964: Studies in Fluviati Sedimentation six cyclothems from the Lower Old Red Sandstone, Anglo Welsh Basin. Sedimentology 3 : 163 - 198. Allen, J.R.L. 1965: A review of the origin and characteristics of recent alluvial sediment~. Sedimentology 5 : 89 -191. Allen, J.R.L. 1965a: Fining upwards cycles in alluvial successions. Geological Journal, 4: 229 - 246. Allen, J.R.L. 1965b: The sedimentation and palaegeography of the Old Red Sandstone of Anglesey, North Wales. Proc. Yorkshire Geological Society, 35: 139 - 185. Allen, J.R.L.i Friend, P.F. 1968: Deposition of the Catskill Facies, Appalachian Region: with notes on some other Old Red Sandstone Basins. In: Late Paleozoic and Mesozoic Continental Sedimentation, northeastern North America (Ed. by G. de V. Klein), -304- Special Paper of the Geological Society of America, 106: 21 - 74. Allen, J.R.L. 1970a: Studies in fluviatile sedimentation: A comparison of fining-upwards cyclothems with special reference to coarse-member composition and interpretation. Journal of Sedimentary Petrology 40: 298 - 323. Allen, J.R.L. 1970b: A quantitative model of grain size and sedimentary structures in lateral deposits. Geological Journal 7: 129 - 146. Allen, J.R.L.; Banks, N.L. 1972: An iriterpretation and analysis of recumbant-folded deformed cross-bedding, (.; ~f/ Sedementologre 19: 257 = 283. .. Allen, J.R.L. 1974: Studies in fluviatile sedimentation: lateral variation in some fining upwards cylcothems from the Red Marls, Pembrokeshire. Geological Allen, J.R.L. 1981: Lower cretaceous tides revealed by cross-bedding with mud drapes. Nature 289 : 579 - 581. Andrews, P.B. 1982: Revised Guide to Recording Field Observations in Sedimentary Sequences. New Zealand Geological Survey Report 102, Upper Hutt 74pp. Barwiss, J.H. 1978: Sedimentology of South Carolina tidal creek point bars and a comparison with their fluvial counterparts, 129 ~ 161. In: Fluvial Sedimentology Ed. by Miall, D. Canadian Society of Petroleum Geologists Memoir 5: 859pp. Barwiss, J.H. 1985: Tubes of the Modern Polychaete Diop atra Cuprea as Current Velocity Indicators and as Analogs for Skolithos - Monocraterion. In: Curren, H.A. (ed). Biogenic Structures: their use 305- in Interpreting Depositional Environments. Society of Economic Paleontologists and Mineralogists Special Publication No. 35: 225 - 237. Bernard, H.A.; Major, C.F.Jnr 1963: Recent meander belt deposits of the Brazos River: an alluvial 'sand' model. Bulletin of American Association of Petro leum Geologists, 47: 350pp. Berryman, K.R. 1975: Immediate Report: Earth Deformation studies reconnaissance of the Alpine Fault. Earth Deformation section, D.S.l.R. Berryman, K.R. 1979: Active Faulting and derived P.H.S. directions in the South Island, New Zealand, in The Origin of the Southern Alps, Royal Society of New Beuf, S.; Biju-Duval, Bi de Charpal, 0; Rognon P.; Gariel 0; Bennacef, A. 1971: Les Gres duPaleozoique Inferieur au Sahara. Editions Technip. Paris. 464pp. Bishop, D.G. 1986: Geological map of New Zealand Sheet B46 PUYSEGUR - New Zealand Geological Survey. Government Printer, New Zealand. Blatt, H.i Middleton, G.; Murray, R. 1980: Origin of Sedimentary Rocks. Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 782pp. Bluck, B.J. 1967: Deposition of some Upper Old Red Sandstone Conglomerates in the Clyde area: A study in the significance of bedding. scottish Journal of Geology 3, part 2 : 141-167. -306- Boersma, J.R. 1969: Internal structure of some tidal mega ripples on a shoal in the Westerschelde Estuary. The Netherlands report of a preliminary investigation. Geologie en Mijnbouw 48 (4) : 409-414. Boersma, J.R.; de Raaf, J.F.M. 1971: Tidal deposits and their sedimentary structures (Seven examples from Western Europe). Geologie en Mijnbouw 50 (3) 479-504. Boersma,J.R.; Terwindt, J.H.J. 1981: Neap-spring tide sequences of intArtidal shoal deposits in a mesotidal estuary. Sedimentology 28: 151-170. Bolitho, W.J. 1937: Memorandum to: The Secretary, Employment Division, Department of Labour, Wellington. ·24pp. Boyer, S.E.; Elliott, D, 1982: Thrust Systems. The American Association of Petroleum Geologists, 66 (9): 1196-1230. Bradshaw, J.D.; Adams, C.J.; Andrews, P.B. 1980: Carboniferous to cretaceous on the Pacific margin of Gondwana: The Rangitata Phase of New Zealand. Fifth International symposium, Wellington, New Zealand: 217 - 221. Bradshaw, J.D. 1986: Reassembly of crustal blocks in the South West Pacific: impact of Crustal extension implicit in new models of passive margin development. Geological Society of New Zealand Inc. 1986 Annual Conference: Programme and Abstracts, p 27. Bradshaw, J.D. 1986: Book Review on Cretaceous Cenozoic Sedimentary Basins of the West Coast Region, South Island, New Zealand, by: Nathan, S.; Anderson, H.J.; Cook, R.A.; Hoskins, R.H.; Raine, J.I.; Smale, D. New Zealand Geological Survey, Basin Studies Bulletin. In: Geological Society of New Zealand Newsletter 74: 50-54. -307- Breyer, J.A.i McCabe, P.J. 1986: Coals Associated with Tidal Sediments in the Wilcox Group (Paleogene), South Texas Journal of Sedimentary Petrology 56 (4). Brown, K.W. 1986: The Palynology of the Kaitangata Coalfield, South-east otago. MSc thesis, University of Canterbury, New Zealand. Bull, W.B. 1972: Recognition of alluvial-fan deposits in the stratigraphic record. In: Recoghition of Ancient Sedimentary Environments. Ed. by K.J. Rigby and W.K. Hamblin. Special publication of the Society of Economic Paleontologists and Minerolo gists, (Tulsa) 16: 68 - 83. Campbell, J.R.; cutten, H.N.C. 1985: Foreland Structure West of the Alpine Fault in the Region of the Glenroy Valley, South Nelson. Christchurch Conference Programme and booklet. Miscellaneou~ Publication 32A. Geological Society of New Zealand Inc. p 28. Cant, D.J.; Walker, R.G. 1976: Development of a braided- fluvial fac model for the Devonian Battery Point Sandstone, Quebec. Canadian Journal of Earth Collinson, J.D.; Thompson, D.B. 1982: Sedimentary Publishers Allen & Unwin. 