Jil. 21, No.5 (Vol. 21, No.5) Sep-Oct 1995 KANDUNGAN (Contents) . ·.··.:.A.....· ...•• .J.· ·.• •. :.'·.1.·•• . .•: .• i:.• .•·.·. •. .•. :·.· ••. ·•. 4.· ..• ••.p. .:.··. ••.••. .•"1 . •.••. i•.( .·•. .•. ·'.'·····. l.··.p..•·.•... N..•..·. • t.· .•. .. •·.· ..• 1.:••.•.: ..··.':.· .•. .•:•. ·.·.· .•...:.·.:, ... :.:.: •.:..•...•.•. : .... .'.':. .•:. .. ••.'.• '." .••..'.)) .• '.• '... '....... '............. '..... '........... '.... :....:..... '... ............ : ...•. '..•. :.'.. :.•.:.. '.. .'.... '.. :............ :.. :.'... :.. '.'.. :......... ...•....•... :.:.•..• .•..•'.: .•.•.•.: ...•.:.: .•.•...• .•...• ).:, ......... ,.. } •• ,. •• :.:.:.:.: .. ................................P .. ts...• :.:.:.:.:.:.:.:.:.:~.· ·. : .:N.....·.· •. .:.:.:.:.:.:.:.:.:.:.:.:.;.:.:.;.;·.~··. ~.··.~ ....... ;.:.;.:.:.:.;.;.;~.··.·. ·. · ... ;.........~ .:.··.·.·'. :...~ .: ,. ..;9....·· .• : ....·.:. I . ~:.~~•:.•. P.•.............. •.··.•. , ..: ... :.....·.P........• •.·. • .........· ~.......$ •.·.•.. :.:.:.:.:.:.:.:.:::::. ~jjj~tij~~: ;:rr:.:.:. ·).,..·······.:::·,,::·:·i.·j::::::::~~r ~ ~~ ;:~:~:;:;:;:;:::: : ::::::::: ... :::::::: Mohd Shafeea Leman and Yusri Zakariah: Iron rich conglomerate of Ma'Okil Formation 293 at Bukit Lop, Chaah, Johor Syed Sheikh Almashoor: Located: The extension ofBok Bak fault in north Kedah and Perlis, 301 Peninsular Malaysia A.J. Barber: Continent-island arc collision: The Australia-Banda Arc collision zone 305 Hamzah Mohamad: Geological history of the Earth's crust: the Malaysian perspective 306 R.M. Spang: Some aspects of modern rock slope engineering 307 Pergau Dam Site Visit 309 Forum on "Environmental Geology & Geotechnics" - Report 312 Welcoming Address by Dr. Khalid Ngah, President Geological Society of Malaysia 314 Opening Address by Ir. Tan Meng Leng, Director-General DOE Malaysia 315 Abstracts of Papers 316 ......',' ............ :.:.:-:.;.:::::::.:.:-:.:-:.:.:::.:.:.:.:.:.:.: :;: :.:.:.:.: ..... :- ...: ..... :.;.:.:.:.;.:.;.:.:.:.:.;.:.:.:.:.: :.:.:.:.:.:-:.:::.: ..... ................................... :-: ... :.:.:.:.:-.. :.:.:.;.:.:.:.:........ ::::::::: ....... :.: :::. .:.:::::::.' ::~~~~:··:~~;)frf~:r : :: r(i :::)t ::::\v ..:.:.;.: ::::::/.,::;::::\;: ~:~:::::. i·: · ~ ~R!!~t~ : gg!!~.:.IR~~tlIN . ~B.~Yf~ .. 8!1fi i ~§8~~mr·.: ..,.. .. ...,:::::;.iii .•· ·:i..::.:.::.:::.: •••••••• ·:::::::::::;;.:.'::::.:;:;:;:;::\.:':.:.:::::,:,;" •• ::::.\,. Keahlian (Membership) 320 Pertukaran Alamat (Change of Address) 320 Pertambahan Baru Perpustakaan (New Library Additions) 321 Annual Geological Conference '96 - First Circular 322 Young Geoscientist Publication Award 324 Local News 325 Academy of Sciences Malaysia - Inauguration Ceremony 343 Mineralisation in the Caledonides 344 30th International Geological Congress 345 Minerals, Metals and the Environment II Conference 350 The Fifth AsialPacific Mining Conference & Exhibition 351 A Workshop on Tuffs 353 Kalendar (Calendar) 355 Majlis (Council) 1995/96 Presiden (President) KhalidNgah Naib Presiden (Vice-President) Ibrahim Komoo Setiausaha (Secretary) Ahmad Tajuddin Ibrahim Peno1ong Setiausaha (Asst. Secretary) Nik Ram1i Nik Hassan Bendahari (Treasurer) Lee Chai Peng Pengarang (Editor) TehGuanHoe Presiden Yang Dahulu (Immediate Past President) : FatehChand 1995-97 1995-96 Khoo Kay Khean Abd. Ghani Mohd Rafek Hoh Swee