Clarifying note: The Tusk, not Dr. Burchard, suggested the name Crater Burchard for this feature. And yes, I  know craters are named geographic features.

The always sanctimonious but well informed Paul Heinrich had a helpful post on the Meteorite-list serve today disputing the cosmic origin of circular features identified by Hermann Burchard in the South China Sea and posted last month on the Cosmic Tusk. Paul is one of those guys that doesn’t sleep well if someone is still up having some fun. But nonetheless he is a fine scientist and always willing to dig deep in the literature and his own extensive knowledge base to dispute claims he finds thinly supported.

I’ll leave it to the crowd to sort through Heinrich’s criticisms, but they seem solid. However, I have to take issue with his claim that common folks using Google Earth to poke around for craters is simply “dubious” and cannot contribute to the search for craters. The world is a big place and crowd sourcing is a valid approach for citizens to scientists. A few meteor wrongs, or Google crater that are truly center-pivot irrigation, do not stress the system so badly that it deters professional research.

I have a feeling that if Heinrich falsely believed he had stumbled upon a previously un-noted math proof, Dr. Burchard would graciously walk him back. In fact I know he would.

Message: 10

Date: Thu, 5 Dec 2013 10:14:50 -0500

From: “Paul H.” <inselberg@cox.net>

Subject: [meteorite-list] An Evaluation of the Proposed Spratly

Islands    Impact Structure

To: “meteorite-list@meteoritecentral.com”

<meteorite-list@meteoritecentral.com>

Message-ID: <20131205101450.SVDSW.383296.imail@eastrmwml214>

Content-Type: text/plain; charset=utf-8

 

In November 3, 2013, on the Cosmic Tusk, Hermann G W

Burchard proposed that the region underlying the Spratly Islands

is the center of a multi-ring circular to oval impact structure,

informally called Crater Burchard, that has a diameter of

about 275 km (175 miles). Given that crater are not normally

named after people, but after geographic locations, this proposed

impact structure will be referred to as the ?Spratly Islands

Impact Structure? for purposes of discussion after the Spratly

Islands in the South China Sea. The center of this proposed

275 km (175 miles) in diameter impact structure is an atoll

called Union Reefs, or Union Bank at Latitude 9.788666? and

Longitude 114.351768?. Burchard speculates that the Union

Reefs atoll might lie on top of the top of the central uplift of

such an impact crater. he further speculates that this proposed

crater might be the long searched for Australasian tektite impact

crater Burchard (2013). The existence of this impact structure

is based entirely upon hypothetical circular features found by

the visual examination of bathymetry as portrayed by Google

Earth.

 

The Spratly Islands is part of a larger area called the “Dangerous

Ground.” The Dangerous Ground is a part of southeast South

China Sea that is characterized numerous low islands, reefs,

submerged banks, shoals, and atolls that often rise abruptly from

the depths of the South China Sea. Because this area is poorly

and inconsistently charted, it was, and in part still is, a dangerous

place for navigation. Tropical depression, typhoons, unpredictable

squalls, modern day pirates, and armed naval vessels involved in

various international jurisdictional disputes are additional hazards

found within this region (Anonymous 2011).

 

Burchard (2013) is right about there being significant information

(?news?) about the geology of the Spratly Islands and adjacent

Dangerous Ground having been collected because of the oil and

gas potential of the area. Contrary to what he assumed, specifics

about the geology of region were quite easy to locate and were

collected in only a few hours of effort. In addition to geological

research associated with oil and gas studies, detailed geological

data for this part of the South China Sea was gathered during

Ocean Drilling Program (ODP) Leg 184 (Shipboard Scientific

Party 2000a). Thus, the published data available for the Spratly

Islands and adjacent Dangerous Ground includes seismic lines

that cut across the proposed impact structure and an ODP drillhole,

ODP Site 1143 of Leg 184, that lies just within the alleged rim

of the proposed Spratly Islands Impact Structure. The drillhole

at ODP Site 1143 was continuously cored to from the sea floor

at a depth of 2772 m below sea level to a depth of  512.4 m

(1,680 feet) below the sea bottom (Shipboard Scientific Party,

2000b).

 

Because of their potential oil and gas potential and the multiple

and contentious international claims and jurisdictional disputes

concerning the Spratly Islands and adjacent Dangerous Ground

region, they have been the subject of intensive and repetitive

geological studies from a wide variety of governmental and

nongovernmental agencies and private corporations of various

nationalities. Although much of the data, including seismic lines

and drillhole data, remain proprietary, scientifically significant

and revealing data, including regional multi-channel seismic

data, and their interpretations, have been published in sufficient

number to provide a clear picture of their geology as discussed

in Blanche and Blanche (1997), Hutchison (2004, 2010),

Hutchison and Vijayan (2010), Hinz and Schlueter (1985),

Metcalfe (2010), Wei-Weil and Jia-Biao (2011), Zhen et

al (2011) and various other publications.