240pp. Cooper, R.A. 1974: Age of the Greenland and Waiuta Groups, South Island, New Zealand. New Zealand Journal of Cotton, C.A. 1956: Coastal history of Southern Westland and Northern Fiordland. Transactions of the Royal Society of New Zealand, 83 {3}: 483-488. -308- cotton, R.J. 1985: Report on Paringa Licence CPL 35 175. Unpublished report. Pike River Coal Company, Auckland, New Zealand: 39pp. Cox, A. 1877: Report on the Westland District. Zealand Geological Survey Report on Geological Exploration 1874 - 76 (9): 63 - 93. Demico, R.V.i Kordesch, E.G. 1986: Facies sequences of a semi-arid closed basin: the Lower Ju'rassic East Berlin Formation of the Hartford Basin, New England, U.S.A. Sedimentology 33: 107 - 118. Dennison, J.M.V.i Shea, J.H. 1966: Plate Tectonics and Sandstone Compositions. American Association of Petroleum Geologis.t.s 63: 2164-2182. Diegel, F.A. 1986: Topological constraints on imbricate networks, examples from the Mountain city window, Tennessee, U.S.A. Pergamon Press Ltd. Journal of Structural Geology, 8: (3/4) 269-279. Diessel, C.F.K. 1984: Coal Geology. Part I and II. Australian Mineral Foundation. Workshop Course 282/84. Douglass, C. 1890: General Report, map and cross section, Coal Formation, Arnott Range, South Westland. General Survey Office, Wellington, New Zealand. Ekdale, A.A. 1985: Paleogeography - imatology and ecology, 50: 63-81. In: Paleoecology of the Marine Endoberthos. sevier Science Publisher B.V., Amsterdam. Emery, K.O. 1968: Relict sediments on continental shelves of the world. American Association of Petroleum Geologists, Bulletin 52: 445-464. -309 Esso Exploration and Production (N.Z.) Ltd 1968: Geoph ysical report PPL712 (South Greymouth) (Unpublished Petroleum Report P.R. 400. lodged in New Zealand Geological Survey Library, Lower Hutt.) , Evans, H.J. 1937: Memorandum on Prospecting' Party to the Haast Area. Addressed to: The Secretary. Empl'oyment Division, Department of Labour, Wellington. 8pp. Folk; Andrews; Lewis. 1980: Detrital Sedimentary Rock Classification and Nomenclature for use in New Zealand. New Zealand Journal of Geology and Geophysics 13. Gair, H.S.~ Gregg, D.R. 1962: Geology of the Whakapohai (Unpublished Geological Survey.) Galehouse, J.S. 1971: point counting, Procedures in Sedimentary Petrology, 385-407. Glennie, K.W. 1970: Desert Sedimentary Environments. Amsterdam: Elsevier Publishing Co. Haast, J. 1879: Geology of the Provinces of Canterbury and Westland, New Zealand. Times Office, Christ church, New Zealand. 486pp. Hantzschel, W. 1975:, Treatise on Invertebrate Paleontol ogy, Part W. Miscellanea. Supplement: Boulder, Colo. and Lawrence, Kansas; Geological Society of America and University Kansas Press: 229pp. Harms, J.C. 1969: Hydraulic significance of some sand ripples: Geological Society of America Bulletin, V. 80: 363 - 396. -310- Harms et ale 1975: Stratification produced by migrating bedforms. In: S.E.P.M. Short Course, notes 2. Depositional Environment as Interpreted from Primary Sedimentary Structures and stratified sequences. Harms, J.C.; Southard, J.B.; Walker, R.G. 1982: Structures in clastic rocks. S.E.P.M. Short Course no.9. Calgary. Hill, G.W. 1985: Ichnofacies of a mo~ern size-graded shelf, Northwestern Gulf of Mexico. In: Biogenic Structures: Their use in interpreting depositional environments (Ed. Curran, H.A.). society of Eco nomic Paleontologists and Minerol6gists. Special Publication No. 35 : 95 -210. Hooke, R. Le B. 1972: Geomorphic evidence for Late Wisconsin and Holocene tectonic deformation, Death Valley, California. Bulletin of the Geological Society of America 83: 2073 - 2098. International Committee for Coal Petrology, 1971: Inter national Handbook of Coal Petrology. Centre Nationale de la Recherche scientifique. Paris. (Supplement 2nd Ed.) Jackson, R.G. 1978: Preliminary evaluation of lithofacies models for meandering alluvial streams. In: Fluvial Sedimentology, Miall, A. D. (ED.). Canadian society of Petroleum Geologists, Memoir 5: 543-577. Kreisa, R.D.; Moiola, R.J. 1986: Sigmoidal tidal bundles and other tide-generated sedimentary structures of the curtis Formation, Utah. Geological Society of America Bulletin, 97: 381-387. Laird, M.G. in press (1987): Sheet S37 - Punakiki. Geological Map of New Zealand 1: 63360. Depart ment of Industrial and Scientific Research, Wel lington, New Zealand. - 31 1 - Lewis, D.W. 1982: Practical Sedimentology. Geology Department, University of Canterbury, New Zealand. Lewis, D.W. In Press: Gravity Flow Deposits: Processes and tectonics, subaerial to deep marine, .Northern South Island. Cretaceous to Rent, New Zealand. International Association of Sedimentologists 12th International Sedimentological Congress: Excursion 31B~ McCartney, J.T.; Teichmuller,·M. 1972: Coal Classifi cation by reflectance of vitrinite. Fuel 51: p68. McKee, E.D.; Crosby, E.J. 1967: Flood Deposits, Bijou Creek, Colorado, June 1965. Journal of Sedimentary Petrology. 37 (3): 829-851. McNaughton, D.A.; Gibson, F.A. 1970: play developing in New Zealand.· Mason, B. 1961: Potassium - Argon ages of metamorphic rocks and granites from Westland, New Ze·aland. New Zealand Journal of Geology and Geophysics, 4: 352- 356. Miall, A.D. 1977: A review of the braided river deposi tional environment. Earth Science Review, 13: 1 - 62. Miall, ~.D. 1978: Lithofacies types and vertical profile models in braided river deposits: a summary. In: Fluvial Sedimentology, 597-605. Miall, A.D. (Ed.) 1978: Fluvial Sedimentology. Canadian Society Petroleum Geologists, Memoir 5. Miall, A.D. 1982: Analysis of fluvial depositional systems. American Association of Petroleum Geologists, 20: 75pp. -312- Mildenhall, D.C. 1975: Collection of Palynological Samples for age and environment studies in New Zea land~ New Zealand Geological society, Technical Guide. Miller & Knox. 1985:, Biogenic Structures and Depositional Environments of a Lower Pennsylvanian Coal Bearing Sequence, Northern Cumberland Plateau Tennessee, U.S.A. In: Biogenic Structures, their use in interpreting depositional environments. Curran, H.A. (Ed.). Society of Economic Paleontologists and Mineralogists special Publication 35: 347pp. Moss, A.J. 1972: Bed-load sediments. Sedimentology, 18: 159 - 219. de Mowbray, T.; Visser, M.J. 1984: Reactivation Surfaces in ; subtidal Channel deposits, Oosterschelde, South west Netherlands. Journal of Sedimentary Petrology 54: no.3. Murchison, M; Westall, S.T. 1968: Coal and Coal Bearing Strata. Inter University Geological Congress. 13th. Oliver and Boyd, Edinburgh. 418pp. Mutch, A.; McKellar, I.C. 1964: Sheet 19 Haast. Geolo gical Map of New Zealand 1:250.000. New Zealand Department of Scientific and Industrial Research, Wellington. Nathan, S; 1977: cretaceous and Lower Tertiary stratigraphy of the coastal strip between Buttress Point and Ship Creek, South Westland, New Zealand. New Zealand Journal of Geology and Geophysics. 20 (4): 615-654. Nathan, S. 1978: Upper Cenozoic stratigraphy of South Westland, New Zealand. New Zealand Journal of Geology and Geophysics. 21 (3): 329 - 361. -313- Nathan, So; Smale, D. 1983: Petrological studies of cretaceous and Tertiary sediments from the west Coast Region. New Zealand Geological Survey Report, G 71. Nathan, S., et ale 1986: cretaceous and cenozoic sedimentary basins of the west Coast Region, South Island, New Zealand. New Zealand Geological Survey Basin Studies Newman, J.; Newman, N.A. 1982: Reflectance anomalies in Pike River coals: evidence of variability in vitri nitetype, with implications for maturation studies and 'suggate Rank.' New Zealand Journal of Geology and Geophysics, 25: 233 - 243. Newman, J. 1984: The petrology and paleoenvironmental setting of Brunner coal in Webb/Baynes Sector, i Buller Coalfield. Prepared for the New Zealand Mines Division, Ministry of Energy. New Zealand Newman,J. 1985: Paleoenvironments, coal properties, and their interrelationship in Paparoa and selected Brunner Coal Measures on the West Coast of the South Island. PhD thesis, University of Canterbury, New Zealand. 