Chee Abdul Rahim Samsudin Ibrahim Abdullah Effendy Cheng Abdullah Mohd Shafeea Leman Tan Boon Kong Jawatankuasa Kecil Pengarang (Editorial Subcommittee) Teh Guan Hoe (PengerusilChairman) Fan Ah Kwai Ng Tham Fatt J.J. Pereira , Lembaga Penasihat Pengarang (Editorial Advisory Board) AwPeckChin Foo Wah Yang Mazlan Madon P.H. Stauffer Azhar Hj. Hussin C.AFoss Ian Metcalfe Tan Boon Kong K.R. Chakraborty N.S. Haile S. Paramananthan Tan Teong Hing Choo Mun Keong C.S. Hutchison John Kuna Raj Teoh Lay Hock Chu Leng Heng Lee Chai Peng Senathi Rajah H.D. Tjia Denis N.K. Tan Leong Lap Sau Shu Yeoh Khoon Yeap Cheng Hock The Society was founded in 1967 with the aim of promoting the advancement ofearth sciences particularly in Malaysia and the Southeast Asian region. - The Society has a membership ofabout 600 earth scientists interested in Malaysia and other Southeast Asian regions. The membership is worldwide in distribution. Published by the Geologl9al Society of Malaysia. Department ofGeology. University of Malaya. 59100 Kuala lumpur. Tel: 603-757 7036 Fax: 603-756 3900 PrInted by M Prlntfng Works Sdn. Bhd.. 29 Jolon Rlong. 59100 Kuolo Lumpur. Iron rich conglomerate of Ma'Okii Formation at Bukit Lop, Chaah, Johor MOHD SHAFEEA LEMAN AND YUSRI ZAKARIAH J abatan Geologi U niversiti Kebangsaan Malaysia 43600 UKM Bangi, Selangor Abstract: Matahari Mining Sdn. Bhd. which operate at the southeastern spur ofBukit Lop, near Chaah, exposed about 40 m thick ofconglomerate which belongs to the continental Upper Mesozoic Ma'Okil Formation. The conglomerate unit overlies a massive andesitic volcanic rock. The lowest bed ofthe conglomerate is essentially made ofangular to subrounded pebbles and cobbles of hematite derived from the nearby primary hematite ore body. The clasts of this conglomerate are poorly sorted and the matrix is made of very fine-grained hematite. Iron clasts are also present in the overlying conglomerate, the percentage and size of which decrease toward the top of the conglomerate unit. This in situ nature of iron conglomerate deposition suggests that the iron clasts were deposited as an alluvial fan deposit along the foot of a fault scarp. The paleoslope is directed toward the northwest. The farthest distribution of the iron pebbles is about 50 m from the centre of the fan. This fault might represent part of the Ma'Okil wrench fault mentioned by Burton (1965) along which Bean (1968) recognised several iron ore deposits. The absence of goethite cement or matrix suggests that the depositional environment of the conglomerate was not very much influenced by water. INTRODUCTION immediately southeast of the basin, is believed The operation site of the Matahari Mining to be part of the basal (continental origin) Sdn. Bhd. is located on the southeast corner of conglomerate of the Upper Mesozoic Ma'Okil Bukit Lop, about 10 km southwest of Chaah Formation. Town (Fig. 1). The mine was reopened in 1985 after its last closure in 1965. Iron and baryte GEOLOGICAL SETTING were mined from several primary hematite­ Bukit Lop is situated in northwest Johor, baryte ore bodies emplaced parallel or about 10 km southwest of Chaah Town. The subparallel to the ?flow bedding of the andesitic Ma'Okil Formation is the youngest rock volcanic host rock. Part of the mining history formation exposed in the area west of Chaah and geology