 

The above research found that at the surface the Spratly Islands

consist of reefs, banks, and shoals that are composed of

biogenic carbonate that have accumulated on the higher crests

of major sea-floor seafloor ridges. These ridges consist of a

series of uplifted fault-blocks, called horsts, which are part of

a series of parallel and en echelon, half-grabens and rotated

fault-blocks. The axes of the ridge crests (horsts) and their

associated grabens form well-defined linear trends that lie

parallel to magnetic anomalies of the contiguous oceanic crust

of the adjacent South China Sea. These fault-blocks consist of

Triassic, Jurassic, and Cretaceous strata that include calcalkalic

extrusive rocks, intermediate to acid intrusive rocks, sandstones,

siltstones, dark-green claystones, and metamorphic rocks

that include biotite-muscovite-feldspar-quartz migmatites or

gamet-micaschists (Blanche and Blanche 1997, Hutchison 2004,

2010, Hutchison and Vijayan 2010, Hinz and Schlueter 1985,

Wei-Weil and Jia-Biao 2011).

 

These horsts and grabens are the result of two distinct periods

of tectonic stretching of continental crust along underlying

deeply-rooted detachment faults. The early period of tectonism

occurred during the Late Cretaceous and Early Oligocene and

resulted in the formation of horsts, half-grabens, and rotated

fault-blocks. This tectonism was associated with the rifting

and stretching of continental crust that corresponded with the

initial sea-floor spreading within the South China Sea. Further

stretching and block faulting of continental crust occurred

within the Spratly Islands and adjacent Dangerous Ground area

during the Late Oligocene-Early Miocene and eventually halted

afterwards. After tectonic activity had ceased, the crest of the

horsts that lay in shallow water were colonized and biogenic

carbonates accumulated on them to form reefs, shoals and

cays known as the Spratly Islands (Wei-Weil and Jia-Biao

2011, Zhen et al. 2011)

 

The history of faulting and related tectonism within the Spratly

Islands and adjacent Dangerous Ground region can be confidently

reconstructed on the basis of regional unconformities that can be

clearly seen and identified in regional and local seismic sections.

Because they have been dated using biostratigraphy in drillholes

that intersect them, they form timelines that can be traced using

seismic across the entire Dangerous Ground region, including

the Spratly Islands. The most important of these unconformities

is known as either the ?Mid-Miocene,? “Breakup,” or ?T60″

unconformity (Hutchison 2004, Hutchison and Vijayan 2010,

Wei-Wei and Jia-Biao 2011, Zhen et al. 2011). This unconformity

is an angular unconformity that separates syn-rift strata, which

accumulated during the faulting that formed these regional half-

grabens and rotated blocks, from post-rift strata, which

accumulated after the regional tectonism had ceased during the

Early Miocene. The T60 unconformity clearly demonstrates that

faulting within Spratly Islands and Dangerous Ground had

ended by Early Miocene (Hutchison and Vijayan 2010, Wei-Wei

and Jia-Biao 2011, Zhen et al. 2011). Thus, there is complete

absence of either any significant faulting or any other tectonism

that can be associated with a 0.78 Ma extraterrestrial impact. The

relatively undisturbed and intact nature of post- Early Miocene

sediments within the Spratly Islands and Dangerous Ground region

completely refutes any hypothesis about they being the site of a

relatively large 0.78 Ma extraterrestrial impact being associated

with the Spratly Islands and Dangerous Ground region.

 

Equally revealing are the cores recovered from drilling at ODP

Site 1143. The examination of these cores by Shipboard Scientific

Party (2000b) found only one recognizable lithologic unit, which

is subdivided into two subunits, Subunits, IA and IB, within the

512 m-long (1,780 foot-long) core. The upper 160 m (525 feet)

of the sedimentary sequence, Subunit 1A, consists of typically

massive, olive-gray, light grayish green, hemipelagic, calcareous

clay with abundant nannofossils and foraminifera. Distinct green

clay layers are present. Foraminifer ooze turbidites were also occur

within this subunit. The turbidites are normally graded. They

often exhibit a scoured basal contact. The part of the sedimentary

sequence that is below 160 m (525 feet), Subunit 1B, consists

of are clayey nannofossil mixed sediment, nannofossil clay, and

nannofossil ooze with clay. This subunit has a higher carbonate

content; more turbidites; and fewer green clay layers then

Subunit 1A. In addition, it contains infrequent dark gray volcanic

ash layers and volcanic breccias. Subunit 1B also exhibits trace

fossils, such as Zoophycos and Chondrites, and sedimentary

structures associated with slumps and turbidites (Shipboard

Scientific Party 2000b).