269pp. Newman, J. 1986: Coal type, rank and paleoenvironments in the Upper Waimangaroa sector, Buller Coalfield. Prepared for the New Zealand Mines Division as part of Coal Resources Survey. 49pp. Newman, N.A. 1985: Mineral Matter in west Coast coals. Draft Report to the New Zealand Energy Research and Development Committee. To be published as N.Z.E.R.D.C. Report. 314 Nio, S.D.: Siegenthaler, C.; Yang, C.S. 1983: Megaripple cross-bedding as a tool for the reconstruction of the palaeo-hydraulics in a holocene subtidal environment, south West Netherlands. Geologie en Mij·nbouw 62: 499 - 510. Norrish, K.; Hutton J.T. 1969: An accurate x-ray spetrographic method for the analysis of a wide range of samples. Geochim. Cosmochim. Acta. 33, 431 - 454. pettinga, J.R. 1980: Geology and landslides of the east ern Te Aute district, Southern Hawkes Bay. PhD thesis, University of Auckland. Raine, J.I. 1984: Outline of a Palynological Zonation of cretaceous to Paleogene Terrestrial Sediments in the West Coast Region, south .Island, New Zealand. Report. No. 109 New Zealand Geological Survey, Lower Raine, J.I. 1986: Palynological Dating of Late Cretaceous Rocks in south Westland (Map areas F36, F37 and G36) Report J.I.R. 11/86. New Zealand Geological Survey: .2mh. Raymond, G.R. 1985: Paleoenvironmental Analysis of the Taratu Formation (upper Members), Kaitangata Coal field, south otago. MSc thesis, university of Canterbury, New Zealand. Reading, H.G. (Ed.) 1978: Sedimentary Environments and Facies. Oxford, England. Blackwell Science Publication. Reineck, H.E.; Wunderlich, F. 1968: Classification and origin of flaser and lenticular bedding. Sedimen tology II: 99 - 104. -315- Reineck, H.E.; Singh, I.B. 1973: Layered sediments of Tidal flats, beached and shelf bottoms of the North Sea. In Depositional Sedimentary Environments. springer Verlag, New York. Reineck, H.E. 1975: German North Sea tidal ats. In: Ginsburg R.N. Ed. Tidal Deposits: 5 - 12. Springer, New York. Reineck, H.E.; Singh, I.B. 1980: Depositional sedimentary environments with refernce to Terrigenous Clastics. Springer-Verlag, New York; Heidelberg; Berlin. 439pp. Renton, J.J. 1982: Mineral matter in doal. In: Meyers, -ReA. Cede). Coal Structure. Academic Press, New York. 283 - 326. Rose, R.V. 1985: The Alpine Fault and structure of the Haast in the Glenroy and Matakitaki Valleys, South East Christchurch Conference Programme and Abstracts booklet. Miscellaneous Publication 32A. Geological Society of New Zealand Inc. p.73. Rust, B.R. 1978: Depositional models for braided alluvium. In: Fluvial Sedimentology (Ed. by Miall, A.D.) Canadian Society Petroleum Geologists 5: 605 - 625. Sewell, R.J.; Nathan, S. In prep: Geochemistry of Late Cretaceous and Early Tertiary Basalts from South Westland. New Zealand Geological Survey, church. 21pp. Seilacher, A. 1953: Studien zur Palichnologie II. Die fossilen Ruhespuren (Cubichnia): Geologie, Palaontologie, Abhandl. Ve98: 87 - 124. Seilacher, A. 1967: Bathymetry of trace fossils. Marine Geology 5: 413 - 428. -316- Sibson, R.H.; White, S.H.; Atkinson, B.K. 1979: Fault Rock Distribution and structure within the Alpine Fault Zone: A preliminary Account. In: The Origin of the Southern Alps, Bulletin 18, Royal Society of New Zealand: 55 -66. stach, E.; Chandra, D; Mackowsky, M.-TH.; Taylor, G.H.; Teichmuller, M.; Teichmuller, R. 1975: Stach's Textbook of Coal Petrology (2nd Ed.). Gebruder Borntraeger, Berlin; stuttgart. 428pp. stear, W.M. 1985: Comparison of the bedform distribution and dynamics of modern sandy ephmeral flood deposits in the South Western karoo region, Marshalltown, South Africa. sedimentary Geology 45: 209 - 231. stewart, M.; Nathan, S. : Paper on the Greenland Group of South Westland. University of Canterbury, New Zealand. straaten, L.M.J.V. Van. 1951: Texture and genesis of Dutch Wadden Sea sediments. Proc. 3rd Interna tional Congress of Sedimentology, Netherlands: 225 - 255. Suggate, R.P. 1959: New Zealand Coals, their geological setting and its influence on their properties. Zealand Geololgical Survey, Bulletin 134: 113pp. Suggate, R.P. 1968: The Paringa Formation, Westland. New Zealand Journal of Geology and Geophysics 11 (2): 345 - 350. Suggate, R.P. 1978: The Geology of New Zealand. Government Printer, Wellington, New Zealand. 819pp. Terwindt, J.H.J. 1970: Observation on Submerged Sand Ripples with Heights Ranging from 30 to 200cm occuring in Tidal Channels of South West Netherlands. Geologie en Mijnbouw, 49 (6): 489 - 501. -317 Van den Berg, J.H. 1981: Rhythmic seasonal layering in a mesotidal channel abandonment facies, Oosterschelde mouth, South West Netherlands, In: Nio, S.D.; Schuttenhelm, R.T.E.; Van Weering, . C.E. (Eds.): Holocene Marine Sedimentation in the North Sea Basin.I.A.S. Special Publication 5. "Blackwell (Oxford); 147 - 159. Van den Berg, J.H. 1982: Migration of large-scale bedforms and preservation of crossbedded sets 'in highly accretional parts of tidal channels in the Oosterschelde, South West Netherlands. Geologie en Mijnbouw 61: 253 - 263. Visher, G.S. 1965: Fluvial processes _as interpreted from ancient and recent fluvial deposits. In: Primary Sedimentary Structures and their Hydrodynamic Interpretation ( . by Middleton, G.V.). Special Publication of the Society of.Economic Paleontolo- Visser, M.J. 1980: Neap-spring cycles reflected in Holocene sub-tidal, large-scale bedform deposits: A preliminary note, Walcott, R.I. 1979: Plate Motion and Shear Strain in the Vicinity of the Southern Alps, In: The Origin of the Southern Alps. Royal Society of New Zealand, Bulletin Walker, T.R. 1967: Formation of red beds in ancient and modern deserts. Bulletin of the Geological society of America, 78: 353 - 368. Walther,. J. 1894: Einleitung in die Geologie als Histo- rische Wissenschaft, Bd. 3. Lithogenesis der Gegenwart: 534 - 1055. Fischer Verlag Jena. -318- Wellman, H.W.; Willett, R.W. 1942: The Geology of the West Coast from Abut Head to Milford Sound - Part I. Transactions of the Royal Society of New Zealand 71 (4): 282 - 306. Wellman, H.W. 1951: The Geology of Bruce Bay Haast River, South Westland. New Zealand Geological Survey Bulletin (2nd Ed.) n.s. 48. Wellman, H.W. 1955: The Geology between 'Bruce Bay and the Haast River, South Westland. New Zealand Geo logical Survey Bulletin (2nd Ed.) n.s.48. Woodcock, N.H.; Roberston, A.H.F. 1982:. Wrench and thrust tectonics a~9lJ.lg"l a Mesozoic-Cenozoic continental margin: A:q.