Berikut makalah Pak Tjia tentang tumbukan meteor di Semenanjung Malaya. Sayangnya saya tidak punya gambarnya. RDP
HC Potential of Meteorite Impact Structures, Focus on Sundaland H. D. Tjia Jakarta, January 21, 2004 Craters abound on the surfaces of the Moon, solid planets and their satellites. Prior to the manned Apollo missions, views that the craters of the Moon were products of volcanism or of meteorite impacts were shared about equally. The collected Moon rocks show definitive features of high pressure but relatively low-temperature metamorphism that overwhelmingly favour impact origin. On Earth, the suspected impact depression in the Southwestern United States known as Meteor crater, was found associated with high-pressure quartz, or coesite. Currently some 300 terrestrial structures are considered products of impacts by extraterrestrial objects. Almost two hundred of these have been proven as such by combinations of the following: (1) arcuate to circular surface morphology, (2) circular gravity anomaly patterns, (3) shatter cones, (4) poly-megabreccias containing cleaved quartz, (5) quartz and feldspars with mosaicism (patchy extinction), (6) high-pressure quartz polymorphs of coesite and stishovite, (7) anomalously high Iridium, (8) diaplectic glass, and (9) microdiamonds. The comparatively low density of terrestrial impact craters on the Earth's surface is attributable to reworking by exogenous processes of weathering, erosion, organic activity, burial by younger deposits, and the 70 per cent surface cover by water. Impact craters should be as common on Earth as on the solid extraterrestrial bodies. Calculations suggest a mean probability of over 15,000 significant impact craters having hit land since the Archaean. On land the average depth to diameter ratio of an impact crater is 1 : 0.2 , while rim height is about 4 per cent of the total diameter. Also on land, the diameter of simple, bowl-shaped impact craters probably do not exceed 4 km in igneous rocks and about 2 km in sedimentary rock. Beyond these limits, complex crater morphologies develop as result of flattening through gravity. The petroleum significance of meteorite impact structures is -so far- very minor, but may be more important for several reasons. Renewed attention to impact structure plays is relatively recent and was fueled by the 1991 single-strike discovery (25 MMBO, 15 BCFG recoverable reserves) in the vicinity of Ames, Oklahoma, U.S.A. About twenty years earlier other significant discoveries were made at Red Wing Creek, North Dakota (20 MMBO, 25 BCFG), and at the world-famous Chicxulub region, Yucatan Peninsula, Mexico (total recoverable reserves of 30 BBO, 15 TCFG). However, the structures of these earlier finds were not identified as astroblemes and at the time of their discoveries the respective reservoirs were considered ordinary fractured carbonates and fractured granite-and-carbonates. The petroleum occurrences in the vicinity of Ames, a small town in Oklahoma, U.S.A., were the main topic of a special meeting in the early 1990s. The reservoir rocks of the Ames structure are lithified "basement" granodiorite and Cambro-Ordovician Arbuckle dolomite breccia on the crater rim; 2D seismic indicates an erratic, pocket-like distribution of its porosity and permeability. Trapping is by subsurface closures with one known structural closure. A dolomite caprock and overlying Middle Ordovician Simpson Shale provide the cap and seal. The source consists of the Arbuckle sediments or rocks that were exposed to the "cracking" environment of the meteor impact, and the shales that were deposited in the crater. Flow is c. 250 to 500 BOPD; with some of the wells producing in excess of 250,000 bbl oil, while one particular well has yielded 3 BCFG. Recovery has been in the 10% to 60% range. Continental Southeast Asia includes the tectonic platforms of Indosinia and Sundaland . By virtue of its longer exposure, its thinly covered pre-Tertiary "basement" areas can be expected to host more impact