related to this iron mineralization Town. On the southeastern part of Bukit Lop was published by Bean in 1968. (southwest of Chaah) this formation Recently, while studying the geology of unconformably overlies the oldest rock formation the iron mine and the surrounding area, the of the area, i.e. the Upper Permian Lop present authors noted the occurrences of iron Formation (Fig. 1). In the area west and rich conglomerate overlying the andesitic northwest of Chaah Town, the Ma'Okil volcanic rock. This conglomerate which obtains Formation overlies the Middle to Upper Triassic much of its source material from the underlying Gemas Formation, uncomformably. Primary volcanic rocks and the primary iron ore body iron and baryte mineralization emplaced within ISSN 0126-5539 Warta Geologi, Vol. 21, No. 5, S~ct 1995, pp. 29~299 to Kuahdumpur Iron conglomerate ucu....... _'. _ ..._ v >v y~ v v v v . flllllt v v v v " ... .•._ . \ (?Iateral) v v v "\ v v II V v · ~'V V V V V v v"" -"V\ , v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v Singapore V v v v v v v v v v v v v v v v 1v v v v v v v v v v v v v v v v v LU Ma'Okil Formation 1 2km v v v v v v v vi v v v v v v v v v ~ v v v v v v v v v v v [~:=JLop Formation v v v v v v v v t v v vvvvvvvvvvv~vvvvvvvvvv DGemas Formation v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v v V V V V V V V V V V V v ' v v v v v v v j v v v v v v v v v v v v v v v v ~ v v v v v v v v lv v v v v v v v v v v v v v v v _ mine pit v v v v v v v v v v v ' v v v v v v v v v v v v v v . "V~ - Y .•.. Y__ . I1 _ ..'C. _I1 _ v. _V_Y .. Iy... _.Y_ _. I1 ._ .V.. ..Y _ _'L. .. Y. •.. Y_ .Y._.Y ._Y ... Y .• ..Y .. _. v.. ~ southeast - ... .. .-- .. ~ :»-._-_.. _ northwest " # Figure I b. Southeast - northwest section (not to scale) , ~ ' \\ ' " -...... v v " -~ '- " v v v v v v v v v V I' .... , V V V I volcanic rock 0\; v v v I - andeslte/ v v agglomerate/ v v .:/ v , v v v v breccia v v v V\ •••••• vvvvv V V V V V V V V V V v v\v v v v v v v v v v v v v v ~ v v v v 7 v v v v v v v v v v v v v v v v v v v v v v v v j .v .....v ... v .... v. ... .v . .....v ... v v v v V · v" It . )/:/ u v v v v v v v v v v v v bar scale : 5meter v v v v v v v v v v c: v v v v v v y ... _v .. v. .... ..y. ._ .. _v..__ .'! . ... .. ... __.. .. .. ..... ._ . ....j y .. y ._. _v _ ~ ...y .. ':'. v v . , v . .."- .. v .. to 10hor Baharu "\ ( southwest northeast ) 103.00' I a. Southwest - northeast section Figur-e 1. Geological setting and geological section of the study area. IRON RICH CONGLOMERATE OF MA'OKIL FORMATION AT BUKIT Lop, CHAAH, JOHOR 295 the volcanic unit of the Ma'Okil Formation Bukit Lop. The mine pit excavation work was played a very important role in the development made to follow the trend of the primary hematite of mining in this area. lode which is roughly trending northeast­ southwest. There is no conglomerate found in THE MA'OKIL FORMATION the southeastern face of the mine pit. The conglomerate unit overlies the andesitic volcanic The name Ma'OkiI Formation was rock which hosted the iron mineralization (Fig. introduced by Loganathan (1978) for the 1). This volcanic rock probably belongs to one continental Upper Mesozoic rock unit which is of those volcanic units described earlier by largely exposed within the vicinity of Ma'Okil Loganathan (1978) from the conglomerate unit Forest Reserve.