~alia 'Complex, South West Turkey .. Journal I_i"----..... of Geological Society of London, 139: 147 - 163. Woodward, D.J. 1979: The Crustal structure of the Southern Alps, New Zealand, as Determined by Gravity. Origin of the southern Alps, Bulletin 18. Royal Society of New Zealand: 95 - 98. Yang, C.S.: Nio, S.D. 1985: The estimation of palaeohydrodynamic processes from sub-tidal deposits using time series analysis methods. Sedimentology, 32: 41 - 57. Young, D.J. 1968: Engineering geology of the Paringa - Haast section of State Highway Six, south Westland. New Zealand Journal of Geology and Geophysics, 11 (5) : 1134 - 1158. 319- APPENDIX 1 stratigraphic Columns Abbreviations are those used in Andrews (1982) -Re vised Guide to Recording Field Observations in Sedimentary Sequences. A few modifications are made e.g. "gry" to replace "gy" and "fn" instead of "f". To indicate the adjective "slightly" the noun is placed in brackets, e.g. slightly carbonaceous = (carb). To indicate "very" the word is underlined, e.g. very angular = ang. The first letter of grain size names are in the upper case, e.g. sandstone = Sst. The lower case is used for descriptive terms, e.g. pebbly = pebb, . quartz = qz. The term massive, abbreviated mass, is used to describe a bed of any thickness which does not show depositional sedimentary structures. The term bioturbated, abbreviated biot, is used to describe beds. which have lost depositional sedimentary structures due to the effects of organisms. The term burrowed, abbreviated burr, is used to describe beds in which both burrows and depositional sedimentary structures still exist. Under Andrews textural classification system, "Brec cia" is a soft sediment term and "Conglomerate" (cgl) is used for all indurated sediments coarser than sandstone, regardless of texture. Therefore, angular b9ulder to pebble sediments are described "Cgl" in the descriptive column and in the additional graphic column. All other symbols used in the additional graphic column, some with ight modi fica- tion, are taken from Andrews (1982). The paleontological column lacks macro/micro faunal data because, with the exception of 3 macrofossils in the upper part of the Tauperikaka Formation, identified by Speden (In: Nathan 1977), no other fauna have been located in sediments stratigraphically older than the Arnott Basalt. Data from sediment compositional studies are shown in Tables; 5.1i 5.2; 5.3; 5.4; 5.5 and not included on the col umns. 20- APPENDIX TWO Sedimentary structures and Textures Codes for lithofacies have not been taken trom authors such as Miall (1977), who produced facies codes for sedimentary structures of modern and ancient braided stream deposits, for two reasons: (1) South Westland lithofacies may include different combinations of sedimentary structures and textures compared to those shown by other workers; (2) the use of previous workers faoies codes may unintentionally infer a preferred environment of deposition. Where correla tions between the lithofacies in this study and facies codes of other workers can be illustrated this is done so within the text. Codes lithofacies follow a system in which the first two letters. stand for the Formation Member e.g. "To" stands for Topsy Member, "Ra" stands for Rasselas Member. The following capital letter(s) stand for the grainsize e.g. "B" breccia, "Gil = granules, Ii e" conglomerate, "S" = sandstone, liZ" = siltstone, 11M" = mUdstone. The final letter stands for a dominant sedimentary structure e.g. c = trough cross-bedding, p = planar cross-bedding, , e = epsi lon cross-bedding, f = flaser bedding, h = horizontal bed ding, r = ripples, 1 = laminated or low angle 'cross strati fication, m = massive or structureless, i = imbricated, b = burrowed. Other codes have been used to avoid repetition of letters for lithofacies of the same formation e.g. the Tau perikaka Formation, Paringa Member where a = large scale planar tabular cross-bedding and b = stacked non erosive lensoidal sets. -321- APPENDIX 3 Rock Samples Quoted In This Thesis And Samples Col lected And Submitted For Microflora During This Project. POLLEN SAMPLES: (N.B. all pollen samples are listed in the N.Z.G.S. pollen record file with a written descrip tion of the locality, position of the samples within the stratigraphy and associated lithologic data. The position of pollen samples within the stratigraphic'column and the lithologies from which the samples were taken is also shown on stratigraphic columns (in map pocket) and on maps (Fig.5.54). The results of pollen analyses are shown both on the stratigraphic columns and within sections dealing with the age of the formations. List Of Pollen Samples: FOSSIL RECORD NUMBER GRID REFERENCE FORMATION NAME (N.Z.M.S 260 sheet) (N.Z.M.S 260 sheet) F36/f009 093E 168N Butler 1'36/fOlO 093E 168N Butler F36/f011 093E 168N Otumotu GJ6/f019 235E 244N Tauperikaka G36/f019 237£ 244N Tauperikaka G36/f020 243£ 243N ,Tauperikaka G36/f021 237£ 244N Tauperikaka G36/f022 243£ 243N Tauperikaka G36/f023 243E 243N Tauperikaka G36/f024 243E 243N Tauperikaka G36/f025 244E 242N Tauperlkaka 1'36/1:012 093E 168N Otumotu F36/f013 093E 168N Otumotu F36/f014 093E 168N Otumotu F36/f015 093E 169 Otumotu F36/f016 093£ 16BN Otumotu F36/f017 094E 168N Otumotu F36/f018 094E 169N Otumotu F36/f019 094E '169N Otumotu F36/f020 094E 16BN Otumotu 1'36/ f021 095£ 168N Otumotu F36/f022 095E 16BN otumotu F36/f023 094E 169N otumotu G36/f026 323£ 255N Butler G36/f027 326E 255N Butler G36/f028 326E 255N Butler G36/fJO 236E 214N Butler G36/f31 195E 195N Butler -322 List or Bock SamplES; lL.JlLt....t1.!4 11966 p.et C tic 11S72 p. SIR No, f36/p27 p.s.l.'R li'~. n6/1'36 Rock Ty0e:; rine Sandstone. rock rVtHp Cce:sQ to fine $11",y sandstone. full XAIMP full Name: pink, hd, ripple lam-, \fell sort, tn. qz J3rn-c;y, hc!, ripple )C. ... bdd 4 veIl sort - ce~, micac, carbonac, lithareni~e. mod sort, crs ... !n, dol. cemented, iticac, Grid Reference: 1I.2.1I.,s. 260 l'36/091161 carbonac 1 i thereni te. LoCAtion ogt"ils; South Westland. Monro Beach. coas~al G;"~d EE.jlle~ent;e: N.%.I!.S. 260 Fl6/0SJl68 Clift, R~H.St Monro Track. rirs~ 2~ of Locet{co De,cPg! SO\lth Westlane. :t exposure. Point.. Beach eli!! exposure f ot\!lllotu Stratigraphic Pas. Tauperikaka rormation. Moeraki Member. Eoaach~ Date Collected I 14/3/95 O~u..,otu rornation~ Top cf Topsy M,el'O.bar'. IntErbedded sanestone and mudstone 20C1ll V.of C Ho. 11967 from fault cont-ac't \lith Butler FOrDZI D.S.I.D lIo. FJ6/p29 tion. Bock Typ~: CoarsQ to medium sandstone:~ pati cel'ect.ed; 15/3/&5 rull Name: White J qrn spackled, hd, bndd, \fell sort, crs - med, dolomite cem, glc U of !: 110. 11913 teldsl1reni to. p.StI.B. No. 1'36/1'37 Grid Beferene!!: N.Z. M.S. 260 r36/092168 Rock Type; \'ery coarSEl to tine sanestono. Location Details, South Westland. Monro Beach, coastal full NAme: S:-n, \o"thd, marocn; hd,. lamin, poor scrt, cl,\U. R.H.S. Monro Track. very crs ... fn carbonDc litha'renite. stratigraphie pos. Tauperikaka Formation. LowQr Parinqa Grid Eet'@"',nce: N.Z.M.S. ao T36/09Jl68 Member LoeC;ion petaJls: south We~'tland. O Location oetailsl Seuth W~stland. 