structures than regions containing thick Cenozoic sediments. Good reservoir is provided by brecciated and fractured basement rocks, while traps may comprise rim anticlines, irregularly distributed breccia pockets within craters, and central rebound peaks (in the larger impact structures). Internal seals may be provided by impact-melt cloaks and a top seal by the blanketing sediments. For the Southeast Asian impact structures, the hydrocarbon charge is likely to originate in the Tertiary basins. Several impact structures have been recently discovered in pre-Tertiary Peninsular Malaysia. In the Langkawi islands three of four arcuate ridges are associated with cleaved quartz that crops out as a sill and dyke complex. Other shock-metamorphic features include ribbon quartz and mosaicism. The two major craters, named Mahsuri Rings, partially overlap and each is about 2.4 km across. In 280o - 100o direction their centres are 600 metres apart. Bouguer gravity cross sections prove their crater form, one being 45 m deep, the other attaining 107 m depth into the target rocks of Carbo-Permian Singa Formation. Both depressions are filled, the top surface consisting of Quaternary alluvium. The partially encircling hills of Singa Formation crest at less than 150 m elevation and are open to the west. Towards SW are two other circular/arcuate topographic features: Temoyong Ring and horseshoe-shaped Tepor Island. The diameters decrease in the same direction: approximately 800 m and 500 m, respectively. These four ring-like structures have been interpreted as products of serial impacts by a flight of extraterrestrial projectiles arriving from the Southwest. The impact age is not yet determined and field relations only indicate a post-granite (Triassic-Jurassic) event. In the case that the morphologically young Mahsuri Rings are not exhumed features, impact could have occurred within the last 10 million years. Another proven impact structure is the Paloh Ring that straddles the state boundary between Terengganu and Pahang. The proof consists of planar deformation features (PDFs) and mosaicism in vein quartz intruded into undivided Carboniferous metasedimentary strata that compose the lower eastern slope of the 623m high Paloh peak. PDFs are also seen in thin sections of quartz phenoclasts of polymict-breccia boulders in Sungai Mengkuang that drains the east side of the hill. Bukit Paloh is the peak on the high, circular topography surrounding a deep depression, now referred to as Paloh Ring-1. This ring-like topography is 3.5 km across and has local relief of the order of 150 to 200 metres. A small -about 0.5 km across-circular depression is located on the Paloh Ring-1. The south half of the larger ring consists of felsic igneous rock whose K/Ar age is 243 Ma, while the north half is composed of Carboniferous metasedimentary rocks. The youthful morphology of Paloh Ring-1 points to a geologically young impact event, estimated to be not later than Late Miocene. More than a decade earlier, PDFs in quartz were discovered in partly weathered granite underlying the Quaternary basalt at Gebeng, some 40 km SE of Bukit Paloh. The granite at Bukit Ubi quarry, located in the same area but nearer to Kuantan town, also contains quartz with PDFs. These two findings are the initial proofs for impact products in the whole of Malaysia. It is unresolved if the Gebeng-Bukit Ubi impact products and those at Bukit Paloh originated from the same event. The third proven impact products are at Bukit Bunuh near the world-famous palaeolithic site of Kota Tampan along the Perak River. Recently Mokhtar Saidin, geo-archaeologist of Universiti Sains Malaysia, verbally reported a 1.74 Ma fission-track age for a volcanic agglomerate composed of unsorted small to huge fragments of quartz, quartzite, schist, felsic igneous rocks, and other as yet unspecified rock types. The megabreccia is set in light-coloured groundmass, superficially resembling volcanic tuff. Thin-section examination of the quartz turned up parallel