 

These sediments can be readily dated from the abundant

microfossils, including nannofossils and foraminifera. These

fossils demonstrate that the Pleistocene/ Pliocene boundary is

located between 93.5 and 94.3 m (307 and 309 feet) below the

sea bottom and the Pliocene/Miocene boundary is located

between 213.0 and 200.6 m (699 and 658 feet) below the sea

bottom. In addition, a clear paleomagentic declination change

of nearly 180? at 43.2 m (142 feet) below sea bottom and in the

middle of Core 184-1143C-5H was interpreted to represent the

Brunhes/Matuyama reversal at about 0.78 Ma. The sedimentary

sequence cored at ODP Site 1143 clearly shows that hemipelagic

sedimentation of fine-grained terrigenous material and calcareous

nannofossils occurred essentially uninterrupted from the late

Miocene to present at this site (Shipboard Scientific Party

2000b).

 

Being located just within the rim of the proposed Spratly Islands

Impact Structure, this core, as does published seismic sections,

demonstrates the lack of any significant Pleistocene-age

extraterrestrial impact structure being associated with the Spratly

Islands. The ODP Site1143 cores, seismic data, and other

published research effectively refute the existence of the

proposed Spratly Islands Impact Structure and relegates it to a

long of imaginary extraterrestrial impact structures that have

been proposed solely on the basis of remote sensing data. It

shows how dubious a methodology using Google Earth alone

to identify extraterrestrial impact craters.

 

Note: For other examples of the dubious use of Google

Earth to identify extraterrestrial impact structures, go read

 

1. The Manuel Benavides Craterwrong and Cratermania

http://www.mail-archive.com/meteorite-list@meteoritecentral.com/msg92117.html

 

2. Preliminary Evaluation of a Proposed ?Younger Dryas

Impact? Crater

https://www.mail-archive.com/meteorite-list@meteoritecentral.com/msg102013.html

 

References,

 

Anonymous, 2011, Sailing Directions (Enroute): South China

Sea and the Gulf of Thailand, Publication 161, 13th edition,

National Geospatial-Intelligence Agency, Bethesda, Maryland.

 

Blanche, J. B. and J. D. Blanche, 1997, An Overview of the

Hydrocarbon Potential of the Spratly Islands Archipelago

and its Implications for Regional Development. in A. J.

Fraser, S. J. Matthews, and  R. W. Murphy, eds., pp. 293-310,

Petroleum Geology of South East Asia. Special Publication

no. 126, The Geological Society, Bath, England 436 pp.

 

Burchard, H. G. W., 2013, Crater Burchard? The Cosmic

Tusk. November 3, 2013 http://cosmictusk.com/crater-burchard/

 

Hinz K., and H. U. Schlueter, 1985, Geology of the Dangerous

Grounds, South China Sea, and the continental margin off

southwest Palawan: results of SONNE Cruises SO-23 and

SO-27. Energy. vol. 10, no. 3-4, pp. 297-315.

 

Hutchison, C. S., 2004, Marginal basin evolution; the southern

South China Sea. Marine and Petroleum Geology. vol. 21,

no. 9, pp. 1129?1148

 

Hutchison, C. S., 2010, The North-West Borneo Trough Marine

Geology. vol. 271, pp. 32?43

 

Hutchison, C. S., and V. R. Vijayan, 2010, What are the

Spratly Islands? Journal of Asian Earth Science. vol. 39,

no. 5, pp. 371?385.

 

Metcalfe, I., 2011, Tectonic framework and Phanerozoic

evolution of Sundaland. Gondwana Research. vol. 19, pp. 3?21

 

Wei-Wei1, D., and L, Jia-Biao, 2011, Seismic Stratigraphy,

Tectonic Structure and Extension Factors Across the Dangerous

Grounds: Evidence from Two Regional Multi-Channel Seismic

Profiles. Chinese Journal of Geophysics. vol. 54, no. 6,

pp. 921?941.

 

Shipboard Scientific Party, 2000a, Volume 184 Initial Reports.

(South China Sea) Proceedings of the Ocean Drilling Program,

Initial Reports. vol. 184, Ocean Drilling Program, Texas A&M

University, College Station, Texas.

 

Shipboard Scientific Party, 2000b, 4. Site 11431. Proceedings

of the Ocean Drilling Program, Initial Reports. vol. 184, Ocean

Drilling Program, Texas A&M, University, College Station,

Texas.

 

Zhen, S., Z. Zhong-Xian, L. Jia-Biao, Z. Di, and W. Zhang-

Wen, 2013, Tectonic Analysis of the Breakup and Collision

Unconformities in the Nansha Block. Chinese Journal of

Geophysics. vol. 54, no. 6, pp. 1069-1083.

 

Yours,

 

Paul H.