14m from tip of oturnotu to X GrId Reference: N.Z.H.S. 260 FJ6/093l69 p.C::,l.FL '~o. T3 6/p,9 Location petails: Tauperikl1ka FormatIon. Top of Rlu.s:elas E0c:)( Tvp'! Granule to ~!ne 5an~stone MembQr~ Massive biot. sandstones. fV'l Kalj,e: Gy \o~hd erllnge, hd l • bndd,. poorly sort, ~raphlc Po •• South westland. Tip of Otumotu Point. tSolor:l'te cam li'thareni'te. pate' Collected: 15/3/05 !jr.fd He'erenc!!: N.Z.~.S. :60 Fl6/093168 Locat ~ cn Pe-t.8'" S ; .sect}. Wes't.l!ne!.. otumotu SEech6 11.0! C No. 11970 n.u.ll~-eoH"~O 'fOs. Otu;metu Tcrmation 4 Topsy Me~er.. 2~%D 1l...S....L..B.i!:! • FJ6/plJ :rom Otu~c'tu/Bu~ler contact.. Bock Type: MedIum to fine sandstone. Pcte eel' ected; ZO/3/ES Full Name; Pink, hd, ripple X-bdd, v-vell sort. med-tn. dor-cem, micac. C'arbonec, feld u of e NQ. 11$ E'.;"] r;ar:,!p j Srn-gy '-"t.hd orallg:o: .. l:;rn J hd , x-bdd, p.S. I .F.. lio. FH/p45 mod"sort, ~ med carbonZic ieldspethic Rocis l'~Pi! Mediu. to fine sandstone. lhharen1te. I)!ll NI!jiJi: Gy, hel pocrly sort, m-fn ~olomite cam !l:Jd 1je'e""ence: ".Z.H.S. 260 'l6/051168 sUP litharenite. Woca-;:en Oet!f'u SoU~h WEstl.,;" (see lH70) Gr~d Ee!,·g-,ce: N.Z.M.S. 260 1"36/095168 :t:,~tjenrchic PO!. O.!m !!"om !'ault (5ee 11970). Los~ticn Jet!!i' S1 South welitland, ctUJIlotu Eoaacl'). 361D do.. '", !leo,::. Ce; jeco;e!!: 1~/3/H. frem t.ul~ ..~ gut in bEach clitf. ot\,;motv fen.ation, ToP of TZilHoIeritiki Member. n~:.u~ eel' fcked i H/3/S5 -323- U of C Np. lt9?S LoCAt.lcn Qeta{'sf South West.land. OtUlliotu B£ilc;h~ O.$.t.S. No, 1!'J6/p4G StrAtjc-~ph~e pes Top cf Butler rOrnlation,. Boek Ty:;I,: Fine sandstone. Pate Cel) ec;eC i ~/~/66 Full Na;ne: Ok qy, Mdt Mass, poorly gor~ fn dolo mite cern sub li':.harenite. Yo sf C. ~et llS~5 Grid 8e:,;oencal II.Z.M.S. 250 FJ6/09S16i1 D. C'."" .R. No. S57/1'!2 Loca~i2n Details: South Wes~l,and. Otumotu S(I]!!ch. 19~;n Bo.-X typ@:: Coarse to very tine 5andstone~ down trom faul~ed qu: in beach clit'!. Tl:ll N!.pg; ,,"11fte "'''tho,' orZH'H3& brn, mod sort crs to St~)tiq~~ph~. O:umo:u rQ~ation, top ot' Tau~eri~iki en , It.icac l!tharfiinit.e. M'em.bEJ r. G"';d Be'E--epce: H/3/95 l.9cat. icp Pita1 '!,; SoU~h W'estland~ Bullock Creek. =trl!,le!,!p"'~c pogo '!8uperikalr.& lcnation, Moeraki Membe::. U of C '19. l1979 Dat.t Ce"~ctec; ~re lS~4 p.S.LB, Ho. FJ6/p47 Cel'tc;e"'j S~ Kat.h·en (Geol. Survey) 80ck Tyy,: Medium to fine sandstone. fyll tla::1e: Brn, ~hd orange brn, hd, lam mod sore p, of C, No, 11$!6 ~ad-!n ear~Qna~, ~lcae sub lithara~ p,S.1 H. Hc. se7/p5~ nite. Roe).: TYPil Gr~nuJa to very fine Gandstone« grid 'Be dra.aoC9t II.I.M.S. 260 FJ~/094lGa l\111 NaIjle; White ~thd orange hrn t mod sort qranu)er Locatfgo Details! South W~s;land. Otumotu Beach t to very tn %fl.ic!:c sub"'litharenit,&. S; ... ,tig"'aphfe P9s • Otumo~u Fo~ation, Topsy Member. 471'0 Grld Re"e .... epc;e: ? dovn f~om Ot~otu/Butler contact. Locat l en Petal 1 s; South Westland. Breccia Creek. oa:e Col1~ct;ed: 2 lll/SS Str0't ir:"'aph i c; jOg:,; I lauperikak. Tormation, Moeraki Member. pat! Ce'leeted; pre l$H U of C Ho. 11990 Col!ect.tti S. Nathan (Gaol. Survey) p.S.!.S. l«>. Boak Type: Fine sandstone. U, of C. No. laS7 Full Ham,: White, hd, rlppla lam, well sort~ t'n, n.C,I.R. No. 587/p71 earbonac with Zst laminae. Feldspa~hic Bock Type: Very co.rs~ to very tine sancstcne. litha:::eni~e:. L~~l liam(t! ""}j.1te, \r\·thd orange br1'l, hd, ,Poorly t.o vP ; d a#!,.G,..t\ng~! II. Z. H. S. 260 FJ Rock Tyne: Very ccarse ~o fine sandstone. U. of C. No, usss. G"'i4 Be"'E;;-enee: N.Z.H.S. 260 TJGI091161 D. S. I t Ht No. 567/»70 !Qeatlcn Oeb!.!ls: South Westlo!nd. Monro iJeach" L.H.S. cf Boel> :Vpt: Coars~ to medjum sandstone. Monro Track. full Name: Grn f hd , ~ell sort ~o very ~el1 sort. Tauperikaka Tormatjon. Top cf MoeTak1 very anq • sub rnd gle sub fel.arenite, Member. Grid Ref,p'''6oCt; 1 Date Cc-l1 tctgd: B/(/e6. Location Pit.!.i'l s; South ~estl.nd. Stat. H19h~.y Six, euttinq on north side of Breccia Creek. u c,..' C No. 11$E2 Tauparikaka Fcrmations Paringa or p.S.!.! No. Rasselas Menmers - boundary. noel< r;"ypet Granule to !ine sandstone. pre !9S' j')J~1 t\!pe: ColJec.,or: loI"hit.e, ""htd yellOW brn f hd t Dod: sort. S. Nat.han (G.el. Survey) .ran~le to !n teldspathic lithu."il:e. q .... id Ee"e. ... e.nce! N.Z.M.S. 260 GJ6/2252<4 t1. of C. Se. 11966b Location petel's: South Westland. Lagoon Creek. Above I), S, 1. ll, )10. first set ot ",·et.erfallst 150($1; 'type: Medium Sandstone Tauperikaka Tormation, Moeraki MeJl'il::ler. full Ne?t: 8rn, hd, well sort, med sub !eldsare Dete eel' ect.E:d: ll/21£5 nite t su~ litharenit.e. Grid Bet'@¥gnetlr N.Z.M.s. :60 T37/04l0£7 U of C No Locat1eo pet.~j1 $; Lav Coal Measures Cupper)~ Sandstone D.S.I.B. No, above coal se.am. Foek 1... met coarse to medium sandstone. S~r&tio"'!pbie PQ§~ Coal Creek, sll}) on L.H.S~ loitjle: plte C9~1'ct.ed; DJ'l Grn, crang& brn, hd, x-bdd, mod h well 20/11/86 sort very an9 ... rnd 91c !eldsareni'te. C... id Xe"erence: N.Z.M.S. 260 G•• ( •• 2 p, or c. No. USES Locatipn pet;!!'!H South ~estlftndw La900n Cr4ek, 700m u~ C • .!LT.jL No, t:Olll first waterfall on I..H.s. Roek 'Type; Sedimentary Dyke!'. fine $!riTlcb:ton&., TalJPftri~aka Fornation, Botton ot RaS5.e ... full Name; Gy vthd yel, he! fQssiliferous tn Sst. 1 as MEm.ber. Grid Be!'e"ence; 1I.2.M.S. 260 TJ£/C9716B 18/3/05 LocO; I en pete floe; South Westland. Otumotu Beach. :i1:;tAticr~phlq POSt Wit.hin OtUInOt.u rcnnatlon~ Tau\Jer1t!ki P. ef C, 110, 11984 Mer1\l:::ler. p.S,TtR. So. pct, Cpllecte4; 8/'1 B 6 Bock Tvp" Medium to tine sandst.one. full t\tme:j L;;h't ern, ''thd ora"g_, hd, rippl. lalli, mod \Jell sort mec-tn, mieee tele!spa'thic lithanr.i':.e. II.X.M.S. 260 r36/0SS168 -324- p.ot C lie. 11990 f"I,C:.".R No. Focit "!'vpe: Conglomerate. Cobble to pebble - pebble clast. TV'l l:cioIg: G~n, hd, fn Sst - pabb. Gr: d E,e .. e. ... ence: )I.Z.Y..S. 260 Tl6/0~00&7 !.,ocat~en ~et u ot e Nc. 1195-1 P.S.!.B. No. Rock '!'\'pe: Basal tic Dyke. Full Name: Orange, hd, microphenocrystic (Olivine alte:red to Idinc;site) plac;ioclase. Besalt with )(enclyths. Grid Fe"ereece: N.Z.M.S. 260.F36/0S3168 Locl.!ticp petailo:.j SO\.lt.h Westland. Otwnotu Beach. ll.I.U.igr!ph~e POOl •. Basaltic oy~e. hrno'tt Basalt? In otumotu Formation, Topsy Member. :5m ~oYn treD contact ct Topsy/B'Jtler Tcr mation. Do:te Ce" acted; 20/3/15 P. of e. No, 11992 p.S.LB, No. Bock Type' Basal t Full Name: sa, porphyritic (elinop)'roxene/clivine) basalt. Cirid Befe'"enc@: N.Z.M.S. 260 f36/055136 Location Deta'!s; south Hestland. Grave Creek. Against ~ault between Tauperikaka and B\.ltler formations. Strat(craphic tlos. lHtl'lin T21uperi~ak8 Fornation. p~te eo"ecteC: S/"/S6 Y. ef C, lie. 11993 D.S.T •. B. No. Bock Type: Basaltic Dyke Fy'l Name: Oran96, hd, microphenocrystic (clivine altered ldingsite), plagioclase basalt \"'i'th :>:enolyths. Grid Bgf!p'enc@: N.Z.H.S. 260 f36/093168 Locction petai1 s; So~th ~estlan~. Otumotu Beach. St ... atigrapiic ":100:., ~rnott Basalt in otumotu formation, Topsy Member. 