planar fractures, mosaicismal extinction and also several cleavage sets. Detailed studies are in progress, but there is little doubt that this "agglomerate" is in fact suevite , an impact breccia. In spite of alteration by oxidation, hydrolisis and local secondary mineralisation of fractures and other voids, porosity estimates by visual inspection are of the order of 10 per cent. Satellite and synthetic-aperture radar images complemented by topographic maps and aerial photographs indicate over 60 prominent arcuate and circular features throughout Malaysia. Craters, geological and geophysical field studies, presence of suevite, and PDFs in quartz prove the impact origin for the Mahsuri Rings in Langkawi, the Paloh Ring-1 on the Terengganu-Pahang border, and the megabreccia at Bukit Bunuh (Kota Tampan) in central Perak. Thirty seven other arcuate/circular features could be impact products and will need confirmatory studies; eight other structures appear to represent domal intrusions or exhumed volcanic complexes, while the remaining sixteen are meander scrolls and structural basins. Contributing factors of extraterrestrial impacts to petroleum systems comprise depressions favouring source-rock development, enhancement of reservoir quality in most of the target rocks, providing a trapping environment for fluids, and perhaps accelerate maturation. Given that prominent impact structures are not rare in Malaysia and that during the Cretaceous-Palaeogene vast regions of continental Southeast Asia were subaerially exposed, impact-structures probably occur in significant numbers. The initial steps of testing impact-structure plays include expansion and verification of the regional database of impact structures and re-examination of seemingly anomalous subsurface structures that are already known. 2011/4/8 R.P.Koesoemadinata <[email protected]> > Saya telusuri di Internet, ternyata banyak sekali lapangan minyak di > Amerika yang sudah ada dan diterangkan secara conventional, sekarang mulai > diterangkan sebagai akibat meteoric impact. Yang terjadi adalah "fracturing" > atau "brecciation" dari formasi yang ada di bawah impact crater ini yang > menjadikkanya sebagai reservoir. Saya kira soal heat yang ditimbulkan untuk > mematangkan source rock tidak ada yang menyinggung. Yang penting adalah juga > keberadaan seal di atasnya, yaitu formasi serpih post-impact. > Konsep ini masih kontroversial dan masih ada pro- dan kontranya, tetapi > mainstream geologist saya kira belum menerimanya, tetapi sudah banyak tokoh2 > petroleum geologist yang meyakininya, seperti Paul Weimer yang sekarang > President AAPG, sangat meyakinkan bahwa Red Wing Creek field (dalam formasi > Paleozoic) itu adalah hasil dari impact crater. > Juga ternyata lapangan minyak terbesar ke-2 di Mexico, Cantrell field juga > dihubungkan dengan Chicxulub impact crater (berada di bawah), yang terjadi > antara Kapur dan Tersier (KT boundary, 65,5 juta tahun yang lalu). Juga > lapangan offshore Mumbai dihubungkan dengan meteor impact ini. Selain itu > masih banyak contoh2 lain di dunia. > Selain itu banyak pula yang meyakini bahwa peranan meteor impact pada > mineral deposit itu jauh lebih besar dari pada diperkirakan semua, bahkan > endapan nikel di Sudbury Canada yang berupa lopoltih itu ditafsirkan > sebagai meteorit raksasa. Ada juga yang berspekulasi bahwa fracturing ini > sampai ke mantle, dan menghidupkan lagi anorganic origin of oil. > Dalam hal Majalengka crater complex berdasarkan peta geologi yang ada > daerah ini mencakup Bogor Trough dan juga sebagian Northwest Java shelf > basin. Di Bogor trough ini sudah terkenal banyak oil seeps (terutama di Jawa > Tengah, walaupun batuan induknya belum jelas, tetapi pasti ada. Oil seep di > Palimanan sudah terlalu jauh. Meteor Majalengka ini (kalau betul ada) > kelihatannya menimpa singkapan formasi deep marine turbidits Cinambo berumur > Oligo-miocene yang mungkin merupakan batuan induk. > Jika benar geo-circles di Majalengka itu meteor impact yang jadi masalah > adalah seal. Apakah formasi Citalang dan sebagian Fm Kaliwangu yang berumur > Pliocene itu dapat merupakan seal yang baik. > Sekali lagi bahwa ada beberapa seismic lines tahun 89 yang memotong complex > crater Majalengka ini, entah disurvei oleh Pertamina entah oleh pemegang > Citarum block. Sangat menarik untuk dipelajari apa yang ada di bawahnya ini, > saya taruhan itu merupakan "blur" saja yang ditafsirkan sebagai thrusting. > > Pertanyaan penting lagi apakah pemegang block Citarum atau Pertamina berani > melanjutkan explorasi berdasarkan konsep meteor impact sebagai play yang > masih bersifat unconventional ini. Ini akan sangat menarik sekali bahkan > mungkin akan menemukan lapangan minyak raksasa, karena sebenarnya radius > aggregate dari lingkaran-lingkaran ini adalah lebih dari 5 km. Selain itu > jika ada yang berani, apakah BPMigas akan menyetujuinya.? > > Kalau saja ada bilioner yang cukup gila untuk melakukan pemboran explorasi > di sini dan berhasil menemukan cadangan, tentu orang akan berlomba-lomba > mencari geo-circles di Google Earth. > Apakah di antara anggota IAGI net ini mungkin bisa memberikan penjelasan > geologi lain bagi Geocircles Majalengka ini, dengan tektonik lengser > barangkali? > Wassalam > RPK > - > ---- Original Message ----- > > *From:* Yanto R.Sumantri <[email protected]> > *To:* iagi-net <[email protected]> > *Sent:* Friday, April 08, 2011 12:13 PM > *Subject:* Re: [iagi-net-l] Majelangka Dihantam Meteor Raksasa 4 Juta > Tahun Lalu ! > > > > Betul pak Koesoema , memang sulit untuk menerangkan mekanisme > nya. > Saya masih bertanya apa pengaruh suatu tumbukan terhadap komposisi suatu > masa di bumi ? bagaimana dan apakah terjadi perubahan kimia / fisika > dari masa yang ditumbuk ? > > Mungkin ada rekan yang tahu atau mengetahu reference - nya > > > si Abah > > On Fri, April 8, 2011 9:09 am, R.P.Koesoemadinata wrote: > > Young Earth argument, wah saya tidak membaca sampai kesitu. > > > > Tetapi saya kira yg unik dari Majalengka Crater Complex ini merupakan > > multiple craters, yang mungkin ditumbuk oleh se-rentetan meteor yang pada > > tempat yang sama, mungkin seperti Levy-Schumacher meteors yang menghantam > > Jupiter. > > > > Saya belum pernah membaca adanya multiple craters ini ditempat lain di > > bumi ini, barangkali ada yang mengetahui? > > > > > > > > Dari segi ekonomi, barangkali di bawah Majalengka Impact crater complex > > itu bisa terjadi akumulasi minyak bumi seperti di lapangan Chicxulub di > > Mexico. Daerah ini sebelah utaranya masuk Block Jawa Barat Utara dari > > Pertamina, sedangkan bagian selatannya adalah masuk Citarum Block. Tetapi > > apakah para pemegang block ini berani mengexplore lebih lanjut. Seingat > > saya di daerah ini ada beberapa seismic lines, tetapi apa yg > diperlihatkan > > oleh seismic sections ini saya tidak tahu, mungkin blur saja. Barangkali > > ada yang berpendapat lain? > > > > > > > > Sampai kini saya lihat di forum ini belum ada bantahan mengenai hipotesa > > impact craters ini, karena saya kira akan sulit sekali dijelaskan dengan > > tectonics biasa maupun dengan gliding tectonics. > > > > Wassalam > > > > RPK > > > > > > > > To: [email protected] > > Sent: Friday, April 08, 2011 7:29 AM > > Subject: Re: [iagi-net-l] Majelangka Dihantam Meteor Raksasa 4 Juta > > Tahun Lalu ! > > > > > > Pak Koesoema, > > Sepertinya argumentasi "Young Earth" tentang clues for meteoric crater > > ini bagian dari diskusi creationism bahwa usia bumi tidak milyaran tahun > > itu ya ? > > > > Btw, kalau diameter crater sebesar 3.5 Km, diperkirakan energi tumbukan > > yg dihasilkan oleh meteor ini setara dengan 400 megaton atau setara > > letusan Krakatau 1883. Ini energinya, dampaknya tentu sangat berbeda. > > > > Salam > > > > rdp > > > > 2011/4/7 R.P.Koesoemadinata <[email protected]> > > > > Terima kasih > > R{K > > ----- Original Message ----- > > > From: Edison Sirodj > > To: <[email protected]> > > Sent: Thursday, April 07, 2011 8:42 PM > > Subject: Re: [iagi-net-l] Majelangka Dihantam Meteor Raksasa 