25m dovn trom contact of 'Topsy/S~tler formation. Date Col1ectet1· 20/3/65 -325- APPENDIX 4 Plant Macrofossils from the Butler Formation at Mt. Arthur I 'South Westland. Plant macrofossils have been sampled during the map ping stages of this thesis from indurated sediments, mapped as part of the Butler Formation, which crop out in Butler creek, Mt Arthur. The plant fossils are described and interpreted by Mr. I. Daniel of the Botany Dept. University of Canterbury, and the results are presented below. The plants represented by fossils are: Eguisetum sp.: several stern fragments, no leaf whorls. Taeniopteris cf. stipulata Hector ex McQueen 1956 : only one species of taeniopterid is present represented by four specimens ranging in width from 1.2cm to 2.5cm but lack ing base or apex. Eretmophyllum sp.: of one species ranging from O.5cm to 1.5cm wide plus one complete leaf I4.5cm long and 1cm wide. Ginkgo sp.: one fragmentary specimen showing charac teristic venation but lacking base, petiole and margin. Coniferales possibly all Podocarpaceae at least four, possibly six species are represented. Sp .. A: common, branching twigs, characterised by spirally arranged, imbricate, somewhat elongate scale leaves 1-2mm long. Several branchlets show gradation outwards from adult to juveni leaves, latter linear, 2-5mm long decreas ing in length towards the branch tip, spreading, somewhat falcate with base not constricted and apex apparently blunt. The adult form compares with Dacrydium cupressinum Ett. of Pakawau but the transition of adult to juvenile foliage is similar to praedacridiodes Ett. also of Pakawau. -326 Associated with Sp. A adult foliage are structures which are tentatively interpreted as one male strobilus 1 cm long, and at least four terminal female strobili reduced to one perhaps two ovules Sp. B: common, twigs up to 4cm long, characterised by linear to lanceolate leaves less than lcm long and lmrn wide· in two rows, departing at a wide angle (co 60 degrees) and generally spaced at intervals greater than the leaf width. Leaves are generally straight, have a constricted base and rounded apex. It has the general appearance of Podocarpus ferrungineus G.Benn. ex Don and is similar to Podocarpus parkeri Ett. (PI XXIV fig.l2) (which Ettingshausen compares to P.totara) but the leaves of Sp.B are half the size of all the species named. ~ : four fragments of twigs characterised by spirally arranged linear leaves Imm wide and more than Icm long, departing at ~ 45 degrees. and spaced at intervals the same as the leaf width. Leaves have an acute upward curved apex possibly pungent (most are ing) and decurrent base not constricted. It has the general appearance of Podocar pus hochstetteri Ett of Shag Point but the leaves compare better with Podocarpium tenuifolium Ett of Pakawau, both of which Ettingshausen compares with Podocarpus tenuifolia D.C. of New Caledonia. ~ : one block with several twigs similar to Sp.C but leaves only 2-3mm long, less regular and delicate. Pos sibly is an immature form of SpeC but is difficult to dis tinguish from juvenile Sp.A. ~ : one block with three twigs characterised by spirally arranged scale leaves up to 3mm long, alternate, with acute, outward curved apex and decurrent bases enclos- ing the stem. Leaves depart or less than 45 degrees. No comparison is made. ~ : two blocks with several twigs similar to Sp.E but leaves narrower, less regular, more spaced along the -327- stem and delicate. Possibly is an immature form of Sp.E and is similar to the more delicate twigs illustrated by Etting shausen as Dacrydinium cupressinum but leaves are not curved upwards. Dicotyledonous Leaves : eight species are described using the venation terminology of Dilcher D.L. 1974 Bot. Rev. 40 (1) 1-157. ~ : nine adult leaves (up to II+cm long and 8+cm wide) and one juvenile (4cm long and 2cm wide). None shows margin or apex, two show the base with margin entire but the margin not extending as far as the .lowest secondary veins. Leaves are characteristically large, membranaceous with midrib grooved, slightly sinuous, secondaries arising at an acute angle increasing upward, straight below but curved above and parallel, unbranched except for lowest pair, base obtuse decurrent, margin entire in basal portion of lamina. The juvenile appears to have serrate teeth but most are the result of lamina erosion exposing secondary veins. It may be compared with Fagus producta Ett. of Pakawau and with confirration of margin could be placed in Nothofagus. ~ : many leaves usually conspicuously graphitised, 3,5 - 6.5cm long and 1.2 - 2cm wide, narrow oblong, coriac eous, characterised by sernicraspedodromous venation, midrib stout, straight, secondaries departing at right angles with simple intersecondaries, margin serrate. No comparison can be made with previously described fossils but it is almost ~ertainly proteaceous. ~ : five leaves 6+ cm long and 3.2 - 4cm wide, nembranaceous, characterised by cladodromous venation, nidrib straight, secondaries recurved, irregular, not paral lel, apex acute, base asymmetrical acute decurrent, margin antire. No comparison is made. ~ : one leaf 2cm long and 1.6cm wide, membrana :eous, characterised by reticulodromous venation, midrib 3inuous, base obtuse decurrent, margin crenate. No -328- comparison is made. ~ : three leaves 3+ cm long and O.7cm wide, coriaceous, lorate, characterised by simple craspedodromous venation, midrib stout, curved, secondaries depart at wide acute angle, some branch near margin, no inter secondaries , base acute cuneate, margin crenate. Tentatively compared with Dryandroides pakawauica Ett. ~ : one apical fragment of a membranaceous leaf with distinctive simple craspedodromous venation, midrib weak, sinuous, secondaries departing at an acute angle, branched, curved, margin entire. The venation may be com pared to that of Grewiopsis pakawauica Ett. ~ : one leaf with base and petiole plus three fragments of laminae. Large (9+ cm long and 6+ cm wide) chartaceous leaf characterised by eucamptodromous or brochi dodromous venation, midrib massive, straight, secondaries depart at wide angle, thick, curved, sometimes branch- ing near margin, base acute decurrent, margin entire, petiole 2cm long, strong. It is probably lauraceous and may be compared with Beischhmiedia tarairoides Pensler. ~ : fragment of membranaceous leaf showing dis tinctive serrate margin with obtuse convex teeth and angular sinuses, each tooth served by a secondary or branch thereof. Although of like appearance to Spel, the venation pattern is not sufficiently similar to allow it to be included in that taxon. other fragments of lamina show similar branching secondaries, but all lack midrib, apex and base, and should be included here rather than in Sp.l. Carpolithus sp : two oval structures showing an inner core and outer layer, 5mm long and 3mm wide, assumed to be seeds. with three circular (lmm diameter) bodies at irregular intervals similar to the young ovules of Podocar pus spicatus R.Br. ex Mirbel. -329 The plant material has been coalified, the thicker leaves presenting shiny black surfaces while thinner leaves are dull~ The sediments are indurated, generally poorly bedded and grade from dark mUdstone to light sandstone. Logs and pebbles are reportedly scatt.ered through the sedi ments but very few stems are present in the samples studied. Leaves are scattered through the sediments, separate, and often shattered by compression shifting. Very few of the blocks have comminuted, mixed plant material typical of . stream deposition. In the finer grained sediments, where leaves are superimposed, the more membraneous leaves warp over each other, the veins of one affecting the course of veins of another. More coriaceous leaves have little effect on each other. The presence of various ages of leaves of the same species of dicot, of putative male and female reproductive structures of podocarps, and of a com plete leaf of Eretmophyllum 14.5cm long, suggests periodic wind of some strength as the dispersal agent rather than seasonal leaf fall. It is suggested that the plant material has been deposited by wind or flotation in a lacustrine environment. is further suggested that the vegetation is floristically relatively poor and lacks understory represen tatives, especially ferns. -330 APPENDIX 5 Results from Pollen Analyses from the cretaceous Sequence Analysed from Previous Workers (in Nathan 1977) TAlJPeRIKAKA COAL MeASURES Plallt microfoJ.riir (by G. J. Wilson) Spores and pollen were recovered from five samples (S77/f571, f572, f574; SIl7/fS 11, f538). Assemblages are "ery sparse (usually l.ess than, 50 ~tllyn?mo~phs per slide). highly carbonised. and poo~ly prese.rved\ m~klOg speClfi~ Id~nttfi~utlon Im possible in some cuses. The follOWing species lIst IOcorporates IdentificatIOns made earlier by D. J. McIntyre and G. Norris: TriJi/es spp. ?Ci(atrkosisporiles sp. Podosporites alllarctiws (Cookson) Phyl/odadidill!s mall/soll;i Cookson Podo(arpidiles spp. Trkolplies sp. ProteaciditeI cf. craUIII Cookson P. aif. tllbercula/lI! Cookson . P. parl'lI! Cookson Beallpreaidiles d. elegallIiforlllis Cookson NOlho/agiditerkailallga/a (Te Punga) ?N. waipawaensis (Couper) Haloragacidites harrisii (Couper) Several of the palynomorph species are restricted to the Haumurian-Teurian interval and the presence of NOlholagidiles kaitallgata (Te Punga) suggests a Haumurian age. A lack of dinoflagellate cysts and other marine palynomorphs, and the abundance of carbonised plant remains, indicates that the coal measures accumulated under non marine conditions. WHAKAPOHAI SANDSTONE Plant Aiicr%uilt (by G. J. Wilson) Eight samples from the Whakapohai Sandstone yielded palynomorph assemblages (S77If570, fS73; SS7/f507, f50S, f533, f534, f537, f539). Dinoflagellate cysts were reco,rded from most samples in addition to spores and pollen. Assemblages are fairly sparse, carbonised, and poorly preserved, although preservation is better than in assemblages from the underlying Tauperikaka Coal Measures. Relatively good assemblages, dominated by dinoflagellate cysts, were obtained from S77/f570 and S87/f507, f508, f539. The following species list incorporates identifications made earlier by D. J. McIntyre and G. Norris: Pollen and spores Dinoflagellate cysts Ly(opodillmiporiles sp. As(odinillm sp. CYa/hid;tes sp. Cyc/onephelillm sp. 1 Latrobosporites d. ohaiensis (Couper) C),clonephelillm sp. 2 Podocarpid;tei d. marwicki Couper CleiJtosphaeridillll/ sp. Podocarpidites spp. Odonto(hiJina sp. Phyllocladidile! mawsonii Cookson Deflandrea aff. erelacea Cookson ProteaciditeJ cE. erasS/lS Cookson Deflandrea cf. (ookson; Alberti Proteacidites sp., , Cribroperidillililtl cE. edulardsi (Cookson & Eisenack) Notho/agidites kaitangala (Te Pungu) Notho/agidiles sp. Tricolpit!!s sp. Haloragaddites harrisii (Couper) Age ranges for the dinoflagellate cysts. spores, (lnd pollen indicate a Haumurian (uppermost Cretaceous) age. The dinoflagellate cysts indicate a marine or bmckish depo5itional environment and the large amount of carbanised plant fragment indicates that deposition probably occurred close to land. Macr%ssils (by I. G. Speden) Specimens have been collected from tlVO localities. Fragments of two single valves of ?IIlOteramllS sp. indet. were found in fine-grained bioturbated sandstone on the roadside near Arnott Point' (S77/£573), and part of a slightly crushed body whorl of an ammonoid, here identified as Koumaticeras (Nalalites) bemOll; Henderson, from a roadside cutting north of Emily Creek (SS7/f54l) (Fig. 18). ' The indeterminate 11lOCMTlJIfIllS specimens indicate only a pre-Paleocene u~e. Koss '!Ialireras , ARNOTT BASALT A single sump Ie (SS7/f506) from the basal tuff contained a poor shallow-water fauna. c<,Jnsisting. of very lurge Cyc/a!/llllilla sp. and coarse Ht.lplophragmoides sp. Age IS Indeterminate (R. H. Hoskins pers. comm.). The poorly preserved molluscs seen at SS71961293 are unidentifiable. -331- APPENDIX 6 Analytical Information For South Westland Coals. positeNo. I 2 I Research Ass. No. 39/201 39/202 39/203 39/204 39/205 39/206 39/207 39/208 39/209 33/268 33/269 33/270 ckness (m) 0.20-0.25 0.20-0.25 1.5m 1.5-2.0m 500cm 40-50cm 0.02 0.10 0.50 0.55 0.8 1.62 W'1oi sture % 3.3 3.5 1.2 1.3 1.4 0.54 6.3 2.1 2.3 2.8 1.9 1.3 \sh % 14.6 12.2 24.6 10.5 13.6 42.0 10.5 54.9 24.6 8.5 26.6 21.7 lolat i Ie Matter % 36.1 37.5 31.6 36.0 38.4 . 26.2 27.3 18.9 18.1 22.7 19.6 21.5 'i xed Carbon % 46.0 46.8 42.6 52.2 46.6 31.3 55.9 24.1 55.0 66.0 51.9 55.5 MJ/Kg 27.70 28.34 26.29 31.26 30.39 20.27 27.30 12.74 25.0 I 31.10 24.94 27.44 Jrifie value Btu/lb 11,910 12,180 11,300 13,440 13,060 8,714 11,740 , 5,480 10,750 13,370 10,720 11,800 Jhu r % 3.90' 4.11 4.99 6.01 5.80 4.27 0.92 0.62 0.58 0.42 0.31 0.53 :ible Swell ing No. I I 3Y, 9 8 !Y. o II III III 8ll .t i Ie matter drrrnl>sl % 42.56 43.37 39.94 39.39 43.81 40.44 31.70 3;.52 21.88 24.79 2'1.52 25.68 reloeoll ini te % 21.3 18.6 29.2 34.0 20.6 20.4 100 n.a 19.6 47.8 37.4 48.4 )esmocoll ini te % 53.6 57.2 52.4 51.6 59.0 56.0 n.a 53.0 29.0 33.2 32.6 Ii trodetr ini te % 4.2 3.8 0.8 0.6 5.0 3.4 n.a 0.8 0.6 2.8 2.4 Indeterminate vi tr ini te% 3.6 4.2 7.6 5.4 3.8 2.4 n.a 0.6 1.6 2.8 0.6 :0 II in i te % 0.2 n.a re II in i te % n •• ipor in i te % 0.6 n.a :ut i n i te % 0.8 1.0 0.2 0.2 0.2 n.a tes in i te % 0.6 0.6 1.0 0.6 n.a 0.4 .iptodetrini te % 1.3 3.4 1.2 1.4 1.8 n.a 0.2 txudatinite % 0.8 1.8 n.a Icgradofusinite % ·yrolus lni te % Indiflerentiated % 0.2 0.2 n.a 9.2 8.6 8.4 4.2 'usinite ,em i -I U 5 in i t e % 1.4. 