4 Juta > > Tahun Lalu ! > > > > > > pak Kusuma, saya ada papernya pa Tjia, sewaktu seminar expat di KL > > 2008. InsyaAllah besok sy upload. > > > > > > salam, > > edison sirodj > > > > Sent from my iPad > > > > On Apr 7, 2011, at 20:28, "R.P.Koesoemadinata" > > <[email protected]> wrote: > > xpat > > Memang saya pun pernah mendengar adanya ceramah Prof Tjia itu > > mengenai meteor crater itu serta potensi minyak buminya di Jakarta > > > > Saya check di internet publikasi mengenai meteor crater itu yang > > saya ketemukan adalah > > 1. Meteor crater di Bukit Bunuh, Perak di mana diketemukan batuan > > suevit sedangkan publikasinya adalah mengenai paleo-anthropologi > > (out of Malaysia) dimana pemandangan geomorphologi dari crater > > masih terlihat > > 2. Meteor crater di Langkawi (Seranai Publications) > > 3. Google juga menunjuk adanya artikel Prof Tjia di Bull Geol Soc > > Malaysia, Dec 2010, namun di periodical ini tidak diketemukan > > mengenai meteor crater. > > > > Yang mengenai di Borneo belum diketemukan publicationsnya > > Wassalam > > RPK > > > > ----- Original Message ----- > > > From: benyamin sembiring > > To: [email protected] > > Sent: Thursday, April 07, 2011 5:37 PM > > Subject: Re: [iagi-net-l] Majelangka Dihantam Meteor Raksasa 4 > > Juta Tahun Lalu ! > > > > > > salam, > > > > > > Pak Vic, sorry, karena judul yg dibawakan Prof Tjia saat itu > > adalah HYDROCARBON POTENTIAL OF METEORITE IMPACT STRUCTURES > > FOCUS ON SUNDALAND > > Saya rasa untuk Indonesia, ternyata yang dibahas di malaysia > > (walaupun masih satu pulau dgn indonesia, di kalimantan) > > sori, ada sedikit kekeliruan > > > > > > M A L A Y S I A > > > > > > Identified 60 large to medium > > > > ring-like structures > > > > > > 3 proven impact structures > > > > üPDFs > > üImpact breccia or suevite > > üC r a t e r s > > > > > > salam > > benz > > > > > > Pada 7 April 2011 17:10, benyamin sembiring > > <[email protected]> menulis: > > > > Salam, > > > > > > Pak Vic, tentang meteor impact sudah pernah dilakukan > > afternoon talk oleh IAGI di Tham Nak Thai resto, Menteng, > > tahun 2003/2004?. Saat itu pembicaranya adalah Prof Tjia Hong > > Jin. Seingat saya beliau menjelaskan pembentukan > > cekungan-cekungan oleh karena adanya meteor impact. Banyak > > gambar-gambar yang disajikan, termasuk di Indonesia. Semoga > > saya gak salah. > > Acara itu memang minim peserta, yang hadir nampaknya saat itu > > para senior/sepuh geologi, lebih tepat seperti reunian senior > > geologi. Materi presentasi apakah diberikan kepada IAGI waktu > > itu saya agak lupa. > > Nampaknya, Prof Tjia sudah punya lebih dari satu meteoric > > creater impact. > > > > > > Salam > > benz > > > > > > > > > > > > Pada 7 April 2011 15:08, Rovicky Dwi Putrohari > > <[email protected]> menulis: > > > > > > Sebuah hipotesa menarik dari Pak Koesoema tentang > > kemungkinan hantaman meteor di dekat Majalengka. Meteoric > > crater impact diketemukan di hampir semua belahan dunia, > > namun sepi di Indonesia. Kalau saja hipotesa Pak > > Koesoemadinata ini benar, maka penemuan ini akan menjadi > > Meteoric Crater Impact pertama di Indonesia. Meteoric Impact > > Ini sedang ditinjau oleh Mahasiswa dari Geologi ITB > > > > Majelangka Dihantam Meteor Raksasa 4 Juta Tahun Lalu ! > > Penyebaran kawah benturan meteor di seluruh dunia. > > > > Selanjutnya silahkan baca di sini : Meteori crater impact > > pertama di Indonesia, Bahkan mungkin pertama di Asia > > Tenggara !! > > > > > > > > Rovicky > > > > > > > > > > > > > > > > > > > > > > > > __________ NOD32 5559 (20101024) Information __________ > > > > This message was checked by NOD32 antivirus system. > > http://www.eset.com > > > > > > > > > > -- > > "Success is a mind set, not just an achievement" > > > > > > > > > -- > _______________________________________________ > Nganyerikeun hate batur hirupna mo bisa campur, ngangeunahkeun hate jalma > hirupna pada ngupama , Elmu tungtut dunya siar Ibadah kudu lakonan. > > -- *"Success is a mind set, not just an achievement"*