1.0 1.8 0.6 n.a 5.6 7.0 4.6 2.8 ,clerotini te % 0.4 tr 0.4 0.6 0.8 0.2 n •• 1.2 nertodetr ini te % 1.0 2.6 0.3 0.2 0.8 0.2 n.' 1.2 1.6 3.4 2.8 letaexudat ini te % 0.6 0.2 2.2 0.8 1.4 0.4 n.a 0.8 0.4 :Iay % 6.5 1.4 0.4 0.4 5.0 n •• 5.4 3.4 10.6 5.0 !uar tz % 3.6 3.4 1.4 1.2 2.0 6.2 n •• 2.2 0.2 0.6 Iyr 1 te 96 1.2 0.4 0.8 1.0 1.2 3.4 n •• 0.2 0.2 laema t j te 96 0.2 0.6 3.4 1.6 0.2 n •• 0.6 ,imoni te % 0.2 0.2 1.8 n •• 0.8 Ither % 'otal vi tr ini te % 82.7 84.0 90.0 91.6 88.4 82.2 100 n •• 74.0 79.0 76.2 84.0 'otal exinite % 3.3 5.8 1.4 1.6 4.8 0.6 n.' 0.4 0.2 'otal inertinite % 2.0 4.4 2.9 2.8 4.8 1.4 n.' 18.0 17.2 16.4 10.2 'otal mineral matter % 11.5 5.8 6.2 4.0 3.8 16.4 n •• 9.2 3.4 10.8 5.8 andom n.a n.a n.a n.a 0.72 n.a 0.75 n •• 1.31 n •• 1.19 n.a ue Preservation Index 0.36 0.32 0.54 0.67 0.35 0.35 0.63 2.03 1.28 1.47 ue Gelilieation Index infinity 11.6 infinity 29.5 11.3 34.9 1.3 3.3 2.9 6.9 -332- I te No. 4 2 3 4 6 esearch Ass. No. 33/271 33/272 36/281 40/332 40/3)3 40/334 401335 40/330 40/331 "0/329 ess (m) 0.5 3.47 3.0 0.10 0.10 0.10 0.10 0.05 0.06 0.30 5 ture % n-a 1.9 11.9 2.3 1.6 1.3 2.0 1.9 1.1 2.\ % 81.9 16.2 53.5 41.7 31.8 11.8 54.2 44.7 57.3 58.8 at i Ie Mat ter % n-a 22.0 15.3 14.6 16.4 19.2 13.9 14.2 12.6 17.4 ed Carbon % n-a 59.9 19.3 41.4 50.2 67.7 29.9 39.2 29.0 21.7 MJ/Kg n-a 29.09 18.41 22.96 31.i!i! 13.59 17.68 12.90 11.41 flc value Btu/lb n-a 12,510 7,'JIO 9,870 13,520 5,840 7,600 5,550 4,910 n-a 0.41 0.50 1.30 1.20 0.26 0.35 0.90 0.24 ,Ie Swelling No. n-a 5 I e rna It e r drrm.Ils f n-a 25.23 19.8 20.3 20.7 21.9 19.7 18.2 34.7 ocoll inite % n-" n-a 23.9 21.6 18.8 20.0 29.2 21.0 35.6 4(.9 mocollinlte % n-a n-a 18.6 24.i! 33.0 48.0 14.2 33.8 \0.2 15.5 rodetrinite % n-" n-a 1.3 3.6 3.2 4.0 3.2 1.2 1.6 2.6 eterminate vi tr ini te% n-a n-a 1.3 2.8 0.2 4.0 0.2 1.8 1.4 1.2 I In i te % n-a n-a 0.4 0.2 0.4 0.2 l j n i te % n-a n-a 0.4 0.0 r j n 1 te % n-a n-a 0.5 1.2 in i te % , n.. a n-a 0.6 tr 1.8 ini te % n-a n-a 0.8 tr tr tr tr tr todetr ini Ie % n-a n-a 0.6 0.2 Ir 1.4 datini te % n-a n-a 0.3 tr radofusinite % n-a n-a 4.0 1.6 0.6 tr ofusini te % n-a n-a 5.2 5.6 % ifferentiated n-a n-a 2.7 4.2 2.4 l n i te i .. fusinite % n-a n-a 2.7 4.0 i!.2 0.2 3.4 1:1l erotlnlte % n-" n-a 0.2 r todetr Inl Ie % n-a n-a 1.6 3.0 6.8 7.4 1.0 2.4 tr 1.4 aexudat ini te % n-Q n-a 0.2 0.8 0.4 1.0 0.4 0.6 % n-a n-a 35.0 20.6 13.2 2.8 28.2 22.2 20.6 17.9 r tz % n-a n-a 8.0 13.4 7.6 0.2 19.0 7." 29.0 7.1 ite % n-a n-a 1.7 1.0 2.0 1.6 4.2 1.4 1.0 tr nat i te % n-a 0.2 0.4 0.2 0.2 Ir 0." ani te % n-a n-a er % n-a '2.41 a) vi trini te % n-a n-a 44.0 52.6 55.6 76.0 46.8 57.8 48.8 62.4 al exinl te % n-a n-" 2.8 0.2 5.60 al inert inl te % n-a n-a 7.0 12.0 21.2 19.4 2.8 10.4 0.6 4.04 al mineral matter % n-a n-a 45.0 35.4 23.0 4.6 50.4 31.8 50.6 26.2 n-a n-a 0.81 1.04 1.32 1.39 1.29 1.42 1.38 0.77 Preservation Index n-a 1.20 0.98 0.89 0.53 1.63 0.77 3.03 2.64 Gelificalion Index n-a n-a 4.2 1.64 1.38 1.75 37.5 2.76 infinity 10.57 • IIptodetrinite or clay -333- APPENDIX 7 Preparation of Particulate Coal Mounts. The following procedure was'used to prepare particu late coal mounts: 1) Each sample is crushed until a size that will pass easily through a sample splitter. The sample is split to obtain a representative sub-sample. The sub-sample is then ground and passed through a sieve stack until the whole sample passes through a 1mm mesh. Grinding is accomplished with a hand-operated coffee grinder. Fines less than O.lmm are discarded and the samples is split to obtain a repre sentative sub sample of approximately 109 to 15g. 2) Preparation of specimens under pressure. The ground coal sub-sample is mixed with a lucite l with a coal to resin ratio of 2 : 1. The mixture is placed in a PR-10 LECO mounting press. A heating jacket raises the tempera ture of the sample to 28 Fahrenheit. The sample is then cooled to room temperature under a constant pressure of 4200 P.S.I. with a Leco water cooling jacket. The prepared spe cimens are circular disc shaped. 3) Each mount has the sharp edges ground using a diamond wheel and the sample number is placed on the mount with a pneumatic scriber. 4) Polishing. The mount is ground using a P600 grade sand paper whilst maintaining an even flat surface. Scratches are then removed using a P1200 grade sandpaper. The mount is rinsed to remove sand grains from the mount surface. The second polishing stage involves grinding with moistened chromic oxide on a polishing wheel. As the South Westland samples are relatively hard, only 1.5 to 2 minutes polishing with light hand held pressure is required. The mount is checked under the microscope to ensure the removal of all scratches caused by the sandpaper. The surface of the mount carefully washed with liquid soap and water to 33~- remove the chromium oxide. The third polishing stage involves polishing with magnesium oxide, moistened to a paste, on a velvet cloth. The mount surface is cleaned thoroughly with liquid soap and soft tissues to remove any surface oil seeping from the coal ~articles. 335- APPENDIX 8 Selected Diffractograms Of Rock Samples And Low Temperature Coal Ash From The South Westland Sequence. The codes for minerals indicated in diffractograms are: C - High Mg Calcite D - Dolomite (or Ankerite) F - Feldspar, m - Microcline G - Gypsum I - Illite K - Kaolinite Mu - Muscovite P Pyrite Q - Quartz The letter "F" is used to show and where microcline has been identi in significant quantities within sample by other techniques (e.g. in thin section under the microscope) the letter "mn is added. The peaks that sent both illite and muscovite are differentiated on the assumption that rock samples contain muscovite (which has been optical identified) and coal contains illite, as coal samples with illite peaks contain a high proportion of clay (evident during coal petrographic analysis). -336- Diffractrogram 1 U of C 11975 D D Q K K Q i~4~t~~~AAJwvLuQ JWl~UL.l ... Q Diffractogram 2 Uof C 11976 Q Q 0 Q I1u LLi;;iJvU Hu 3 g , . , I I Diffractogram 3 Uof C 11971 r K I", Q HOI I \.\L~.J "'- .. -337- f 1 t I , • •• I' t , t I • ., I • ''11'' Diffractogram 4 II Uof C 11981 i I IC Diffractogram 6 33/268 Q flO L:::!~LL~~~~ Diffractogram 7 33/270 Q Q I Ie -JJ8- Q K K Di ffra t gram 8 36/281 Q I I I I j , t I I I J , I I I j t I Diffractogram 9 IQ 391209 ~ !I i .. Q Q Diffractogram 10 391202 Q Q o Q Q Q o C> III 13 II! 1 ! , ! ! ,:':, , ! ! ! ! ! ! , 13 ! , I 1'1 I'" -339- o Diffractogrrun II o 39/203 Q ro p p .\Jl"l'-A",,"'-trt', o Q Diffractogrrun 12 39/205 Q Q PQ Q PO P (j P (j , • I I I I I • I ! f • I Diffractogrrun 13 39/207 ,:1;